The main hydrocarbon raw materials for petrochemical syntheses are mixtures of gaseous, liquid and solid hydrocarbons.

Natural gases consist mainly of methane and other saturated hydrocarbons; they also contain inert gases (nitrogen, carbon dioxide) and rare gases (argon, xenon). Natural gases are produced during the development of gas and condensate fields.

Associated petroleum gases obtained as a by-product during oil production. These gases are dissolved in reservoir oil and are released during its production due to a decrease in pressure. Associated petroleum gas consists of saturated hydrocarbons ranging from methane to pentanes and usually contains some inert gases; Associated gases from some fields also contain free hydrogen sulfide. As a rule, associated petroleum gases contain significant amounts of hydrocarbon components - ethane, propane and butanes, which are valuable raw materials for petrochemicals.

Oil refining gasesare formed in the processes of cracking, coking, reforming; they are also selected at oil stabilization and direct distillation plants. Depending on the nature of these processes, the composition of the resulting gases varies within wide limits. For example, catalytic reforming gases contain up to 60% hydrogen; the rest is saturated hydrocarbons. Cracking and coking gases consist of saturated and unsaturated hydrocarbons.

Oil stabilization gasesThey are characterized by a high content of propane, butane, pentane and isopentane, which makes them a valuable raw material for the production of butadiene and isoprene.

Gas gasolines boils away in the range of 30-120 0 C; they contain butane, pentane, isopentane, as well as C6 and C7 hydrocarbons of normal and isostructure.

Gas condensatesboils away in the range 40-360 0 C. They contain 15-30% aromatic hydrocarbons; 25-40% naphthenes and 20-60% paraffins (depending on the field).

Liquid distillates and petroleum products, formed during various oil refining processes, are also used as feedstock in petrochemical processes, or more precisely as a source for isolating certain groups of hydrocarbons. Thus, aromatic hydrocarbons are isolated from the products of catalytic reforming, olefins from the products of thermal and catalytic cracking, and paraffins from the products of dewaxing of diesel fuel.

Hydrocarbons isolated from hydrocarbon raw materials are of great practical importance. For example, natural gas methane is used as fuel and raw material for the production of hydrogen, acetylene, ammonia and methanol. Ethane serves as a feedstock for pyrolysis processes to produce ethylene; gas condensates – raw materials for the production of butadiene, isoprene, aromatic hydrocarbons.

v Requirements for hydrocarbon raw materials

Hydrocarbon feedstocks for petrochemical processes are usually subject to much more stringent requirements than feedstocks for petroleum refining processes.

The reactions used in petrochemical synthesis are mostly catalytic or radical chain, and in order to obtain the required products, high selectivity of the catalyst is required, side reactions are completely unacceptable, etc. Therefore, a high degree of purity of raw materials is required. Thus, for the production of ethyl alcohol by direct hydration of ethylene, 97-98% ethylene, practically free of hydrogen sulfide (up to 0.002% H 2 S), is required. The production of high-density polyethylene requires 99.99% ethylene, completely free of acetylene.

Thorough purification of ethylene from hydrogen sulfide when producing ethyl alcohol is necessary because the rectification equipment for separating the resulting alcohol from the reaction mixture quickly corrodes and fails. For the same reason, ethylene should not contain acetylene.

When oxidizing liquid and solid paraffins to alcohols and acids, it is necessary that the feedstock contain a minimum amount (up to 0.5%) of naphthenic and aromatic hydrocarbons that inhibit oxidation. Equally important is the absence of phenols, nitrogen and sulfur compounds that interrupt the oxidation chain. In this regard, the requirements for the sulfur content in aromatic hydrocarbons are strict (no more than 0.02%) and its permissible content is constantly decreasing.

In some cases, it is necessary to purify hydrocarbon raw materials from isomers and homologues of the same chemical nature. Thus, if paraffins contain isocarbons, the subsequent oxidation products contain an increased amount of low molecular weight acids, as well as isoacids with an extremely unpleasant odor.

The admixture of dienes in olefins leads to the development of resin formation during isomerization and alkylation.

For hydrocarbon raw materials there must be restrictions on the content of carbon oxides, ammonia and humidity.

All of the above indicates the need for careful preparation of hydrocarbon raw materials.

v The importance of preliminary preparation of hydrocarbon raw materials for processing

Hydrocarbon raw materials must meet high requirements determined by the specifics of further chemical transformations of hydrocarbons. One of the main requirements for hydrocarbon raw materials is the minimum content or complete absence of substances of a different chemical nature. Careful preparation of hydrocarbon raw materials for processing is necessary to prevent corrosion of process equipment; the service life of catalysts increased; clogging of pipelines and their throughput were excluded; the amount of by-products decreased, the yield of the target product increased and its quality increased.

Introduction

Petrochemical synthesis is the production of chemical products based on oil and hydrocarbon gases by synthetic means. Hydrocarbons of oil and natural flammable gases, associated petroleum gases, oil refining gases serve as the main raw materials in the production of the most important mass synthetic products: plastics, rubbers and fibers, nitrogen fertilizers, surfactants and detergents, plasticizers; fuels, lubricating oils and additives, solvents, extractants, etc. All these products are widely used in various industries. households and in everyday life, the development of MH is associated with them. new fields of technology (cosmonautics, nuclear energy, etc.). In industrialized countries, petrochemical synthesis has enabled the creation of a large and rapidly growing petrochemical industry. Oil and gas hydrocarbons, being worthy, more technologically advanced and cheap raw materials, displace other types of raw materials (coals, shale, plant, animal raw materials, etc.) in almost all processes of organic synthesis. Petrochemical synthesis is based on the successes of organic chemistry, catalysis, physics. chemistry, chem. technology and other sciences and is associated with an in-depth study of the composition of oils and the properties of their components. The processes of processing hydrocarbon raw materials into target products are based on numerous reactions of organic chemistry: pyrolysis, oxidation, alkylation, dehydrogenation and hydrogenation, halogenation, polymerization, nitration, sulfonation, etc.; The most important among them are catalytic reactions. In the production of products. Petrochemical synthesis plays an important role in the preparation of hydrocarbon feedstocks and the production of primary feed hydrocarbons: saturated (paraffin), unsaturated (olefinic, diene, acetylene), aromatic and naphthenic. The main part of them is converted into functional derivatives with active groups containing oxygen, nitrogen, chlorine, fluorine, sulfur and other elements.

Saturated (alkane) hydrocarbons occupy an important place in terms of volume of use in petrochemical synthesis.

Chapter. 1. General safety rules when working in a chemical laboratory

1.1. Safety precautions

1. Working alone in the laboratory is strictly prohibited, since in the event of an accident there will be no one to help the victim and eliminate the consequences of the accident.

. While working in the laboratory, it is necessary to maintain cleanliness, silence, order and safety rules, since haste and negligence often lead to accidents with serious consequences.

. Every worker must know where fire protection equipment and a first aid kit containing everything necessary for first aid are located in the laboratory.

. Smoking, eating, and drinking water are strictly prohibited in the laboratory.

. You cannot begin work until students have mastered all the techniques for doing it.

. Experiments should be carried out only in clean chemical containers. After finishing the experiment, the dishes should be washed immediately.

. During the work, it is necessary to maintain cleanliness and accuracy, to ensure that substances do not come into contact with the skin of the face and hands, since many substances cause irritation of the skin and mucous membranes.

. No substances may be tasted in the laboratory. You can sniff substances only by carefully directing vapors or gases towards yourself with a slight movement of your hand, and not by leaning towards the vessel and without inhaling deeply.

. Any container where reagents are stored must have labels indicating the names of the substances.

. Vessels with substances or solutions must be grasped by the neck with one hand and supported by the bottom with the other.

. It is strictly forbidden to draw organic substances and their solutions into pipettes with your mouth.

