水蒸汽对PtSn／Al2O3催化剂结构及反应性能的影响

比较研究了Ａｌ２Ｏ３负载的铂及ＰｔＳｎ催化剂在氮气及水蒸汽稀释条件下的丙烷脱氢性能，并利用ＸＰＳ及氢脉冲吸附对催化剂进行了表征。结果表明，水蒸汽可促使Ｐｔ／Ａｌ２Ｏ３催化剂的铂晶粒烧结。与在氮气氛中相比，在水蒸汽存在下反应显著提高了Ｐｔ／Ａｌ２Ｏ３的丙烷转化率，却降低了丙烯的选择性。另一方面，水蒸汽可调变ＰｔＳｎ／Ａｌ２Ｏ３催化剂的结构，破坏了ＰｔＳｎ／Ａｌ２Ｏ３中与锡相互作用的铂簇团结构。从而导

Effect of Steam on the Structure and Performance of PtSn/Al2O3 Catalysts

PtSn/Al2O3 catalysts prepared by coimpregnation with nominally 0.35% Pt and different contents of tin (02.5%) were tested for propane dehydrogenation in the presence of steam and nitrogen, respectively. The results showed that the addition of steam instead of nitrogen enhances the conversion of propane obviously and suppresses the selectivity to propene over the Pt/Al2O3 catalyst, as well as decreases the activity of PtSn/Al2O3 in propane dehydrogenation. Hydrogen chemisorption results indicated that the amount of high temperature adsorption sites of PtSn/Al2O3 catalysts decreases upon pretreatment by steam. XPS showed that the steam treatment modified the distribution and nature of the surface Cl- of PtSn/Al2O3. These results suggested that the decrease of the activity of the PtSn/Al2O3 for propane dehydrogenation in steam could be, probably, ascribed to the steam destruction of active Pt ensembles which are able to interact with tin.