The method of producing formaldehyde

 

(57) Abstract:

The invention relates to the oil and gas industry, in particular to the field of utilization of associated petroleum gas, namely the technology of obtaining of formaldehyde in aqueous formalin solution. The aim of the invention is the utilization of associated gas that is flared at oil fields, reducing pollution, and improving the selectivity of the process for formaldehyde. The objective is achieved by the fact that for utilization of associated petroleum gas as an oxidation catalyst is used maintenability catalyst supported on silica gel in the amount of 0.15 to 1% by weight of the carrier, and the oxidation is carried out at a temperature of 600-650oC when the content of methane in methane-air mixture 26-35 about. % .

The invention relates to the oil and gas industry, in particular to the field of utilization of associated petroleum gas, namely the technology of obtaining of formaldehyde in aqueous solution of formalin.

A known method of producing formaldehyde by the oxidation of methane with oxygen at a temperature 520-670oC and a pressure of 0.1-5.0 MPa in a stationary catalyst bed where the cat is . The yield of formaldehyde is 3.5% selectivity to formaldehyde 38,0% methane conversion of 6.7% [1]

The disadvantages of this method of producing formaldehyde are: low selectivity for formaldehyde and low methane conversion, and the application of increased pressure and oxygen as oxidant.

Closest to the proposed method is a method of producing formaldehyde by oxidation of natural gas with oxygen at elevated temperature in the presence of the oxide catalyst in a fluidized bed when the catalyst is used molybdenumalloy catalyst supported on silica gel. The catalyst composition: Moa, WbOcwhere a=1-2, b=1, c is determined by the valency and the process is conducted at 650-700oC and the methane content in the mixture to about 6-20. Feed space velocity of methane-air mixture 3000-4000 h-1the conversion of methane to 13.2-33% at capacity 46-65,6% [2]

The disadvantages of this method [2] is the low selectivity to formaldehyde and the use of high concentrations molibdenovokislogo catalyst (35 wt.), supported on silica gel.

The aim of the invention is the utilization of associated gas is electively process for formaldehyde.

This objective is achieved in that for utilization of associated petroleum gas as an oxidation catalyst is used maintenability catalyst supported on silica gel in the amount of 0.15 to 1% by weight of the carrier, and the oxidation is conducted at temperatures 600-65oC when the content of methane in methane-air mixture 26-35 about.

The process is carried out in a reactor made of stainless steel (18CR10NITI) in a stationary catalyst bed. The catalyst loading to 0.72 g (0.5 cm3). Feed space velocity of methane-air mixture is 6000-7000 h-1. Formaldehyde and water vapor condense with fridge, water-cooled, and collected in a glass receiver.

Example 1. The preparation of the catalyst. The estimated number of paramolybdate ammonium (NH4)6Mo7O244H2O dissolved in distilled water upon acidification of the solution with hydrochloric acid to pH 4-4,5 when the temperature of the solution 60-70oC. Then enter the required amount of cobalt acetate Co(C2H3O2)24H2O to achieve a molar ratio of Mo:Co is 10:1. In all experiments, this ratio remains constant, the only change is in the content of these salts in solution to receive mogannam solution of the catalyst is impregnated with crushed silica gel (0.5-1 mm) at a temperature of 60-70oC. the Solution is evaporated under stirring and then the granules of the catalyst is kept in an oven at 100-110oC. This catalyst load when the temperature of the experience 600-650oC when the flow of 1.5 l/g steam-air mixture with a water content of about 5.

The estimated number of paramolybdate ammonium (NH4)6Mo7O244H2O number 0,160 g (0,0038 g in terms of cobalt) to achieve a molar ratio of Mo:Co equal to 10:1. The obtained homogeneous solution of the catalyst, where the cations Mo6+and Co2+present in the form of salts, impregnated with 100 g of crushed silica gel (0.5-1 mm) at a temperature of 60-70oC. the Solution is evaporated under stirring and then the granules of the catalyst is kept in an oven at 100-110oC.

