CAREER: Inorganic-organic hybrid microreactors for fundamental study of cellulose hydrolysis by solid acids

Worcester Polytechnic Institute, Worcester MA

Investigators

Abstract

Abstract - Timko, 1554283 Lignocellulosic biomass, the world's most abundant source of renewable carbon, has promise as a carbon neutral energy source that can reduce the need for petroleum-based transportation fuels, chemicals, and materials. Despite progress and promise in the development of many different biofuel technologies, none have proven economically viable. The aim of this project is to make production of fuels and chemicals from biomass resources economically viable. The poor economics of biomass conversion to fuels and chemicals is due largely to biomass resistance to chemical and biological attack. Three primary platforms have been suggested for overcoming biomass recalcitrance: bio-oil (produced via pyrolysis or liquefaction), synthesis gas (produced by gasification), and sugars (produced by pretreatment and enzyme hydrolysis). This proposal is focused on the sugars platform. Biomass resistance to chemical and biological attack makes recovery of monosaccharides expensive and energy intensive. The focus of this work is on recovery of monosaccharides from biomass because this step represents the key technological bottleneck of the sugars platform. The overarching research objective is to understand the fundamental mechanisms underlying cellulose deconstruction by solid acid catalysts. The approach consists of constructing polymer-brush modified inorganic particles (silica and zeolites) as catalytic microreactors with: 1) well defined external acidity that can be accessed by insoluble substrates, 2) cellulose targeting/binding/solubilization capability to provide interactions between insoluble substrates and external surfaces of solid acids, and 3) internal pore structure and acidity that can be accessed by small molecule soluble substrates. Specific questions to be addressed include: 1) what is the structure/property- function relationship that governs the catalyst-biomass interaction? 2) what is the relationship between solid acid strength and cellulose hydrolysis activity? and 3) what is the balance between external acidity for cellulose chain breaking and internal acidity for hydrolysis of soluble fragments? The project will evaluate the hypothesis that solid acid catalysis is mediated by binding interactions and strong acidity. In the research component of this work, the underlying mechanism will be examined to: 1) understand the role of catalyst-cellulose binding and the relationship between cellulose adhesion, catalyst surface composition, and catalyst surface energy; 2) quantify the role of acidity and answer the question of how acidic the surface needs to be to catalyze hydrolysis; 3) differentiate between external acidic sites required to convert insoluble substrates and internal acidic sites capable of converting soluble carbohydrates. The research objectives will be integrated with educational and outreach aims to use data-to-music tools to attract students from under-represented backgrounds to careers in STEM fields and to appeal to a broader range of learning styles at the undergraduate level than are typical in the engineering curriculum. In terms of education, the use of music to teach difficult concepts to college engineering students could improve training for students that use learning styles that are not typical in engineering curricula. This has potential to improve retention of a broader range of undergraduate students in STEM fields. The outreach component will provide K-12 students with an engaging STEM experience that empowers rather than alienates. Specifically, research data will be converted into sounds and re-modulated into music, a process that mimics the practice of sampling that drives hip hop music composition.