BG109348A - Method for the processing of natural gas into fuels - Google Patents

Abstract

The method is applied in the catalytic processing of natural gas for the production of synthetic fuels and other chemical products. The method comprises a phase of the processing of natural gas into a mixture of carbon monoxide and hydrogen (synthesis gas) and phase of catalytic conversion of synthesis gas into motor fuels. The process of preparing the mixture of hydrogen and carbon oxide runs at a temperature ranging from 800 to 900 degrees C and pressure 0.1-1 MPa in the presence of catalyst sorbent saturated in advance with oxygen in result of its processing with an oxygen-containing gas. The catalyst sorbent is based on aluminium oxides and mixed oxides, including nickel, cerium, zirconium and iron, having the following composition, in wt. %: mixed oxide - not more than 20, and aluminium oxide - the remaining part of the composition. The catalyst sorbent is in the form of granules with surfaces from 100 to 200 m2/g. The regeneration of the catalyst sorbent is effected at temperatures from 500 to 600 degrees C in a flow of gases containing 1-5 vol.% oxygen, until its saturation with oxygen, which concludes by the discontinuation of the oxygen absorption by the catalyst.

Description

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FIELD OF APPLICATION

The method of processing natural gas into fuels is applicable for catalytic processing of natural gas in the presence of a sorbent catalyst to a mixture of hydrogen and carbon monoxide (synthesis gas) - raw material for the production of synthetic fuels and other chemical products.

BACKGROUND OF THE INVENTION

It is known that the mixture of hydrogen and carbon monoxide (synthesis gas) is widely used in chemical processes such as methanol synthesis, higher alcohols, aldehydes, in the preparation of synthetic motor fuels (Fischer-Tropsch process). For each of these processes, a synthesis gas with a certain ratio of hydrogen and carbon monoxide (H2 / CO) is required. Catalytic and thermal conversion reactions of paraffins are used to prepare the mixture of hydrogen and carbon monoxide with one or the other H2 / CO ratio. (Gas Chemistry in the 21st Century Problems and Prospects, Proceedings of the Moscow Seminar on Gas Chemistry 2000-2002, pp. 138-141, M., 2003). The most widely used is the steam conversion of natural gas (methane), both catalytic and non-catalytic, in which gas synthesis with H2 / CO> 3 ratio is formed, which is only suitable for ammonia synthesis processes. In addition, the disadvantages of this process are the high cost of the necessary superheated steam and the formation of excess amounts of carbon dioxide.

The conditions under which the steam conversion process takes place are the following:

- Catalytic conversion-1 ~ 850 ° C, p ~ 1 -4 MPa and Ni catalyst;

- At non-catalytic conversion -1 ~ 1000 ° - 1600 ° C, p <0.5 MPa;

CH4 + H2O + 2O6 kJ ^ CO + CH ₂

Carbon dioxide conversion of methane yields a mixture of hydrogen and carbon monoxide in the H2 / CO ~ 1 ratio, which is required in the formaldehyde reaction.

CH4 + COg + 247 kJ2 - ^ 2C (NH3 ₂ • · 4 • · ··· · * ·

The conditions for the process of carbonic acid conversion are as follows: t ~ 750 ° - 850 ° C, p ~ 2 MPa, Ni catalyst and Ni compounds.

CH3 + 2H2O + CO ₂ +659 kJ4 - * 2CO + 8H ₂

The conditions for the process of steam-oxygen conversion are as follows: t 900 ° - 950 ° C, p ~ 2-4 MPa and Ni catalyst

2CH4 + 1 / 2O ₂ + H ₂ About +169 kJ2—> 2CO + 5H ₂

Steam oxygen conversion produces a synthesis gas of H2 / CO = 2.5.

The reactions of vapor, vapor, oxygen and carbon dioxide conversion of methane are endothermic and are accompanied by a coke formation process and therefore require high energy consumption. Substantial investment is also required for the gas synthesis equipment required, and they account for between 30% and 70% of production value, such as the production of methanol and synthetic motor fuels (Oil and GazEurasia, p. 85 No. 9, 2003).

