Simply Assembly of Acidic Nanospheres for Efficient Production of 5‐Ethoxymethylfurfural from 5‐Hydromethylfurfural and Fructose

Abstract

A series of organic–inorganic acidic hybrids in uniform nanospheres were prepared by self‐assembly of phosphotungstic acid (HPW) and pyridine (PY) or triethylamine (TEA) without using a template and surfactant. The prepared samples were characterized by XRD, TEM, FTIR, and N2 adsorption–desorption isotherms, and their surface acidity was determined by titration. Particularly, PY‐PW‐1 showed a predominant catalytic performance in the near complete etherification of 5‐hydromethylfurfural (HMF) to 5‐ethoxymethylfurfural (EMF) with a high yield of 90 % at 80 °C in 24 h, which might be ascribed to its relatively high acidity and smaller particle size. This kinetic study elucidated the superior activity of PY‐PW‐1 in the HMF‐to‐EMF conversion. Fructose could also be directly converted to EMF in a moderate yield of 55 % at an elevated temperature of 120 °C by a cascade reaction process. In addition, PY‐PW‐1 could be reused five times with no evident loss of its catalytic activity. Importantly, the downstream product of EMF (i.e., ethyl levulinate) in an excellent yield of 93 % could also be achieved from HMF by further increasing the reaction temperature to 140 °C.

Upgrading of Carbohydrates to the Biofuel Candidate 5-Ethoxymethylfurfural (EMF)

“…Fe 3 O 4 @SiO 2 -HPW catalyzed the reaction of HMF with ethanol, and therefore, the activity increased dramatically and the production of EMF yield reached 83.6% [49]. Wang et al [50] also applied Fe 3 O 4 @SiO 2 -HPW for EMF production from HMF to obtain the same effect, which was in accordance with the results of Liu and Zhang [51] [53] studied the uniform nanospheric hybrids by controlling the molar ratio of phosphotungstic acid (HPW) and pyridine (PY) or trimethylamine (TEA) in different nanosizes. Particularly, PY-PW-1 showed an excellent catalytic activity with 90% of EMF, which attribute to the relatively strong acidity and regular pore size.…”

3-Bromopyridine-Heterogenized Phosphotungstic Acid for Efficient Trimerization of Biomass-Derived 5-Hydroxymethylfurfural with 2-Methylfuran to C21 Fuel Precursor

“…After each cycle of the reaction, the catalyst was removed from the reaction system by centrifugation and then washed with 20 mL ethanol for three times, which was finally dried at 80°C for 24 h. The recovered catalyst was utilized directly for the next run under identical reaction conditions. [50][51][52][53][54][55][56] could also be observed for HPyPW and 3-BrPyPW. This result indicated that even HPW was decorated by different organic species; it could well maintain the original HPW cubic basically.…”

“…Taking the above problems into consideration, it is highly desirable to heterogenize HPW using a high-efficiency method. For example, Wang et al [50] and Fang et al [51] prepared electric flocculation of HPW and silica-supported HPW heterogeneous catalysts for the con-version of glucose into 5-hydroxymethylfurfural (HMF) with a good yield of 61.7% and 78.3%, respectively. Due to heterogeneous functionalization, these catalysts could be reused at least four or five times without significant loss of catalytic activity.…”

Catalytic Conversion of Carbohydrates into 5‐Ethoxymethylfurfural by a Magnetic Solid Acid Using γ‐Valerolactone as a Co‐Solvent

“…Heterogeneous acid catalysts have the advantages of being readily separable and recyclable, which have been utilized for the synthesis of EMF from HMF,, 5‐chloromethylfurfural (CMF), or biomass‐derived carbohydrates (Table S3 in the Supporting Information) ,,,,,,. However, effective catalytic systems with high activity and selectivity towards the synthesis of EMF are still limited.…”