Date of Award

8-2015

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

Advisor

G. Peter van Walsum

Second Committee Member

M. Clayton Wheeler

Third Committee Member

Adriaan van Heiningen

Abstract

Due to current practices in the petroleum industry, fossil fuel availability is permanently decreasing while their use significantly contributes to the accumulation of greenhouse gases. The sustainability and feasibility for the conversion of biomass to hydrocarbon fuels has therefore become an essential research focus. While fuels are burned for energy and release CO2 into the atmosphere, replanting previously harvested biomass guarantees that CO2 will be recycled back through the growth of new foliage. Cellulose in biomass can be converted into valuable chemicals such as levulinic and formic acid through acid catalyzed hydrolysis and dehydration. These hydrolysis products can be further upgraded to liquid fuels through the thermal deoxygenation (TDO) method. Currently, the preferred method of acid catalyzed hydrolysis of biomass is performed with sulfuric acid. It is necessary to recover the sulfuric acid for both economical and environmental reasons. The recovery and recycling of the sulfuric acid has proven to be a significant hurdle with many challenges affecting the scale-up and commercialization of the biomass hydrolysis processes.

Hydrolysis of cellulose using a class of acids called α-hydroxysulfonic acids presents a novel approach to simplifying acid recovery and recyclability. We have shown that specific α-hydroxysulfonic acids can be synthesized to effectively hydrolyze carbohydrates to levulinic and formic acid. The acid catalyst and its constituents exist in equilibrium with each other. Therefore, the acid can be easily reverted to its non-acidic constituents by employing the proper conditions. The equilibrium between them is subject to the nature of the constituents used to synthesize the acid. The ability to tune the α-hydroxysulfonic acids in response to desired acid strength and decomposition method becomes a viable approach to process design. Complications in downstream processing can be minimized as separations, neutralization, and purification steps can be simplified or avoided. This thesis presents the results of an investigation into the use of several different α-hydroxysulfonic acids for conversion of cellulose and glucose to levulinic and formic acids.

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