Palladium-based catalysts for biomass hydrogenation reaction in the condensed-phase
Date
2020-12
Authors
Cheng, Yan
Major Professor
Advisor
Shanks, Brent H
Tessonnier, Jean-Philippe
Vigil, Dennis
Kraus, George A
Raman, Raj
Committee Member
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Abstract
To address to the requirement of catalysts for biomass conversion, palladium-based
catalysts were studied for aqueous phase hydrogenation, especially carbonyl group, which
is common in the biomass-derived molecules. A three-phase fixed-bed reactor was used to
evaluate the catalysts’ performance. XRD, XPS, TEM, ICP, chemisorption, TCD and IR
were used to characterize the catalyst surface. A Pd-Fe bimetallic catalyst was found to be
more active than its Pd monometallic counterpart. Then the Pd-Fe catalysts were used to
study the kinetic of acetone hydrogenation in aqueous phase to explain the fundamental
reason for the activity enhancement compared with Pd. Based on the knowledge of Pd-Fe
and Pd system, more Pd-based bimetallic catalysts will be synthesized and tested for the
same reaction, in attempt to correlate the electron property and the catalytic performance.
The secondary metals include Cu, Zn, Cr, and W.
The addition of Fe in Pd catalysts forms PdFe nanoalloys, which was attributed to
the improved activity of acetone. The PdFe bimetallic catalysts were considerably more
active than Pd catalysts not only for carbonyl hydrogenation, but also for aromatic rings
and C=C bonds, although to a lower extent to which the activity was enhanced. The primary
results from the kinetic study suggested that PdFe increased activity by altering the
favorable acetone adsorption configuration from di-σ (η2) to on top (η1) and reducing the
activation energy of surface reaction. Besides Fe, Cu and Zn were found to be promoters
to different degrees, while Cr and W impeded the reaction significantly.
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dissertation