美国斯坦福大学Matteo Cargnello团队报道了钯催化剂中蒸汽预热处理生成晶界提高甲烷C-H活化。相关研究成果发表在2021年9月24日出版的国际学术期刊《科学》。

由于原子的特定排列与晶体表面，不同缺陷可能表现出高反应性。

研究人员发现，与传统预处理相比，钯催化剂的高温蒸汽预处理可使甲烷氧化中的碳氢（C–H）活化的质量比反应速率提高12倍。综合实验和理论研究，研究人员发现在蒸汽预处理和氧化过程中通过孪晶增加晶界密度是导致反应性增加的原因。晶界在反应期间高度稳定，并且显示出比钯-氧化铝（Pd/Al2O3）催化剂上的其他位置高至少两个数量级的比速率。

理论计算表明，缺陷结构引入的应变能增强C–H键的活化。通过激光烧蚀引入晶界导致速率进一步增加。

附：英文原文

Title: Steam-created grain boundaries for methane C–H activation in palladium catalysts

Author: Weixin Huang, Aaron C. Johnston-Peck, Trenton Wolter, Wei-Chang D. Yang, Lang Xu, Jinwon Oh, Benjamin A. Reeves, Chengshuang Zhou, Megan E. Holtz, Andrew A. Herzing, Aaron M. Lindenberg, Manos Mavrikakis, Matteo Cargnello

Issue&Volume: 2021-09-24

Abstract: Defects may display high reactivity because the specific arrangement of atoms differs from crystalline surfaces. We demonstrate that high-temperature steam pretreatment of palladium catalysts provides a 12-fold increase in the mass-specific reaction rate for carbon-hydrogen (C–H) activation in methane oxidation compared with conventional pretreatments. Through a combination of experimental and theoretical methods, we demonstrate that an increase in the grain boundary density through crystal twinning is achieved during the steam pretreatment and oxidation and is responsible for the increased reactivity. The grain boundaries are highly stable during reaction and show specific rates at least two orders of magnitude higher than other sites on the palladium on alumina (Pd/Al2O3) catalysts. Theoretical calculations show that strain introduced by the defective structure can enhance C–H bond activation. Introduction of grain boundaries through laser ablation led to further rate increases.

DOI: abj5291

Source: https://www.science.org/doi/10.1126/science.abj5291