. When heating liquid and solid substances in test tubes and flasks, do not point their openings at yourself or your neighbors. You should also not look from above into openly heated vessels to avoid possible injury when the hot mass is released.

. After finishing work, you must turn off the gas, water, and electricity.

. It is strictly forbidden to pour concentrated solutions of acids and alkalis, as well as various organic solvents, strong-smelling and flammable substances into sinks. All this waste must be poured into special bottles.

. Every laboratory must have protective masks and goggles.

. In each laboratory room it is necessary to have fire protection equipment: a box with sifted sand and a scoop for it, a fire blanket (asbestos or thick felt), charged fire extinguishers.

. There should be a “Safety Corner” in an accessible place in the classroom-laboratory, where it is necessary to place specific instructions on work safety methods and rules of behavior in the chemistry laboratory.

. When working in a laboratory, it is necessary to use personal protective equipment and observe personal hygiene rules.

1.2 General provisions for working in a petrochemical synthesis laboratory

The laboratory consists of scientists, engineers and laboratory assistants invited from leading scientific centers. The main direction of the laboratory's work is the creation of technologies for the production of products of basic organic synthesis. Homogeneous and heterogeneous catalyst systems are also being developed for new and existing petrochemical processes.

Research and development work of the NHS laboratory is devoted to:

new polymerization catalysts for the production of high molecular weight compounds;

chemical modification of industrial polymers;

development of new technologies for obtaining existing monomers;

obtaining new promising monomers;

searching for methods of disposal and processing of waste from chemical enterprises.

To carry out the assigned tasks, the laboratory is equipped with all the necessary equipment. A line of modern computer-controlled reactors is used to operate under pressure. Work with organometallic compounds and other substances highly sensitive to moisture and oxygen is carried out in glove boxes. The MARS chemical microwave system allows reactions to be carried out at temperatures up to 3000C and pressures up to 100 atm. The laboratory is equipped with auxiliary general laboratory equipment from leading global manufacturers.

Organization of work in laboratories

Laboratories on processes and apparatus of chemical and food technology are equipped with semi-industrial (pilot) installations on which students experimentally study processes. Processing the experimental data obtained at the installations using mathematical methods makes it possible to analyze the influence of parameters on the process.

The laboratories conduct laboratory work in the following disciplines: “Processes and apparatus of chemical technology”, “Processes and apparatus of food production”, “General chemical technology”, “Modeling and computer calculation of chemical technological processes”, etc.

Processing of experimental data and method of experiment planning

The main goal of experiment planning is to achieve maximum measurement accuracy with a minimum number of experiments performed and maintaining the statistical reliability of the results. Experimental planning is used when searching for optimal conditions, constructing interpolation formulas, selecting significant factors, assessing and clarifying constants of theoretical models, etc. Experimental planning (active experiment) in chemistry, a section of material statistics that studies methods for organizing a set of experiments with various conditions to obtain the most reliable information about the properties of the object under study in the presence of uncontrolled random disturbances. The quantities that determine the conditions of a given experiment are usually called factors (for example, temperature, concentration), their totality is called factor space. A set of factor values ​​characterizes a certain point in the factor space, and the totality of all experiments constitutes the so-called factorial experiment. The location of points in the factor space determines the experimental plan, which specifies the number and conditions for conducting experiments with recording their results.

The planning of the experiment began with the works of P. Fischer (1935). He showed that rational planning of an experiment provides no less significant gains in the accuracy of estimates than optimal processing of measurement results. Experimental planning is used to study and mathematically describe processes and phenomena by constructing mathematical models (in the form of so-called regression equations) - relationships that, using a number of parameters, connect the values ​​of factors and the results of the experiment, called. responses. The main requirement for factorial experimental plans, in contrast to a passive experiment, is to minimize the number of experiments in which reliable estimates of the calculated parameters are obtained while maintaining acceptable accuracy of mathematical models in a given region of the factor space. In this case, the task of processing the results of a factorial experiment is to determine the numerical values ​​of the specified parameters.

Extreme problems aim to determine the best value of the objective function, which takes the value of the process characteristics of interest to the researcher. Such problems can be solved in at least two ways: with and without constructing a mathematical model. Based on the selected plan, a model is built that corresponds to the response under consideration, and, using it, using known methods for searching for an extremum, they find the values ​​of the factors at which the objective function determined by the model will be extreme. If the found values ​​of the factors corresponding to the extreme point lie on the boundary of the applied plan, the planning area is either shifted or expanded and a new model is built, after which the search for the extremum is repeated. The problem is considered solved if the calculated coordinates of the extremum point are located inside the area characterized by the plan used.

In practice, this approach is often implemented using the so-called steep ascent method (Box-Wilson method). Select a starting point; Based on its results, the parameters of the 1st order mathematical model are calculated. If the model is adequate, it is used to determine the direction of change in factors corresponding to the movement towards the extreme value of the objective function in the direction of the gradient or anti-gradient (respectively when searching for the maximum or minimum). Movement in the chosen direction is carried out using sequential experiments and is carried out until the response changes in the desired way. The stated procedure is repeated until an adequate model is constructed at each stage. The inadequacy of the model obtained at the next stage indicates that an extremum region may have been reached in which the linear model can no longer be used. To clarify the position of the extremum in this area, you can use a 2nd order model constructed using appropriate plans.

Direct experiment on the object (without building a model). The strategy for conducting experiments is determined by the chosen optimization method. In this case, the value of the objective function is not calculated from the model, but is found directly from experiments performed under appropriate conditions. Most often, to find the best value of the objective function, the sequential simplex method, the Gauss-Seidel method, etc. are used. The study of the kinetics and mechanisms of processes is associated, as a rule, with the development of so-called determinative models that reflect the physicochemical essence of the phenomena under study and contain descriptions of the mechanisms (kinetics) of elementary processes occurring in them.

Among the problems solved by experimental planning methods are:

) determination (clarification) of model parameters;

) so-called discrimination, i.e., rejection of verifiable mechanisms of elementary processes.

To clarify the parameters of determining models, it is necessary to choose an experimental design that will provide the best estimates of the quantities being determined. When specifying parameters, experimental planning faces a number of difficulties.

The main ones include:

) the need to have a separate plan for each class of models, that is, in each specific situation, the researcher must calculate the optimal location of points in the factor space for setting up clarifying experiments;

) the need to calculate the parameters of determining models using optimization methods; this is usually due to the nonlinearity of these models with respect to the parameters being determined.

The task of discrimination is to select a model among several competing ones that most correctly reflects the mechanism of the process and has the best predictive ability. This task is realized by comparing the results of assessing the model’s compliance with experimental data when using different descriptions of the same process or phenomenon. The simplest discrimination method consists of calculating the parameters of each proposed model from experimental data and then comparing the residual variances. The model with the minimum residual variance is taken as the selected model. If it is not possible to select a mechanism that does not contradict experimental data, then either the area under study is expanded or the location of points in the factor space is shifted and the operation is repeated. The advantage of this approach is that the researcher simultaneously solves both problems - calculating parameters and discriminating models. The disadvantages include the fact that this often requires a lot of time for experiments and calculation of model parameters.

Practical work on petrochemical synthesis

Practical work is based on the successes of organic chemistry, catalysis, physical chemistry, chemical technology and other sciences and is associated with an in-depth study of the composition of oils and the properties of their components. The processes of processing hydrocarbon raw materials into target products are based on numerous reactions of organic chemistry: pyrolysis, oxidation, alkylation, dehydrogenation and hydrogenation, halogenation, polymerization, nitration, sulfonation, etc.; The most important among them are catalytic reactions. In the production of products from petrochemical synthesis, a large place is occupied by the preparation of hydrocarbon feedstocks and the production of primary feed hydrocarbons: saturated (paraffin), unsaturated (olefinic, diene), aromatic and naphthenic. The main part of them turns into functional derivatives with active groups containing oxygen, sulfur and other elements. Of great importance are the processes of conversion of paraffin hydrocarbons into synthesis gas (a mixture of carbon monoxide with hydrogen, see Gas conversion). The raw materials can be natural gases, associated gases, oil refineries and any petroleum fractions. Ammonia serves as the starting product for the production of fertilizers (ammonium nitrate, urea), hydrocyanic acid, etc. Two-stage methane conversion also produces concentrated carbon monoxide, which is used for many processes. Methanol is produced from carbon monoxide and hydrogen - the raw material from which formaldehyde is obtained, an important product for the production of plastics, varnishes, adhesives and other materials.