In all the following examples, the molar ratio of Mo:Co remains constant (10:1), the only change is the absolute content of these salts in solution to obtain maintenability catalysts with the content of 0.15 to 1 wt. by weight of silica gel.

Examples 2-6 illustrate the effect of the concentration molibdenovokislogo catalyst on silica to yield formaldehyde and selectivity of the process.

Example 2. The catalyst is prepared analea process 650oC, the methane concentration of about 30. in methane-air mixture, the volumetric rate of feed of the mixture of 3.7 l/h Output of the reaction products about. CO23,96; HCHO 20,5. The selectivity to formaldehyde is 83.8% methane Conversion 20,45 mol.

Example 3. The process is carried out analogously to example 2, only the content molibdenovokislogo catalyst 0,25. by weight of silica gel. The output products of the reaction,about% CO24,95; HCHO and 9.2. Selectivity for formaldehyde 65,0% Conversion of methane to 22.6 mol.

Example 4. The process is carried out analogously to example 2, only the content molibdenovokislogo catalyst of 0.5 wt. by weight of silica gel. The output products of the reaction, about. CO22,9; HCHO and 12.4. The selectivity to formaldehyde 81% Conversion of methane to 14.6 mol.

Example 5. The process is carried out analogously to example 2, only the content molibdenovokislogo catalyst 1 wt. by weight of silica gel. The output products of the reaction, about. CO22,4; HCHO 17,4. The selectivity to formaldehyde 87,9% Conversion of methane to 7.0 mol.

Example 6. The process is carried out analogously to example 2, only the content molibdenovokislogo catalyst 1.5 wt. by weight of silica gel. The output products of the reaction,about% CO22,5; HCHO is 14.6. The selectivity of the process formald the IDA and the selectivity of the process.

Example 7. The process is carried out analogously to example 2, and the content of catalyst as in example 3 except that the temperature of the process 550oC. the Yield of the reaction products, about. CO20,5; HCHO 2,94. Selectivity for formaldehyde 85,5% Conversion of methane to 1.7 mol.

Example 8. The process is carried out analogously to example 2, the content of the catalyst according to example 3 except that the temperature of the process 600oC. the Yield of the reaction products, about. CO20,9; HCHO of 7.85. Selectivity for formaldehyde 89,7% Conversion of methane to 2.9 mol.

Example 9. The process is carried out analogously to example 2, the content of the catalyst according to example 3 except that the temperature of the process 650oC. the Yield of the reaction products about. CO24,95; HCHO and 9.2. Selectivity for formaldehyde 65,0% Conversion of methane to 22.6 mol.

Examples 1,10, 11, 12 illustrate the effect of the concentration of methane in methane-air mixture at the exit of formaldehyde and selectivity of the process.

Example 10. The process is carried out analogously to example 2, only the concentration of methane in methane-air mixture is about 26. CO21,16; HCHO 14,1. Selectivity for formaldehyde 92,4% Conversion of methane to 6.3 mol.

Example 11. The process is carried out analogously to example 2, only the concentration of methane in methane is ASS="ptx2">

Example 12 (comparison). The process is carried out analogously to example 2, only the concentration of methane in methane-air mixture is about 15. The output products of the reaction,about. CO24,9; HCHO 13,0. Selectivity for formaldehyde to 72.6% Conversion of methane to 14.3 mol.

The proposed method allows to dispose of gas flared in the field, useful for the chemical industry connection formaldehyde increases the selectivity of the process to 92% vs. 65.6% in the known method, and also simplifies the process by reducing the temperature of 600-650oC against 650-700oC in a known way.

The method of producing formaldehyde by oxidation metadatareader gases oxygen in the presence of a molybdenum-containing catalyst at elevated temperature, characterized in that the catalyst used maintenability catalyst with a molar zootechnie Mo From 10 to 1, and applied to the silica gel in an amount of 0.15 to 1.0 wt. and oxidation is carried out at a temperature of 600 to 650oWhen the content of methane in methane-air mixture 26 35 about.

 

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