(573a) Understanding Trends in C-H Bond Activation in Heterogeneous Catalysis
Natural gas, composed primarily of methane, is a valuable energy source that currently accounts for 24% of worldwide energy needs1. However, due to a lack of transportability, the natural gas extracted alongside crude oil at remote drilling locations is often flared resulting in the loss of a valuable chemical feedstock and increased CO2 emissions1. Discovery of an efficient catalyst for direct on-site partial methane oxidation to higher value commodity chemicals or liquids fuels could result in reduced CO2 emissions and significant economic savings. While electronic structure calculations are becoming increasingly relevant in this search, they are often problematic due to the high cost of transition state barrier calculations. In the present work, we use density functional theory to establish a unifying framework for predicting C-H activation barriers on the wide range of catalysts that activate C-H bonds via a radical intermediate using a single universal descriptor. We demonstrate the relevance of this scaling approach by combining it with a thermodynamic analysis to generate a map of methane activation rates that successfully rationalizes available empirical data. Using this activity map as a guide, we identify several oxide materials that show favorable methane activation potential and conduct a more thorough analysis of these systems. This model will facilitate the fast and efficient screening of a wide range of potential C-H activation catalysts, bypassing the need for tedious transition state barrier calculations and allowing for greener chemistry by selectively testing promising materials.
- Horn, R. & Schlögl, R. Methane Activation by Heterogeneous Catalysis. Catalysis Letters 145, 23:39 (2015).