Halogen derivatives of paraffins are produced on an industrial scale. Methane chloride, chloroform, carbon tetrachloride and other products are obtained from methane. Methylene chloride and carbon tetrachloride are good solvents. Chloroform is used for the synthesis of tetrachlorethylene, chlorofluoro derivatives, valuable tetrafluoroethylene monomer and others. Chlorination of ethane produces hexachloroethane and other chlorine derivatives. The product of chlorination of paraffin paraffins, chlorinated paraffin-40, is used as a plasticizer, and chlorinated paraffin-70 is used for impregnation of paper and fabrics with increased fire resistance. Products of complete fluorination of narrow fractions of kerosene and gas oil are valuable lubricants and hydraulic fluids with high thermal and chemical resistance. They can operate for a long time at 250-300C in very aggressive environments. Freons - chlorofluoro derivatives of methane and ethane - are used as refrigerants in refrigeration machines. A mixture of nitroparaffins is produced by nitration of propane and paraffins boiling above 160-180C with nitric acid. They are used as solvents and intermediate products in the synthesis of nitro alcohols, amino alcohols, and explosives. Naphthenes. Of these hydrocarbons, only cyclohexane has gained great importance. In small quantities, cyclohexane is released by precise rectification of gasoline fractions of oil (containing 1-7% cyclohexane and 1-5% methylcyclopentane). Methylcyclopentane is converted to cyclohexane by isomerization with aluminum chloride. The industrial demand for cyclohexane is satisfied mainly by its production by hydrogenation of benzene in the presence of a catalyst.

The oxidation of cyclohexane with atmospheric oxygen produces cyclohexanone and adipic acid, which are used in the production of polyamide synthetic fibers (nylon and nylon). Adipic acid and other dicarboxylic acids obtained from the oxidation of cyclohexane are used for the synthesis of esters used as lubricating oils and plasticizers. Cyclohexanone is used as a solvent and also as a camphor substitute. Much attention is paid to the development of microbiological synthesis based on petroleum feedstock. Protein and vitamin concentrates for animal nutrition are obtained from paraffin hydrocarbons.

Chapter. 2. Types of processes

1 Hydrogenation and dehydrogenation processes

In organic synthesis, hydrogenation reactions (addition of H2) involve any molecules that are unsaturated. Fischer-Tropsch syntheses from CO and H2, the synthesis of methanol from CO, CO2 and H2 are also classified as hydrogenation reactions, however, in the Fischer-Tropsch synthesis of hydrocarbons, in addition to the addition of H2, destructive hydrogenation with the cleavage of the C-O bond also occurs. Destructive hydrogenation also includes hydrogenolysis of the C-C bond - hydrocracking processes, for example,

and hydrogenolysis of the C-S bond (processes of hydrodesulfurization of petroleum fractions)

The reverse reaction to hydrogenation, the process of dehydrogenation, occupies an important place in industrial organic synthesis and in oil refining processes. Alkanes and alkylbenzenes are dehydrogenated (synthesis of butadiene, isoprene, styrene), naphthenes (benzene from cyclohexane), alcohols (synthesis of formaldehyde, acetone, isovaleraldehyde, cyclohexanone). Metals and their compounds are used as hydrogenation catalysts:

Metal catalysts - Pt, Pd, Ni, Co, Rh, Ru, Cu - in the form of bulk metals, alloys, supported catalysts (M/support) and skeletal metals (Raney nickel, Raney copper), which are obtained by leaching Al from Al alloys Ni, Al-Cu, etc.

Metal sulfides - NiS, CoS, Mo2S3, W2S3.

Metal oxides are used for dehydrogenation processes, since at high temperatures (> 200°C) metals are too active and lead to destructive processes. The following oxides are dehydrogenation catalysts: ZnO, Cr2O3, Mo2O3, W2O3, MgO. At high temperatures (> 450°C), dehydrogenation of alcohols is also observed on -Al2O3.

The most important stage of hydrogenation processes is the activation of the hydrogen molecule. In the case of metal complexes in solutions, the mechanism of hydrogen activation is now clear:

The transformation of the primary complex depends on the nature of the metal, its oxidation state and the ligands in the coordination sphere. Homolysis and heterolysis are possible:

The participation of the undissociated H2 molecule in homogeneous hydrogenation processes has not yet been established. Hydrogenolysis of the M-C bond, for example, during the hydroformylation of olefins

is also considered as a result of homolytic cleavage of the H2 molecule at the Co atom. On the surface of metals, homolytic cleavage of H2 takes place with the formation of surface hydrogen atoms and hydrogen atoms dissolved in the metal lattice. In the presence of a polar solvent (S), the process of H2 adsorption on metals can occur heterolytically and even be accompanied by complete ionization with the transfer of 2ē to the metal.

In this case, the molecule of the hydrogenated compound is reduced by electrons bound to the metal. When constructing kinetic models of hydrogenation processes on metals, the concepts of a homogeneous surface, a uniform-inhomogeneous surface (Langmuir-Hinshelwood model) and a non-uniform surface are used. For example, during the hydrogenation of ethylene within the framework of the hypothesis about the interaction of ethylene and hydrogen adsorbed on the surface of Nitv:

(6);

On a homogeneous surface:

(7);

On a uniformly non-uniform surface:

(8);

The reforming process is aimed at isomerization and aromatization of n-paraffins without changing the molecular weight (number of carbon atoms) in the original molecules during the transformation process. Main reactions:

a) aromatization

b) dehydrocyclization of paraffins

(10);

c) skeletal isomerization

d) dehydrogenation

Reforming is used to produce high-octane gasoline and aromatic compounds from naphtha (boiling point 80 - 160 ° C), which are extracted from gasoline and used as raw material for hydrocracking or organic synthesis. The process is carried out in the range of 380 - 520°C at a pressure of 10 - 40 atm on heterogeneous bifunctional catalysts - metal and acid - Pt on Cl- or F- promoted aluminum oxide (or aluminosilicate). Recently, Pt-Re/Al2O3 or polymetallic catalysts on Al2O3 have been used. The main problem in the reforming process is the process of deactivation and coking of the catalyst (see Appendix 1).

Ions located in a rectangle may contain delocalized electrons. Examples of hydrogenolysis of C-S bonds involving transition metal complexes have already appeared. Studies of such systems will make it possible to establish the mechanism of the process and the nature of possible intermediates.

The alkylation process is widely used in the petrochemical industry to produce high-octane gasoline components. The feedstock for the process is isobutane and butane-butylene or propane-propylene fraction obtained through catalytic cracking.

The technological plant for sulfuric acid alkylation includes several sections. Initially, materials for alkylation must be cooled to a temperature of 4 - 50C (400F) and transferred to the liquid phase.

This process is carried out in a refrigeration unit at elevated pressure (3 - 15 atm). Next, the substance enters the reactor block consisting of several separate reactors. In addition, in the reactor, sulfuric acid is added to the liquefied reaction products as a catalyst for the process.

