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

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

Synthesis of large-pore zeolites from chiral structure-directing agents with two l-prolinol units

Enantiopure chiral organic dications based on two l-prolinol units linked by para-xylene units effectively structure-directs the crystallization of several zeolites including beta, while the meta-xylene derivative is a much less efficient director.

Direct Synthesis of Ti-Containing CFI-Type Extra-Large-Pore Zeolites in the Presence of Fluorides

Ti-containing zeolites showed extremely high activity and selectivity in numerous friendly environmental oxidation reactions with hydrogen peroxide as a green oxidant. It will be in high demand to synthesize Ti-containing crystalline extra-large-pore zeolites due to the severe restrictions of medium-pore and/or large-pore zeolites for bulky reactant oxidations. However, the direct synthesis of extra-large-pore Ti-zeolites was still challengeable. Here, we firstly report a strategy to directly synthesize high-performance Ti-containing CFI-type extra-large-pore (Ti-CFI) zeolites assisted with fluorides. The well-crystallized Ti-CFI zeolites with framework titanium species could be synthesized in the hydrofluoric acid system with seed or in the ammonium fluoride system without seed, which showed higher catalytic activity for cyclohexene oxidation than that synthesized from the traditional LiOH system.

Correction: Synthesis of nanostructured catalysts by surfactant-templating of large-pore zeolites

Correction for ‘Synthesis of nanostructured catalysts by surfactant-templating of large-pore zeolites’ by Aqeel Al-Ani et al., Nanoscale Adv., 2019, 1, 2029–2039.

Correction: Synthesis of nanostructured catalysts by surfactant-templating of large-pore zeolites

Correction for ‘Synthesis of nanostructured catalysts by surfactant-templating of large-pore zeolites’ by Aqeel Al-Ani et al., Nanoscale Adv., 2019, DOI: 10.1039/c9na00004f.

Synthesis of nanostructured catalysts by surfactant-templating of large-pore zeolites

Zeolites and related crystalline molecular sieves are utilised in a wide range of reactions and processes due to their regular microporous structure, strong acidity, shape selectivity and ion-exchange properties.