Oxidative coupling of methane over LaAlO3 perovskite catalysts prepared by a co-precipitation method: Effect of co-precipitation pH value

论文摘要

Oxidative coupling of methane（OCM） was conducted over LaAlO3X catalysts that were prepared by a coprecipitation method using different co-precipitation pH values（X = 6–10）. The aim is to investigate the effect of p H values on the catalytic activity of La AlO3 catalysts in this reaction. The results showed that the co-precipitation pH value affected greatly on the formation of chemical species of precipitate precursors in the co-precipitation step, leading to different phases of the finally obtained LaAlO3 catalysts.When the co-precipitation pH value increased up to 8, the lanthanum-related phases such as La2 O3 and La（OH）3 were gradually formed as by-products, preventing the formation of LaAlO3 perovskite crystalline structure and facilitating the formation of oxygen vacancies on catalyst surface. However, at pH value of9 or higher, the lanthanum content in the precipitate precursor was increased greatly. Not LaAlO3 perovskite but lanthanum-related phases were developed as main phases, reducing their catalytic activities in this reaction. Among LaAlO3 catalysts, the one prepared at pH = 8 showed the highest C2 yield due to its well-developed oxygen vacancies and electrophilic lattice oxygen. Therefore, the co-precipitation pH value strongly affected the LaAlO3 catalyst activity in OCM reaction. A precious pH control should be required to prepare various perovskite catalysts for the OCM.

论文目录

• 1. Introduction
• 2. Experimental
•   2.1. Catalyst preparation
•   2.2. Catalyst characterizations
•   2.3. Catalytic reaction
• 3. Results and discussion
•   3.1. Formation of precipitate in the co-precipitation step
•   3.2. Formation of LaAlO3catalysts
•   3.3. Catalytic activity in the OCM reaction
•   3.4. Selective oxygen species for the OCM
• 4. Conclusions

文章来源

类型: 期刊论文

作者: Yujin Sim,Jihoon Yoo,Jeong-Myeong Ha,Ji Chul Jung

来源: Journal of Energy Chemistry 2019年08期

年度: 2019

分类: 工程科技Ⅰ辑

专业: 化学

单位: Department of Chemical Engineering, Myongji University,Clean Energy Research Center, Korea Institute of Science and Technology

基金: supported by C1 Gas Refinery Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT&Future Planning(2015M3D3A1A01064908)

分类号: O643.36;O621.251

页码: 1-8

总页数: 8

文件大小: 543K

下载量: 45