In the liquid-phase dimethyl ether process, methanol synthesis catalyst (Cu / ZnO / Al2O3) and methanol dehydration catalyst (gamma-alumina) are slurried in an inert liquid medium. The inert liquid medium used in this investigation is a white mineral oil, Witco-40. This multiphase reaction is conducted in a mechanically agitated slurry reactor. In this process, syngas conversion can be significantly improved by coproduction of dimethyl ether along with methanol. The coproduction strategy improves the thermodynamic and kinetic environment of the reaction system. The effects of catalyst loadings in the slurry and the roles played by carbon dioxide in dimethyl ether synthesis were studied by conducting kinetic experiments. The liquid-phase dimethyl ether synthesis process exhibits higher carbon dioxide tolerance as compared to the liquid-phase methanol synthesis process, whose optimal carbon dioxide concentration in the unbalanced syngas feed is around 8%. These results have been experimentally confirmed.