The identification of catalytic pathways for generating renewable fuels and fuel additives from biomass-derived feedstocks is of critical importance for increasingly carbon-neutral operations and the improved economic viability of processes for renewable feedstock valorization. Here, we present our latest work on designing catalyst combinations consisting of multifunctional bimetallic Zn-Y/Beta zeolites and “single-atom alloy” (SAA) Pt-Cu supported metal catalysts for the thermocatalytic upgrading of ethanol into butene-rich olefins as precursors to jet-range (C8-16) hydrocarbons. Ethanol conversion to 1,3-butadiene and subsequent hydrogenation to butene isomers occurs through a complex reaction network consisting of dehydrogenation, aldol condensation, dehydration, and selective hydrogenation reactions where each reaction step requires unique active site requirements for efficient conversion. The development of multifunctional catalysts, accomplished here through the incorporation of multiple transition metals (e.g. Zn, Y, Cu, Pt) onto a single support (e.g. Beta, Al2O3), is investigated using a suite of in situ and ex situ characterizations (e.g. EXAFS, HAADF-STEM, pyridine DRIFTS) to identify Lewis and Brønsted acid sites. These site configurations and mixed metal center identities are correlated to specific reaction steps at 588 K and are evaluated at both high (&gt;95%) and low (&lt;10%) ethanol conversions. Reaction testing at high conversions indicates improved ethanol valorization into butene-rich olefin streams (65% butenes, 78% C3+ olefin selectivity at 94% conversion) while avoiding further hydrogenation to form butanes or other saturated hydrocarbons. This is ethanol-to-olefins (ETO) reaction network is accomplished without cofed hydrogen over a SAA Pt-Cu catalyst capable of catalyzing butadiene hydrogenation at stoichiometric hydrogen and butadiene partial pressures.

Two-bed thermochemical ethanol valorization to butene-rich olefin mixtures over mixed metal catalysts using in situ hydrogen generation

ACS Spring Meeting 2021

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