The number of sections and the design of the reactor must ensure long-term residence and periodic mixing of molecules in the reactor zone to carry out the alkylation reaction. After 15 - 20 minutes, the reactor products are fed to the acid separation unit. The acid settling tank is a vessel without stirring. It separates acid from hydrocarbons. The difference in density between the substances allows the hydrocarbons to rise to the top of the container. The acid, in turn, sinks to the bottom and returns to the reactor. And the hydrocarbons are sent to a special vessel for alkaline washing. In the alkaline washing unit, alkylation products are treated with sodium hydroxide, which neutralizes the acid. After washing, the hydrocarbon mixture enters sequentially into three standard distillation columns - debutanizer, deisobutanizer, and depropanizer. They separate the mixture into alkylate and saturated gaseous hydrocarbons. In this case, isobutane is sent to the refrigeration unit to repeat the process.

Equipment for alkylation process:

Refrigeration unit GOST 11875-88

This standard applies to general purpose rotary drum refrigerators used in the chemical and other industries for cooling explosion-proof bulk materials. The standard does not apply to drum coolers for the cement and expanded clay industries

Reactors for alkylation GOST 20680-2002

This standard applies to steel apparatus with mechanical mixing devices with a nominal volume of 0.01 to 100 m3. , intended for carrying out various technological processes in liquid media with a density of up to 2000 kg/m3. and dynamic viscosity not more than 200 Pa. s at an operating temperature from minus 40 to plus 350 degrees. C and a working excess pressure of no more than 6.3 MPa, for rubberized devices for the manufacture of metal structures, as well as for devices operating in the absence of pressure and under vacuum with a residual pressure of not less than 665 Pa. The standard does not apply to devices with enamel coating and devices made of cast iron and non-metallic materials, as well as heated by flue gases or open flames.

Acid separation unit and alkaline washing unit GOST 26159-84

This standard applies to cast iron vessels and apparatus used in the chemical, oil refining and related industries. Establishes general requirements for standards and methods for calculating the strength of structural elements of vessels and apparatus operating under static loads

Distillation columns GOST 21944-76

This standard applies to column devices with an internal diameter from 400 to 10,000 mm, made of sheet steel.

3 Oxidation processes

During the redox reaction, the reducing agent gives up electrons, that is, it is oxidized; The oxidizing agent gains electrons, that is, it is reduced.

Moreover, any redox reaction represents the unity of two opposite transformations - oxidation and reduction, occurring simultaneously and without separating one from the other.

Oxidation is the process of losing electrons, with an increase in the degree of oxidation.

When a substance is oxidized, its oxidation state increases as a result of the loss of electrons. The atoms of the substance being oxidized are called electron donors, and the atoms of the oxidizing agent are called electron acceptors. In some cases, during oxidation, the parent molecule may become unstable and break down into more stable and smaller constituent parts (see Free radicals). In this case, some of the atoms of the resulting molecules have a higher oxidation state than the same atoms in the original molecule. The oxidizing agent, accepting electrons, acquires reducing properties, turning into a conjugate reducing agent: oxidizing agent + e− ↔ conjugate reducing agent.

Reduction is the process of adding electrons to an atom of a substance, while its oxidation state decreases. During reduction, atoms or ions gain electrons. In this case, the oxidation state of the element decreases.

In any redox reaction, two conjugated redox pairs take part, between which there is competition for electrons, as a result of which two half-reactions occur: one associated with the addition of electrons, i.e. reduction, and the other with the release of electrons, i.e. e. oxidation. In redox reactions, electrons are transferred from one atom, molecule, or ion to another. The process of losing electrons is oxidation. During oxidation, the oxidation state increases. The process of adding electrons is reduction. During reduction, the oxidation state decreases. Atoms or ions that gain electrons in a given reaction are oxidizing agents, and those that donate electrons are reducing agents.

4 Processes of esterification, hydrolysis, hydration, dehydration

Hydrolysis reactions are the processes of substitution or double exchange that occur under the influence of water or alkalis. They can be classified into hydrolysis reactions that occur with the cleavage of C-Cl, C-O, C-N, etc. bonds. In contrast to hydrolysis, hydration reactions are reduced to the addition of water at unsaturated C-C bonds, at the triple CN bond of nitriles, etc. Some hydration reactions are equilibrium; the reverse process of water splitting is called dehydration, which can be not only intra-, but also intermolecular. The process of esterification is the reaction of alcohols with organic acids, their anhydrides or acid chlorides to form esters. The amidation process is the reaction of ammonia, primary or secondary amines with carboxylic acids to produce acid amides. These reactions are reversible and are in many ways similar to esterification reactions, but differ from the latter in that the equilibrium is strongly shifted to the right.

Conditions for obtaining glycerin from non-edible raw materials:

hypochlorination of allyl chloride into dichlorohydrin followed by its saponification into epichlorohydrin and alkaline hydrolysis;

hydrolysis of allyl chloride into allyl alcohol followed by its epoxidation with hydrogen peroxide into glycide alcohol and hydrolysis to form glycerol;

isomerization of propylene oxide into allylic alcohol and subsequent processing as in the second method.

Alcohols can be obtained from olefins directly by hydration or indirectly through several sequential reactions. Direct hydration of olefins results in the formation of secondary or tertiary alcohols (except ethylene, from which ethyl alcohol is obtained). Of the indirect methods for producing alcohols, the best known is the method based on the addition of sulfuric acid to olefins. First, mono- or diesters of sulfuric acid are formed, which are then hydrolyzed to the corresponding alcohols. When studying methods for producing ethyl alcohol, pay attention to the factors that determine the choice of method for ethylene hydration. In addition, there are two known technological methods for the direct hydration of ethylene, differing in the supply of steam and the method of heating the vapor-gas mixture. To obtain isopropyl alcohol, the industry uses the method of direct hydration of propylene. Methods for direct hydration of propylene are more diverse than for ethylene, what are the similarities and differences between these methods. What explains the increased attention to the safety of alcohol production? When studying the production of ethyl acetate, pay attention to the total yield of ester, which is 95% of theoretical, how can this be explained? Amidation processes are of great importance for the industry of basic organic and petrochemical synthesis, as they make it possible to obtain very valuable products and intermediates for further syntheses. The most important ones include: the production of dimethylformamide, dimethylacetamide, ethanolamides, plasticizers, herbicides, pressure gauges for synthetic fibers.

5 Processes of addition and condensation at the carbonyl group

Carbonyl compounds are compounds containing one or more carbonyl groups (C=O). These include CO, CO2, carbonates, urea and many others. However, in organic chemistry, carbonyl compounds are understood only as aldehydes and ketones, and to a lesser extent carboxylic acids and their derivatives. In aldehydes, the carbonyl group is bonded to one hydrocarbon radical and one hydrogen atom, while in ketones, the oxo group is bonded to two hydrocarbon radicals.

The carbonyl carbon, being in a state of sp2 hybridization, forms a double bond with the oxygen atom. Oxygen in oxo compounds has two nonbonding pairs of electrons. Oxygen has a higher electronegativity than carbon, and the electrons of the y- and, especially, p-bonds of carbon and oxygen are strongly biased towards the oxygen atom. In other words, the carbonyl group is highly polar. The chemical consequence of the polarity of the carbonyl group is a variety of addition reactions of various polar reagents at the carbonyl group.

The lone pairs of electrons on the carbonyl oxygen give the carbonyl group the properties of a weak Lewis base, which plays an important role in interpreting the chemical properties of aldehydes and ketones.

Attachment of organometallic compounds:

Organometallic compounds combine with carbonyl compounds to form magnesium or lithium alkoxides, which readily hydrolyze to alcohols. When a Grignard reagent is added to formaldehyde, primary alcohols are obtained; the same reaction with other aldehydes and ketones leads to the formation of secondary and tertiary alcohols, respectively. The production of secondary and tertiary alcohols from organomagnesium compounds and aldehydes or ketones is often complicated by side processes. Side reactions can be completely eliminated if organolithium compounds are used to attach to the carbonyl group. In this case, it is even possible to synthesize tertiary alcohols containing simultaneously three tertiary alkyl groups at the carbonyl carbon atom:

Oxidation of carbonyl compounds:

Aldehydes are easily oxidized to carboxylic acids not only under the action of reagents such as permanganate or dichromate, but even under the action of such weak oxidizing agents as silver ion. Therefore, to identify aldehydes, the “silver mirror” reaction is used: the aldehyde reacts with Tollens’ reagent (silver ammonia solution) to precipitate metallic silver in the form of a mirror coating. The oxidation of ketones occurs under more severe conditions, using strong oxidizing agents in an acidic or alkaline environment, since the reaction is accompanied by the rupture of the carbon-carbon bond. Many ketones are cleaved on either side of the carbonyl group, resulting in a mixture of acids.

