Sustainable Approach using Functional Organic Nanomaterials for Greener Biomass Conversion

Abstract

The growing human population and rapid industrial modernization have led to a significant increase in global energy demands. Traditionally, this demand has been met using non-renewable resources such as fossil fuels, which, while effective, are nearing depletion and contribute significantly to climate change through the emission of greenhouse gases. As a result, there is a pressing need to transition towards more sustainable chemical industries. Biomass, with its high carbon content, offers a promising alternative to fossil fuels. Similar to the petrochemical industry, bio-based chemical industries utilize a platform chemical approach, where biomass is converted into a small number of intermediates for the production of various value-added chemicals. This thesis investigates the development of sustainable and cost-effective organic nanomaterials for the thermo-catalytic conversion of biomass-derived monomers into value added chemicals. The research emphasizes the chemo-catalytic transformation of lignocellulose, a key biomass component, into platform chemicals that can be further processed into valuable products such as polymers, plastics, and fuels. The study employs innovative catalytic systems derived from diverse biomass sources, including sporopollenin, as well as commonly available bench-top chemicals like para toluenesulfonic acid and NaBH4. One significant advancement presented is the synthesis of HMF (96% selectivity) and furfural (90% selectivity) directly from glucose using a novel Fe²⁺@SO₃-CD nanocomposite. This catalyst, featuring dual Brønsted and Lewis acid sites, enables fine control over product selectivity by tuning the acid sites and solvent ratios. Mechanistic insights into the catalytic process were gained through ¹³C NMR, highlighting distinct pathways for furfural and HMF synthesis. Additionally, the research introduces a Brønsted acid catalyst derived from biomass waste, capable of converting glucose to 5 HMF in water with high yield and selectivity. The catalyst, functionalized with mono- and di-phosphoesters, demonstrates strong glucose interactions, enhancing the efficiency of the conversion process. This environmentally friendly approach offers potential for large-scale 5-HMF production. Further innovations include the development of a Ba3MgSi2O8 nanomaterial, encapsulated in empty sporopollenin, which serves as a Lewis base catalyst for glucose-to-fructose isomerization. This nanomaterial achieved Page v Abstract impressive conversion rates, demonstrating the potential for sustainable catalytic methods in biomass conversion. The thesis also explores the use of microwave heating and NaBH4 in a novel metal-free cascade process to synthesize lactones from biomass derived precursors. This method, applied to the production of industrially relevant compounds such as GVL and succinic anhydride, offers significant efficiency and sustainability advantages over conventional heating techniques. In conclusion, the research presented in this thesis provides valuable insights into the catalytic conversion of biomass into high-value chemicals, offering promising avenues for sustainable industrial applications. Through innovative catalytic systems, this work contributes to the ongoing transition towards renewable and eco-friendly chemical production processes.