Hydrogenation of carbon dioxide into methanol on a Cu/Zn/Al_2O_3 catalyst in a fixed-bed reactor

摘要

The catalytic hydrogenation of CO_2 to CH_3OH has a bright prospect along with high market demand. Methanol (CH_3OH) was needed as raw material in the petrochemical industry to produce formaldehyde, chloromethane, amine acetate and also as an new alternative environmentally friendly energy. This study aims to obtain a Cu/Zn/Al_2O_3 catalyst design and the effect of feed temperature on CO_2 conversion, CH_3OH selectivity, and CH_3OH yield. The preparation of Cu/Zn/Al_2O_3 catalysts by co-precipitation method resulted in the percentage ratio of Cu/Zn/Al metal composition of 66,7: 27,4: 4,29 and the catalyst surface area of 98,3411 m~2/g. The H_2:CO_2 ratio in the feed gas is 3: 1. The fixed-bed reactor has the dimension of 1.5 cm in inner diameter, 5 cm in length of reactor bed, and is equipped by a furnace upstream the reactor bed. The reaction was carried out at the pressure of 30 bar and the flowrate is kept constant. The feed temperature varies at 220, 250, 280 °C. At the feed temperature of 250 °C, the best performance is obtained: the CO_2 conversion of 21.8%, the CH_3OH selectivity of 82.76%, and the CH_3OH yield of 18.04%, which is reached after 240 minutes of the reaction (steady state).