| This paper maily focused on how to enhance catalytic performance of low-cost TS-1. Firstly, TS-1synthesized with sodium salts was tested. The propylene epoxidation on fixed bed shows that small amounts of sodium salts added in TS-1leads to an improvement of the selectivity of PO. For funther study, TS-1zeolites modified through impregnated method with different sodium salts aqueous were used in the epoxidation of propylene. It was found that the existence of sodion is benefit for TS-1catalyzed the propylene epoxidation with H2O2. When TS-1samples modified with Na2SO3, Na2CO3and NaNO3, the catalytic performance of corresponding TS-1samples were different. The TS-1modified by Na2CO3has the best catalytic performance, and then Na2SO3. The catalytic performace of TS-1modified by NaNO3is not so good, because of deactivation in short time. It implies that the anion of salts used in modification of zeolite could influence the catalytic performance of TS-1.The second part of this paper is a comparison study about some different modification methods. TS-1samples were characterized by means of XRD, UV-Vis, FT-IR, N2adsorption, NH3-TPD and SEM. And the epoxidation of propylene was used to evaluate the catalytic performance of different samples. Results obtained are as following:TS-1samples were treated by TPAOH, TPAOH/Na2SO3, TPABr/NaOH, respectively. The latter two showed better performance in epoxidation of propylene than the former one. Especially, TPABr/NaOH treatment is more economic. The H2O2conversion keeps98%and PO selectivity raises to90%, so that the space time Yield of PO reaches up to180g/(kgcat.·h). After100h of continuous reaction, the catalyst shows good catalytic stability.When NaOH replaced with KOH, TPABr/KOH treatment still has better catalytic performance than others such as TPAOH, KOH and TPAOH/KOH modification methods. It indicates that modification of TS-1by different inorganic base along with TPABr would increase the epoxidation capacity significantly. |
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