凝胶法制备条件对载体硅胶孔结构的影响

以水玻璃、硫酸为原料采用凝胶法制备了烯烃环氧化催化剂载体硅胶,为探讨制备条件对硅胶孔结构的影响,采用物理吸附仪对不同条件下制备的硅胶进行了表征,结果表明:溶胶pH值、老化温度和老化时间、氨水pH值对硅胶孔结构影响显著,当溶胶pH值为1.5,在80℃下用pH 10.5的氨水浸泡老化凝胶2 h,所得硅胶的比表面积在300 m2.g-1左右,孔径和孔容分别在9.71 nm和0.92 cm3.g-1以上,以此硅胶为载体制得的非均相催化剂Ti/SiO2对于氯丙烯和环己基过氧化氢的环氧化反应具有明显的催化活性。

Effects of preparation conditions of gel method on pore structure of silica-gel carrier

Silica-gel carriers were prepared with the water glass and sulfuric acid by gel method.In order to investigate the effects of preparation conditions on pore structure of silica gels,they were characterized by physical adsorption instrument.Experimental results show that the gelation pH、aging temperature、aging time and ammonia pH value have great effect on pore structure of silica gels.Under following optimal preparation conditions:gelation pH 1.5,gels are aging 2 h at 80 ℃ with ammonia pH 10.5,the specific surface area of silica gels is around 300 m2·g-1,the pore diameter and pore volume are separately over 9.71 nm and 0.92 cm3·g-1.The heterogeneous catalyst Ti/SiO2 prepared using this silica-gel carrier have obvious catalytic activity on epoxidation of allyl chloride and cyclohexyl hydroperoxide.