Wu Pingping, He Zhengke, Liu Yonghui, Song Lei, Wang Chunzheng, Muhumuza Edgar, Bai Peng, Zhao Lianming, Mintova Svetlana, Yan Zifeng
State Key Laboratory of Heavy Oil Processing, CNPC Key Laboratory of Catalysis, College of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China.
School of Materials Science and Engineering, Institute of Advanced Materials, China University of Petroleum (East China), Qingdao 266580, China.
ACS Appl Mater Interfaces. 2021 Oct 27;13(42):49780-49792. doi: 10.1021/acsami.1c10207. Epub 2021 Oct 12.
A balance between catalytic activity and product selectivity remains a dilemma for the partial oxidation processes because the products are prone to be overoxidized. In this work, we report on the partial oxidation of benzyl alcohol using a modified catalyst consisting of nanosized Au-Pd particles (NPs) with tin oxide (SnO) deposited on a mesoporous silica support. We found that the SnO promotes the autogenous reduction of PdO to active Pd species on the Au-Pd NP catalyst (SnO@AP-ox) before H reduction, which is due to the high oxophilicity of Sn. The presence of active Pd species and the enhancement of oxygen transfer by SnO led to high catalytic activity. The benzaldehyde selectivity was enhanced with the increase of SnO content on catalyst SnO@AP-ox, which is ascribed to the modulated affinity of reactants and products on the catalyst surface through the redox switching of Sn species. After H reduction, SnO was partially reduced and Au-Pd-Sn alloy was formed. The formation of Au-Pd-Sn alloy weakened both the catalytic synergy of Au-Pd alloy NPs and the adsorption of benzyl alcohol on the reduced catalyst, thus leading to low catalytic activity.
对于部分氧化过程而言，催化活性与产物选择性之间的平衡仍然是一个难题，因为产物易于被过度氧化。在这项工作中，我们报道了使用一种改性催化剂对苯甲醇进行部分氧化，该催化剂由纳米尺寸的金钯颗粒（NPs）组成，氧化锡（SnO）沉积在介孔二氧化硅载体上。我们发现，在氢气还原之前，SnO促进了Au-Pd NP催化剂（SnO@AP-ox）上PdO自还原为活性Pd物种，这是由于Sn具有高亲氧性。活性Pd物种的存在以及SnO对氧传递的增强导致了高催化活性。在催化剂SnO@AP-ox上，随着SnO含量的增加，苯甲醛选择性提高，这归因于通过Sn物种的氧化还原转换调节了反应物和产物在催化剂表面的亲和力。氢气还原后，SnO被部分还原并形成了Au-Pd-Sn合金。Au-Pd-Sn合金的形成削弱了Au-Pd合金NPs的催化协同作用以及苯甲醇在还原催化剂上的吸附，从而导致低催化活性。
