Date of Award

2021

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Chemical and Biomolecular Engineering

First Advisor

Raymond J. Gorte

Abstract

Efforts have been devoted to understanding the upgrading of plant-based biomass waste into useful chemicals to replace the current petrochemical production. An extensive amount of work has been accomplished in the past few decades but there are still many uncertainties. The transformation of furanic compounds, which present a major fraction in lignocellulosic biomass, is one of them. Furans are important solvent molecules in industry, and they are also critical feedstock to produce other valuable chemicals. The work in this dissertation mainly focused on bridging the gap between different chemistry for a complete industrial production process. Two reactions that I have extensively studied were the acylation of furans and the dehydra-decyclization of cyclic ethers to corresponding conjugated dienes. Selective Friedel-Crafts acylation of furans to a type of alkyl furan ketone molecules is very useful for increasing the molecular weight of biomass in a controlled manner, and product from this reaction can be applied in many fields. The acylation reaction was classically performed with acid anhydride or chloride, using strong Lewis acids as catalysts (such as AlCl3) through homogeneous reactions. To enhance the reaction efficiency and reduce separation cost, I used non-branched long-chain carboxylic acids as acylation agent and Brønsted acidic zeolites as catalyst. A proper reaction condition was demonstrated for the direct acylation reaction, and solvent was found to play an important role during reaction, which can be utilized for further reaction performance improvement. The second reaction is to produce conjugated dienes from cyclic ethers, and it also has been studied over various Brønsted zeolitic materials. Conjugated dienes are the backbone monomers in synthetic rubber production. Previous works on zeolites have either low selectivity to desired conjugated diene products or low reaction rates, and having protons as active sites, oligomerization of unsaturated hydrocarbons was another big issue. In my work, ZrO2 was identified to be a promising catalyst to produce C4~C5 conjugated dienes from corresponding cyclic ethers at quantitative conversion. ZrO2 has shown a significant performance compared to other common-seen Lewis acids, and possible reaction mechanism on ZrO2 was tabulated for further catalyst improvement.

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