Reduction of carbonyl compounds:

Aldehydes are reduced to primary alcohols, and ketones are reduced to secondary alcohols either as a result of catalytic hydrogenation or through the use of complex hydrides: sodium borohydride and lithium aluminum hydride. Sodium borohydride, unlike lithium aluminum hydride, provides selective reduction of the carbonyl group of aldehydes and ketones in the presence of other functional groups (ester, nitrile, amide) and double C-C bonds, which this reagent does not affect.

By reducing ketones to a methylene group with amalgamated zinc in hydrochloric acid (Clemmensen reduction), alkylbenzenes with a primary alkyl group are obtained

b-Halogenation of carbonyl compounds:

Aldehydes and ketones are capable of reacting with halogens by replacing hydrogen atoms at the b-carbon atom.

In an alkaline environment, the reaction is difficult to stop at the monohalogenation stage, since the monohalogen derivative under these conditions undergoes subsequent halogenation more quickly than the starting aldehyde or ketone. Therefore, under the specified conditions, all b-hydrogen atoms are replaced by halogen. Monohalogencarbonyl compounds are prepared in the presence of acids

6 Sulfonation and sulfation processes

Sulfonation (sulfonation), introduction of the SO2OH sulfo group into the org molecule. connections; in a broad sense, sulfonation is the introduction of the SO2X group (X = OH, ONa, OAlk, OAr, Hal, NAlk2, etc.). On the introduction of the SO3H group with the formation of O-S bonds (O-sulfonation, sulfation, sulfoesterification).

The reverse process of sulfonation (removal of the SO2X group from the molecule of an organic compound) is called. desulfonation (desulfonation). Sulfonation is carried out directly using sulfonating agents or indirectly, for example by introducing a sulfo group in the composition of sulfoalkyl fragments (CH2)nSO2X. Sulfonating agents: H2SO4, SO3 and its complexes with org. compounds (esters, tertiary amines and phosphines, amides of carboxylic acids, tri-alkylphosphates, etc.), oleum. SOCl2, halogensulfonic acids and sulfamic acids, dialkyl sulfates, acyl sulfates.

Sulfonation of aromatic hydrocarbons proceeds through the electroph mechanism. Substitutions (see Appendix 2).

The reaction is carried out in both the vapor and liquid phases (solvents: SO2, CC14, freons, etc.). When sulfonating with sulfuric acid, an excess of acid is used to shift the equilibrium to the right or water is bound by adding oleum, azeotropic distillation, etc.

Compounds with electron-donating substituents are more reactive and are preferentially sulfonated. in ortho and para positions; compounds with electron-withdrawing substituents in the meta position. In most cases, when substituted benzenes are sulfonated, mixtures of isomers are formed, the ratio of which depends on the nature of the substituent, the sulfonating reagent and reaction conditions (concentration of reagents, temperature, solvent, presence of catalysts, etc.). By selecting the optimal conditions, selective sulfonation is possible. Thus, sulfonation of toluene with sulfuric acid at 20 °C leads to equal amounts of o- and n-toluenesulfonic acids, and when using SO3 under the same conditions - exclusively to the n-isomer; when sulfonating phenol in the cold, preim. o-phenolsulfonic acid is formed, whereas at 100°C-n-phenolsulfonic acid. As a rule, such differences are due to the transformation of some isomers into others, thermodynamically more stable, due to isomerization or reversibility of sulfonation. For example, naphthalene at temperatures below 100°C initially forms α-naphthalene sulfonic acid, which converts over time. into the β-isomer as a result of sequential desulfonation-resulfonation. sulfonation at 160°C leads exclusively to β-naphthalene sulfonic acid (see Naphthalene sulfonic acid).

For sulfonation of heterocyclic compounds (furan, pyrrole, thiophene, indole, etc.), SO3 complexes with dioxane or pyridine are used. The same reagents are used for sulfonation of aliphatic compounds. compounds containing strong electron-withdrawing groups; in this case, as a rule, a-sulfo derivatives are formed (see Appendix 3).

Indirect methods of sulfonation include sulfomethylation, sulfoethylation, etc. (see Appendix 4).

Sulfonation is used in the production of surfactants, ion-exchange membranes and resins, biologically active substances, dyes, etc.

Conclusion

During the period while I was doing my internship, I became familiar with the equipment related to petrochemical synthesis and saw how to work with it correctly. I was given safety instructions and shown the work place and how to use it.

The teacher showed how to carry out work on petrochemical synthesis.

Hydrogenation, dehydrogenation, and alkylation processes were carried out. Knowledge is used to carry out esterification hydrolysis, hydration, dehydration, addition and condensation at the carbonyl group, sulfonation and sulfation.

esterification hydrolysis dehydration carbonyl

References

1. Large encyclopedic dictionary. Chemistry. M., 2001.

2. Grushevitskaya T. T., Sadokhin A. P. Concepts of modern natural science.

. Concepts of modern natural science. Under. ed. V. N. Lavrinenko, V. P. Ratnikova. M., 1997.

. Kuznetsov V.I. General chemistry. Development trends. M., 1989.

. Kuznetsov V.I., Idlis GM. , Gutina V.N. Natural science. M., 1996.

. Molin Yu. N. On the role of physics in chemical research. Methodological and philosophical problems of chemistry. Novosibirsk, 1981.

. Chemistry // Chemical encyclopedic dictionary. M., 1983.

. Pilipenko A. T., Pyatnitsky I. V. Analytical chemistry. - M.: chemistry, 1990.

. V. P. Vasiliev Analytical chemistry - M.: Bustard 2004

. Fundamentals of Analytical Chemistry / Ed. Academician Yu. A. Zolotov. - M.: Higher School, 2002. Book. 1, 2. 15. Agafoshin N.P. Periodic law and periodic system of elements by D.I. Mendeleev Dmitry Ivanovich. M.: Education, 1973.

. Evdokiomv Yu., candidate of chemistry. Sci. On the history of the periodic law. Science and Life, No. 5 (2009).

. Makarenya A. A., Rysev Yu. V. D. I. Mendeleev Dmitry Ivanovich. - M.: Education, 1983.

. Makarenya A. A., Trifonov D. N. Periodic law of D. I. Dmitry Ivanovich Mendeleev. - M.: Education, 1969.

Application

1. (Deactivation and coking of the catalyst).

2. (Sulfation of aromatic compounds).

3. (Sulfalation of heterocyclic compounds).

4. (Sulfomethylation, sulfoethylation).

Topic: Current state of petrochemical synthesis. Main products and technologies

Introduction

1. Alternative fuels, raw materials

1.1 Dimethyl ether

1.2 Synthetic gasoline

1.3 Alcohol fuels

1.4 Biomass fuel

2. Technologies

2.1 Synthesis of DME from natural gas (via methanol)

2.2 One-step synthesis of DME from synthesis gas and synthesis of gasoline (via DME)

2.3 Unconventional processes and technologies for producing motor fuels

2.3.1 BIMT technology

2.3.2 BIMT-2 technology

2.3.3 BICYCLAR process

Conclusion

Literature

Introduction

The development of the fuel industry is determined by a number of factors. The increase in costs for searching, production and delivery to places of mass consumption of petroleum raw materials ultimately led to an increase in the cost of fuel obtained from oil. Increasing demands from environmentalists for the quality of produced motor fuel also causes an increase in the cost of processing initial oil fractions.

