RU2436760C1 - Method to process carbon-bearing gases and vapours - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to the method of processing gases and vapours that contain from 30 to 60 at. % of carbon, and also up to 70 at. % of oxygen and hydrogen, by exposure of a raw mixture that contains them to accelerated electrons to produce radiolysis products, in process of which a condensed fraction containing the target product is continuously removed from the radiolysis products, and the remaining part is mixed with source gas and/or vapour to produce the raw mixture, besides, hydrogen or hydrogen-bearing compounds of carbon are added to the mixture, or a condensed low-boiling fraction is added with boiling temperature below the boiling temperature of the target product, thus maintaining carbon percentage in the reaction mixture from 16 to 35 at. %, preventing oxygen content from going higher than 23 at. %.

EFFECT: method provides for the possibility to produce target fuel or raw materials for heavy organic synthesis from gaseous and steam-like raw materials, including carbon oxides, synthesis gases, cracking gases, steam-like products of biomass destruction, vapours of saturated and non-saturated organic compounds and production wastes; expands assortment and increases yield of synthesised commercially valuable condensed organic compounds; simplifies technology of their production due to replacement of high-temperature catalytic processing for direct electrophysical treatment, which does not require complicated preparation of raw materials; develops conditions for efficient management of the treatment process, composition and quality of the finished product.

7 cl, 10 ex, 2 tbl

Description

The invention relates to the field of production of fuel and intermediates for heavy organic synthesis from carbon oxides or light organic compounds and can be used in the utilization of gaseous flue gases, industrial waste, synthesis gases, biogas, cracking gases, natural and associated petroleum gas.

Known methods for processing gases and vapors by exposing them to ionizing radiation through radiolysis (A.K. Pikaev. Modern radiation chemistry. Radiolysis of gases and liquids. M: Nauka, p. 48-53), including the formation of radiolysis products ( Woods RJ, Pikaev AK Applied radiation chemistry: radiation processing. NY .: Wiley. 1994. P.166-168, 187-193, 473-484).

However, this known method produces a mixture of products with a low content of that fraction, which can be used as liquid motor fuel or raw materials for heavy organic synthesis. Along with the low yield of economically valuable synthetic products, they are obtained only in a mixture with undesirable radiolysis products.

Closest to the proposed is a method of processing gaseous alkanes by exposure to ionizing radiation on the raw material mixture containing them to obtain radiolysis products, while the condensed fraction and hydrogen are constantly removed from the radiolysis products, and the remaining part is mixed with the starting alkanes to obtain the raw mixture (RF patent No. 2099317, publ. 12/20/1997).

However, the application of this known method is limited to the processing of saturated hydrocarbons - alkanes. This method is unacceptable for obtaining fuel or raw materials for heavy organic synthesis during the processing of many other gases and vapors, including carbon oxides, synthesis gases, cracked gases, vaporous products of biomass destruction, vapors of unsaturated organic compounds and industrial emissions. The use of this known method for processing other gases does not lead to the production of liquid motor fuel or valuable intermediates for heavy organic synthesis.

The technical result achieved by the implementation of the present invention is:

- expanding the range of acceptable starting materials, including through the use of inorganic raw materials (CO, CO ₂ and H ₂ and unsaturated organic compounds (such as alkenes, ketones, aldehydes, acids, esters);

- the possibility of using untreated artificial or natural multicomponent gas mixtures containing hydrocarbons;

- expanding the range and output of valuable condensable organic compounds;

- simplification of the technology for their production by replacing high-temperature catalytic processing with direct electrophysical processing, which does not require complex preparation of raw materials;

- increasing the completeness of utilization of the source gases and vapors, including by preventing coking processes and the formation of organic deposits on the walls of the reaction equipment;

- creating conditions for effective management of the processing process, composition and quality of the product.

This is achieved by the fact that in the processing method by applying accelerated electrons to a mixture of gaseous or vaporous raw materials with the resulting radiolysis products with the exception of their condensable fraction, hydrogen or hydrogen-containing carbon compounds, or a condensable low-boiling fraction with a boiling point lower, are added to the raw material mixture than that of the target product, maintaining the carbon content in the reaction mixture in the range from 16 to 35 at.%, while not allowing the oxygen content to exceed e 23 at.%.

Among the hydrogen-containing carbon compounds added to the feed mixture, it is recommended to use predominantly aliphatic (acyclic or alicyclic) hydrocarbons, alcohols or esters, whose molecules contain an average of up to 6 carbon atoms.

