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Transfer Hydrogenation of Fatty Acids on Cu/ZrO2: Demystifying the Role of Carrier Structure and Metal–Support Interface
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-07-16 , DOI: 10.1021/acscatal.0c02320
Zihao Zhang 1, 2 , Meizan Jing 3 , Hao Chen 1 , Francis Okejiri 4 , Jixing Liu 4 , Yan Leng 4 , Haolan Liu 5 , Weiyu Song 3 , Zhaoyin Hou 5 , Xiuyang Lu 1 , Jie Fu 1, 2 , Jian Liu 3
Affiliation  

The catalytic transformation of renewable fatty acids into value-added fatty alcohols without the use of gaseous hydrogen is a versatile technique for the utilization of microalgae and waste cooking oil, where Cu-based catalysts are considered to be the most suitable candidate. However, the interpretation of the structure–reactivity relationship caused by different crystal types of carriers and the metal–support interface is not well understood. Herein we synthesized ZrO2-supported Cu nanoparticle catalysts via different preparation methods and reduction temperatures under similarly exposed surface facets and Cu valency but different polymorphic phases of ZrO2 (monoclinic ZrO2: m-ZrO2; tetragonal ZrO2: t-ZrO2) and the metal–support interface. Interestingly, the as-synthesized Cu/t-ZrO2 catalysts showed remarkably better catalytic performance than Cu/m-ZrO2 for the in situ hydrogenation of lauric acid in the methanol–water system. Combined experimental and density functional theory (DFT) calculation results ascribed the lower efficiency of m-ZrO2 as a carrier to weakly adsorbed reactant and intermediate molecules as well as the absence of an oxygen vacancy in the crystal phase. The interface-rich Cu/t-ZrO2 catalysts displayed higher activity normalized to the surface-exposed Cu sites toward lauryl alcohol production than the interface-deficient counterparts. DFT calculation results further revealed that this metal–support interface plays an important role in promoting the C–O bond or H–H bond cleavage in two possible reaction routes, thus reducing the activation barrier of the overall reaction.

中文翻译:

脂肪酸在Cu / ZrO 2上的转移加氢:揭示了载体结构和金属-支持界面的作用

在不使用气态氢的情况下将可再生脂肪酸催化转化为增值脂肪醇是利用微藻类和废食用油的通用技术,其中铜基催化剂被认为是最合适的选择。但是,对于由不同类型的载流子和金属-载体界面引起的结构-反应性关系的解释尚不清楚。本文中,我们通过不同的制备方法和还原温度,在相似暴露的表面小平面和Cu价但ZrO 2的多晶相不同的情况下(单斜ZrO 2:m-ZrO 2;四方ZrO 2:t-ZrO),通过不同的制备方法和还原温度合成了ZrO 2负载的Cu纳米颗粒催化剂。2)和金属支撑界面。有趣的是,合成的Cu / t-ZrO 2催化剂在甲醇-水系统中对月桂酸进行原位加氢时,其催化性能明显优于Cu / m-ZrO 2。结合实验和密度泛函理论(DFT)的计算结果归因于m-ZrO 2作为载体弱吸收反应物和中间分子的效率较低,并且在结晶相中不存在氧空位。富界面Cu / t-ZrO 2与缺乏界面的同类催化剂相比,该催化剂表现出更高的活性,该活性被标准化为对月桂醇生产的表面暴露铜位。DFT计算结果进一步表明,这种金属-载体界面在促进两种可能的反应途径中的C-O键或H-H键裂解方面起着重要作用,从而降低了整个反应的活化障碍。
更新日期:2020-08-21
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