【作者】 司莎；

【导师】 隋志军；

【作者基本信息】 华东理工大学 ， 化学工程， 2012， 硕士

【摘要】 Pt-Sn双金属催化剂是应用最为广泛的丙烷脱氢催化剂,但这种催化剂上仍存在结焦失活现象。因此Pt-Sn催化剂的构效关系以及催化性能改进仍是近年来本领域的研究热点。本文以NaBH4为还原剂的采用化学还原法制备了非负载、γ-Al2O3和纳米碳管负载的具有不同组成和结构特征的Pt-Sn体相合金(金属间化合物)以及γ-Al2O3负载Pt-X (X=Ir、Co)合金催化剂；采用XRD、N2物理吸附、HRTEM、氢气化学吸附以及TPO-TPR等方法表征了催化剂结构,并考察了其催化丙烷脱氢反应性能。研究结果表明本文方法可以制备出非负载与负载的PtSn、PtSn2、Pt2Sn3以及PtSn4合金,所得合金晶相结构较为单一,Pt/Sn比与前驱体溶液中类似；γ-A1203负载的合金催化剂中,催化活性随着Pt/Sn比的降低而增加,L-PtSn/Al-B(Sn：Pt为4.3,Pt理论负载量为1wt%的y-Al2O3负载Pt-Sn催化剂)具有最高的催化活性,其初始活性(TOF=0.39)低于类似粒径的单Pt催化剂L-PtSn/Al-F (TOF=0.43),但合金催化剂稳定性高,3小时反应后活性均高于单Pt催化剂,其中3小时的L-PtSn/Al-B的TOF为0.35,L-PtSn/Al-F的TOF为0.17；纳米碳纤维负载的各种PtSn合金催化剂其活性和丙烯选择性均高于γ-Al2O3负载催化剂；采用本文制备方法所得PtCo和PtIr合金催化剂没有观察到核壳式结构的存在,其催化稳定性和选择性均高于单Pt催化剂。本文研究结果对于阐释PtSn合金的形成与Pt-Sn双金属催化剂的催化剂失活的关系以及高性能丙烷脱氢催化剂的开发具有重要的借鉴意义。更多还原

【Abstract】 Supported Pt-Sn bimetallic catalyst is one of the widely used catalysts in propane dehydrogenation process. Although it has been industrialized for many years, this catalyst still suffers from coking and deactivation. Many research work has been focused on the structure-performance relationship and improving catalytic performance. Unsupported,γ-Al2O3 and carbon nanotube supported PtSn bulk alloy (intermetallic compound) with different compositions and structural properties and Pt-X (X=Ir, Co) nanoalloy were prepared by chemical reduction method using NaBH4 as reduction agents. All the catalysts were characterized by XRD, N2 physisorption, HRTEM, H2 chemisorption and TPO-TPR methods and tested in propane dehydrogenation. It was found that PtSn, PtSn2, Pt2Sn3 and PtSn4 bulk alloys could be synthesized by the method used in this article. The obtained alloys had single crystallinity and the Pt/Sn ratios in these alloys were similar to those in the precursor solutions. The activity ofγ-Al2O3 supported alloy catalyst increased with the decrease of Pt/Sn ratio. Supported PtSn4 catalyst had the highest activity. Though its initial activity is lower than that of single Pt catalyst, the alloy catalyst had higher stability and activity after 3 hours reacting than that of Pt catalyst. Carbon nanotube supported PtSn alloy catalyst has higher performances thanγ-Al2O3 supported catalysts. Core-shell structure was not observed in Pt-Co and Pt-Ir alloy prepared in this article and their catalytic perfromances is inferior to PtSn alloys. The results obtained here were helpful for illustration of the effect of occurrence of PtSn alloys in Pt-Sn bimetallic catalysts on the catalyst deactivation and maybe useful for the development of highly efficient propane dehydrogenation catalyst.更多还原