(491a) Biomass – Flare Gas Synergistic Co-Processing over Fe / Ni / Pd Doped Mo2c Supported on Graphene Nanosheets: Experimental and DFT Integrated Approach to Hydrogen Production

Biomass – flare gas synergistic co-processing is a novel energy generation and conversion technology that aims at harnessing abundant renewable energy source: biomass and reduce greenhouse gas emissions from flaring in stranded shale plays. In this study p-cresol is used as a model biomass-lignin molecule for methane assisted reforming studies, then scaled-up to model alkali lignin and eventually hardwood biomass in a detail bottom-up approach to gain the molecular level understanding of the reaction mechanism and ascertain the role of active sites. Novel in-situ catalyst synthesis using biomass precursor was achieved through pyrolysis to yield graphene nanosheets (GNS) supported transition metal and Mo₂C nanoparticles. Initially, experimental work and DFT modelling calculations were performed for methane assisted p-cresol reforming using Fe, Ni, Mo₂C, Fe-Mo₂C, Ni-Mo₂C, Pd-Mo₂C supported on GNS. Detailed mechanistic investigation of methane – p-cresol synergistic reaction experimentally and through molecular simulations helped ascertain the unique reaction pathway occurring on dual active sites on a transition metal doped β-Mo₂C-GNS catalyst. Transition metal doped Mo₂C viz.: Fe-Mo₂C-GNS and Ni-Mo₂C-GNS are equally effective as Mo₂C-GNS for methane dissociation and p-cresol HDO but present significantly lower barrier for H₂ (1.15, 1.13 eV vs. 1.70 eV) and CO (2.87, 2.80 eV vs. 3.67 eV) gas-phase desorption. Dual active sites are required for hydrogen rich syngas production through methane assisted p-cresol reforming as validated by experiments, DFT calculations, and micro-kinetic modelling (MKM). Lignin and hardwood biomass both having higher O:C weight ratio compared to p-cresol (0.46, 1.09 vs. 0.19) were co-processed with methane over FeMo-GNS, NiMo-GNS, and MoPd-GNS catalysts. Transition metal doped Mo₂C was found to be highly active for simultaneous CH₄ activation and extensive hydrodeoxygenation of p-cresol, lignin, and hardwood biomass. Up to 99% hydrogen present in lignin could be valorized as syngas with a concentration of > 65%.