STUDY OF PROPERTIES OF CuO-ZnO-Al2O3 CATALYSTS FOR METHANOL SYNTHESIS

In this work, a comprehensive study of modern industrial catalytic systems of the MM-7 and K brands was carried out. The best sample, the catalyst of the MM-7 brand, was investigated before and after 5 years of commercial exploitation in a large-scale methanol synthesis unit. To study the physicochemical characteristics of the catalysts, the methods of X-ray phase analysis, scanning electron microscopy, low-temperature nitrogen adsorption-desorption, Hammett indicator method, and gas chromatography were used. Temperature-programmed recovery of the samples was carried out. The paper presents data on the phase composition of catalysts, their morphology, specific surface area, dispersion and size of copper particles. It was found that the MM-7 catalyst in terms of its physicochemical characteristics and catalytic activity is better than the K catalyst. The study of the spent catalyst after 5 years of commercial exploitation showed that the loss of activity occurs due to thermal deactivation and poisoning with catalytic poisons - sulfur compounds. The catalytic activity of the sample was evaluated by the specific productivity for methanol in the catalytic high-pressure unit PKU-2. The conditions of experiment were as close as possible to industrial ones: the pressure in the reactor was 2.0 MPa the range of the investigated temperatures was 200-300 degrees C, and the volume hourly space velocity of 8705 h(-)(1). The specific productivity for methanol is reached 0.07 mu mol/gcat.s at 260 degrees C. The data of the samples on the selectivity to methanol are also given. The maximum selectivity for methanol is reached with a catalyst of the MM-7 brand and is 98.7% at 220 degrees C. Methane and dimethyl ether have been identified as by-products at the methanol synthesis.