This work studied the direct synthesis of dimethyl ether from synthesis gas (CO/H2/Ar = 48/48/4 by mole) at low temperature (170-200 ºC). The experiment was carried out in the bench scale reactor over the hybrid catalysts of Cu/ZnO-HZSM5 via co-precipitation using ammonium carbonate as the precipitant agent and physical mixing method. Methanol was used as a catalytic solvent. The effects of reactors in series (1, 2 or 3 reactors), flow rate of synthesis gas (80, 120 and 160 ml/min), catalyst loading (5, 10 and 15 g), amount of methanol (10, 30 and 50 ml), catalyst size (355-500, 500-710 and 355-710 µm) and temperature (170, 180 and 190 ºC) on dimethyl ether synthesis were investigated. The performance indices to predict the synthesis of dimethyl ether was CO conversion. The result showed that CO conversion increased with increasing number of reactors, catalyst loading and decreasing flow rate of synthesis gas with 50 ml of methanol. The maximum CO conversion of 60% was provided by the condition of 5 g of catalyst loading per reactor, 50 ml of methanol, synthesis gas flow rate 80 ml/min and three reactors in series.
