Hydrophobic microporous and mesoporous oxides as Brønsted and Lewis acid catalysts for biomass conversion in liquid water

摘要: The use of heterogeneous catalysts in liquid water, even at the moderate temperatures (<523 K) typical most condensed-phase biomass conversion processes, is often fraught with issues related to structural instability and active site inhibition caused by deactivation mechanisms that differ from those prevalent gas phase higher temperatures. For porous silica-based oxides, one strategy address these design or functionalize oxide surfaces hydrophobic moieties domains. Hydrophobic can be present either external crystallite within internal voids where sites typically reside. Both extracrystalline intracrystalline environments prevent condensation bulk water void spaces thus alleviate any transport restrictions its presence may cause, while only influence kinetic effects molecular sites. As a result, both have fundamentally different consequences for reactivity, spite phenomenological similarities their on observed reaction rates. conceptual distinction between two forms hydrophobicity, together accurate assessments contributions measured rates, inform placement domains appropriate locations solids cause predictable changes reactivity. This mini-review discusses concepts context recent studies used Bronsted Lewis acidic microporous mesoporous oxides catalytic reactions biomass-derived molecules biphasic water–organic mixtures.