Hydrogen-free hydrogenolysis of strong C-S, C-O, and C-N bonds

点击翻译按钮获取中文摘要

This proposal reflects fundamental discovery and development research directed toward mitigating two significant impediments to a sustainable modern economy: heavy petroleum utilization and renewable biomass "valourization" specifically targeting waste wood and agricultural lignin. We seek disruptive innovation in both industries, one moribund, one emergent. Bitumen refining is capital- and energy-intensive, consuming hydrogen at very high temperatures and pressures. The highest molecular weight fraction of bitumen, the asphaltenes, contain most of the refractory sulfur, nitrogen, and metal compounds in heavy oil. Asphaltenes are barely soluble in the petroleum matrix, fouling pipelines and refineries. Removing heteroatoms and metals from heavy oil is currently accomplished by pyrolytic coking, destroying ~20-30% of the hydrocarbon value in bitumen to convert the remainder into fuels and petrochemicals. Petroleum coke is toxic, valueless, environmentally persistent, and produced on unimaginable scale. The inefficiency of this process is unsustainable, but alternative de-asphalting methods are rudimentary and more expensive than coking. No "techno-economic" new methods or technologies have emerged have appeared in decades. Under NSERC support, we have discovered two radically new, obstacle-free, and inexpensive pathways to hydrogen-free hydrodesulfurization of the asphaltenes and native lignin: reductive electrocatalysis and heterogeneous hydrogen-transfer catalysts under (very) mild conditions. Electrocatalytic upgrading of bitumen asphaltenes recently crossed from discovery science to process development;  funding from other sources is now used for that purpose. In this proposal, however, we propose to investigate novel catalyst design and synthetic and supramolecular modelling of asphaltene structures and aggregation, about which little is known.         Lignin is the oxygenated polymer that gives woody biomass its structure and strength. Forestry and agricultural waste-woods have no economic value in today's market: pyrolytic gasification is regressive and energetically counterproductive. No non-destructive processes for lignin depolymerization have been reported - until now. Heterogeneous copper catalysts for hydrogen-free depolymerization and deoxygenation of lignin and model compounds have been demonstrated, albeit not optimized.  The nanocatalysts function by hydrogen-transfer hydrogenolysis, stripping hydrogen from a neighbouring alcohol and it using to cleave the carbon-oxygen bond that holds the polymer together. The products are simple aromatic alcohols. No complex bio-oils or gases. Electrocatalytic depolymerization/deoxygenation of lignin remains at the discovery stage, and provides another of this proposal.   Inorganic and organic synthesis, heterogeneous catalysis, reaction mechanisms, supramolecular chemistry, and computational theory:  discovery research witin the constraints of industrial reality.