Obtaining glucose-based 5-hydroxymethylfurfural on large-pore zeolites

Abstract

Obtaining such substances-platforms as, in particular, 5-hydroxymethylfurfural is one of the areas most actively investigated at present. They can act as raw materials for the further production of a new generation of biopolymers, fuels, pharmaceuticals, dietary supplements, and other chemicals. This paper reports the catalysts, synthesized by using methods of ion exchange and impregnation, based on the large-pore zeolites X, Y, and M, which contain the cations of rubidium, lanthanum, calcium, and ammonium. It was found that the zeolites' specific surface was 400‒500 m2/g; the selected synthesis conditions did not cause noticeable destruction of the microporous structure. In the presence of the synthesized catalysts, glucose dehydration in the aqueous medium and in dimethyl sulfoxide was carried out at 150–160 °C. The higher efficiency of polycationic forms of zeolites in a non-aqueous medium has been established. In the latter case, a 40 % yield of 5-hydroxymethylfurfural was achieved at an almost complete glucose conversion. Deactivated catalyst samples were investigated using the methods of infrared spectroscopy and differential thermal analysis/thermogravimetry. It was found that the catalyst accumulates fewer oligomerization process by-products when the reaction is implemented in dimethyl sulfoxide. The loss of mass by the samples deactivated in an aqueous medium is 30‒33 %, while in dimethyl sulfoxide – up to 24 %. The obtained results are important for practical application as the only volatile conversion product is 5-hydroxymethylfurfural with a yield of up to 40 %. That is acceptable for the possible implementation of a one-stage process of obtaining 5-hydroxymethylfurfural in the future

Catalytic Synthesis of Methyl Glycolate from Glyoxal Methanol Solution over Base Catalysts

“…5-HMF yields for them are 50 and 83 %, respectively, with practically complete conversion of fructose. The yields were even higher than in the transformation of glucose over polycationic faujasites 29 and hydrogen forms of zeolites modified with nickel. 41 As can be seen from Fig.…”

“…Peculiarities of exchanges were selected based on previous experience in introducing these cations into faujasite-type zeolites. 26,29 For comparison, the polycationic sample (M-PC) based on synthetic mordenite (NaM, SiO 2 /Al 2 O 3 =9.7, produced by JS "Sorbent") was obtained similarly. The sequence of exchanges: four exchanges for calcium at 363 K, two exchanges for lanthanum at 363 and 423 K, and one exchange for ammonium at 363 K.…”

“…[23][24][25] Recently, the efficiency of the calcium-lanthanum-ammonium form of faujasite, previously well established as catalysts for the alkylation of isobutane with butenes, [26][27][28] has been found in the conversion of glucose into 5-HMF in aqueous and DMSO media. 29 On the other hand, zeolites, especially natural ones, are wellknown materials for sorption and purification. [30][31][32] Therefore, the aim of the present work was the investigation of the activity of zeolite catalysts based on natural Transcarpathian clinoptilolite for the fructose conversion into 5-HMF.…”

Transformation of Hexoses on Natural and Synthetic Zeolites

“…Conditions of ion exchange were selected based on the results of previous works. 23,24 For comparison, a range of samples was used. Ammonium and hydrogen forms of zeolite Y and M were synthesized from sodium forms of powder zeolites.…”