Partial Oxidation of Methane with Sol-Gel Fe/Hf/YSZ Catalyst in Dielectric Barrier Discharge： Catalyst Activation by Plasma

The catalytic conversion of methane to methanolis one of the major challenges faced by chemists .Methane ,as the major constituent of natural gas ,isthe cheapest source of hydrocarbons ,and the demandfor methanol is expectedtoincreaseinthe nearfuture .Currently, methanol is produced using synthesis gas(CO, CO2,and H2) . However ,this process can bedrastically changed if an effective method to oxidizemethane to methanol is found .Catalytic homogeneousoxidation of methane at lowtemperatures is…     

Room temperature ionic liquids for propyne–propylene separations: Solubility behaviors and selectivity investigation

Room temperature ionic liquids (RTILs) have been discovered as very promising media for acetylene–ethylene separation. In this work, propyne and propylene solubility behaviors in dialkylimidazolium-based RTILs bearing various kinds of anions have been investigated for the feasible extraction process of propyne from propylene mixture. Solubility–molar volume relationship supported by thermodynamic analysis indicated that physical absorption mechanism plays dominantly in determining the propylene solubility. Meanwhile, unlike the acetylene solubility, which is controlled almost exclusively by hydrogen bonding interaction (chemical interaction) between the anion of RTIL and the solute, the solubility of propyne is a result from a tradeoff between chemical and physical interactions. Generally speaking, the trend of the ideal absorption selectivity for propyne over propylene is close to the acetylene–ethylene case where the higher the hydrogen bond basicity and the smaller the molar volume of RTIL results in the greater the selectivity for propyne.     

Cu–Zn–Cr2O3 Catalysts for Dimethyl Ether Synthesis: Structure and Activity Relationship

The CuO dispersed on ZnCr₂O₄ catalysts derived from Cu–Zn–Cr hydrotalcite like layered double hydroxide precursors with varying Zn/Cr ratios have been synthesized, characterized by BET—Surface area, X-ray diffraction (XRD), temperature programmed reduction (TPR), electron spin resonance (ESR), N₂O titrations and the activities were evaluated for single step dimethyl ether (STD) synthesis from syngas. It is observed that the copper species were in highly dispersed state over Cu–ZnO–Cr₂O₃ at high Zn/Cr ratios while the copper cluster were present at low Zn/Cr ratios. The ESR analysis revealed signals due to isolated Cu²⁺ at high Zn/Cr ratios and clustered Cu²⁺ at low Zn/Cr ratio in fresh catalysts and only Cr³⁺ species in used catalysts. The TPR results indicated that the reduction peak shifted to high temperatures with an increase in chromium content due to large copper crystallites, which was supported by XRD analysis. The conversion of syngas to DME was well correlated with the copper metal surface areas, indicating that STD synthesis can be controlled by methanol synthesis rate.     

Ionic liquids for acetylene and ethylene separation: Material selection and solubility investigation

Potential applications of ionic liquids (ILs) for the green separation process of acetylene in ethylene and for the storage of acetylene were investigated. To deal with this proposal, the solubilities of the unsaturated hydrocarbons in various ionic liquids were evaluated. The solubility of ethylene shows a solubility parameter-dependent behavior as indicated by the proportional relationship between the natural log value of Henry's law constant and the inverse molar volume of ILs. This correlation suggests the most important role of voids formation within IL to accommodate the solutes and the applicability of regular solution theory to model the solubility behavior. Whereas, in addition to the free-volume contribution of ILs, the solubility of acetylene is largely controlled by a specific solute–solvent interaction as a result from the association of the acidic hydrogen character in acetylene and the relative basicity of the anion. Those two different solubility behaviors result in a high absorption selectivity of acetylene over ethylene in the basic ILs. ¹H NMR experiment clearly demonstrated the presence of a substantial interaction between the acetylene and the anion of IL. Interestingly, this solute–solvent interaction is reversible as indicated by the absorption–desorption test of acetylene in [BMIM][Me₂PO₄].     

Ionic liquid-derived zinc tetrahalide complexes: structure and application to the coupling reactions of alkylene oxides and CO2

Various alkylene carbonates have been prepared in high yields by the coupling reactions of alkylene oxides with CO₂ in the presence of a dialkylimidazolium zinc tetrahalide complex, prepared from imidazolium halides and zinc halides. The single crystal X-ray diffraction analysis of an active species (1,3-dimethylimidazolium)₂ZnBr₂Cl₂ showed that two 1,3-dimethylimidazolium cations were paired with a dibromodichloro zincate dianion.     

Hydrotalcite derived Cu-Zn-Cr catalysts admixed with γ-Al2O3 for single step dimethyl ether synthesis from syngas: Influence of hydrothermal treatment

The Cu-Zn-Cr catalysts derived from hydrotalcite (HT) structures were prepared by the hydrothermal and non-hydrothermal methods. The catalysts were admixed with Al₂O₃ to synthesize DME (dimethyl ether) from syngas. XRD analysis revealed the presence of hydrotalcite (HT)-like structures in the oven dried form was decomposed to disperse copper species in the calcined conditions. ESR spectra of the fresh calcined catalysts disclosed both the isolated and clustered copper species and bulk Cr³⁺ species are seen in used catalysts. The TPR analysis indicated that the Cu²⁺ ions are reduced in two stages. DME synthesis experiments showed that the CO conversion and DME yield were linearly correlated with Cu metal surface areas of Cu-Zn-Cr catalysts admixed with γ-Al₂O₃. Activity results indicated that hydrothermal treatments have pronounced influence on the dispersion of copper species and consequently on DME synthesis rates.