Study On The Design And Synthesis Of Silicoaluminophosphate Molecular Sieves

Compared with silicon-based molecular sieves,silicoaluminophosphate molecular sieve is a novel molecular sieve material.This material has attracted widespread attention and research,and has shown good performance in many catalytic aspects.This thesis mainly includes three parts.The overall research focuses on the synthesis and catalytic performance of silicoaluminophosphate zeolite,especially their synthesis routes.In the first part,this research proposes a new synthesis route for zeolites.The template reagent is designed according to the intermediates of known reactions to reversely synthesize molecular sieve materials suitable for the reaction.Three kinds of organic substances similar to the intermediate structure proposed in the hydrocarbon pool mechanism of MTO reactions were designed and used as structure-directing agents to hydrothermally synthesize the AEI-type SAPO-18 molecular sieves in the silicon-phosphorus aluminum system,and their physicochemical properties were investigated.The feasibility of zeolite synthesis between reaction intermediate and molecular sieve structure has been briefly addressed.The second part briefly introduces the reaction mechanism of methanol to olefin reaction,especially the hydrocarbon pool mechanism.The prepared SAPO-18 was used to catalyze the reaction of methanol to olefins,and the related catalytic performance was analyzed.The through a simple post-treatment,adjust the framework composition of SAPO-18 and load metal Cu for electrocatalytic reduction of CO₂.The third part is to further verify the synthetic route proposed in this thesis.An organic substance similar to the five-membered ring in the hydrocarbon pool mechanism was selected,and a zeolite suitable for the reaction of methanol to olefins was prepared in a silicon-phosphorus aluminum system.As a result,CHA-type SAPO-34,a typical zeolite for the reaction,was obtained.This further shows that the synthetic route proposed in this paper is universal.In addition,the synthesis conditions of SAPO-34 were also investigated in detail,and SAPO-34 with a size of about 200 nm was obtained.