【摘要】 通过掺杂Al对无定形层析硅胶进行表面改性,采用固体离子交换法制备了CuCl/SiO2-Al2O3催化剂,并考察了它在甲醇液相氧化羰基化合成碳酸二甲酯反应中的催化性能.结果表明,掺杂Al制备的SiO2-Al2O3载体仍保持了硅胶的无定形结构,比表面积降为200m2/g,但表面酸性明显增强,具有B酸中心.CuCl不仅分散于SiO2-Al2O3载体表面,而且与载体表面的B酸发生离子交换作用形成了表面Cu+物种,使催化剂比表面积降为148m2/g,且两种Cu+物种共同构成了催化活性中心.当CuCl/SiO2-Al2O3催化剂的Si/Al比为5,在500℃焙烧时,催化剂上甲醇氧化羰基化反应的碳酸二甲酯的选择性和时空收率分别达到74%和1.27g/(g.h).更多还原

【Abstract】 Aluminum was doped into amorphous silica gel to modify its surface structure. The obtained SiO2-Al2O3 support was used to prepare the CuCl/SiO2-Al2O3 catalyst by solid-state ion exchange, and the catalyst activity for liquid-phase oxidative carbonylation of methanol to dimethyl carbonate was investigated. The results showed that the prepared SiO2-Al2O3 support kept the amorphous structure of the silica gel. The BET specific surface area of the silica gel was decreased to 200 m2/g, and the surface acid sites (including Brnsted acid sites) were increased. In the CuCl/SiO2-Al2O3 catalyst, CuCl was not only dispersed on surface but also was ion exchanged with surface Brnsted acid sites of the SiO2-Al2O3 support to form Cu+ species, which resulted in a decrease in BET specific surface area to 148 m2/g. These two kinds of Cu+ species on the catalyst surface were both active centers for the oxidative carbonylation of methanol to dimethyl carbonate. When the catalyst was prepared with Si/Al molar ratio of 5 and was calcined at 500 ℃, the selectivity and space-time yield of dimethyl carbonate reached 74% and 1.27 g/(g·h), respectively.更多还原