Another important factor determining the trajectory of changes in the fuel sector of the energy sector is due to the need to reduce emissions of carbon dioxide into the atmosphere, which is the main greenhouse gas. From an environmentalist's point of view, none of the currently existing types of fuel can be considered acceptable. All that is used in transport to produce energy is carbon compounds. When they are burned in a car engine or in the furnace of a power plant (factory or power plant), carbon dioxide is formed (optimally) and released into the atmosphere. The future of road transport and large energy installations is usually associated with the use of electric energy and hydrogen, produced from renewable energy sources by methods that, as it now seems, will not harm the environment. The implementation of these ambitious projects is associated with many technical problems, the solution of which will take quite a long time even if global scientific and technical potential is mobilized.

Currently, against the backdrop of rising prices for oil and its processing methods, growing motorization and the growing need of civilization for high-quality fuel, chemists are turning their attention to non-oil sources for the production of new compositions of hydrocarbon fuels that have become familiar to the motorist consumer.

Currently, the only economically acceptable way to improve the environmental friendliness of vehicles is to switch them to alternative fuels, ensuring the reduction of harmful emissions into the environment from vehicle engines to a level that meets strict European standards. The European Commission is planning to develop a large-scale program for the introduction of alternative types of motor fuels. By 2020, over 1/5 of oil-based fuels should be replaced by alternative products such as biofuels, natural gas and hydrogen.

1. Alternative fuels, raw materials

1.1 Dimethyl ether

The synthesis of dimethyl ether (DME) and gasoline through dimethyl ether is one of the new directions in the field of processing natural gas and other carbon sources (coal, wood residues, etc.). The main routes for processing methane into motor fuels are shown in Scheme 1. As can be seen from the diagram, the synthesis of DME fits into the scheme of natural gas processing as an alternative route to the synthesis of methanol.

Motor fuels

Hema 1 Main ways of processing natural gas into motor fuels

1.2 Synthetic gasoline

The raw materials for the production of synthetic non-petroleum gasoline can be coal, natural and associated petroleum gases, biomass, shale, etc. The most promising source for the production of alternative motor fuels is natural gas, as well as the synthesis gas obtained from it (a mixture of CO and H2 in various proportions). Where natural gas is easily recovered, it can be used in compressed and liquefied states as a motor fuel for internal combustion engines. Liquefaction of natural gas, compared to compression, has the advantage of reducing the volume of its storage system by almost three times.

The use of alternative fuels obtained from natural gas ensures a reduction in the content of toxic components in vehicle exhaust gases.

1.3 Alcohol fuels

A significant disadvantage of this type of fuel remains its high cost - depending on the production technology, alcohol fuels are 1.8-3.7 times more expensive than oil ones. Among various alcohols and their mixtures, methanol and ethanol are most widely used as motor fuels. Synthesis gas is currently used to produce methanol, but natural gas is the preferred feedstock for large-scale processes. From an energy point of view, the advantage of alcohols lies mainly in their high detonation resistance, which determines the predominant use of alcohols in spark-ignition internal combustion engines. Their main disadvantages are low heat of combustion, high heat of evaporation and low vapor pressure.

Ethanol is generally better in performance than methanol. The cost of ethanol is on average much higher than the cost of gasoline. Currently, methanol as a motor fuel is used in limited quantities. It is mainly used to produce synthetic liquid fuels, as a high-octane fuel additive and as a raw material for the production of an anti-knock additive - methyl tert-butyl ether.

One of the most serious problems hampering the use of methanol additives is the low stability of gasoline-methanol mixtures and their sensitivity to the presence of water. The difference in the densities of gasoline and methanol and the high solubility of the latter in water lead to the fact that the entry of even small amounts of water into the mixture causes its immediate separation, and the tendency to separation increases with decreasing temperature, increasing water concentration and decreasing the content of aromatic compounds in gasoline. To stabilize gasoline-methanol mixtures, additives are used - propanol, isopropanol, isobutanol and other alcohols.

1.4 Biomass fuel

Biomass is a very promising renewable raw material. It can be used to produce ethanol as an alternative fuel. It is estimated that so much biomass is grown and grown in the wild each year that it can produce eight times more energy than all fossil fuels currently provide. Research aimed at creating the production of liquid fuels from renewable raw materials of plant origin has been expanding in recent years.

Bioethanol and biobutanol are produced by fermentation. A wide range of carbohydrate materials can be used as raw materials for fermentation: sugars, starch, cellulose, etc. The basis for the production of bioethanol from starch is two stages: hydrolysis of starch to glucose under the action of enzymes and fermentation of glucose to ethanol. A significant drawback of this technology is due to the fact that when the concentration of ethanol in the reaction mixture increases above a certain level, it begins to have an inhibitory effect on the fermentation process. In addition, fermentation usually results in the formation of a number of metabolites, which at elevated concentrations also reduce the efficiency of the process.

Modern research to improve existing processes for the production of bioethanol is carried out mainly in two directions: the development of fermentation systems operating in a continuous mode, and increasing the productivity of ethanol extraction and purification methods in order to reduce energy costs for the production of fuel alcohol.

2. Technologies

2.1 Synthesis of dimethyl ether from natural gas (via methanol)

Natural gas is the simplest and most accessible raw material for the synthesis of dimethyl ether and, accordingly, the process of producing DME based on natural gas has the best economic indicators. Currently, industrial production of DME (aerosol filler) is approx. 150 thousand tons per year and is based on methanol processing. A simplified scheme for the production of DME based on natural gas through the synthesis and subsequent dehydration of methanol can be represented as Scheme 2.

Scheme 2 Scheme for the synthesis of DME from natural gas through the stages of synthesis and dehydration of methanol

Let us consider the individual stages of this synthesis.

Methane conversion.

Conversion of methane (reforming) into synthesis gas is a high-temperature process that can be carried out using various reactions (involving various reagents). Among them:

steam reforming CH4+H3O=CO+3H3 (1)

carbon dioxide conversion CH4+CO2+2CO+2H3 (2)

incomplete oxidation CH4+1/2O2=CO+2H3 (3)

Reactions (1) and (2) are highly endothermic, so autothermal reforming—steam reforming in the presence of oxygen—has become widespread. To the reactions (1) and (3) occurring under autothermal reforming conditions are added highly exothermic reactions of complete oxidation:

CH4+2O2=CO2+2H3O (4)

H3+1/2O2=H3O (5)

CO+1/2O2=CO2 (6)

These processes provide compensation for heat losses in reaction (1), but lead to additional costs of raw materials.

Synthesis gas is a mixture of CO and hydrogen with a small amount of CO2, which may also contain nitrogen. The most important characteristic of synthesis gas is the H2:CO concentration ratio. To synthesize methanol, this ratio must be greater than two, which makes the use of steam reforming inevitable (reaction 1).

Reforming conditions are the result of a compromise between the requirements of thermodynamics (increasing temperature and decreasing pressure to increase equilibrium methane conversion), economics and materials science. At high temperatures (800-900 ºС) and not too high pressure (1-3 MPa), the thermodynamics of the process are favorable, which allows the reaction to be brought to a transformation close to complete. The compromise achieved leads to the fact that in the process of methanol synthesis, the reforming stage requires approximately 2/3 of capital investments and more than half of operating costs. This circumstance led to the search for new ways to convert natural gas into synthesis gas.

Direct gas-phase selective oxidation of methane into CO and H2, i.e. into synthesis gas (reaction 3) would be the simplest of the alternative methods, however, the selectivity of this process under practical conditions is low (at 50%). High selectivity can be achieved at high temperatures (approx. 1500 K), when the equilibrium is favorable specifically for the formation of synthesis gas. However, carrying out the process at such temperatures is associated with a number of difficulties due to very stringent requirements for the reactor material in contact with a corrosive environment at high temperatures, and the complexity of controlling the process, since the laws of combustion of “rich” mixtures have been relatively little studied.

