不同沉淀剂制备的Ag/TS-1催化丙烯直接气相氧化合成环氧丙烷

Synthesis of Propylene Oxide by Gas-Phase Propylene Epoxidation over Ag/TS-1 Prepared with Different Precipitators

在 4 2 3K、常压固定床石英反应器中 ,以丙烯直接气相氧化为探针反应 ,考察了催化剂制备方法、沉淀剂的种类和浓度对制备的Ag/TS 1催化剂催化性能的影响 ,采用TEM ,XRD和UV Vis等表征手段对Ag/TS 1催化剂进行了分析 .结果表明 ,沉积 沉淀法是最佳的催化剂制备方法 ,但浸渍法也可制得具有环氧丙烷选择性的催化剂 .K2 CO3 是一种良好的沉淀剂 .以K2 CO3 为沉淀剂 ,硅钛比为 6 4的TS 1为载体制备的Ag/TS 1催化剂上的丙烯转化率为 1 72 % ,环氧丙烷选择性为98 2 % .少量单质银的存在有利于环氧丙烷的生成 ,除银粒子的分散状态外 ,银粒子与载体TS

The effects of preparation method and precipitator for TS 1 support on the gas phase propylene epoxidation over the Ag/TS 1 catalyst were investigated in a fixed bed quartz reactor at 423 K and ambient pressure. The Ag/TS 1 catalyst was characterized by TEM, XRD and UV Vis spectroscopy. The results show that the deposition precipitation method is optimum, but Ag/TS 1 prepared by the impregnation method also shows moderate selectivity for propylene oxide (PO). Alkaline metal carbonate such as K 2CO 3 is a suitable precipitator for the preparation of the Ag/TS 1 catalyst. The existence of K + can improve both the propylene conversion and the PO selectivity. A propylene conversion of 1 72% and a PO selectivity of 98 2% are obtained over Ag/TS 1( n (Si) / n (Ti) =64) prepared using 0 07 mol/L K 2CO 3 as the precipitator. The characterization indicates that a small quantity of metal silver favors the formation of PO. The dispersion of silver species and the interaction between silver species and TS 1 play important roles in improving the catalyst selectivity.