The known method involves the mandatory removal of hydrogen from the feed mixture, while in the present invention, hydrogen, on the contrary, should be added. The addition of hydrogen or hydrogen-containing gas provides a stable target product, which is especially important when processing oxygen-containing raw materials. In the known method, the raw material mixture should be freed from the entire condensable fraction, while in the present invention only from the high boiling fraction.

Typically, the target product is a wide fraction with a boiling point that meets regulatory requirements. Part of the condensable fraction — the condensable low-boiling fraction — in which the boiling point is lower than that of the target product, it is advisable to return to the exposure zone. The low boiling fraction, being an undesirable part of the condensate, is at the same time a valuable intermediate for faster obtaining the desired target product. Moreover, the present invention is also suitable for the processing of gaseous alkanes - they can be introduced into the reaction mixture instead of hydrogen or along with it.

The known method is oriented to the processing of light alkanes; the target product is also alkanes. The present invention provides for the processing of light alkanes, but these alkanes do not act as the main raw material, but as an auxiliary reagent, which, along with hydrogen, is added to the reaction mixture to convert carbon oxides and / or light unsaturated organic compounds into stable liquid fuel or intermediates for heavy organic synthesis.

The authors of the present invention for the first time found that the range and range of raw materials suitable for conversion into liquid fuel can be significantly expanded. As a result, it is possible to diversify the types of synthesized liquid fuel, purposefully regulating its operational characteristics at the synthesis stage. These effects are achieved if, instead of removing hydrogen, use its addition or the addition of a hydrogen-containing gas in combination with an increase in the concentration of volatile components. An increase in the concentration of volatile components is achieved due to the fact that not only unreacted raw materials are returned to the impact zone, but also the synthesized fraction with a boiling point lower than that of the target product.

In a specific embodiment, hydrogen or a hydrogen-containing gas can be added in a plasma state, i.e. carrying out an independent or non-independent electric discharge in the zone of hydrogen or hydrogen-containing gas inlet, so that the added gas prevails in the plasma volume. For example, hydrogen may be supplied across the flow of the feed mixture through the pores or capillaries of the autocathode. The plasma-chemical processes initiated at the same time make it possible to increase the yield of target products due to the intensification of the decomposition of raw materials.

Also, to increase the yield of the target products, it is recommended that the components of the reaction mixture or the entire reaction mixture be subjected to thermocatalytic destruction, increasing the content of unsaturated intermediates.

The sequence of radiation and plasmochemical or thermocatalytic effects plays an insignificant role, since the reaction mixture returns to the exposure zone after the stage of separation of the target condensable fraction, i.e. it is recycled in a closed cycle.

Depending on the component composition of the feed and the reaction mixture, it is recommended to differentiate the irradiation intensity of the components of the feed mixture. In places of local increase in the concentration of specific components (for example, due to the introduction of hydrogen or a hydrogen-containing gas, separation of the condensed phase, inertial separation of components during turbulence, etc.), irradiation with a higher or lower intensity can be provided. This differential exposure is intended to eliminate the excessive heterogeneity of the composition of the irradiated medium.

In a specific embodiment, it is also recommended to remove inert or undesirable components from the reaction mixture, such as carbon black, sulfur, noble gases, nitrogen, nitrogen and sulfur oxides, etc.

It is recommended to use synthesis gases and vapors arising from various methods (pyrolytic, plasmochemical or radiolytic) of the dry distillation of vegetative or fossil forms of biomass (wood, straw, coal, shale, peat, etc.) as the initial raw material.

In a particular embodiment, the mixture is circulated through the exposure zone in such a way that the ratio of the consumption of the raw material mixture in the exposure zone to its conversion rate is at least 3. The nomenclature and molecular weight distribution of the products are controlled by varying the temperature and pressure, preventing the accumulation of the target product in gas-vapor phase. The temperature and pressure of the reaction mixture are selected so that:

- provide a vaporous aggregate state of the feedstock;

- provide a vapor state of the synthesized target products, i.e. the possibility of their removal from the reaction zone with a gas stream. The condensation conditions are determined by the desired molecular weight distribution of the target products and the preservation of the raw material in a vaporous or gaseous state. The ultimate pressure is 0.6 MPa.

Humidity control of the reaction mixture is necessary in order to regulate the relative content and nomenclature of oxygen-containing compounds in the target product. Humidity control is especially appropriate at elevated temperature of the reaction mixture, when the processes of condensation of water vapor are weakened. For example, in the processing of mixtures enriched with CO, low humidity helps to increase the valuable fractions of alkanes, aliphatic alcohols and ethers, while in wet mixtures the undesirable fraction of acids and esters becomes predominant. At a moisture content of more than 7%, the reaction mixture is excessively enriched with peroxides, which entails the production of an unstable final product or the development of uncontrolled chain processes fraught with the destruction of equipment.

