REACTION PATHWAYS AND CATALYTIC REQUIREMENTS FOR ALDEHYDE DEOXYGENATION ON SOLID BR0NSTED ACID CATALYSTS

摘要

Light aldehydes in the effluent of biomass pyrolysis stream undergo catalytic deoxygenation reactions on solid Breinsted acid (e.g. H-MFI zeolite), solid base (e.g. alkali ion exchanged zeolites and alkaline earth metal oxides), or solid acid and base (e.g. MgO/HY) bi-functional catalysts at ambient pressures and moderate temperatures (423-673 K). The deoxygenation catalysis and its product distributions have been studied extensively, but details of the mechanism, rates of the individual reaction pathways, and the requirements of active sites and the reaction environment have not yet been well understood. On Bronsted acid sites contained within medium pore microporous crystalline materials (H-MFI), aldehyde deoxygenation occurs via competitive and sequential pathways of inter- and intra-molecular C=C bond formation, alkylation/dealkylation, and H transfer steps to evolve larger, unsaturated aldehydes, alkenes, and aromatics with carbon numbers ranging from C6 to C_(15+).