Dahao Jiang

N-Heterocyclic carbene catalyzed direct carbonylation of dimethylamine

N-Heterocyclic carbene (NHC) catalyzed direct carbonylation of dimethylamine leading to the formation of DMF was successfully accomplished under metal-free conditions. The catalytic efficiency was investigated and the turnover numbers can reach as high as >300. The possible mechanism was also proposed.

Catalytic upgrading of ethanol to n-butanol: A progress in catalyst development

Because n-butanol as a fuel additive has more advantageous physicochemical properties than those of ethanol, ethanol valorization to n-butanol through homo- or heterogeneous catalysis has received much attention in recent decades in both scientific and industrial fields. Recent progress in catalyst development for upgrading ethanol to n-butanol, which involves homogeneous catalysts, such as iridium and ruthenium complexes, and heterogeneous catalysts, including metal oxides, hydroxyapatite (HAP), and, in particular, supported metal catalysts, is reviewed herein. The structure-activity relationships of catalysts and underlying reaction mechanisms are critically examined, and future research directions on the design and improvement of catalysts are also proposed.

Active oxygen species on Mg–La mixed oxides: the effect of Mg and La oxide interactions

Mg–La mixed oxide catalysts with tunable interactions between Mg and La oxides were synthesized. The catalyst with a strong interaction had higher amounts of oxygen vacancies and surface adsorbed oxygen species, resulting in a better performance in H2 oxidation and CH4 oxidative reactions.

Thermal oxidation to regenerate sulfone poisoned Pd-based catalyst: effect of the valence of sulfur

Sulfur deactivation is a serious problem which largely limits the industrial application of noble metals as catalysts. Here we report a thermal oxidation method to regenerate sulfone poisoned Pd/C catalyst applied in the hydrogenation of sodium-m-nitrobenzene sulfonate (SNS). It was found that the initial activity of Pd/C catalyst could be substantially recovered after treating it in air at temperatures as low as 100 °C. And the catalyst could be reused for at least 20 times without the significant loss of activity. The properties of deactivated and regenerated catalysts were studied in detail by BET measurement, X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and Fourier transform infrared spectroscopy (FT-IR). The results indicated that the main surface sulfur species found on deactivated and regenerated Pd surfaces were Sn and sulfate (SO4), respectively. The change of the valence of sulfur species was found to be the key factor influencing the catalytic activity of the Pd-based catalyst.

Identification of active sites for hydrogenation over Ru/SBA-15 using in situ Fourier-transform infrared spectroscopy

Abstract The active sites for hydrogenation over Ru/SBA-15 catalysts were identified using in situ Fourier-transform infrared spectroscopy. The amount of active sites was proportional to the interfacial circumference of the Ru particles. In contrast, the rate of hydrogen spillover from Ru to the support was inversely proportional to the size of the Ru metal particles. Consequently, a catalyst with small Ru metal particles has a high rate of hydrogen spillover but a low density of active sites, whereas one with large Ru particles has a low rate of hydrogen spillover but a high density of active sites. The formation of these active sites is probably an intermediate step in hydrogen spillover.