射频等离子体辅助制备S_(2)O_(8)^(2-)/CeO_(2)固体超强酸催化剂的研究

Preparation of S_(2)O_(8)^(2-)/CeO_(2)solid superacid catalyst assisted by radio frequency plasma

以商用CeO_(2)为载体,采用过量浸渍法浸渍(NH_(4))_(2)S_(2)O_(8)溶液,用射频等离子体以辉光放电形式辅助制备了S_(2)O_(8)^(2-)/CeO_(2)-RF固体超强酸催化剂。利用XRD、SEM、BET、FT-IR、Py-IR等对催化剂的孔结构、键结合方式、微观形貌、酸量及酸性质等进行了表征。通过色氨酸与甲醇的酯化反应评价了S_(2)O_(8)^(2-)/CeO_(2)-RF固体超强酸催化剂的活性。结果表明,与传统600℃焙烧法相比,射频辉光放电等离子体辅助制备的催化剂比表面积大、颗粒分散、酸量高、反应速率快。在反应温度为150℃、反应压力为1 MPa的条件下,S_(2)O_(8)^(2-)/CeO_(2)-RF催化剂上色氨酸甲酯的产率为82%,并且在1.5 h后反应趋近平衡。

Taking commercial CeO_(2)as support,S_(2)O_(8)^(2-)/CeO_(2)-RF solid superacid catalyst is prepared via excessively impregnating(NH_(4))_(2)S_(2)O_(8)solution assisted with radio frequency plasma in the form of glow discharge.XRD,SEM,BET,FT-IR and Py-IR are employed to characterize the pore structure,bond bonding mode,micro morphology,acid content and acid property of the catalysts.The activity of S_(2)O_(8)^(2-)/CeO_(2)-RF solid superacid catalyst is evaluated in esterification of tryptophan and methanol.It is shown that the catalyst prepared under the assistance of radio frequency glow discharge plasma has larger specific surface area,more dispersive particles,higher acid content and faster reaction rate than the catalyst prepared by traditional calcination method at 600℃.The yield of methyl tryptophane reaches 82%over S_(2)O_(8)^(2-)/CeO_(2)-RF catalyst at 150℃and 1 MPa,and the reaction approaches equilibrium after 1.5 h.