CATALYTIC SYNTHESIS OF SYNTHESIS GAS FROM METHANE

Introduction. Methanol is considered one of the most important products of organic synthesis. It is widely used as a solvent, semi-finished product in the production of other organic products (formaldehyde, methyl methacrylate, methylamine, acetic acid, urea, etc.). Also, recently in the microbiological synthesis of proteins, methanol is widely used as raw material, an energy source, and also for the synthesis of a component of motor fuel-methyltretbutylefir (an effective antidetonator). Currently, methanol ranks 7-8 among other organic synthesis products in terms of production volume. Methods of processing methane: first, synthesis-production of gas and production of chemical products based on it; second, oxidation of methane ( natural gas) production of ethylene; third, direct catalytic oxidation of methane(natural gas)up to products containing oxygen. Let's focus on three alternative methods of producing methane-conversion and synthesis-gas. 1) Conversion with water vapour:

Conducting steam reforming of hydrocarbons has the following disadvantages: the high cost of superheated steam; formation of excess CO2. The synthesis of H2: CO = 3: 1 is suitable for the synthesis of gaseous ammonia and not suitable for the synthesis of methanol, acetic acid and hydrocarbons by the Fischer-Tropsch method.
2) Partial oxidation with oxygen: 4  has not yet been commercialized due to the lack of a long-term stable catalyst but is important in terms of CO2 loss. Methane synthesis gas and conversion with carbonate is a promising method for obtaining initial reagents for hydrocarbon production by the Fischer-Tropsch method.
Carbonate conversion of methane is also a promising method with the simultaneous use of two different greenhouse gases, which has significant environmental and economic implications. Another advantage of this method is that the process of carbonate conversion of methane is carried out at normal atmospheric pressure (0.1 MPa) at a temperature of 650-800 °C [4].
Hydrocarbons are produced from synthesis gas in two stages: In the next step, methanol is processed into gasoline or lower olefins. The process consists of three consecutive steps: At present, the reaction of producing hydrocarbons using the mutual conversion of carbon dioxide and water vapour at normal atmospheric pressure is of great interest to scientists. Schematically, this process can be represented by the following reaction equation: CH4 + CO2 → 2CO + 2H2 CO + 3H2 → CH4 + H2O 2CO + 5H2 → C2H6 + 2H2O CO2 + H2 → CO + H2O In general nMe + 3CO2 + 5H2O → CH4 + C2H6 + nMeO The implementation of this reaction is important not only from an energy point of view but also from an environmental point of view. In the chemical industry, which is used as a synthetic gaseous feedstock, two groups are isolated. The first group includes only processes aimed at hydrogen production. It is aimed at producing ammonia and hydrogen. The second direction deals with the production of gas and hydrogen in different proportions (Table 1). Synthesis gas is obtained by converting natural gas. There are the following methods of converting natural gas: steam, steam-oxygen; Paro is carbonate. In all the above transformations, the CO: H2 ratio is higher than 3. For steam transformations, the ratio CO:H2 and (CO+CO2):H2 is shown in Table 2. Experimental part. Analysis of gases was carried out by a Crystal 2000М chromatograph using thermal conductivity detectors and flame ionization detectors connected in series. Separation of the analysed mixture was carried out on a column filled with Porapak Q at the following temperature-programmable modes: determination of components Н2, СО, СО2, СН4 -Тколонки = 30°С; 60 °С, Тдетекторов=150 °С, assay time -1 min; determination of Н2О -column temperature rise to 110 °C (heating rate -40 °C per minute), analysis time -4 minutes. The rate of the reaction mixture, reaction products, argon carrier gas entering the reactor and chromatograph was measured by soap-foam flowmeters. The composition of the reaction mixture was measured after the catalyst reached a steady-state, which was judged by the constancy of chromatographic peak areas. The main indicators of the reaction were the conversion of methane, the consumption rate of methane, carbon dioxide and the formation of carbon monoxide and hydrogen. The quantitative interpretation was performed by absolute calibration using Chromatic Analyst 2.5. The number of moles of reagents and products in the analyzed dose was calculated using regression equations of the type: The content of products in the gas phase (the rate of formation of mol/(h * ha. f.)) was determined by the formula: Methane vapour-carbonate conversion was performed in a flow laboratory device. Experimental studies were carried out with the participation of a 2 cm 3 cylindrical reactor a catalyst with a diameter of 2 cm and a length of 20 cm.
Results and discussion. Tables 3-4 show the material balance of experiments for the hydrogen-to-hydrogen steam conversion of methane and carbon under various conditions. The material balances of hydrogen and carbon are the most important criteria for the reliability of experiments. It follows from the studies that the largest deviation in carbon is 4.0 ± 0.5%, in hydrogen-2.7 ± 0.5%. These are valid measures.  Various factors (CO2:CH4 ratio, temperature, initial space velocity and other factors, the yield of the desired product, process conversion and selectivity, and catalyst activity) were used to determine optimal conditions for the methane-tocarbonate vapour conversion reaction. the influence of promoters has been studied. As the amount of СО2 in the feed increases (except for stoichiometric ratios), the methane conversion varies within 96-99%. As the ratio CO2: CH4 increases, the conversion CO2 decreases to 88%. Based on the results obtained, it can be concluded that the optimal ratio of CO2: CH4 in the carbonate conversion reaction of methane is 1.5. Under these conditions, the maximum yield of CO is 96% and the yield of hydrogen is 92%. The effect of temperature on the rate of steam-carbonate conversion of methane was studied in the range 700-9000 °C with a pitch of 500 °C in the ratio CO2:CH4=1,5.
Based on the results of studies on the effect of temperature on the reaction of methane vapour carbonate conversion, it can be noted that the yield of synthesis gas, the conversion of starting materials and the selectivity of the process are the highest at 820 °C. the maximum hydrogen yield is 96%, the conversion of methane is 99.2%, the selectivity of the components of synthesis gas is 87-98%. The conversion of methane is 98.6% at a space velocity of 1000 h -1 . Above this, methane conversion is reduced due to saturation and coking of the active catalyst centre.
The reaction proceeds according to a radical mechanism. Therefore, the determination of the activation energy (Ea) of the catalytic methane carbonation reaction in the presence of the catalyst (Ni2O3)x*(Co2O3)y*(ZrO2)z*(B2O3)k/Al2O3 provides important information for evaluating the efficiency of the catalyst and the reaction mechanism. In this catalyst, the activation energy (Ea) of the methane vapour carbonate conversion reaction was determined.