The operation to completely remove hydrogen is rational for the processing of gaseous alkanes, but makes it impossible to target the conversion of carbon oxides and unsaturated organic compounds. The value of traditional types of liquid motor fuels is largely determined by the presence of hydrogen and the absence of unsaturated bonds in fuel molecules.

Carbon oxides are inevitable products of fuel combustion. The task of their disposal relates to the most pressing global problems. Recently, many technologies for the production of traditional and alternative fuels are considered through the prism of utilization of carbon oxides and are perceived as an integral part of the strategy for the conversion of renewable raw materials.

The authors of the present invention for the first time found that the yield of the target conversion of carbon oxides, biomass distillation products, and other mixtures of saturated and unsaturated organic compounds can be significantly improved, and the technology for obtaining economically valuable products from them can be greatly simplified if the target fraction of condensed ones is removed during the action of ionizing radiation synthetic products and use additives of hydrogen or hydrogen-containing gases.

For the first time it was established that such a new operation ensures the focus of the process of radiolysis of gases and organic vapors, making it possible to balance the ratio of C, O, and H atoms in the final product. Moisture, as well as an economically valuable condensable fraction present in the zone of exposure to ionizing radiation, are harmful impurities, the level of which in the zone of influence must be monitored and not allowed to exceed their permissible limit.

It is important that the mixture of condensable organic products removed from the reactor does not need further additional purification and, being a waste of the radiolysis process, is at the same time an economically valuable product.

The most suitable raw materials for processing are gases and vapors containing from 30 to 60 at.% Carbon. Raw material molecules may also contain up to 70 atomic percent oxygen and / or hydrogen.

Additionally, introduced hydrogen or hydrogen-containing gas should provide such an average composition of the reaction mixture inside the reaction zone, including the irradiation zone and the zone of post-radiation reactions, so that the atomic fraction of carbon is not less than 16%, but not higher than 35%, while the atomic fraction of oxygen does not exceed 23%

The following are examples illustrating the invention.

Example 1. As a raw material, a mixture of CO (A) and H ₂ (B) with an average atomic composition of C is 18%, O is 18%, and H is 64%. The gas mixture at a pressure of 1.5 atm. and a temperature of 37 ° C with a speed of V = 4 g / kW · h pass through a steel reactor placed under a beam of a linear electron accelerator U-10-10T, where it is exposed to a stream of accelerated electrons with a density of D = 55-75 μA / cm ² and energy E = 0.7 MeV. At the outlet of the reactor, the mixture of unreacted raw materials and radiolysis products is cooled to 16 ° C, condensing low-volatility components, which are separated in an inertial gas-liquid separator. An anhydrous fraction with a boiling point below 37 ° C was left in the reaction mixture. The resulting condensate - a mixture of liquid alcohols, ethers and hydrocarbons - is drained into a storage tank. The composition of the removed mixture includes 49.2% aliphatic alcohols, 41.3% alkyl esters and 9.5 wt.% Alkanes. The yield of the organic mixture per 1 kWh of absorbed electron energy was ~ 1.2 kg. The average octane number of the target product is 106. The composition of the product includes: C - 25, H - 63 and O - 12 at.%. At the same time, about 29 wt.% Water is formed in parallel. The beginning of the boiling of the target organic fraction is 35.6 ° С, the end of boiling is 187 ° С. The total consumption of raw materials amounted to 1.68 kg / kW · h. Thus, with a complete conversion of the feed, 71 wt.% Of the target organic product and 29 wt.% Of water were obtained.

The results are shown in table 1, where a is the source of gaseous or vaporous raw materials; B — auxiliary hydrogen-containing gas; D — target product; F = [A] / [B] is the molar ratio of A and B in the raw material mixture; E is the electron energy; I is the current density in the electron beam; t is the temperature of the reaction mixture in the irradiation zone; V is the relative gas flow in the irradiation zone (ratio of flow to conversion rate); P is the gas pressure in the irradiation zone; U is the potential difference in the discharge device (plasmatron); g and G are the mass and energy yields of the target product, respectively; Δt _kip - the boiling range of the target product; OH - the octane number of the gasoline fraction; W is the moisture content in the reaction mixture supplied to the irradiation zone.

Example 2. According to the method of example 1, a pair of acetone (A) was processed in a mixture with hydrogen (B). An anhydrous fraction with a boiling point below 65 ° C was left in the reaction mixture. The process conditions and the results are presented in table 1.