Also known is a method of producing synthesis gas at H2 / CO ~ 2 ratio by selective catalytic oxidation of hydrocarbons with oxygen (SCTsang, J. B. Claridge and MLH Green, recent advances in the conversion of methane to synthesis gas , Catalysis Today, 1995, v. 23, 3-15). In contrast to steam and carbonic acid conversion, selective catalytic oxidation of hydrocarbons (CCS) proceeds with greater selectivity, ie less by-products are obtained. Also, the process is exothermic and runs efficiently over small contact periods, allowing it to flow in autothermal mode and reducing the size of the reactor, which in turn reduces both energy and capital costs (DA Hickman, LD Schmitd,

Synthesis of gas formation by direct oxidation of boundaries ^ e · in ^ Catalytic. Selective

L.D. Schmidt, Comparison of monolith-supported metals for direct oxidation of methane to syngas. J. Catal, 1994, v. 146, 1-10). The flow of both the exothermic reaction of the RMSE and the endothermic steam conversion of natural gas using the same catalyst allows a process to be produced for a mixture of hydrogen and carbon monoxide enriched in autothermal mode. (J.W. Jenkins and E.Shutt, The Hot Spot ™ Reactor, Platinum Metals Review, 1989,33 3,118-127).

The study of the RMS of methane in a pilot unit with a block catalyst containing Pt-Pd (LKHoshmuth, catalytic partial oxidation of methane over monolith supported catalyst, Appl. Catal., B: Environmental, vl 1992 89) shows that over time for contact ~ 0.02s full oxidation of methane takes place in the front layer of the block, and in the subsequent layers - steam and carbonic acid conversion of methane. Therefore, in order to obtain the maximum amount of synthesis gas, the catalyst must be active simultaneously in these three reactions. Accordingly, a catalyst with a large unfolded surface is required to effectively effect slow methane conversion reactions. At the same time, due to the large temperature gradient along the block, the catalyst must have high thermal stability.

Pt-Rh networks or block media containing 10% Rh are used for the RMS process at low contact times - 10 ^-2 s, which is very expensive and economically unprofitable. (Synthesis of gas formation by direct oxidation of methane in Catalytic Selective Oxidation, ACS Symposium series, 1993, p. 416-426; PM Tomiainen, X. Chu and LD Schmidt, Comparison of monolithsupported metals for direct oxidation of methane to syngas. J .Catal, 1994, v. 146, 1-10).

Also known is the RMS method of methane for the production of hydrogen and carbon monoxide (US5149464) at a temperature of 650-900 ° C and a volumetric rate of 40,000 - 80,000h ^_1 (0.05-0.09s) in the presence of a catalyst , which is a transition metal or oxide deposited on a thermo-Stabilizer o * YsD on ^^ f ^ by ······ * · · * · * · the following elements (M): Md, B, Al, Ln, Ga, Si , Ti, Zr, 'Hf J 51 I' * of a perovsk-like mixed oxide of the general formula MxM'yOz with a pyrochlorine structure, where M ¹ is a transition metal, including elements of group VIII. The atomic ratio of the elements of group VIII to the base elements in these compounds is 1: 1 or 3: 1, and the content of precious metals is 32.9-48% by weight. Conversion of methane in the presence of mixed oxides Pr2Ru2O7, Eu2Ir2O7, La2MgPtO6 at a volumetric rate of 40,000 h ^_1 and t = 777 ° C does not exceed 94%, and an increase in volumetric velocity up to 80,000 h ^_1 results in a decrease in the conversion of methane to 73 % and CO and H2 selectivity up to 82% and 90% respectively.

The closest in technical nature and achievable effect to the claimed method is the MSF method of hydrocarbons for the production of synthesis gas in the presence of a catalyst based on mixed oxides with a perovskite structure. (RU2204434).

