The Investugation On The Preparation Of Platinum-based Catalysts For Dehydrogenation Of Propane

As we all know,propylene is an important basic chemical raw material,which can be used to prepare polypropylene,acrylonitrile,acetone,propylene oxide and a series of common basic chemical products.In recent years,with the improvement of production technology and the rapid increase of social market productivity,the demand for propylene is on the increase.At present,naphtha pyrolysis ethylene by-product is still the most important source of propylene,followed by petroleum catalytic cracking by-product,but the yield of propylene is low because of the by-product of the two technologies.In order to meet the increasing demand of propylene,propane dehydrogenation technology(PDH)development is imperative.At present,the process technology is widely studied and applied in the world,and has brought significant economic value to the petrochemical industry.Among the catalysts for propane catalytic dehydrogenation to propylene,Pt-based catalysts have been widely studied due to their advantages in various aspects.This paper mainly focuses on propane dehydrogenation reaction,studies the influence of platinum-based catalyst on its reaction performance,conducts a systematic investigation on the preparation factors of platinum-based catalyst,as well as the factors such as catalyst support agent to optimize the modified catalyst,so as to develop a catalyst with excellent performance suitable for propane catalytic dehydrogenation reactionIn this paper,Pt-based propane dehydrogenation catalyst was prepared by alumina as the support,and the traditional propane catalytic dehydrogenation process was systematically studied,so as to explore the better propane dehydrogenation performance under the condition of hydrogen presence under the catalytic reaction conditions.In the process of preparing platinum-based catalyst,the influence of PtSn ratio,roasting temperature and other factors on the propane dehydrogenation reaction performance of the catalyst was investigated.Among them,the optimal PtSn ratio was 5:1,the suitable roasting temperature of the support was 600?,and the catalytic reaction performance test showed that the propane conversion rate was more than 30%,the propylene selective in more than 78%The catalytic performance of the catalyst was improved by adding other metal auxiliaries.In this paper,the influence of M content on the dehydrogenation performance of catalyst was further investigated.It was found that when M content was 1.5wt%,the propane conversion rate was slightly reduced by about 28%,but the propylene selectivity was significantly improved by more than 85%.However,as the alkali metal M content continued to increase to 2.0wt%,the acidity of the catalyst was seriously poisoned and the catalyst activity was seriously reduced,especially the propane conversion rate was reduced to 20%This paper continued to optimize the catalyst support to improve the propane dehydrogenation performance of catalyst.PtSn/ZSM-5 catalyst and PtSn/ATn catalyst were prepared and their propane dehydrogenation performance was evaluated.The influence of acidity in zeolite was investigated,and the influence of Si-Al ratio on the reaction performance of ZSM-5 zeolite catalyst was further investigated.It was found that the supported catalyst of ZSM-5 zeolite could optimize its catalytic stability and propane conversion.However,the selectivity of propylene was seriously reduced,which did not lead to better optimization of catalyst performance for propane dehydrogenation.In order to improve the selectivity of propylene,the paper continued to explore related work.The composite TiO2-Al2O3 supports with different content of TiO2 prepared by the sol-gel method were employed to fabricate the PtSn supported catalysts for propane dehydrogenation to propylene.The results of catalyst activity tests indicated that the addition of TiO2 in the Al2O3 support can significantly improve the dehydrogenation performance over the obtained catalysts,especially the PtSn/AT20 catalyst with the 20 wt%addition of TiO2.The TiO2 with appropriate addition amount in the composite support would result in proper acidity of the catalyst for balancing the formation of coke,side reactions and the reaction performance during the PDH reaction.Moreover,the enhanced metal-support interactions between the active component and the composite support could be achieved for improving the dispersion of Pt-Sn on the support,and preventing the Pt aggregation during the reduction and regeneration process.The results from this study could enlighten us to develop novel catalysts for seeking the superior catalytic performance in the reaction of propane dehydrogenation to propylene.