硼杂碳包镍负载钯催化芳香醇需氧氧化  

Aerobic oxidation of aromatic alcohols catalyzed by palladium nanoparticles supported on boron-doped carbon-encapsulated nickel

作　　者：刘英[1] 余建飞[1] 张勋高[1] Liu Ying Yu Jianfei Zhang Xungao(College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, Chin)

机构地区：[1]武汉大学化学与分子科学学院,湖北武汉430072

出　　处：《工业催化》2017年第4期34-40,共7页Industrial Catalysis

基　　金：湖北省自然科学基金(2013CFB291)资助项目

摘　　要：以硼杂碳包镍(Ni@BC)为载体,采用乙醇还原前驱体H_2PdCl_4法制备了一种新型磁可分离Pd/Ni@BC催化剂,并对其进行AAS、TEM、XRD和XPS表征,选取苯甲醇需氧氧化为探针反应,考察催化剂用量、反应温度和反应时间对催化性能的影响,研究催化剂对其他芳香醇的催化性能和循环使用性能。AAS结果表明,Pd负载质量分数为9.1%,与理论负载量一致。TEM结果显示,Pd纳米颗粒均匀分散在载体表面,平均粒径为4 nm。XRD和XPS结果均表明,催化剂的活性物种为Pd0。在反应温度80℃、O2_压力101.325 k Pa(流速20 m L·min^(-1))、CH_3CN为溶剂和K_2CO_3为碱性助剂条件下,Pd/Ni@BC对多种芳香醇的氧化反应表现出很高的催化活性和选择性,能将苯甲醇、对甲基苯甲醇、对乙基苯甲醇、对异丙基苯甲醇、肉桂醇、安息香、二苯甲醇以及邻甲基苯甲醇等定量转化为相应的醛或酮。催化剂重复使用5次,苯甲醇转化率由97.3%降至78.9%,Pd的少量脱落和部分氧化是催化剂活性降低的主要原因。A novel magnetically nickel （Pd/Ni@ BC） catalyst was separable prepared palladium nanoparticles supported on B-doped carbon-coated from H2PdC14 precursor with ethanol as a reductant. The catalyst was characterized by AAS, TEM, XRD and XPS, respectively. The aerobic oxidation of benzyl alcohol was selected as a probe reaction to optimize the reaction conditions including catalyst amounts, reaction tem- peratures and reaction time. On this basis, the catalytic performance of the catalyst for the other aromatic alcohols and the recycling performance were investigated. The results of AAS revealed that the loaded Pd mass fraction was 9.1%, which was consistent with the theoretical load. TEM observations showed that Pd nanoparticles were dispersed uniformly on the surface of Ni@ BC support with the narrow size distribution and the average diameter of about 4 nm. Both XPS and XRD results confirmed that zerovalent palladium was the active species on the surface of the catalyst. Pd/Ni@ BC catalyst for the oxidation of aromatic alcohols exhibited high catalytic activity and selectivity, and aromatic alcohols such as benzyl alcohol, 4-methyl benzyl alcohol, 4-ethyl benzyl alcohol, 4-isopropyl benzyl alcohol, cinnamyl alcohol, benzoin,diphenylmethanol and 2-methyl benzyl alcohol could be quantitatively converted into the corresponding aldehyde or ketone under the optimum condition as follows ：CH3CN as the solvent,K：CO3 as alkaline additive, Oz pressure 101. 325 kPa （flow rate 20 mL · min^-1）and reaction temperature 80 ℃. The conversion of benzyl alcohol decreased from 97.3% to 78.9% after five recycles. The decrease of catalytic activity of the catalyst was attributed to the leaching and partial oxidation of the palladium nanoparticles.

关 键 词：催化化学 钯纳米颗粒 硼杂碳包镍 绿色催化 芳香醇需氧氧化 磁分离 

分 类 号：O643.36[理学—物理化学] TQ426.6[理学—化学]