真空冷冻干燥法制备CuO－ZnO－Al_2O_3合成甲醇催化剂

METHANOL SYNTHESIS FROM CO_2+H_2 ON CuO-ZnO-Al_2O_3 CATALYST PREPARED BY VACUUM FREEZE DRYING

研究了用真空冷冻干燥法制备ＣｕＯ－ＺｎＯ－Ａｌ＿２Ｏ＿３催化剂，提出用叔丁醇代替水作介质的新方法，采用该方法可以使干燥速度显著加快。考察了反应温度、压力、空速及催化剂组成对ＣＯ＿２＋Ｈ＿２催化合成甲醇的影响。

The preparation of CuO-ZnO-Al_2O_3 catalyst by vacuum freeze drying wasstudied.A new method was proposed,in which t-butanol was used as solvent instead ofwater. The new method could be operated at-15℃,which is higher than-50℃ as in thecase of water, Therefore, drying speed was greatly enhanced.The synthesis of methanolfrom CO_2+H_2 was also studied.The effects of preparation method, catalyst composition andreaction conditions, such as temperature,pressure and space velocity, on activity andmethanol selectivity were investigated.The results indicated that the catalysts containing3%-8% Al_2O_3 and CuO/ZnO=1～2 show a higher activity and selectivity. A maximumvield of methanol was observed at about 240℃,2MPa,3600h￣(-1), which indicated that the re-action shifts from kinetic to thermodynamic limitation. Selectivity to methanol increased withincreasing space velocity.It suggested that methanol is produced directly from the hydro-genation of CO_2 rather than from CO formed by reverse watergas shift reaction.