Design of Nanostructured Organic-Inorganic Hybrid Catalysts for Biorenewable Conversion

ABSTRACT

PI: Brent Shanks and Bert D. Chandler

Institution: Iowa State University

Proposal Number: 0455965

Title: Design of Nanostructured Organic-Inorganic Hybrid Catalysts for Biorenewable Conversion

Research

A significant challenge in the application of chemical catalysts to biorenewables is the need for selective conversion of these highly functionalized molecules. While this specificity has been demonstrated with biocatalysts, the control of the reaction environment around the active site has been more elusive for chemical catalysts. However, the recent advancements in materials synthesis, which has led to the construction of nanostructured organic-inorganic hybrid catalysts, hold promising potential for biorenewable conversion. In the proposed work this potential will be explored in the industrially-relevant oligosaccharide hydrolysis reaction to fermentable sugars. Oligosaccharide hydrolysis can be catalyzed by mineral acids, but the catalyst also causes yield loss by significant degradation of the resulting monosaccharides. While hydrolytic enzymes can selectively hydrolyze oligosaccharides, they typically can only operate at relatively mild conditions. To create well-defined and robust reaction domains, organic-inorganic hybrid catalysts will be synthesized and tested for hydrolysis activity and selectivity.

This research project will have two primary components. The first will focus on the synthesis, characterization, and testing of acidic organic-inorganic hybrid mesoporous catalysts for the hydrolysis of cellobiose. For this portion of the project, the mono-functionalized mesoporous silica will provide the surface area and porosity for the reaction of cellobiose over the organic acid sites. Materials having a range of acid values will be synthesized to determine the relationship between acid strength and the rates of hydrolysis and degradation. In the second portion of the project, the organic-inorganic hybrid mesoporous silicas will be multi-functionalized to create a specific reaction environment within the pores. Multi-functionalization techniques will be used to prepare acid/base catalysts that mimic the catalytic action of hydrolytic enzymes.

Broader Impact

The use of biorenewable feedstocks has an important role in the future of a sustainable chemical industry. However, the effective utilization of biorenewables will require development of new catalyst technologies in which both chemical catalysts and biocatalysts will likely play a role. Chemical catalysts will contribute to biorenewables when the catalytic materials are specifically tailored to the unique challenges presented by biological-based molecules. While the project will examine nanostructured organic-inorgainic hybrid nanostructured catalysts designed particularly for oligosaccharide hydrolysis, the synthesis strategies and the concept of well-defined reaction domains has broader applicability as a general approach to biorenewable reactions. Even the specific catalysts, which provide cooperative acid-base pairs, in the project have applicability in a range of catalytic rea