EAGER: GOALI: Explicating the gas-surface coupled reaction in oxidative coupling of methane via reaction kinetics, operando spectroscopy, photoionization spectrometry

Lehigh University, Bethlehem PA

Investigators

Abstract

Methane is the major component of natural gas, and while catalysts and processes that convert it directly to higher-value hydrocarbons have long been sought, none have achieved widespread industrial application. This Early-concept Grant for Exploratory Research (EAGER) project addresses one of those technologies – Oxidative Coupling of Methane (OCM) – to generate fundamental insights that have potential to overcome barriers to commercialization. OCM offers scalable technology that would utilize methane more efficiently, and with lower net carbon emissions than current technology, thus supporting the U.S. transition to sustainable energy, while ensuring energy security. Beyond the technical aspects, the project includes several on-going educational and outreach activities at the investigators’ institution. The project addresses several knowledge gaps in catalytic OCM technology: 1) lack of understanding of how the catalyst, as opposed to the gas phase reactions, couples with the reactant species to activate methane and generate radical species, 2) which reaction mode (heterogeneous or gas phase) controls selectivity to desired versus undesired products, and 3) what are preferred catalyst and reactor designs for converting methane selectively to value-added ethane and ethylene (i.e., C2) products. Collaboration with scientists at Sandia National Labs is key to addressing those challenges. Specifically, the investigators will utilize a novel reaction chamber at Sandia National Labs for probing radical species in the near-surface region of a catalyst. The instrumentation has previously been used for identification of gas phase radical species in pure gas phase combustion studies (utilizing vacuum-ultraviolet photoionization mass spectrometry (VUV-PIMS)). Kinetic and mechanistic details of the high-temperature OCM reaction have eluded prior investigators because of lack of experimental capability to quantitatively interrogate the coupling between the catalyst and gas phase species as related to the surface generation of radical species and subsequent reaction of those species in the gas phase. The Sandia instrumentation has the potential to take mechanistic and kinetic aspects of catalyzed OCM to new levels of understanding. The kinetic data (as related to both surface and gas-phase reactions) will be fed into reactor design models (developed by a collaborator at the National Renewable Energy Laboratory (NREL) to identify catalyst and reactor designs that favor high conversion of methane selectively to C2 hydrocarbon species. In a separate thrust the GOALI partner PCI, Inc will conduct a thousand-hour durability evaluation of the state-of-the-art catalyst under industrial operating conditions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.