Black rock series (BRS) is of great potential for their plenty of valued oxides which include vanadium, iron, alumina and silica oxides, etc. BRS was used for directly preparing of selective catalytic reduction (SCR) catalyst by modifying its surface texture with SiO2-TiO2 sols and regulating its catalytic active constituents with V2O5 and MoO3. Consequently, 90% NO removal ratio was obtained within 300–400 °C over the BRS-based catalyst. The structure and properties of the BRS-based catalyst were characterized by the techniques of N2 adsorption–desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and NH3-temperature programmed desorption (NH3-TPD). The results revealed that the BRS-based catalyst possesses favorable properties for NOx removal, including highly dispersed active components, abundant surface-adsorbed oxygen Oα, well redox property, and numerous Brønsted acid sites. Particularly, the BRS-based catalyst exhibited considerable anti-poisoning performance compared with commercial TiO2-based catalyst. The former catalyst shows a NO conversion surpassing 80% from 300 to 400 °C for potassium poisoning, and a durability of SO2 and H2O exceeding 85% at temperatures from 300 to 450 °C.

•Size controllable nano-Bi was fabricated via electroreduction of BiOX0.5Y0.5.•Nano-Bi catalysts were applied to the electroreduction of CO2 to formate.•The maximal faradaic efficiency for formate over nano-Bi was 98.4% at −1.6 V.•Nano-Bi catalysts exhibited favorable stabilities (>14 h).The size tunable nano-Bi catalyst was fabricated via electroreduction of di-halogen bismuth oxyhalide (BiOX0.5Y0.5, X, YCl, Br, I) and applied in CO2 electrochemical conversion to fomate. The nano-Bi particle size was controlled by changing with the halogen species used in precursors. A significant size effect on electrochemical active surface area (SE) and current density, as well as faradaic efficiency for formate was observed. The nano-Bi derived from precursor BiOCl0.5Br0.5 possessed minimum particle size of 10 nm and exhibited electrochemical active surface area (SE) of 4.63 cm2 mg−1. With the optimal precursor loading amount of 0.75 mg cm−2, the maximum Faradaic efficiency found for formate was 98.4% at −1.6 V (vs. SCE) with the desirable stability of 14 h, that is 92.7% and 86.2% corresponding to the nano-Bi electrode derived from BiOI0.5Br0.5 and BiOCl0.5I0.5, respectively. Characterization analysis revealed that the prepared catalyst film was composed of Bi3+ and Bi0, and the ratio of Bi0 to Bi3+ was closely related to the halogen species in precursors. The dominant exposed (012) plane of nano-Bi over electrode revealed the intrinsic property of the size controllable catalytic activity. The Tafel analysis suggested that the formation of surface-absorbed species via one electron transferring mechanism would be the initial rate determining step over the nano-Bi electrocatalyst for CO2 electrocatalytic reduction.Download high-res image (128KB)Download full-size image

The application of monolithic coated catalysts to NOx abatement is a crucial issue for practical applications to enhance the mechanical strength, economize the cost, facilitate recycling etc., compared with conventional monolithic extrusive catalysts. In the present work, cordierite honeycomb monoliths coated with V, W and Ti catalyst were synthesized, characterized and tested in the selective catalytic reduction (SCR) of NO with NH3. The coating process conduced a high dispersion of active species, and generated an enrichment of tungsta and vanadia on the surface of the coating. Raman and UV-Vis DRS spectra confirmed the speciation of vanadia, which was mainly presented in an isolated state with a large proportion of 88.68%; the other oxides were found in the polymeric state possessing one mono–oxo VO terminal band and three bridging V–O–M bands (MV or support cation). XPS indicated the co-existence of pentavalent vanadium and a tiny proportion of tetravalent vanadium. The layer coated onto the cordierite substrate possessed a homogeneous distribution with strong adherence and deep penetration with the catalytic components dipping into cordierite. The coated monolithic catalyst exhibited desirable catalytic performance with the NO removal rate exceeding 90% in the range of 350 to 450 °C, and a strong tolerance to poisoning in sulfur and moisture in the NH3-SCR reaction.

AbstractThe pyrolysis of rice straw and sawdust under microwave irradiation was performed with ionic liquids (ILs) 1-butyl-3-methylimidazolium chloride and 1-butyl-3-methylimidazolium tetrafluoroborate as catalysts. With microwave heating for 20 min, the bio-oil yield from rice straw reached 38% and that from sawdust reached 34%. The effects of microwave heating time, microwave power, and IL dosage on bio-oil yields were discussed. The chemical components in bio-oil were analyzed by gas chromatography-mass spectroscopy technique. The main components in bio-oil are furfural, acetic acid, and 1-hydroxy-2-butanone, and their contents mainly depend on the source of biomass and the type of IL used in pyrolysis.

Promoted catalytic reaction between methanol and CO2 for dimethyl carbonate (DMC) synthesis is conducted over K2CO3/CH3I catalyst in the presence of ionic liquid under microwave irradiation. The effect of ionic liquids incorporated with microwave irradiation on the yield of DMC is investigated. DMC was found to form at lower temperature in a relative short time, which indicated an enhanced catalytic process by ionic liquid. Among the ionic liquids used, 1-butyl-3-methylimidazolium chloride is the most effective promoter. Density functional theory calculations indicate that CO2 bond lengths and angles changed due to the molecular interaction of ionic liquid and CO2, resulting in the activation of CO2 molecules and consequently the acceleration of reaction rate.

The application of monolithic coated catalysts to NOx abatement is a crucial issue for practical applications to enhance the mechanical strength, economize the cost, facilitate recycling etc., compared with conventional monolithic extrusive catalysts. In the present work, cordierite honeycomb monoliths coated with V, W and Ti catalyst were synthesized, characterized and tested in the selective catalytic reduction (SCR) of NO with NH3. The coating process conduced a high dispersion of active species, and generated an enrichment of tungsta and vanadia on the surface of the coating. Raman and UV-Vis DRS spectra confirmed the speciation of vanadia, which was mainly presented in an isolated state with a large proportion of 88.68%; the other oxides were found in the polymeric state possessing one mono–oxo VO terminal band and three bridging V–O–M bands (MV or support cation). XPS indicated the co-existence of pentavalent vanadium and a tiny proportion of tetravalent vanadium. The layer coated onto the cordierite substrate possessed a homogeneous distribution with strong adherence and deep penetration with the catalytic components dipping into cordierite. The coated monolithic catalyst exhibited desirable catalytic performance with the NO removal rate exceeding 90% in the range of 350 to 450 °C, and a strong tolerance to poisoning in sulfur and moisture in the NH3-SCR reaction.