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用FT-IR法探索了磷酸硅/磷酸硼催化剂的体相结构,还用真空加热法研究了该催化剂吸水、脱水时的表面状况。结果表明焙烧温度≥650℃时,催化剂中至少存在两种不同晶系的SiP_2O_7,未经水蒸汽处理的催化剂表面没有与B酸中心有关的M—OH基团。该催化剂经水蒸汽处理后,吸附水在催化剂表面发生解离,生成O=P—OH(2900cm~(-1),P—OH(～3660cm~(-1)),B—OH(3700cm~(-1))和Si—OH(3741cm~(-1))羟基基团。这些表面羟基句能起到酸催化作用,促使反应顺利进行。
The phase structure of the Si / PO4 catalyst was explored by FT-IR method. The surface condition of the catalyst was also studied by vacuum heating method. The results show that there are at least two different crystal SiP_2O_7 in the catalyst when the calcination temperature is more than or equal to 650 ℃, and there is no M-OH group in the surface of the catalyst without steam treatment. After the catalyst is treated with steam, the adsorbed water is dissociated on the catalyst surface to generate O-P-OH (2900cm -1, P-OH 3660cm -1, B-OH 3700cm -1) (-1)) and Si-OH (3741 cm -1) hydroxyl groups. These surface hydroxyl groups can act as acid catalysis and promote the smooth progress of the reaction.