The Research Of Modified B-ZSM-5for Methanol To Propylene

Recent years, propylene has been more and more important chemical raw material, and the demand for propylene is increasing largely, however, traditional producing methods of propylene can’t meet the rates of the increasing demand. Methanol to propylene (MTP) has the advantages below:mild reaction condition, cheap raw material, relatively higher selectivity of propylene, and so on. Many research have been done, because of the structure character of ZSM-5, it’s suitable for MTP reaction, so it’s more popular now. Many research are focused on the acid character and the amounts of acid. We took B-ZSM-5as catalyst, the active side of B-ZSM-5have been preliminarily studied, and also the synthesis of catalyst has been studied, in detail, we used different templates and different methods to synthesis catalysts, to see the influences of the factors. The preferred catalyst was modified with active components, the active components was referred to different metallic elements and non-metallic elements.The experiment of the effect of internal and external diffusion, proved that it’s necessary to choose the10-20mesh as the catalyst size, and1g as the amounts of the catalyst packing for the size of8mm which is the inner diameter of reaction tube, accordingly,5g as the amounts of that for the size of13.8mm, which is also the inner diameter of reaction tube.Comparing the pure B-ZSM-5with B-Al-ZSM-5, which were used for MTP reaction, we proved that the framework aluminum is important for MTP reaction. For pure B-ZSM-5, after extrusion with Al2O3, and then was dipped with acid solution, it was active for MTP reaction, it is possible that the treatment with acid make the element aluminum into the framework. What’s more, for the element B in the catalyst B-Al-ZSM-5influenced the selectivity of propylene largely, via experiment, we proved that the B-Al-ZSM-5catalyst with high ratio of silica than aluminum, and low ratio of silica than boron benefit the MTP reaction.Using different templates to synthesis catalysts, via MTP reaction, we had the results that the catalyst synthesized with TPAB as the template was the best one, then is the catalyst used NBA as the template, but NBA is cheap, so it’s clear that the catalyst has the prospect of industrial application. Besides, we have proved that the crystallization time didn’t affect the catalyst performance, however, the performance of catalyst without aging is better than the one with aging.The catalyst synthesized with the template of NBA as the preferred catalyst, it was dipped with different metallic elements and non-metallic elements, via MTP reaction, the reaction temperature is500degrees centigrade, normal pressure, WHSV (methanol)=1h-1. The results showed that the performance of catalyst modified with Ce was the best one, and also the catalyst modified with Ce, whose content is2wt.%is the best one.