Titanium Silicalite-1Catalyzed Allyl Choride Epoxidation To Epichlorohydrin In Fixed-bed Reactor

Epichlorohydrin is an organic synthetic intermediate with many uses. In currentindustrial processes, three main manufacturing routes are: the method via allylacetate, the high temperature chlorination of propylene and glycerol method. Theseprocesses are not suitable in terms of sustainable development. TS-1catalyzedepoxidation of allyl chloride with hydrogen peroxide to epichlorohydrin is a simpleand high selective process, which has a lot of advantages, such as mild conditions,environmentally-friendly, etc. This process will be the main method for theproduction of epichlorohydrin in the furture.In this work, TS-1was prepared through hydrothermal synthesis and shapedinto SiO2-supported TS-1through extrudation and studied in the epoxidation of allylchloride in a fixed-bed reactor. First, the effects of reaction temperature, methanolconcentrations and hydrogen peroxide concentrations on the conversion and productselectivities were investigated; Second, in order to investigate the reason of thecatalyst deactivation in allyl chloride epoxidation, the fresh, deactivated andregenerated catalysts were characterized by XRD, FT-IR, UV-Vis, SEM and TG.Then the deactivated catalyst was regenerated by solvent washing, oxidation andhigh temperature calcination. Finally, the kinetics of the catalyst decay for thisreaction were studied.The results showed that the reaction temperature, methanol concentration andhydrogen peroxide concentrations had no effect on the epichlorohydrin selectivity.However, the catalyst stability was improved with increasing the reactiontemperature and methanol concentrations, and decreasing hydrogen peroxideconcentrations.The catalyst deactivation is not due to the damage of the zeolite framework orthe loss of the framework titanium. The major reason is the blockage of the TS-1catalyst channels caused by bulky organic by-products, which cover the activecenters. Calcination was the most effective regeneration method and the catalyticactivity of TS-1catalysts can be almost recovered to the frech catalyst level.In the allyl chloride epoxidation reaction, high hydrogen peroxideconcentrations and low methanol concentrations led to the fast deactivation rate. Kinetic study results showed that the deactivation reaction was a second orderreaction. The relationship between hydrogen peroxide conversion and reaction timewas obtained.