SYNTHESIS OF A LOW-TEMPERATURE CONVERSION CATALYST OF CARBON MONOXIDE IN AMMONIA PRODUCTION

The processes of preparation of copper-zinc-aluminum catalyst for low-temperature conversion of carbon monoxide with water vapor in the production of ammonia have been investigated. It is proposed to use metal powders of copper and zinc, which were pretreated in oxalic acid solutions using ultrasonic treatment, to obtain a catalyst. It was established by X-ray phase analysis that during the ultrasonic treatment of copper and zinc powders in a solution of oxalic acid, hydrated oxalates of copper and zinc are formed. The temperature range of decomposition of a mixture of copper and zinc oxalates is significantly less than the decomposition of individual oxalates and is 290-360 degrees C, which indicates the possibility of cationic isomorphism and the formation of a solid solution of the CuxZn1-xC2O4 center dot yH(2)O type at the stage of heat treatment. Synchronous thermal analysis data indicates the presence of endo- and exothermic heat effects that accompany the calcination process. It has been shown that endothermic effects are due to the removal of water and the release of carbon monoxide, while exothermic effects are associated with the oxidation of carbon monoxide to dioxide and metal oxidation. The process of conversion of carbon monoxide with the formation of CO2 and H-2 is also possible. The temperature range and composition of the gas phase formed during the heat treatment of copper and zinc oxalates were determined by mass spectrometry. It has been proven that copper and zinc oxides can be partially reduced during the thermolysis of oxalates by gases that are released during calcination. The obtained oxides of copper and zinc are characterized by a high specific surface area, which is 60 and 80 m(2)/g, respectively. The catalyst obtained by oxalate technology is not inferior in its characteristics to industrial analogs. The CO conversion is 92% at an operating temperature of 220 degrees C, the specific surface area is 98 m(2)/g.