Iron(III)‐modified tungstophosphoric acid supported on silica‐pillared montmorillonite as catalysts for fructose conversion to methyl levulinate

Abstract

BACKGROUND Because of the decline in conventional sources of energy and the increasing pollution, the fossil fuel based energy structures is being replaced by renewable energy based structures such as biomass energy. Among current biodiesel sources, methyl levulinate (ML) obtained from catalytic conversion of renewable carbohydrate with methanol has received a great deal of attention. Silica‐pillared montmorillonites (MMTSi) functionalized by iron‐modified tungstophosphoric acid (HPWFe) were prepared, and their physicochemical properties and catalytic effects on ML production studied. RESULTS Catalysts characterization demonstrated the high dispersion and Keggin structure of HPWFe in the framework of MMTSi. Effects of various reaction parameters and catalyst recycling on the reaction performance were studied to optimize fructose conversion. With 4‐HPWFe‐MMTSi as the catalyst, an optimized ML yield of around 74 mol% was obtained at 180°C for 1 h, and the recovered catalyst after calcination was found to retain high activity after being reused five times. CONCLUSION The prepared HPWFe‐MMTSi catalysts showed high porosity, perfect Brnsted‐Lewis acidity and high thermal stability, which made their catalytic activity for fructose conversion and catalyst reusability values higher than others reported in the literature. © 2017 Society of Chemical Industry

Direct Alcoholysis of Carbohydrate Precursors and Real Cellulosic Biomasses to Alkyl Levulinates: A Critical Review

“…However, also in this case cellulose conversion gave only moderate ML yield (24 mol%, according to run ML_135, Table 5), which restricted the use of this catalyst to simpler soluble carbohydrates. Lastly, silica-pillared montmorillonites functionalized by iron-modified tungstophosphoric acid were prepared by Lai et al [110] and tested for fructose methanolysis. The characterization demonstrated the high dispersion and Keggin structure of HPWFe in the framework of the MMTSi.…”

Construction of Z‐scheme Pt‐TiO2/(Er3+:Y3Al5O12@Ta2O5)/HAP and its application in sonocatalytic degradation of prometryn and disinfection of Escherichia coli

“…On the one hand, the combination of the ultrasonic wave with sonocatalyst particles can produce synergistic effects, which can enhance the degradation efficiency of organic pollutants . On the other hand, being similar to the photocatalytic reaction process, the ‘sonoluminescence’ can bring wide wavelength range lights to excite the semiconductor sonocatalyst, producing photo‐generated electrons (e − ) and holes (h + ) on the conduction band (CB) and the valence band (VB), respectively. The generated h + can directly oxidize organic pollutants .…”

“…Since the lack of ultraviolet‐light, the wide band‐gap semiconductor sonocatalysts display a low sonocatalytic activity. Recent studies show that Er 3+ :Y 3 Al 5 O 12 as one of the up‐conversion luminescence agents can convert low energy visible‐light to high energy ultraviolet‐light . Apparently, Ta 2 O 5 with wide band‐gap ( E bg = 4.0 eV) can be stimulated by high energy ultraviolet‐light converted by Er 3+ :Y 3 Al 5 O 12 to carry out sonocatalytic reaction more effectively.…”

Phosphotungstic acid heterogenized by assembly with pyridines for efficient catalytic conversion of fructose to methyl levulinate

“…22 Lai and co-workers reported on the synthesis of ML from fructose in methanol at 180 C for 1 h in the presence of 4-HPWFe-MMTSi catalyst: the ML yield reached 74%, and this catalyst exhibited good reusability. 23 Although they have excellent catalytic performance, these catalysts have their own drawbacks, such as high temperature and pressure, the high cost of preparation, and several synthetic steps. As a promising alternative, the assembly of HPW with basic organic species is an effective way to solidify the homogeneous acid and "tune" its acidity.…”