In Situ Synthesis of Sn-Beta Zeolite Nanocrystals for Glucose to Hydroxymethylfurfural (HMF)

Abstract

The Sn substituted Beta nanocrystals have been successfully synthesized by in-situ hydrothermal process with the aid of cyclic diquaternary ammonium (CDM) as the structure-directing agent (SDA). This catalyst exhibits a bifunctional catalytic capability for the conversion of glucose to hydroxymethylfurfural (HMF). The incorporated Sn acting as Lewis acid sites can catalyze the isomerization of glucose to fructose. Subsequently, the Brønsted acid function can convert fructose to HMF via dehydration. The effects of Sn amount, zeolite type, reaction time, reaction temperature, and solvent on the catalytic performances of glucose to HMF, were also investigated in the detail. Interestingly, the conversion of glucose and the HMF yield over 0.4 wt% Sn-Beta zeolite nanocrystals using dioxane/water as a solvent at 120 °C for 24 h are 98.4% and 42.0%, respectively. This example illustrates the benefit of the in-situ synthesized Sn-Beta zeolite nanocrystals in the potential application in the field of biomass conversion.

Highly Efficient 5-Hydroxymethylfurfural Production from Glucose over Bifunctional SnOx/C catalyst

“…Fructose can be readily dehydrated into HMF with high selectivity and yield. , However, the large-scale utilization of fructose for preparing HMF is restricted owing to its high cost and shortage in nature. Therefore, one of the alternative feedstocks to produce HMF is glucose, because it is the most abundant monosaccharide and the cheapest hexose, making it as a promising candidate to produce fructose, and subsequently HMF …”

“…Therefore, one of the alternative feedstocks to produce HMF is glucose, because it is the most abundant monosaccharide and the cheapest hexose, making it as a promising candidate to produce fructose, and subsequently HMF. 7 Production of HMF from glucose requires two-step catalytic mechanism: (1) isomerization of glucose to fructose by Lewis acid or base assistance, (2) dehydration of fructose to HMF by Brønsted acid. 8 To convert glucose into HMF, several homogeneous catalysts like inorganic acids, 9 metal chlorides, 10 and modified ionic liquid polymers 11,12 have been reported.…”

Sn-Beta Catalyzed Transformations of Sugars—Advances in Catalyst and Applications

“…Here, the hierarchical Sn-Beta was synthesized from hydrothermally synthesized hierarchical Al-Beta (SDA: polydiallyldimethylammonium chloride) by exposure to SnCl 4 vapor (i.e., gas-solid deposition; see previous section), and the resulting catalysts displayed good activity and afforded both higher glucose conversion (99%) and HMF selectivity (42%) than those of conventional Sn-Beta (96% and 32%, respectively) [75]. Similar catalytic performance has also been obtained at lower reaction temperature at prolonged reaction time with analogously in-situ synthesized Sn-Beta zeolites using diquaternary ammonium as the SDA [76].…”

Nanoporous Sn-Substituted ZSM-48 Nanostructures for Glucose Isomerization

“…59 In contrast, the Sn−Si nanobeads contain the higher portion of Sn 2+ with respect to Sn 4+ (Table 2) with a small amount of metallic Sn 0 species as evidenced by the characteristic peak at the binding energy of 484.1 eV (Figure S8). 29,60 In the case of SnO 2 , the binding energies at approximately 486.8 eV and 495.2 relate to Sn 3d 5/2 and Sn 3d 3/2 , 61 and they are similar to those of Sn 2+ species in the as-synthesized ZSM-48 zeolite (486.4 eV). As can be seen in Table 2, Sn−Si nanobeads demonstrate the lowest Sn 4+ to Sn 2+ ratio owing to its lower proportion of Sn 4+ with respect to Sn 2+ species, while the major Sn species in Sn-Si/ZSM-48 samples is Sn 4+ , indicating that Sn−Si nanobeads as starting materials could be transformed to zeolite in which the Sn 4+ species is incorporated in the framework.…”

“…Indeed, the glucose isomerization to fructose is considered as the rate-determining step (RDS), while the produced fructose can be effortlessly converted to 5-HMF over Brønsted acid sites . It is therefore reasonable to extensively develop the first part of the reaction, which typically requires either Lewis acid or Brønsted base catalysts. , Over the past decades, various tin (Sn)-based catalysts have been developed extensively due to their outstanding properties, such as strong Lewis acidity to catalyze glucose isomerization to fructose with respect to other transition metals, eventually leading to reduce the reaction barrier. , In general, homogeneous and enzymatic catalysts can effectively produce fructose from glucose, but they often suffer from the catalyst recovery and reusability. , To deal with these issues, numerous heterogeneous catalysts have been advantageous, such as metal oxides (e.g., SnO 2 , TiO 2 , and MgO), , mesoporous silica (e.g., SBA-15, MCM-41), , hydrotalcite, , and zeolites. − …”