A major disadvantage of all the above methods for producing synthesis gas by oxidizing methane with air is the presence of a significant amount of nitrogen in the synthesis gas. For example, in the patent chosen by us as a prototype, using air as an oxidant in the presence of the methane 27 vol. %, the concentration of synthesis gas is 50% vol. % (the rest is nitrogen).

The use of oxygen as an oxidant requires costly air separation units, which substantially increases the cost of producing synthesis gas.

It is an object of the invention to provide a method for the conversion of natural gas into fuels by creating a thermostable catalyst for the preparation of a mixture of hydrogen and CO, which is effective at low contact times for both the RMS reaction of hydrocarbons and oxygen vapor and carbonic acid conversion of hydrocarbons, in the presence of sulfur-containing compounds, as well as the process of producing a mixture of hydrogen and carbon monoxide with the hydrocarbon. this catalyst.

SUMMARY OF THE INVENTION

This task is solved by creating a method for the conversion of natural gas into fuels, which includes a phase of conversion of natural gas into a mixture of carbon monoxide and hydrogen (synthesis gas) and a phase of catalytic conversion of gas synthesis into motor fuels. The process of preparing the mixture of hydrogen and carbon monoxide is carried out at a temperature of 800-900 ° C, a pressure of 0.1-1 MPa in the presence of a catalyst-sorbent pre-saturated with oxygen as a result of its treatment with oxygen-containing gas. The sorbent catalyst is based on aluminum oxides and mixed oxides, including nickel, cerium, zirconium, and iron oxides, and has the following composition in mass percent mixed oxide - not more than 20% by weight; aluminum oxide - the rest of the composition. The catalyst-sorbent is in the form of granules having a surface 100-200 M ² / g. The regeneration of the sorbent catalyst is carried out at a temperature of 500-600 ° C in a stream of gases containing 1-5 vol.% Oxygen until it is saturated with oxygen, which ends with the termination of oxygen uptake by the catalyst.

An advantage of the method of processing natural gas into fuels is that the catalyst is thermostable to produce a mixture of hydrogen and CO, which is effective at low contact times, both in the reaction of the hydrocarbons with oxygen and in the vapor and carbonic acid conversion of hydrocarbons, in the presence of sulfur-containing compounds.

EXAMPLE IMPLEMENTATION OF THE INVENTION

The use of a catalyst, which is a complex composite containing mixed oxides of perovskite or fluoride structure and transition and / or precious metals and low thermal expansion additives, results in the catalytic conversion of the mixture containing a hydrocarbon or mixture of hydrocarbons and / or air, • ·· · ♦ _u ·· ····

C02 or steam or mixtures thereof, and - nezadalzhiuely © · a ^ n ^ a ^ eriyYniya, ****** ··· ··· * _s · is carried out in the presence of such a catalyst. In this method, high methane conversion and high selectivity, thermal stability of the catalyst are observed, without coke formation and contamination with sulfur-containing compounds.

This technical result is achieved by using a catalyst having the following composition in% by weight:

Transitional or noble element - not more than 10% by weight;

Mixed oxide - not more than 1%;

Material with ultra-low coefficient of thermal expansion (not more than 8 * 10 “6 ° C ^_1 ) - not more than 95%;

AL2O3 - the rest of the mass;

The mixed oxide includes an oxide with a perovskite ΜΈΙ-γΜγΟζ structure and / or an oxide with the fluoride structure Μ ¹ χΜ ² 1-χΟζ, where:

M - element of group VIII (Pt, Rh, Ir);

Μ ¹ - rare earth or alkaline earth elements;

M ² - element of IVb group of the Periodic Table of Chemical Elements;

B - transition element - elements from period IV of the Periodic Table, with 3d electronic shell.

The values of x and y are in the following ranges: 0.01 <x <1; 0 <y <1.

The values of x, y and z are determined by the degree of oxidation of the cations and their stoichiometric ratio.

The term "rare earth elements" is understood to mean elements relating to the group of rare earth elements, including elements of group III b and elements with a 4f electron shell, for example La, Ce, Nd.

By the term "alkaline earth elements" we mean elements referring to group Pa The periodic table of chemical elements, for example Sr, Ca.

