四丙基氢氧化铵处理TS-1催化1-丁烯环氧化

在四丙基溴化铵-乙胺体系中,水热合成了晶粒尺寸为600 nm的小晶粒钛硅分子筛TS-1。将其挤条成型后,采用四丙基氢氧化铵(TPAOH)稀溶液处理,然后用于催化1-丁烯与H2O2环氧化制备1,2-环氧丁烷的反应,并与TPAOH处理前的样品对比。结果表明, TPAOH处理能显著提高TS-1的催化活性及稳定性。原因在于,晶粒外表面无定型载体的晶化疏通了TS-1的孔道,晶粒内部形成的空穴降低了反应物及产物的扩散阻力,且能提高容碳能力;少量四配位骨架钛转化为五配位钛,也使催化活性有所提高。

Epoxidation of 1-Butene Over Tetrapropylammonium Hydroxide Treated TS-1

A small-crystal titanium silicalite-1 (TS-1) with a crystal size of 600 nm was synthesized in a tetrapropylammonium bromide-ethylamine system. The sample was extruded, treated with dilute tetrapropylammonium hydroxide (TPAOH) solution and fed in a fixed-bed reactor to evaluate its catalytic performances of 1-butene epoxidation with H2O2 to 1,2-butene oxide. Via comparing the catalytic performances of the untreated and treated samples, it was found that the treatment with TPAOH could improve the catalytic activity and stability of TS-1 significantly. The reasons are the crystallization of amorphous supports on the external surface unblocking the channels of TS-1, the hollows generated in the crystals decreasing the diffusion limitation of substrates and products, which also increasing the carbon storage ability, and the transformation of tetrahedrally coordinated Ti to pentahedrally coordinated Ti improving the catalytic activity.