Catalytic Performance of [Ti,Al]-Beta in the Alkene Epoxidation Controlled by the Postsynthetic Ion Exchange
作者:Yasuhide Goa、Peng Wu、Takashi Tatsumi
DOI:10.1021/jp048917y
日期:2004.6.1
63% for the former in contrast to 0% for the latter. The ion-exchange treatments with quaternary ammonium salts over calcined [Ti,Al]-Beta showed similar effects, although the treatments with alkali and alkaline earth metal ions were detrimental to the catalytic activity. It is suggested that the quaternary ammonium cations selectively blocked the acid sites deriving from the framework Al, which resulted
已经开发了用于提高 [Ti,Al]-Beta 上烯烃环氧化中环氧化物选择性的新方法。当合成的[Ti,Al]-β用硝酸铵水溶液处理并在低温下连续煅烧时,在以H 2 O 2 为氧化剂的环己烯液相环氧化中环氧化物选择性显着提高。质子溶剂甲醇。达到最大环氧化物产率的最佳热处理温度为 473 K,其中合成后的 [Ti,Al]-β 表现出与在 793 K 下直接煅烧的样品相当的催化活性;然而,前者的环氧化物选择性高达 63%,而后者为 0%。在煅烧的 [Ti,Al]-Beta 上用季铵盐进行离子交换处理显示出类似的效果,尽管用碱金属和碱土金属离子处理对催化活性有害。表明季铵阳离子选择性地阻断了源自骨架 Al 的酸性位点,从而阻止了环氧化物的开环水解,而无机阳离子不仅毒化了酸性位点,还毒化了 Ti 活性位点催化环氧化。离子交换催化剂通过反复煅烧和随后的离子交换很容易再生,因此被证明是一种活性、选择性和可