The question also arises of what to use as an oxidizing agent. If you oxidize methane with pure oxygen, the capital investment and cost of synthesis gas increase, and if you use air, you get “poor” low-quality synthesis gas with a high nitrogen content (at least 50-60% vol.).

The main trends in the development of the environmental protection industry, aimed at increasing the economic efficiency of production and product quality, are associated with saving raw materials, energy and reducing capital costs. The most important of them are the following:

1. Creation of new technological processes based on more accessible and cheaper raw materials. For example, the transition from expensive acetylene to aromatic hydrocarbons, alkenes, alkanes and, finally, synthesis gas in accordance with their value scale:

2. Transition to direct methods of synthesis, eliminating the consumption of inorganic reagents. For example, replacing sulfuric acid hydration of ethylene with direct catalytic hydration in ethanol production.

3. Increasing the selectivity of processes through optimization of parameters, selection of equipment and selection of highly selective catalysts.

4. Reducing the number of production stages. For example, replacing the two-step process of synthesizing acetaldehyde from ethylene via ethanol with a one-step oxidative process:

5. Increasing the unit capacity of devices and thereby reducing capital costs. For example, in methanol production up to 300-500 thousand tons/year.

6. Saving energy and increasing the efficiency of units, in particular through the use of secondary energy resources and the introduction of energy technology schemes.

Synthesis gas as an alternative to oil

After 1945, due to the rapid development of oil production and the fall in oil prices, the need for the synthesis of organic substances from CO and H 2 disappeared. The petrochemical boom has arrived. However, in 1973, the oil crisis broke out - the oil-producing countries of OPEC (Organization of Petroleum Exporting Countries) sharply increased prices for crude oil, and the world community was forced to realize the real threat of depletion of cheap and accessible oil resources in the foreseeable future. The energy shock of the 70s revived the interest of scientists and industrialists in the use of raw materials alternative to oil, and here the first place undoubtedly belongs to coal. The world's coal reserves are huge; according to various estimates, they are more than 50 times greater than oil resources, and they can last for hundreds of years. There is no doubt that the use of synthesis gas will play a key role for organic synthesis purposes in the foreseeable future. Currently, gasoline, gas oil and paraffins are produced on an industrial scale using the Fischer-Tropsch method only in South Africa. Sasol installations produce about 5 million tons of liquid hydrocarbons per year.

A reflection of the intensification of research on syntheses based on CO and H 2 is a sharp increase in publications devoted to the chemistry of one-carbon molecules (the so-called C 1 chemistry). Since 1984, the international journal "C 1 -Molecule Chemistry" began to be published. Thus, we are witnessing an upcoming renaissance in the history of coal chemistry. Let's consider some ways of converting synthesis gas, leading to the production of both hydrocarbons and some valuable oxygen-containing compounds. The most important role in CO transformations belongs to heterogeneous and homogeneous catalysis.

Synthesis gas production

The first method of producing synthesis gas was the gasification of coal, which was carried out back in the 30s of the 19th century in England with the aim of producing flammable gases: hydrogen, methane, carbon monoxide. This process was widely used in many countries until the mid-1950s, and was then replaced by methods based on the use of natural gas and oil. However, due to the reduction of oil resources, the importance of the gasification process began to increase again.

Currently, there are three main industrial methods for producing synthesis gas.

1. Gasification of coal. The process is based on the interaction of coal with water vapor:

This reaction is endothermic, the equilibrium shifts to the right at temperatures of 900-1000?. Technological processes have been developed that use steam-oxygen blasting, in which, along with the mentioned reaction, an exothermic reaction of coal combustion occurs, providing the required heat balance:

2. Methane conversion. The reaction between methane and water vapor is carried out in the presence of nickel catalysts (Ni-Al2O3) at elevated temperatures (800-900?) and pressure:

Any hydrocarbon raw material can be used as a raw material instead of methane.

3. Partial oxidation of hydrocarbons. The process consists of incomplete thermal oxidation of hydrocarbons at temperatures above 1300?:

The method is applicable to any hydrocarbon feedstock, but the most commonly used in industry is the high-boiling fraction of oil - fuel oil.

The CO:H 2 ratio significantly depends on the method used for producing synthesis gas. With coal gasification and partial oxidation, this ratio is close to 1: 1, while with methane conversion the CO: H2 ratio is 1: 3. Projects for underground gasification, that is, gasification of coal directly in the seam, are currently being developed. It is interesting that this idea was expressed by D.I. Mendeleev more than 100 years ago. In the future, synthesis gas will be produced by gasification not only of coal, but also of other carbon sources, including urban and agricultural waste.

Carbon monoxide synthesis

Numerous syntheses based on carbon monoxide and hydrogen are of enormous practical and theoretical interest, since they make it possible to obtain valuable organic compounds from two simple substances. And here the decisive role is played by catalysis by transition metals, which are capable of activating inert molecules CO and H 2 . Activation of molecules is their transfer to a more reactive state. It should be especially noted that a new type of catalysis has been widely developed in synthesis gas transformations - catalysis by transition metal complexes or metal complex catalysis.

Let us note several important key reactions in metal complex catalysis. These are primarily oxidative addition and reductive elimination reactions. Oxidative addition is the addition of neutral AB molecules, such as H2 or halogen, to the metal center of the complex. In this case, the metal is oxidized, which is accompanied by an increase in its coordination number. This addition is accompanied by cleavage of the A-B bond.

The reaction of oxidative addition of a hydrogen molecule, as a result of which its activation occurs, is very important. The reaction of oxidative addition of hydrogen to a square planar complex of monovalent iridium, discovered by Vasco and Dilucio, became widely known. As a result, the oxidation state of iridium increases from I to III.

The reaction opposite to oxidative addition is called reductive elimination, in which the oxidation number and coordination number of the metal are reduced by two.

Let us also note the reaction of migration introduction, which consists in the introduction of unsaturated compounds through the metal-carbon and metal-hydrogen bonds. The CO insertion reaction is key for many processes involving synthesis gas.

The introduction of olefin is the most important reaction among the catalytic transformations of olefins: hydrogenation, hydroformylation, etc.

Fisher-Tropsch synthesis

The Fischer-Tropsch synthesis can be considered as a reductive oligomerization reaction of carbon monoxide, in which carbon-carbon bonds are formed, and in general it is a complex combination of a number of heterogeneous reactions, which can be represented by the summary equations:

The reaction products are alkanes, alkenes and oxygen-containing compounds, that is, a complex mixture of products is formed, characteristic of a polymerization reaction. The primary products of the Fischer-Tropsch synthesis are a- and b-olefins, which are converted to alkanes as a result of subsequent hydrogenation. The nature of the catalyst used, temperature, and the ratio of CO and H 2 significantly affect the distribution of products. Thus, when using iron catalysts, the proportion of olefins is large, while in the case of cobalt catalysts with hydrogenating activity, saturated hydrocarbons are predominantly formed.

Currently, as catalysts for Fischer-Tropsch synthesis, depending on the objectives (increasing the yield of gasoline fraction, increasing the yield of lower olefins, etc.), both highly dispersed iron catalysts supported on oxides of aluminum, silicon and magnesium, and bimetallic catalysts: iron - manganese, iron-molybdenum, etc.

