Novel Complex Titanium NASICON-Type Phosphates as Acidic Catalysts for Ethanol Dehydration

The conversion of ethanol towards ethylene and diethyl ether in the presence of catalysts requires special consideration from the perspective of green chemistry. Ethanol dehydration was studied on a complex titanium phosphate MAlTiP (M0.5(1+x)AlxTi2-x(PO4)3 with M = Ni, Mn (x = 0; 0.2)) catalysts, alongside a NASICON-type structure synthesized by the sol–gel method. The initial catalysts were characterized by N2 gas sorption, SEM, XRD and spectroscopic methods (Raman and DRIFT of adsorbed CO and C6H6). The results revealed that all catalysts exhibited high activity and selectivity at 300–420 °C. The conversion of ethanol increases with the reaction temperature, reaching 67–80% at 420 °C. The MnAlTiP exhibited the highest ethylene selectivity among other catalysts, with 87% at 420 °C. The aluminum modification improved the acid properties of the catalysts, due to the appearance of Lewis acid sites (LAS) and the strength moderate Brønsted acid sites (BAS). It was shown that the activity of complex phosphates in ethanol dehydration increases with the strength of the Brønsted acid sites (BAS).

Biomass-Based Carbon-Supported Sulfate Catalyst for Efficient Synthesis of Dimethoxymethane from Direct Oxidation of Dimethyl Ether

The synthesis of dimethoxymethane (DMM) from direct oxidation of dimethyl ether (DME) is a green and competitive route with good atomic economy and low carbon emission and is also an urgent need. In this work, biomass-based carbon-supported sulfate catalysts were designed and prepared for the efficient synthesis of DMM from DME oxidation. The prepared carbon support from cellulose displayed much larger specific surface area and a developed microporous structure, which effectively benefited a high dispersion of sulfate components, leading to mainly weak acid sites and more oxygen functional groups on the catalyst surface. The Ti(SO₄)₂/PC-H₂SO₄ catalyst exhibits excellent performance for DME oxidation with DMM_1-2 selectivity up to 96.7%, and DMM selectivity reaches 89.1%, notably higher than that of previously reported results. The distinctive surface structure and chemical properties of the carbon support have important impacts on the dispersion state of sulfate species, affecting the acidic and redox properties of the catalysts.

Excellent prospects in methyl methoxyacetate synthesis with a highly active and reusable sulfonic acid resin catalyst

A highly active and reusable sulfonic acid resin catalyst was used for DMM carbonylation to MMAc.