Furthermore, they found that the CO2 hydrogenation rate
was much lower than the CO hydrogenation rate, and this
affected methanol production. However, CO2 decreased the
WGS reaction rate; this prevented methanol conversion into
dimethyl ether, a by-product. By this way, a small fraction of
CO2 accelerated the production of methanol indirectly within
a limited range, showing a threshold value of the CO2 fraction
for maximum methanol synthesis