A 81.1% aromatic selectivity in C₅₊ hydrocarbon was obtained at 320 °C, corresponding to 19.9% CO₂ conversion and 69.4% C₅₊ selectivity in total hydrocorbons.

An efficient rhenium oxide-modified H₃PW₁₂O₄₀/TiO₂ catalyst is found for a new synthesis of dimethoxy dimethyl ether from dimethyl ether oxidation. The effects of Re loading, H₃PW₁₂O₄₀ content and different feedstocks on the performance of Re–H₃PW₁₂O₄₀/TiO₂ were investigated. The results showed that DMM₂ selectivity was significantly improved up to 60.0%, with 15.6% of DME conversion over 5% Re–20% H₃PW₁₂O₄₀/TiO₂. NH₃-TPD, NH₃-IR, Raman spectra, H₂-TPR, XPS and TEM were used to extensively characterize the structure and surface properties of the catalysts. The introduction of H₃PW₁₂O₄₀ significantly affected the structure and reducibility of surface rhenium oxide species, in addition to increasing the acidity of the catalyst. The increased number of Lewis acid sites and weak acid sites and the optimal ratio of Re⁴⁺/Re⁷⁺ of Re–H₃PW₁₂O₄₀/TiO₂ were favorable for the formation of DMM₂ from DME oxidation. The possible reaction pathway of DME oxidation to DMM₂ was proposed.

Dimethyl ether oxidation was conducted over MoO₃–SnO₂ catalysts prepared from different Sn salt precursors. Over the MoO₃–SnO₂ catalyst prepared from SnCl₄, methyl formate selectivity reached 94.1% at 433 K without the formation of CO_x. The performance of the catalyst was determined by the existence form of MoO₃ and the different surface bonding of Mo and O of the catalyst.

Due to its excellent conductivity, good thermal stability and large specific surface area, carbon nano-tubes (CNTs) were selected as support to prepare a Re-based catalyst for dimethyl ether (DME) direct oxidation to polyoxymethylene dimethyl ethers (DMM_x). The catalyst performance was tested in a continuous flow type fixed-bed reactor. H₃PW₁₂O₄₀ (PW₁₂) was used to modify Re/CNTs to improve its activity and selectivity. The effects of PW₁₂ content, reaction temperature, gas hourly space velocity (GHSV) and reaction time on DME oxidation to DMM_x were investigated. The results showed that modification of CNT-supported Re with 30% PW₁₂ significantly increased the selectivity of DMM and DMM₂ up to 59.0% from 6.6% with a DME conversion of 8.9%; besides that, there was no CO_x production observed in the reaction under the optimum conditions of 513 K and 1800 h⁻¹. The techniques of XRD, BET, NH₃-TPD, H₂-TPR, XPS, TEM and SEM were used to characterize the structure, surface properties and morphology of the catalysts. The optimum amount of weak acid sites and redox sites promotes the synthesis of DMM and DMM₂ from DME direct oxidation.