The inclusion in the composition of high-temperature catalysts of components with low or negative coefficient of thermal expansion · * · is * * · (CTE) allows to regulate their coefficient of thermal expansion. In this way, catalysts with high heat resistance are obtained. Such components include cordierite, mullite, complex zirconium phosphates структура, tungstates (M2W3O12, MW2O8), molybdates, vanadates (MV2O7), aluminum titanate. (I. Naroi-Sabo, Inorganic Crystallography, Mir, M., 1971).

The resulting complex composite of the catalyst has a surface area of 2-200 M ² / g and can be in the form of tablets, rings, spheres or blocks of cellular structure.

The processes are carried out by successively passing a gas mixture containing a hydrocarbon or a mixture of hydrocarbons and / or air or steam or a mixture thereof at a temperature of 200-500 ° C through a fixed bed of catalyst.

In order to obtain the required composition of the mixture of hydrogen and carbon monoxide, it is necessary to change the composition of the initial mixture. The starting mixture contains a hydrocarbon or a mixture of hydrocarbons and / or air or steam or CO2 or a mixture thereof and, optionally, sulfur-containing compounds, the process being carried out at temperatures of 500 ° C to 1000 ° C. Natural gas, methane, propane-butane mixture, mixture of heavy hydrocarbons, kerosene, etc. are used as the hydrocarbon feedstock. Oxygen, air, CO2 or water vapor is used as the oxygen-containing gas.

The proposed catalysts are prepared by blending and impregnation methods followed by drying and heating. The process of producing a mixture of hydrogen and carbon monoxide is carried out in a flow reactor at temperatures of 550 ° C - 1000 ° C at different contact times and composition of the reaction mixture. The composition of the initial reaction mixture and the reaction products were analyzed chromatographically. The efficiency of the catalyst operation is determined by the degree of conversion of methane, the selectivity for CO and hydrogen and the amount of mixture of hydrogen and carbon monoxide obtained and their ratio.

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The present invention provides synthesis of Laz, crete <? this; stsjj ...... ...... ··· · ^; · Ballast impurities of nitrogen, in which air is used as the oxidizing agent, and then motor fuels can be obtained from synthesis gas. The use of Fischer-Tropsch gasoline-free gas-fueled propellant production significantly increases the efficiency of the fuel production process while reducing the size of technological equipment and reducing investment costs. This objective is achieved by the use of a solid catalyst-sorbent containing oxygen introduced during its pre-treatment with air. This approach allows the synthesis of ballast nitrogen-free gas from the use of air as an oxidizer from natural gas. In addition, the implementation of the proposed method does not require the addition to the reaction apparatus other than methane of other additional components such as air, water vapor, CO2 or mixtures thereof, which significantly simplify the process, reduce energy costs and investment costs.

Example 1. The powdered Ni, Ce, Zr and Fe oxides were treated with a 10% solution of HNO3 at 40 ° C - 60 ° C. The resulting mass was mixed with γ-Α12Ο3 powder and held for 12h at 50 ° C, after which the temperature was raised to 100 ° C, thereby separating physically bound water and the weight of the mixed oxides reached a constant weight. The resulting mixture was compressed into 3x5 mm tablets. The tablets were then heated at 800 ° C for 5 h. The bulk weight of the catalyst is in the range 0.7 - 0.9g / cM ³ . The air supply was terminated and the catalyst was purged with nitrogen for 2h at 800 ° C and methane was subsequently introduced. The conversion of methane to a CH4 / catalyst volume ratio of = 150 is 94%, and the composition of the resulting mixture in volume percentages is as follows:

H2 is 60.0 vol%; CO- 30.0 vol%; CH4 - 2.0 vol%; CO2 - 5.0 vol%; H2O- 3.0vol.% ·· · * * _w

The synthesis gas obtained is cooled, compressed, and compressed. · Synthesis of hydrocarbons at 300 ° C and a pressure of 30 at. The synthesis of liquid hydrocarbons takes place in the presence of a polyfunctional catalyst containing oxides of iron, zinc and boron in combination with a carrier aluminum and its oxides. The resulting motor fuels are 190g. of 1 nm ³ synthesis gas at 98% carbon monoxide conversion. Other things being equal for the synthesis of liquid hydrocarbons, the use of synthesis gas containing 50% vol. % nitrogen leads to a reduction in the production of motor fuels to 140g. at 1 nm ³ synthesis gas.

