Ruiyang Qu

Investigation of the promotion effect of WO3 on the decomposition and reactivity of NH4HSO4 with NO on V2O5–WO3/TiO2 SCR catalysts

In this study, we systematically investigated the interaction between NH4HSO4 and WO3-promoted V2O5/TiO2 catalysts in the selective catalytic reduction of NO with NH3, along with the promotion effect of WO3 on the decomposition and reactivity of NH4HSO4 with NO. In the NH4HSO4-deposited samples, WO3 addition increased the electron cloud density around the S atoms in SO42−, which was beneficial for the reduction of S atoms with +6 formal oxidation number, as in NH4HSO4, to those in the +4 oxidation state, as in SO2. Consequently, WO3-doping led to an increase in the amount of SO2 released at low-temperature regions during the heating process as well as an obvious enhancement in the decomposition behavior of NH4HSO4, as illustrated by decreases in temperatures attributed to the weight loss peaks. Meanwhile, the introduced WO3 had a slight promotion effect on the reactivity of NH4HSO4 with NO, together with an inhibitory effect on the production of N2O during the reaction process. Finally, WO3-promoted catalysts exhibited enhanced SO2-resistance.

Exploring the role of V2O5 in the reactivity of NH4HSO4 with NO on V2O5/TiO2 SCR catalysts

In this study, attention was focused on the interactions between NH4HSO4 and vanadium species in the selective catalytic reduction (SCR) of NO with NH3, along with the role of vanadium species in the reactivity of NH4HSO4 with NO on V2O5/TiO2 catalysts. Both vanadium and sulfate species occupied the TiO2 surface basic hydroxyl groups; the decreased TiO2 surface basic sites resulting from the introduction of NH4HSO4 in turn promoted the formation of polymeric vanadium species. Given increases in vanadium content, formation of polymeric vanadium species and reactive electrophilic oxygen species on the catalysts occurred, which was an important reason for the enhanced reactivity of NH4HSO4 with NO on the high V content catalysts. Besides, a higher electron cloud density around the S atoms in SO42− could be detected for the high V content catalysts, on which SO42− would be easily reduced to SO2 during the TPSR process. In situ diffuse reflectance infrared Fourier transform spectroscopy confirmed that NH4+ in NH4HSO4 functioned as a reductant during reaction with gaseous NO, while S-containing functional groups were stabilized as tridentate sulfate anions on the catalyst surface.

Promotional effect of doping Cu into cerium-titanium binary oxides catalyst for deep oxidation of gaseous dichloromethane

In recent years, significant effort has been made in the development of novel catalysts for the total oxidation of chlorinated volatile organic compounds. In this work the catalytic activity of Cu doped cerium-titanium binary oxides for the oxidation of dichloromethane (DCM) have been studied for the first time. Combining catalysts characterization and activity data, it was found that Cu ions can uniformly disperse into titanium dioxide to form solid solution and induce the creation of additional surface oxygen species on the catalysts surface, while moderate amount of Ce ions are still needed for the activation of CCl. Detailed analysis of the in-situ FTIR experiment results revealed that the surface oxygen species, especially the hydroxyl groups associated with Cu ions, can promote the deep oxidation of the intermediate species formed in the nucleophilic substitution process occurred on the active sites of catalysts surface. The sample with the Cu/Ce molar ratio of 1:3 obtained a better CO2 selectivity than that reached with cerium-titanium binary oxides. Meanwhile, according to element balance analysis, removal of chlorine from the catalyst surface was also promoted by Cu doping.

Insight into the significant roles of microstructures and functional groups on carbonaceous surfaces for acetone adsorption

To understand the roles of pore structures and functional groups on acetone adsorption, activated carbons (ACs) with different properties were obtained by surface modification. XRD, SEM, TEM and nitrogen adsorption were used to identify the structural characteristics of the ACs, while TG-DTA, FTIR, XPS and Boehm titration were applied to analyse the surface chemistries. The microporous surface areas showed a positive linear correlation to the acetone adsorption amounts, and increasing the carboxylic groups could improve the uptake of strongly adsorbed acetone. HNO3 modified AC (AC-N) was found to exhibit an excellent adsorption capacity of 5.49 mmol g−1, which might be attributed to the developed microporous structures and abundant carboxylic groups. The desorption activation energies (Ed) of strongly adsorbed acetone on AC-N and AC were both determined to be 81.6 kJ mol−1, indicating the same adsorption sites on different activated carbons, suspected to be carboxylic groups. The possible adsorption mechanism of acetone on carbonaceous surfaces was also proposed.