In situ Solid-State NMR/Computational Study of Carbohydrate-Based Biomass Conversion in Porous Catalysts
EMSL Project ID
48898
Abstract
Carbohydrate-based biomass is a renewable alternative to fossil fuels for the production of energy-dense, liquid carbon-based chemicals and fuels. Large-scale applications for biomass-derived feedstocks are highly dependent on the design of effective solid catalysts, together with the selection of appropriate and environmentally-benign solvent systems. The use of solid catalysts facilitates their separation and regeneration, while solvents must be present to enhance contact between the catalyst and the substrate due to the inherently low volatility and high thermal sensitivity of most biomass-derived molecules. Reaction mechanisms over solid catalysts are poorly understood compared to those involving homogeneous catalysts. In particular, the origin of large solvent effects on catalyst activity and stability are at present unknown. We will employ operando solid-state magic-angle-spinning NMR spectroscopy combined with computational analysis to study the reactions of carbohydrates in porous catalysts. Recently-developed EMSL-built NMR rotors capable of withstanding the high pressures and temperatures required for the reactions will enable us to monitor the conversion of monosaccharides inside the porous catalysts (both microporous aluminosilicates and mesoporous silicas). Signals for molecules that are less mobile due to their confinement inside the pores can be distinguished from those of the more mobile molecules in the bulk liquid phase, and quantified separately as the reactions proceed, leading to information-rich kinetic profiles. Using 13C-labelled starting materials, we expect to identify low abundance reaction intermediates and minor products, facilitating detailed mechanistic analysis. State-of-art DFT computations of adsorbed molecules will be conducted in parallel to assist in assigning signals, and to simulate surface-induced orientation and association of substrate and solvent molecules. This integrated experimental-computational approach will provide molecular-level insight into the functioning of porous solids during liquid-phase carbohydrate processing, thereby helping to advance the use of biomass-based renewable energy through the design of high-performance catalyst systems.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2015-10-01
End Date
2017-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Qi L ,Alamillo R ,Elliott W A,Andersen A ,Hoyt D W,Walter E D,Han KS ,Washton N M,Rioux R M,Dumesic J A,Scott S L 2017. "Operando Solid-State NMR Observation of Solvent-Mediated Adsorption-Reaction of Carbohydrates in Zeolites" ACS Catalysis 7(5):3489-3500. 10.1021/acscatal.7b01045