Imogolite Nanotubes As a Catalyst for Biomass Conversion

Rising energy costs and concerns regarding climate change necessitate the development of efficient and sustainable processes for the production of fuels and chemicals. Catalysts are an attractive solution to minimize the cost and environmental impact of these processes. One important process is biomass conversion, which can be employed to produce 5-hydroxymethyfurfual (HMF). HMF is a valuable intermediate for the sustainable production of biofuels, plastics, and chemicals. It is produced by the cascade reaction of glucose to fructose to HMF. Several intriguing catalysts for the isomerization of glucose to fructose have been identified, including immobilized enzymes, triethylamine, and zeolites. While these catalysts have sparked immense interest in this area, further research is necessary to identify novel catalysts for the isomerization reaction that are cost effective and environmentally friendly. The purpose of this research is the study of imogolite nanotubes as a catalyst for the isomerization of glucose to fructose. Imogolite nanotubes offer a highly tunable platform and the capability to design an effective heterogeneous catalyst. The successful synthesis of imogolite nanotubes has been confirmed. Preliminary catalytic tests on the imogolite nanotubes show promising activity for the isomerization reaction. Further work includes the determination of the active site of imogolite that is responsible for the catalytic activity. Extensive characterization of the materials to determine dimensions, composition, and acid-base properties gives insight on the active site. An opportunity to improve the selectivity of the imogolite catalyst for fructose lies in modification of the nanotube structure and composition through changes to the synthesis procedure. Effective modifications to the structure and properties of imogolite have been identified and performed, including methyl functionalization, precise control over dimensions, and heteroatom substitution. The effects of these modifications on surface properties and catalytic activity aid in identification of the active site and enable further tuning of catalytic activity. The results of preliminary tests establish that imogolite has the potential to be applied as an effective isomerization catalyst. Through further investigation of the nature of the catalytic activity, imogolite could be a novel catalyst that aids in the efficient, eco-friendly, and sustainable production of fuels and chemicals from biomass.