Sulfonic Acid-Functionalized Zeolite Beta: Bronsted Acid Catalysts for Reactions Involving Liquid Water

Abstract

The utility of zeolites in biomass upgrading reactions can be limited in cases where stronger Bronsted acidity and/or hydrophobicity are required for effective catalysis. While sulfonated solids/sulfonic acid catalysts can be used in such cases, they forego the advantageous effects of confinement that are afforded by zeolites. Here, acidity, hydrophobicity, and confinement are integrated into a solid material by functionalizing the intrapore voids of zeolite Beta with phenethyl-sulfonic acid sites (PE-Betas). These PE-Betas, along with conventional H-Betas, mesoporous phenethyl-sulfonic acidfunctionalized SiO 2 gel (PE-SiO 2 ), and commercial sulfonic acid catalysts (para-toluenesulfonic acid, Nafion NR50) are evaluated in the hydroxyalkylation/alkylation reaction of 2-methylfuran with acetone. The PE-Betas show superior turnover numbers (TON) due to the combination of high acid site strength and hydrophobicity that arises from the confined PE groups. Further, the hydrophobicity and TON over PE-Betas are invariant with acid site density, showing that these materials effectively decouple the active site density−hydrophilicity relationship that is a fundamental limitation of conventional zeolites. These sulfonic acidfunctionalized zeolites represent a distinct class of water-tolerant, strong Bronsted acid catalysts that may be well suited for a wide range of biomass upgrading reactions that generate stoichiometric amounts of liquid water.

Hydrophobic species-enabled acid–base multi-catalysis for stereoselective access to renewable trans-anethole

“…45 The benzene ring of SA also promoted the hydrophobicity of the catalyst, which enabled 4-MOPE to successfully carry out the next dehydration reaction. 32 In addition, the prepared catalyst can completely convert the substrate and the carbon balance can reach more than 95%. As shown in entry 3 of Table 3, PSA–Hf (2 : 1 : 0.5) had the best proportion of PA, SA, and HfCl 4 , showing the best catalytic activity (97.2% AN yield) and TOF (9.3 h −1 ).…”

“…31 The signals at 1140 and 1235 cm −1 represented the symmetric and asymmetric stretching vibrations of OvSvO, respectively. 32 There was a blueshift in the stretching vibrations of S-O, from 758 cm −1 (SA) to 812 cm −1 (PAS-Hf (2 : 1 : 0.5)). This can explain the extreme bridging connection between the Hf and -SO 3 groups.…”

Aromatic aldehydes as tuneable and ppm level potent promoters for zeolite catalysed methanol dehydration to DME

“…31,32,67 Davis and co-workers have recently shown that grafting phenethyl-sulfonic acid sites into the micropores of the wide pore zeolite H-beta gives a very efficient catalyst for the hydroxyalkylation/alkylation condensation reaction of 2-methylfuran with acetone. 24 This increased catalytic efficiency results from the confinement effect of the zeolite micropores, combined with increased hydrophobicity imparted by the grafting sulfonic acid containing residues into silica-rich micropores. The grafted sulfonic acid contains an aromatic ring and a linking alkyl chain, with a reactive sulfonic acid head-group placed on the aromatic ring.…”

Aromatic aldehydes as tuneable and ppm level potent promoters for zeolite catalysed methanol dehydration to DME

“…25,26,62 Davis and co-workers have recently shown that grafting phenethyl-sulfonic acid sites into the micropores of the wide pore zeolite H-beta gives a very efficient catalyst for the hydroxyalkylation/alkylation condensation reaction of 2-methylfuran with acetone. 23 This increased catalytic efficiency results from the confinement effect of the zeolite micropores, combined with increased hydrophobicity imparted by the grafting sulfonic acid containing residues into silica-rich micropores. The grafted sulfonic acid contains an aromatic ring and a linking alkyl chain, with a reactive sulfonic acid head-group placed on the aromatic ring.…”