Example 2. The sorbent catalyst was prepared as shown in Example 1. The conversion of methane proceeded at a CH4 / catalyst volume ratio of = 150 and a temperature of 700 ° C. In this case, the conversion rate of methane is 60%, and the composition of the synthesis gas obtained in volume ratios is as follows: H2 - 22.8%; CO - 13,6% vol; CH4 - 18.2% vol; CO2 - 13.6 vol% H2O 31.8 vol%

The synthesis gas obtained is cooled, compressed and directed into a hydrocarbon synthesis reactor at 300 ° C and 30at. The synthesis of liquid hydrocarbons takes place in the presence of a multifunctional catalyst containing oxides of iron, zinc and molybdenum in combination with a carrier aluminum and its oxides and phosphates. The resulting motor fuels are 55g per 1 nm ³ synthesis gas at 90% carbon monoxide conversion.

Example 3. The sorbent catalyst was prepared and activated as shown in Example 1. The conversion of methane proceeded at a CH4 / catalyst volume ratio of = 150 and a temperature of 900 ° C. In this case, the conversion rate of methane is 96% and the composition of the synthesis gas obtained in volume ratios is as follows:

H2 is 62.0 vol%; CO - 30.5 vol.%; CH 4 -1.5 vol%;

CO2 - 4.0 vol%; H2O - 2.0 vol%

The resulting synthesis gas is cooled, compressed and directed to a hydrocarbon synthesis reactor at 300 ° C and 30at pressure. The synthesis of liquid hydrocarbons takes place in the presence of »* ya. . subfluent catalyst containing oxides of iron, zinc and molybdenum in combination with a carrier aluminum and its oxides and phosphates. The resulting motor fuels are

55g per n / m ³ synthesis gas at 90% carbon monoxide conversion.

EXAMPLE 4 The process for producing synthesis gas was carried out as described in Example 1. The reactor temperature was then lowered to 500 ° C and 600 ° C, the reactor was purged with nitrogen for 2h, after which the catalyst adsorbent was subjected to oxidative regeneration. in a stream of gases containing 1-5 vol.% oxygen. The regeneration process is terminated by the termination of oxygen uptake by the sorbent catalyst.

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Claims (4)

• Patent Claims • • • · ♦ · · 1. A method for the conversion of natural gas into fuels, comprising a phase of processing natural gas into a mixture of carbon monoxide and hydrogen (synthesis gas) and a phase of catalytic conversion of synthesis gas into motor fuels, characterized in that the production process of the mixture of hydrogen and carbon monoxide takes place at a temperature of 800-900 ° C, a pressure of 0.1-1 MPa in the presence of a catalyst-sorbent pre-saturated with oxygen as a result of its treatment with oxygen-containing gas. A method for the conversion of natural gas into fuels according to claim 1, characterized in that the sorbent catalyst used to prepare a mixture of hydrogen and carbon monoxide by catalytic conversion of methane is aluminum oxide and mixed oxides including nickel, cerium, zirconium and iron oxides and having the following composition by weight: - mixed oxide - not more than 20% by weight - alumina - the rest of the composition 3. The method of processing natural gas into fuels according to claim 2, characterized in that the sorbent catalyst is in the form of granules having a surface area of 100 - 200 M ² / g. 4. The method of processing natural gas into fuels according to claim 1, characterized in that the regeneration of the sorbent catalyst is carried out at a temperature of 500-600 ° C in a stream of gases containing 1-5 vol.% Oxygen until saturated with oxygen, which ends with the termination of oxygen uptake by the catalyst.