铅锰复合氧化物催化苯甲醇液相氧化制苯甲醛

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摘要:

采用浸渍法制备了一系列γ-Al2O3负载铅锰复合氧化物催化剂,并探究了其在以氧气为氧化剂的苯甲醇液相氧化中的催化性能.实验结果表明,Pb/Mn物质的量之比对铅锰复合氧化物催化剂的结构及其催化活性起重要作用.当添加少量Pb时,铅离子替代锰形成了Pb在β-MnO 2中的固溶体,导致β-MnO2晶格发生畸变,形成了较为活泼的晶格氧,使锰氧化物的还原温度显著降低,从而改善了其催化氧化苯甲醇的活性.当Pb/Mn物质的量之比为1∶2时,催化剂活性最高.在100℃下反应3 h,苯甲醇的转化率达到56.2%,苯甲醛的选择性在99.0%以上,且该催化剂可多次循环使用而无明显活性降低.添加大量的Pb将导致分离的铅氧化物以及与铅氧化物发生强相互作用的高分散锰氧化物,导致催化剂活性降低.

A series ofγ-Al2O3 supported lead-manganese composite oxide catalysts were prepared by a facile impregnation method and attempted for the liquid-phase oxidation of benzyl alcohol with molecular O2.The results showed that the Pb/Mn molar ratio played an important role on the structure and catalytic activity of lead-manganese composite oxide catalysts.Adding a small amount of Pb to the Mn/γ-Al2O3,lead ions replaced manganese ions to form a Pb inβ-MnO2 solid solution,resulting in the lattice distortion of-MnO2 and the formation of more active lattice oxygen species,which significantly reduced the reduction temperature of supported manganese oxide,and thus improving its catalytic activity for benzyl alcohol oxidation.As a Pb/Mn molar ratio of 1∶2 was used,the catalyst activity was the highest.At 100℃for 3 h,the conversion of benzyl alcohol reached 56.2%,the selectivity of benzaldehyde was more than 99.0%,and the catalyst could be recycled for several times without significantly lowering its activity.The addition of large amount of Pb would lead to the separated phase of lead oxide species and high dispersed manganese oxides strongly interacted with the lead oxide species,thus resulting in a decrease of the catalytic activity.

作者:

汤清虎黄晓娜赵培正

Tang Qinghu;Huang Xiaona;Zhao Peizheng(School of Chemistry and Chemical Engineering,Henan Normal University,Xinxiang 453007,China)

机构地区:

betway官方app 化学化工学院

出处:

《betway官方app 学报：自然科学版》 CAS 北大核心 2020年第6期50-56,F0002,共8页

基金:

国家自然科学基金(21503070) 河南省教育厅科学技术研究重点项目(19A150030).

关键词:

苯甲醇液相氧化苯甲醛铅锰复合氧化物

benzyl alcohol liquid phase oxidation benzaldehyde lead-manganese composite oxide