Modification Of ZSM-5 And Its Study On The Reaction Of Methanol To Propylene

Propylene as a base material of our chemical industry and a strategic significance technology attracts wide attention.Since Mobil company was the earliest one to research the methanol into olefins on molecular sieves,Nowadays,MTP has been industrialized.However,the activity and life of catalyst have always been the research hotspot.In order to handle the problem of catalyst deactivation and further improve the selectivity for propylene and decrease the generation of aromatic hydrocarbons,a series of research work on the HZSM-5 has been carried out to achieve a more excellent catalyst.Therefore,my research work is as follows:?1?By optimizing type and concentration of organic acids,it has been found that the introduction of mesoporous will increase the specific surface area of the catalyst and acid treatment will change catalyst acid distribution that weak acid will increase and strong acid will decrease.In MTP conversion the prepared mesopore materials shows a lower paraffin and aromatic hydrocarbon selectivity and noticeable stability enhancement.?2?Comparing industrial molding catalysts,Aluminium phosphate?AlPO₄?bound HZSM-5 extrudates and Aluminium bound HZSM-5 were achieved,in addition the reaction temperature and element ratio had been optimized by condition experiment.Characterizations result shows that the binder not only contributes to catalyst shaping,but also it can introduce the large hole,which improves the problem of catalyst mass transfer.What is more,aluminum and phosphorus in binders can change the distribution of acid center and pore structure by adjusting molecular sieves of silica-alumina ratio.In MTP conversion,Al sol/ZSM-5 exhibits excellent stability because of unique pore structure,and AlPO₄/ZSM-5decreases the generation of by-products due to the change of acid center,especially for the ratio of olefin and paraffin.,which can provides a new clue to the optimization of industrial design MTP process.?3?On the base of Aluminium phosphate?AlPO₄?bound HZSM-5extrudates,a hydro-thermal treatment has been used for further enhance the catalyst.After the optimization of hydro-thermal time and water pressure,it has been found that hydro-thermal treatment can rearrange the catalyst pore structure.In addition,hydro-thermal treatment can promote hydrolysis of strong acid center.In MTP conversion,hydro-thermal treatment not only decrease the selectivity of paraffin and arene,but prevents the main product from inactivation and increase the ratio of C₃⁼/?C₃⁼+C₃^-?.