Date of Award

Fall 2023

Document Type

Open Access Dissertation

Department

Chemical Engineering

First Advisor

Christopher Williams

Abstract

Ethylene glycol (EG) is an important industrial chemical in the manufacturing of certain plastics. There is growing industrial interest in the production of dimethyl oxalate (DMO) from syngas, which can be hydrogenated to produce EG. Many studies have focused on the catalytic reduction of DMO using copper-based catalysts on silica supports, but fewer studies have been done on the effects of silver for this reaction. This work presents an in-depth study of silver catalysts prepared via various methods including incipient wetness impregnation, charge enhanced dry impregnation, and the use of various organic solvents. Reaction studies show that using pure methanol as a solvent in the preparation of Ag/SBA-15 catalysts without any water increases catalytic performance and selectivity towards EG. The SBA-15 supported silver catalysts were also compared to two other high surface area silica supports to determine the effect the support had on the activity of the catalyst. Catalysts prepared with SBA-15 showed a superior performance in both activity and EG selectivity when compared to the other silica supports. This held true for catalysts prepared via incipient wetness impregnation as well as using pure methanol as a solvent. Bimetallic silver catalysts were prepared with several metals, including platinum, ruthenium, indium, and copper to study the effects that these bimetallic catalysts had on overall performance of the catalyst. This work found that bimetallic silver and copper catalysts showed the greatest improvements to activity and EG selectivity over all the other bimetallic catalysts tested, as well as the monometallic silver and copper catalysts. The best performing catalyst studied was the 10w%Ag-5.8w%Cu/SBA-15 catalyst. This catalyst outperformed all other catalysts in terms of selectivity and activity and showed high stability even after a time on stream of 72 hours. This catalyst weight loading was also prepared using pure methanol as a solvent. The pure methanol prepared catalyst showed an improved performance over the 10w%Ag-5.8w%Cu/SBA-15 catalyst prepared via incipient wetness impregnation. The effects of temperature, pressure and Ag loading were analyzed first in order to obtain the optimal loading of silver. The highest conversion of DMO and highest selectivity of EG was achieved via a 10w% Ag/SBA-15 catalyst. Various other metals including copper, platinum, ruthenium, indium, and molybdenum were tested to elucidate the effects that additional metals had on the conversion and the selectivity of the reaction. These tests showed that copper was the best performing additional metal for this reaction when paired with silver.

Rights

© 2024, Nicolas Edouard Gleason-Boure

Download

Share

COinS