Fe、V助剂对CuO/Al_2O_3催化剂上CO_2加氢合成甲醇的影响

PROMOTION EFFECT OF Fe AND V ON CuO/Al_2O_3 CATALYST FOR METHANOL SYNTHESIS FROM CO_2 HYDROGENATION

在 3 63～ 473 K,0 .1 MPa压力下 ,研究了 Cu-Fe-V2 O5/ Al2 O3催化剂上 CO2 催化加氢反应 ,对这些催化剂进行了 XRD及 TPR表征 ,并对 XRD结果和 TPR的“ROR”(还原 -氧化 -还原 )过程进行分析。结果显示 :在铜基催化剂中加入 Fe、V使其在 5 0 0 K以下的活性和选择性大为提高 ,且明显改善铜物种的分散度 ,影响催化剂表面的酸度。Fe、V浸渍的先后顺序对催化剂的性能亦有影响。Fe、V的加入及不同的浸渍顺序可能对催化剂上 Cu、Fe、V的分布状态及其相互作用有影响。室温下 ,催化剂上活性铜物种含量增加 ,有利于 H2的解离吸附及 CO2 的配位活化。

The effect of Fe and V promoters on the CuO/Al 2O 3 catalysts were studied by CO 2 hydrogenation,XRD and TPR techniques.It is found that the catalytic activity and selectivity of the catalysts containing Fe and V both obviously increased below 500K,and the catalyst prepared by the following procedure is much better:(Ⅰ) the impregnation of γ Al 2O 3 with V 2O 5 in saturated oxalic acid aqueous solution,(Ⅱ) with Fe(NO 3) 3 aqueous solution and (Ⅲ) with Cu(NO 3) 2 aqueous solution.Fe and V promoters appear to have synergistic effect in the titled reaction.XRD and TPR analysis show that Fe and V promoters are both well dispersed on the surface of Al 2O 3, which could enhance the dispersion of Cu species.Highly dispersed Cu species which could be oxidized at room temperature is probably responsible for high low temperature activity.