氧化石墨烯掺杂锌铝类水滑石负载钯金催化剂的制备及催化性能

Preparation of GO doped Zn-Al LDHs supported palladium gold catalysts and their catalytic performances

采用离子交换-还原法制备了氧化石墨烯(GO)掺杂锌铝类水滑石负载钯金双金属纳米颗粒的催化剂(Pd Au/Zn-Al LDHs/GO),通过XRD、TEM表征了催化剂的结构,以GO掺杂锌铝类水滑石为载体负载钯金纳米颗粒粒径小(约2nm)且分散均匀。以苯甲醇空气氧化形成苯甲醛的反应为模型,评价催化剂的催化性能,探讨了载体及钯、金比例对催化反应的影响。催化结果表明,氧化石墨烯掺杂的锌铝类水滑石是考察载体中最好的钯、金催化剂的载体,随着钯金比的增加催化剂的催化活性先增加后降低,生成苯甲醛的选择性下降,当钯金比例为1∶1时,催化剂(Pd1Au1/Zn-Al LDHs/GO)的综合催化性能最好,催化活性随反应温度的升高而升高,但选择性随温度的升高而下降。在Pd1Au1/Zn-Al LDHs/GO催化下,80℃反应8h后苯甲醇的转化率可达96%,苯甲醛的选择性为93%,催化剂循环使用4次后仍保持较好的催化性能。

Palladium-gold bimetallic nanoparticles deposited on the graphene oxide(GO)doped Zn-Al layered double hydroxide(PdAu/Zn-Al LDHs/GO)were synthesized through the ion exchangereduction method.The as-prepared supported palladium-gold bimetallic catalysts were characterized by XRD and TEM.The bimetallic nanoparticles loaded by the GO doped Zn-Al LDHs as the carrier is uniform and the particle size is about2nm.The catalytic activities of as-prepared catalysts were evaluated by using oxidation of benzyl alcohol to benzaldehyde as the model reaction.The effects of carriers and ratio of Pd/Au on the catalytic properties were investigated.The catalytic results showed that the LDHs/GO was the best among the used carriers.As the increase of ratio of Pd/Au,the activity of supported catalyst increased at first,and then decreased,whereas the selectivity of benzaldehyde decreased.With the ratio of Pd/Au being1∶1at80℃,the performances of Pd1Au1/Zn-Al LDHs/GO is the best.The catalytic activity increased as the increase of temperature,but the selectivity of benzaldehyde decreased.Under promotion of Pd1Au1/Zn-Al LDHs/GO at80℃for8h,the conversion of benzyl alcohol and selectivity of benzaldehyde was96%and93%,respectively.The catalyst of Pd1Au1/Zn-Al LDHs/GO still maintained excellent catalytic performance after four cycles.