Creating Accessible Active Sites in Hierarchical MFI Zeolites for Low-Temperature Acid Catalysis

Highly selective Lewis acid sites in desilicated MFI zeolites for dihydroxyacetone isomerization to lactic acid.

Desilication of commercial MFI-type (ZSM-5) zeolites in solutions of alkali metal hydroxides is demonstrated to generate highly selective heterogeneous catalysts for the aqueous-phase isomerization of biobased dihydroxyacetone (DHA) to lactic acid (LA). The best hierarchical ZSM-5 sample attains a LA selectivity exceeding 90 %, which is comparable to that of the state-of-the-art catalyst (i.e.,...

Catalytic Behavior of Brønsted Acid Sites in MWW and MFI Zeolites with Dual Meso- and Microporosity

The catalytic behavior of Brønsted acid sites in three acidic zeolite materials (one MWW and two MFI zeolites) containing dual meso-/microporosity was studied using ethanol dehydration and monomolecular conversion of propane and isobutane as probe reactions. The meso-/microporous MWW zeolite, MCM-36 or pillared MWW, consists of a zeolitic layer structure, with independent microporosity and meso...

Acid strength and solvation in catalysis by MFI zeolites and effects of the identity, concentration and location of framework heteroatoms

The effects of heteroatom identity (Al 3+ , Ga 3+ , Fe 3+ , or B 3+), concentration and location on catalysis by MFI zeolites are examined and interpreted mechanistically using methanol dehydration rate constants and density functional theory estimates of acid strength (deprotonation energies, DPE). In doing so, we shed light on the concomitant effects of confinement and acid strength on cataly...

Hierarchical Sn-MFI zeolites prepared by facile top-down methods for sugar isomerisation

Acid]Base Catalysis in Zeolites from First Principles

Zeolite materials are microporous aluminosilicates with various uses, including acting as important catalysts in many processes. One such process is the methanol to gasoline reaction, used widely in industry. This reaction is known to be associated with Brønsted acid sites in the zeolite, formed when Si is substituted by Al in the framework, with an associated Hq being bound nearby to maintain ...