(2ib) Oxidative Coupling of Methane: Developing Structure-Property Relationships for High-Performance Metal Oxide Catalysts

- Materials science

- Heterogeneous catalysis

- Crystallization

- Nanotechnology

Abstract

It was fourty years ago that Keller and Bhasin^[1] first reported the oxidative coupling of methane (OCM) in their seminal work. They envisioned the oxidative conversion of methane present in abundant gas resources (e.g., shale and natural gas) into reactive chemical commodities such as ethane, ethylene, propane, etc. (C₂₊ hydrocarbons). Despite significant efforts over the years, commercial implementation of OCM has been restrained, most significantly due to limitations in finding a catalyst leading to a sufficiently high performance as well as a suitable reaction process amenable to the high temperature conditions needed (>700 °C). In spite of a myriad of catalysts that have been studied, the reaction mechanism largely remains elusive, including the nature of active sites, and important molecular reaction steps as are the oxygen and methane activation steps.

In this presentation, we will discuss a collaborative effort in catalyst design, testing, and computational modeling to explore two main research strategies: (1) developing structure-catalytic performance relationships using simple metal oxides, and (2) the evaluation of mixed metal oxide catalyst performance under autothermal reaction conditions. We have developed methods to prepare metal oxide catalysts with various crystal morphologies, and used these materials to assess OCM performance. The results of these studies were rationalized by computational modelling, thus leading to the conclusion that metal oxide crystal habit plays a significant role in OCM catalysis. Here, we will discuss these combined efforts and show how optimized metal oxide systems utilized in an autothermal reactor design enable high-performance OCM under conditions that are close to being commercially viable.

References:

[1] Keller, G. E.; Bhasin, M. M. Synthesis of Ethylene via Oxidative Coupling of Methane. I. Determination of Active Catalysts. J. Catal. 1982, 73, 9– 19.