Example 3. By the method of example 1, carbon oxides (A = CO + CO ₂ ) were mixed with hydrogen and methane (B = H ₂ + CH ₄ ). The dehydrated fraction with a boiling point below 41 ° C was left in the reaction mixture. The process conditions and the results are presented in table 1.

Example 4. According to the method of example 1, a mixture of furfural vapors (A, wood pyrolysis product) and methane (B) was processed. The dehydrated fraction with a boiling point below 170 ° C. was left in the reaction mixture. The process conditions and the results are presented in table 1.

Example 5. The vaporous products of dry distillation of cellulose (A) and hydrogen (B) were processed according to the method of example 1, but hydrogen was supplied to the reaction zone as a plasma. The dehydrated fraction with a boiling point below 170 ° C. was left in the reaction mixture. The process conditions and the results are presented in table 1.

Example 6. According to the procedure of example 5, a pair of 2,3-butanedione (A) and methane (B) was processed, and methane was supplied to the reaction zone as a plasma. The dehydrated fraction with a boiling point below 95 ° C was left in the reaction mixture. The process conditions and the results are presented in table 2.

Example 7. According to the method of example 1, a mixture of vaporous products of dry distillation of wood (A) and ethane (B) was processed; however, ethane was passed through a layer of a platinum catalyst heated to 350 ° C before being fed into the reaction zone, which stimulated the partial conversion of ethane to ethylene and hydrogen . The dehydrated fraction with a boiling point below 170 ° C. was left in the reaction mixture. The process conditions and the results are presented in table 2.

Example 8. By the method of example 1 was processed a mixture of vapors of acetone and propenal (A), but without the addition of hydrogen or hydrogen-containing gas. In the irradiation zone, the processes of fragmentation of raw materials dominate, and the output of the synthesized liquid does not exceed 0.1 kg / kW · h, while the liquid has a resinous consistency. The relevant data in tables 1 and 2 indicate the inappropriateness of the processing of vapors in the absence of hydrogen or a hydrogen-containing gas.

Example 9. An example of processing CO (A) and H ₂ (B) in a humid atmosphere (when water is returned to the reaction mixture) shows the inappropriateness of deviation from the process parameters recommended by the present invention (see table 2).

Example 10. An example of the processing of vapors of acetone (A) and water (B) shows the inappropriateness of establishing a low atomic fraction of carbon (15%) and a high fraction of oxygen (30%) in the reaction mixture. The synthesized liquid has a strongly acidic reaction (pH≤2) and is unstable (see table 2).

The principal feasibility of the new method depends little on the irradiation conditions. However, to ensure the economy of processing and obtaining the highest quality product, it is recommended to use W≤7 wt.%, I≤250 μA / cm ² , V≥3, P≤0.6 MPa and E≥9 MeV. In all cases of the implementation of the new method with modified parameters, the following negative trends were noted:

- lowering the stability of the product and gumming at W≥1 wt.%, I≥250 μA / cm ² , V≤2 or P≥0.6 MPa;

- a destructive decrease in the molecular weight of the reaction mixture at V≤2 and I≥250 μA / cm ² ;

- a noticeable accumulation of highly toxic compounds at W≥7 wt.% or E≥9 MeV.

The electron energy (in the range of the absence of nuclear transformations) does not play a fundamental role for the implementation of the method, but the thickness of the processed gas layer and, as a consequence, the dimensions of the reactor depend on it.

Thus, the method according to the invention provides the targeted conversion of volatile oxidized forms of carbon into economically valuable condensable compounds - fuel compounds and intermediates for heavy organic synthesis. This is especially valuable when utilizing gases such as carbon oxides and alkanes, the release of which into the atmosphere is associated with the greenhouse effect.

Currently, the main directions of utilization of carbon oxides are injection into underground storage facilities or the use of organic compounds in the catalytic synthesis according to the Fischer-Tropsch method. The present invention, in contrast to these approaches, involves the direct one-step conversion of oxidized forms of carbon into economically valuable products without waste.

The disposal of small gas flows by the Fischer-Tropsch method is irrational due to the high cost of processing, the need for large production facilities, the large amount of consumed catalysts and waste generated. The implementation of the present invention can be characterized by a relatively low metal consumption, wastelessness and low cost of gas processing.

The new method allows using compact plants to completely utilize exhaust gases with various C: O: H ratios directly at the place of their formation, without polluting the environment.

The new method provides the following results:

- practically all of the carbon (96-98 at.%) present in the feedstock goes into the liquid recyclable product;

- the liquid synthesized product has reliable domestic and industrial applications as motor fuel and / or intermediates for heavy organic synthesis;

- the dominant by-product is water, the impurities present in it are biodegradable, and their total concentration allows for effective cleaning with conventional aeration tanks or biofilters;

- the method is characterized by environmental rationality, due to the absence of non-recyclable waste and harmful environmental effects, while it is focused on the disposal of the most harmful volatile technogenic carbon compounds;

- the method provides low energy and material consumption of the processing of gases and vapors due to the full use of energy in the gas mixture, low pressures and temperatures, absence or low consumption of catalysts.

