助剂铈对Rh-V/SiO_2催化剂催化CO加氢性能的影响

Effects of Ce and V promoters on catalytic behaviors of Rh/SiO_2 catalyst for CO hydrogenation to C_2 oxygenates

研究了助剂Ce和V对Rh/SiO2催化剂催化CO加氢合成乙醇等C2+含氧化合物的性能的影响。用程序升温脱附(TPR)、CO吸附和程序升温脱附(CO-TPD)对催化剂进行了表征。结果表明,助剂Ce、V的加入显著提高了Rh/SiO2催化剂的活性和选择性,助剂Ce或V的添加抑制了Rh组分的还原,而Rh组分促进了V组分的还原。催化剂最佳w(Ce)为0.5%,此时Rh分散度较高,弱吸附的CO数量较多,从催化剂上脱附出来的未解离CO数量也较多,从而促进了CO插入,提高了催化剂的活性和乙醇等C2+含氧化合物的选择性。w(Rh)=1.0%、w(Ce)=0.5%、w(V)=1.0%的Rh-Ce-V/SiO2催化剂的乙醇选择性和C2+含氧化合物时空产率分别达到31.9%和316.7g/(kg·h)。

The effects of Ce and V promoters on the catalytic behaviors of the Rh/SiO2 catalyst for synthesis of C2 oxygenates （ethanol, etc.） from CO hydrogenation were investigated. The techniques of temperature programmed reduction （TPR）, pulse adsorption of CO and temperature programmed desorption of CO （CO-TPD） were used to characterized the catalysts. The results showed that the addition of Ce and V promoters enhanced the selectivity to C2＋ oxygenates. Ce and V inhibited the reduction of Rh, and Rh promoted the reduction of V. The suitable dosage of Ce was 0.5% by mass. At this amount, the Rh dispersion was well and the numbers of the weak-adsorbed CO on the catalyst and the undissociated CO desorbed from the catalyst were larger that increased CO insertion and the selectivity to ethanol and other Cz＋ oxygenates. The selectivity to ethanol and the yield of C2, oxygenates for the optimized Rh（1.0）-Ce（0.5）-V（1.0）/SiO2 catalyst were 31.9% and 316.7g-1 kg-1. hl, respectively.