Supercritical methanol solvolysis and hydrodeoxygenation (SCM-DHDO) has recently emerged as a promising pathway to produce predominantly light alcohols from woody biomass. This process provides the advantages of complete solubilization of biomass without pretreatment and utilization of methanol as carbon and hydrogen donor. Though promising, the process is still at the proof-of-concept stage with limited insights into catalyst design for reactivity and stability, continuous process feasibility, and fuel application of the final liquid product. Herein, we proposed a catalyst structure-property relationship to guide catalyst formulation for increased the fuel-grade C2-C7 alcohol yield. The down-selected catalyst CuCeAlOx was found to increase C2-C7 alcohol yield by two-fold compared to CuMgAlOx at the same batch reaction conditions. Catalyst reducibility and acidity were proposed to be the key design parameters. Spent catalyst characterization showed that Cu metal sintering and biogenic poisoning were the primary deactivation modes. The catalysts’ performance was then investigated in flow mode using a semi-continuous dual bed solvolysis/catalysis reactor system. Light duty fuel properties of the neat and blended SCM-DHDO oxygenate mixture were experimentally measured and compared to those of ethanol and the base fuel, using both model compounds as fuel surrogates and reaction product by delignified hybrid poplar. The SCM-DHDO fuel, blended 10 vol% in the base gasoline fuel, showed some improvement in energy density and vapor pressure due to higher content of C4-C7 alcohols, but at the trade-off of anti-knock index and oxidative stability relative to commercial E10 (ethanol blended at 10 vol%). Finally, preliminary capital cost analysis of the supercritical reactor identified solvolysis residence time and biomass loading as the major cost drivers to guide future R&D.

Multifunctional catalyst design for one-pot conversion of woody biomass to biofuel

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.