制备条件对铂纳米簇-锡催化剂催化丙烷脱氢性能的影响

结合溶胶凝胶法和化学还原法制备了负载型Pt纳米簇-Sn丙烷脱氢催化剂。基于催化剂的活性评价和BET、XRD、吡啶吸附红外光谱、TG等表征结果考察了载体干燥时间、制备方法、助剂Sn等对Pt纳米簇催化剂催化性能的影响。结果表明,当m(聚乙烯基吡咯烷酮):m(Pt)=30:1,浸渍时间8 h,负载型Pt/SiO_2催化剂表现出较好的催化性能;Sn助剂的添加对Pt/SiO_2催化剂的反应性能影响显著,添加适量Sn不仅增加了催化剂中的Brφnsted酸中心和Lewis酸中心,而且显著抑制了催化剂上的积碳,明显改善了催化剂的稳定性和催化活性。反应30 h后催化剂N(Sn):N(Pt)=25]的丙烷转化率和丙烯选择性仍分别稳定在18.8%和93%。

EFFECT OF PREPARATION CONDITIONS ON CATALYTIC PERFORMANCE OF Pt NANOCLUSTER-Sn CATALYST FOR PROPANE DEHYDROGENATION

Supported Pt nanocluster catalysts for propane dehydrogenation were prepared by combining a sol-gel method and a chemical reduction method.Based on the performance evaluation and the characterizations with BET,XRD,pyridine IR absorption spectrum and thermogravimetric analysis,the effects of the support drying time,preparation method and promoter Sn added on the catalytic activity of the catalysts were investigated.The results indicated that the catalysts prepared under the conditions of m(PVP):m(Pt)=30 and impregnation time 8 h gave high catalytic activity;addition of Sn had significant influence on the catalytic activity of the catalysts:a suitable amount of Sn added not only increased the Br(?)nsted acid sites and moderate/strong Lewis acid sites,but also prevented the catalyst from coking and significantly improved the catalyst activity and the stability.Propane conversion and propene selectivity were still maintained at 18.8%and 93%,respectively,after on stream for 30 h over the catalyst with N(Sn):N(Pt) ratio of 25.