The method according to the invention is implemented using commercially available units, without the use of trunk pipelines and bulky tank farms for storing gas. The synthesized target product is liquid under ordinary conditions and for its collection approximately 500-1000 times less capacious storage facilities are needed than for the source gas. Thus, processing can be carried out directly at the gas source.

Table 1 Example No. one 2 3 four 5 Composition A, at.% FROM fifty thirty 40 45 45 N - 60 - 37 37 O fifty 10 60 eighteen eighteen Composition B, at.% FROM - - 8 twenty - N one hundred one hundred 92 80 one hundred 0 - - - - - F = [A] / [B] 0.57 0.50 0.29 0.20 0.25 E, MeV 0.70 0.45 0.65 1.50 0.65 I, μA / cm ² 55-75 46-69 75-100 58-84 85-105 t, ° C 37 65 41 170 170 V, rel. units 4.0-6.2 8.0-9.4 6.6-12.5 12.7-18.3 5.7-7.5 U, kV - - - - 6.7 P, MPa 0.11 0.11 0.13 0.10 0.11 W, wt.% 1.1 2.5 3.1 1.5 0.3 Composition D, at.% FROM 25 25 25 32 29th N 63 67 67 64 59 O 12 8 8 four 6 g, wt.% 71 77 63 89 98 G, kg / kWh 1.2 1.5 1.1 1.6 1.6 Δt _bale , ° С 36-198 65-215 60-227 164-293 165-275 Och 101-109 100-112 101-111 108-117 107-117

table 2 Example No. 6 7 8 9 10 Composition A, at.% FROM 33 45 36 fifty thirty N fifty 37 52 - 60 O 17 eighteen 112 fifty 10 Composition B, at.% FROM twenty 25 - - - N 80 75 - 90 66 O - - - 10 34 F = [A] / [B] 0.33 0.33 - 0.57 0.40 E, MeV 0.55 0.65 0.45 0.70 1.50 I, μA / cm ² 50-80 85-105 45-70 55-76 58-84 t, ° С 95 167 65 105 160 V, rel. units 7.0-9.8 9.7-11.5 8.0-9.4 4.0-12.2 12.7-18.3 U, kV 8.4 - - - - R, MPa 0.12 0.10 0.10 1.3 1.2 W, wt.% 1.3 1.3 2.2 7.5 62.1 Composition D, at.% FROM 27 29th 39 eighteen twenty N 64 64 52 63 40 O 9 7 9 19 40 g, wt.% 95 97 87 one hundred 48 G, kg / kWh 1.7 1.8 4.5 0.1 0.2 Δt _bale , ° С 94-215 165-305 ≥350 ≥350 35-105 Och 112-119 102-110 - - (pH≤2.0)

Claims (7)

1. A method of processing gases and vapors containing from 30 to 60 at.% Carbon, as well as up to 70 at.% Oxygen and hydrogen, by applying accelerated electrons to the raw material mixture containing them to obtain radiolysis products, during which the radiolysis products are constantly the condensable fraction including the target product is removed, and the remainder is mixed with the feed gas and / or steam to form a feed mixture, with hydrogen or hydrogen-containing carbon compounds or a condensable low boiling fraction added to the feed mixture w boiling point lower than that of the desired product by maintaining the reaction mixture in a carbon content ranging from 16 to 35 at.%, while avoiding excess oxygen content above 23 at.%. 2. The method according to claim 1, characterized in that the process is carried out at a pressure of not more than 0.6 MPa, the current density in the electron beam is not more than 250 μA / cm ² and when the ratio of the flow of the raw material mixture in the exposure zone to its conversion rate is at least 3. 3. The method according to claim 1, characterized in that hydrogen or hydrogen-containing carbon compounds are introduced into the reaction mixture in a plasma state. 4. The method according to claim 1, characterized in that hydrogen or hydrogen-containing carbon compounds are introduced into the reaction mixture after thermal or thermocatalytic treatment. 5. The method according to claim 1, characterized in that use a different intensity of irradiation of the components of the reaction mixture. 6. The method according to PP.1 and 2, characterized in that as the feedstock use gases and vapors generated during the dry distillation of biomass. 7. The method according to claims 1 and 2, characterized in that the reaction mixture is used with a moisture content of not more than 7 wt.%.