Date of Award

May 2019

Degree Name

Master of Science (MS)

Department

Biomedical and Chemical Engineering

Advisor(s)

Jesse Q. Bond

Second Advisor

Benjamin Akih-Kumgeh

Keywords

Bimetallic, Catalyst, Hydrodexoygenation, Platinum, Strong Electrostatic Adsorption, Tin

Subject Categories

Engineering

Abstract

As environmental and economic forces push for movement away from traditional petroleum-sourced chemical and fuel production, it becomes essential for technologies in renewable carbon resources to be developed. In particular, the production of chemical commodities from renewable lignocellulosic biomass provides a unique path away from the use of petrol. Considering the high density of functional groups present in biomass feedstocks, new technologies must be developed to selectively target the removal of functional groups through the application of supported metal catalysts. The ability to target specific functional group removal would allow for biomass feedstocks to produce higher yields of desired commodities without the production of undesired, lower value chemicals. Through the use of promoter metals, such as Sn, it is possible to shift the selectivities of noble metal catalysts (e.g. Pt, Ru, Pd, etc.), often without greatly reducing the intrinsic activity of the monometallic catalyst. While the usefulness of bimetallic catalysts has been observed in many applications, the actual mechanisms by which promoter metals alter the catalyst’s performance is largely left unknown. This gap in knowledge is largely due to the fact that the traditional methods of catalyst synthesis lack the ability to control exact compositions and geometries of surface metal complexes. The synthesis method of strong electrostatic adsorption (SEA) utilizes the surface charging properties of metal oxides to selectively adsorb promoter metals to primary metal sites, potentially allowing for greater control of the composition of metal complexes. This work employs the SEA technique to develop a realistic method for the synthesis of Pt-Sn/Al2O3 bimetallic catalysts. The addition of Sn had profound effects on the selectivity of propionic acid hydrodeoxygenation (HDO), an analog for succinic acid HDO, suppressing nearly all unwanted byproduct production. Through the use of temperature programmed reductions (TPR), ambient-pressure photoemission spectroscopy (AP-PES), chemical and physical adsorptions, and electron microprobe characterization techniques, this work shows that the changes in propionic acid HDO is likely attributed to the changes in oxidation states of Pt metal sites upon the addition of Sn.

Access

Open Access

Included in

Engineering Commons

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