Hydroformylation of olefins

One of the most important examples of industrial processes involving synthesis gas is the hydroformylation reaction (oxo-synthesis). In 1938, Rehlen, while studying the mechanism of the Fischer-Tropsch synthesis, discovered this remarkable reaction, the importance of which is difficult to overestimate. In this process, alkenes in the presence of catalysts, mainly cobalt or rhodium, at pressures above 100 atm and temperatures of 140-180? interact with synthesis gas and transform into aldehydes - the most important intermediates in the production of alcohols, carboxylic acids, amines, polyhydric alcohols, etc. As a result of the hydroformylation reaction, aldehydes with straight and branched chains are obtained, containing one carbon atom more than in the original molecule:

The most valuable are the normal aldehydes, while the iso aldehydes can be considered as undesirable by-products. World production of aldehydes by the hydroformylation process reaches 7 million tons per year, with about half being n-butyraldehyde, from which n-butyl alcohol is obtained. Aldol condensation followed by hydrogenation produces 2-ethylhexanol, used for the production of polyvinyl chloride plasticizers.

Cobalt carbonyls are most widely used as hydroformylation catalysts; recently, the use of rhodium catalysts has been described, which allow the process to be carried out under milder conditions.

Prospects

The process of producing methanol, the most important product of the chemical industry, from synthesis gas, mastered in the 1920s, is of great importance. At the same time, the direct synthesis of other oxygen-containing compounds from synthesis gas also seems very attractive. The use of synthesis gas is described for the production of alcohols of composition C 1 -C 4 (lower alcohols), from which lower olefins are then obtained by dehydration. In the 70s, catalysts of complex composition were proposed, consisting of oxides of copper, cobalt, chromium, vanadium, manganese and alkali metal salts, which made it possible to obtain alcohols of normal structure of the composition C 1 -C 4 from synthesis gas at a temperature of 250? and a pressure of only 6 atm.

The literature describes the formation of a wide variety of oxygen-containing compounds from synthesis gas, for example: acetaldehyde, acetic acid, ethylene glycol, etc.

All these reactions seem quite real. Unfortunately, these methods currently cannot compete with already developed industrial processes, since they occur under very harsh conditions and with little selectivity. It can be hoped that the search for new effective methods for the industrial use of synthesis gas will continue intensively, and there is no doubt that this area has a great future.

LECTURE COURSE ON ALTERNATIVE SOURCES OF HYDROCARBONS

CONTROL

The basic organic synthesis industry is one of the most important sectors of both chemical and petrochemical production. Basic organic synthesis includes the production of monomers for the production of artificial fibers, plastics, synthetic rubbers, surfactants, synthetic fertilizers, solvents and many other products necessary for the normal functioning and development of the economy of any country. In addition to chemical products, to support the economic activities of enterprises, housing and transport around the world, a huge amount of hydrocarbon raw materials is consumed for the functioning of the fuel and energy complex. Therefore, raw materials are one of the main elements of production and largely determine the scale, technology and economics of industry. In this regard, the Department of Chemical and Technical Technologies is already training specialists in the field of technology of organic substances and fuels (including alternative ones).

RAW MATERIAL SOURCES OF KHTOV INDUSTRY

There are mineral (non-renewable) and renewable hydrocarbon raw materials. To mineral include: coals, shale, tar sands, peat, oil and natural gas - once formed from products of organic origin. These also include acetylene based on mineral sources of non-organic origin. Data on reserves of mineral springs are quite contradictory, since they are difficult to assess. However, it is known for sure that the reserves of solid fossil fuels significantly exceed the reserves of oil and gas. Calculations by geochemists show that the ratio of various fossil fuels in the earth’s crust is (in%):

Coals, shale and tar sands - 81-95.8; Peat - 3.4-5; Oil - 0.7-9.8 (90% as fuel); Natural gas - 0.1-4.4 (50-52% converted into electricity)

In addition to mineral - exhaustible sources of energy (fuel >90%) and chemical (5-8%) raw materials, the reserves of renewable sources are limitless - this is biomass. It reproduces spontaneously, regardless of human activity, in just one year in quantities of about 200 billion tons with a total energy potential 3 . 10 21 J, which is ~ 10 times the volume of global fossil fuel production. From the total amount of biomass, ~ 40 billion tons are formed in the form of wood, ~ 30 billion tons in the form of living organisms (~ 10 billion tons of adipose tissue) and ~ 2-3 billion tons in the form of oil-containing components in oil-producing plants (for comparison, according to some data, world oil reserves are currently estimated at approximately 90 billion tons). This exceeds all proven reserves of mineral raw materials, but their collection is difficult, and processing technologies are at the stage of experimental or pilot-industrial research. In this regard, today the most acceptable and cheapest sources for meeting the fuel, energy and chemical needs of the country are: oil, natural and associated gases, as well as oil refining gases. However, it should be noted that in the future the trend will change due to the depletion of reserves of the above mineral springs.

The modern development of most countries in recent years has taken place in conditions of a general economic crisis, in particular the energy and raw materials crisis. Although currently the share of oil and gas in the fuel balance of the main capitalist countries is significant, forecast estimates reveal a general trend aimed at reducing their consumption and a slight increase in the share of coal and other renewable hydrocarbon sources.

World oil consumption in 1970 reached ~3 billion tons, in 1990 this value reached ~4 - 4.5 billion tons per year. in 2000, ~5 billion tons were already processed; in 2020, it is planned to process ~6 billion tons or more. At this level (and it will steadily increase), the service life of these reserves will be about 90/5 = 16 years. ????? This, of course, does not mean that during this time all the oil on earth will be exhausted, but it shows that the current, still prosperous state of oil on the world market is apparent. (This is clearly seen in the interruptions in oil supply in our country, and in particular at the Nyan Refinery Plant, the production of which by the Slav-Neft company in 2015 amounted to 20 million tons per year, and refining at the Nyan Refinery Plant in the most successful year of 2015 in the last 10 years amounted to 13-14 million tons per year, with a plant capacity of 15-16 million tons per year) For comparison, the expected oil production and processing in Russia in 2020 will be no more than 500 million tons, which is less than in 1980 - 610 million tons.

The Russian gas industry is a relatively young branch of the fuel and energy industry, which has been developing at a rapid pace, and already in 1990. natural gas production amounted to 850 billion m3. In 2015, due to the fuel and energy crisis, production will remain at the same level (or slightly less). By the end of 2015, the deficit of gas resources amounted to 20 billion m3, and by the end of 2016-2017 it will increase to 45-50 billion m3. Today's price (as of January 1, 2016) of gas is ~ 280-320 dollars. for 1 thousand m 3. (for now it is 2-3 times cheaper than fuel oil and coal, but the upward trend in prices is obvious). This is due to the fact that the development of new gas fields takes 7 to 10 years, and the cost of exploration, production and transportation is rising.

MODERN TRENDS IN THE DEVELOPMENT OF PETROCHEMICAL SYNTHESIS INDUSTRY AND THE EFFECTIVENESS OF USING ALTERNATIVE SOURCES OF HYDROCARBON RAW MATERIALS

Limited oil and gas reserves have raised new important challenges for the oil refining and petrochemical industries:

deepening oil refining processes with maximum selection of light oil products;

expanding the use of oil as a feedstock for petrochemicals, and to a lesser extent as a fuel (including power plants and heating plants);

widespread use of coal as boiler fuel (in replacement of gas and oil, since its reserves are large);

rational use of fuel and electrical energy in modern oil refining and petrochemical processes;

use of nuclear energy in oil refining and petrochemicals;

development (coal-based) processes for the production of synthetic liquid fuels and natural gas substitutes;

transferring the production of a number of petrochemical products to coal raw materials.

Currently, processes for the production of alternative fuels are also being widely developed. These include:

liquefied and compressed natural gas (as fuel for cars and other types of transport);

liquefied gases (fuels for vehicles);

methanol based on synthesis gas (today it is successfully used directly as fuel or as an additive to gasoline, increasing their octane number, and is also processed into (MTBE) methyl tert-butyl ether, a high-octane additive, into high-octane gasoline, etc.) ;

a substitute for natural gas produced by coal gasification;

ethyl alcohol (as an additive to gasoline, etc.);

acetylene based on calcium carbide and methane pyrolysis (chemical products based on it are varied, since acetylene has 3 double bonds and is very reactive).