助剂对Pt/γ-Al_2O_3催化剂丙烷脱氢性能的影响

采用一系列金属氧化物助剂(Ce,Sn,Zn,V,La,C r,Fe,Zr,M n的氧化物)对Pt/γ-A l2O3催化剂进行修饰,通过丙烷催化脱氢反应考察了不同助剂对Pt/γ-A l2O3催化剂脱氢性能的影响。研究结果表明,经修饰的Pt/γ-A l2O3催化剂的脱氢性能有不同程度的改善。加入CeO2,SnO2,ZrO2助剂,Pt/γ-A l2O3催化剂的丙烷脱氢活性显著提高,丙烷的初始转化率分别提高了9.2%,8.2%,8.1%;加入ZnO助剂,丙烯选择性显著提高,丙烯初始选择性高达97%;SnO2助剂对改善Pt/γ-A l2O3催化剂的稳定性效果最好。采用氢气程序升温还原对催化剂进行表征,表征结果显示,金属氧化物助剂经还原后仍以氧化态形式存在,未以单质形式与铂形成合金。

Effect of Promoters on Dehydrogenation of Propane over Pt/γ-Al2O3 Catalyst

Effect of several oxide promoters(oxides of Ce,Sn,Zn,V,La,Cr,Fe,Zr and Mn)on dehydrogenation of propane over Pt/γ-Al_2O_3 catalyst was investigated.Most of promoters could improve catalytic performance of Pt/γ-Al_2O_3 in propane dehydrogenation.Addition of CeO_2,SnO_2 and ZrO_2 to Pt/γ-Al_2O_3 catalyst could greatly increased its activity and initial conversion of propane could be raised from 34.10% to 43.26%,42.27% and 42.18% respectively over catalysts with above promoters.The initial selectivity to propylene could reach 97% when dehydrogenation was carried out over Pt-based catalyst containing ZnO promoter.Addition of SnO_2 promoter to Pt-based catalyst made the catalyst the most stable in propane dehydrogenation.The catalysts were characterized by means of temperature-programmed hydrogen reduction(H_2-TPR).The results indicated that promoters still existed in oxidative state after catalyst was reduced and Pt-alloy did not form.Performance of the catalyst could therefore be improved.