Isolated Hf‐Isomorphously Substituted Zeolites for One‐Pot HMF Synthesis from Glucose

Abstract

The direct conversion of glucose to 5‐hydroxymethylfurfural (HMF) is a crucial process in biorefinery. However, it still suffers from the rational design of highly efficient catalysts for one‐pot HMF production. Herein, the pioneering design of bifunctional hafnium (Hf)‐incorporated zeolites with fine‐tuned Brønsted/Lewis acidity and hierarchical features has been illustrated via one‐pot hydrothermally prepared protocols. Most importantly, the rationally designed catalyst presents the highly dispersed isolated Hf species located at the zeolite framework, which is close to the Brønsted acid site. The designed catalysts eventually reveal superb catalytic performances in glucose conversion (95.4 ± 1.1%) and HMF yield (63.2 ± 2.0%), as well as excellent catalytic stability, which are significantly improved compared to the well‐known tin‐beta zeolite. In addition, the catalytic activity and mechanistic studies of the Hf‐beta zeolite are confirmed by the density functional theory calculations.

Heteroatom Lewis acid zeolites: synthesis, characterization and application in the conversion of biomass-derived oxygenates

“…Moreover, due to the formation of the more stable [DMSO-H] + complex responsible for the selective conversion of glucose into HMF, the solvent of DMSO was more favorable over dioxane, GVL and tetrahydrofuran. 144,151 In summary, 5-HMF can be obtained by one-pot conversion of glucose on bifunctional heterogeneous catalysts containing both LASs and BASs. The fine-tuning balance between LASs and BASs as well as the appropriate pore size is essential to enhance the catalytic performance.…”

“…The best catalytic performance was demonstrated on Hf-HBEA in DMSO solvents, which showed a glucose conversion of 95.4% and a 5-HMF selectivity of 65.8% at 120 °C for 24 h reaction. 151 Fig. 17 One-pot synthesis of 5-HMF from glucose via glucose isomerization and subsequent dehydration on bifunctional catalysts.…”

“…In addition, the effects of different frameworks were compared using Hf-Beta nanocrystals (Hf-HBEA-NC) and Hf-MFI nanosheets (Hf-HZSM-5-NS). 151 The small pore diameter of Hf-HZSM-5-NS limited the accessibility of bulky glucose to active sites, leading to remarkably lower conversion relative to Hf-HBEA-NC. Then, the catalytic performances of Hf-HBEA-NC and Sn-HBEA-NC were further compared (Table 4, entries 9 and 10).…”

“…Moreover, due to the formation of the more stable [DMSO-H] + complex responsible for the selective conversion of glucose into HMF, the solvent of DMSO was more favorable over dioxane, GVL and tetrahydrofuran. 144,151…”

“…The best catalytic performance was demonstrated on Hf-HBEA in DMSO solvents, which showed a glucose conversion of 95.4% and a 5-HMF selectivity of 65.8% at 120 °C for 24 h reaction. 151…”