KINETICS OF THE SYNTHESIS OF METHANOL FROM CO-BASED AMORPHOUS CATALYSTS(H2 AND CO+CO2+H2 OVER COPPER)

The catalytic behaviour of amorphous alloys (prepared by spark-erosion ) for the synthesis of methanol from mixtures of H-2 + CO and H-2 + CO + CO2 was studied at 10 bar and 200, 225 and 250-degrees-C. Measureme nts of the rates of methanol production from feeds containing from 0 t o 20 mol% CO2, at a constant H-2 : CO ratio, quite surprisingly reveal ed that the presence of carbon dioxide resulted in a large increase in the rate of production of methanol. For a catalyst of composition Cu7 0Zn30, maximum rates were observed at 2 mol% CO2, whereas for a Cu70Zr 30 catalyst, the activity increased with increasing CO2 contents, up t o 10 mol%. These results suggest that with these catalysts the hydroge nation of carbon dioxide is significantly faster than that of carbon m onoxide. Two models for the kinetics of methanol production have been developed from mechanistic considerations reported recently in the lit erature. It turns out that it is best to describe the rate of formatio n of methanol from H-2 + CO and H-2 + CO + CO2 as a combination of the se two models; this corresponds to a mechanism whereby CO2 is the sour ce of carbon for methanol from a mixture of H-2 + CO + CO2.