Study On The Double-templated Synthesis And The Mild Rege Neration Of Ti-HSZ Zeolite Molecular Sieve

Epoxides are a kind of very important organic chemical raw materials and intermediates,and their efficient synthesis has always occupied a very important position in organic chemistry.In 2016,our research group synthesized Ti-HSZ by one-step rotary hydrothermal synthesis.Ti-HSZ not only has high catalytic activity for the conversion of small olefin,but also shows excellent catalytic performance in the epoxidation of macrocyclic monolefin and linear macroolefin molecules.It also has the advantages of environmental friendliness and excellent performance.However,the organic template agent for the preparation of Ti-HSZ molecular sieve is piperidine,which is used as the catalyst for the synthesis of organic template agent with high chemical cost.Therefore,it is necessary to replace a commercially feasible organic template agent with a lower price than piperidine.In this paper,Ti-HSZ zeolite molecular sieve was synthesized by double template agent method.Ti-HSZ zeolites were synthesized with little or no piperidine content.Firstly,the Ti-HSZ zeolite was synthesized by one-step rotational hydrothermal synthesis of hexamethyleneimine(HMI)and piperidine(PI).When PI content is only 5% of the molar fraction of the template and the synthesis time is 3.5d,the Ti-HSZ zeolite with good catalytic performance can be synthesized.By further studying the synthesis conditions of the double template agent,we determined the ratio of synthetic gel,the rotation speed and the range of synthesis time required for the synthesis of 5% Ti-Hz-HP.It was found that the original ratio of synthetic gel,the rotation speed and the synthesis time were still suitable after the replacement of the template agent.Secondly,Ti-HSZ zeolite molecular sieve was synthesized by one-step rotational hydrothermal synthesis of hexamethyleneimine(HMI)and dicyclohexylamine(DCHA)as two template agents to further reduce the PI content in the template agent.It is found that Ti-HSZ zeolites with good catalytic performance can be obtained when the molar fraction of DCHA is 9%,the ratio of water to silicon is 30,and the synthesis time is 4.5 d.It is confirmed that Ti-HSZ zeolite molecular sieve can be synthesized without PI in the template.In addition,the regeneration method and cycle stability of Ti-HSZ catalyst were studied in this paper.By changing the content of hydrogen peroxide in the original regeneration method,an effective catalyst recycling method which can reduce the cost of regeneration was developed.