Selective catalytic reduction

About: Selective catalytic reduction is a research topic. Over the lifetime, 10502 publications have been published within this topic receiving 226291 citations.

Catalytic reduction of emissions from internal combustion engines

Abstract: An apparatus for treating an exhaust gas stream from cold startup through continuous operating conditions of an internal combustion engine includes an oxidizing catalyst bed disposed in an exhaust pipe and a reducing catalyst bed disposed in the exhaust pipe downstream from the oxidizing catalyst bed. The oxidizing catalyst bed has one or more oxidizing catalysts and the reducing catalyst bed has one or more reducing catalysts. A method is provided for treating an exhaust gas stream both during cold start and during continuous operating conditions of an internal combustion engine by passing the stream through an oxidizing catalyst bed having one or more oxidizing catalysts at a light off temperature; a reducing catalyst bed having one or more reducing catalysts and providing hydrogen into the reducing catalyst bed to condition the reducing catalyst; and introducing hydrogen into the internal combustion engine during cold startup.

CoOx catalysts supported on alumina and alumina-baria: influence of the support on the cobalt species and their activity in NO reduction by C3H6 in lean conditions

Abstract: CoO x catalysts (Co 1 and 3 wt.%) were prepared by incipient-wetness impregnation of the supports, Al 2 O 3 and Al 2 O 3 (80 wt.%)-BaO (20 wt.%), and calcined at 500 and 800 °C. The samples were characterized by X-ray diffraction (XRD) and BET techniques. H 2 -temperature programmed reduction (TPR) and UV-Vis diffuse reflectance spectroscopy (DRS) spectra were recorded with the aim to identify the different Co species formed. The presence of Co 2+ species tetrahedrally and octahedrally coordinated appears strongly influenced by the nature of the support and the cobalt content. Co 3 O 4 particles were detected after calcination at 500 °C, a successive treatment at 800 °C promotes the dispersion of Co 3 O 4 clusters in the network of alumina with formation of CoAl 2 O 4 spinels. The catalysts were tested in the selective catalytic reduction (SCR) of NO with C 3 H 6 in the presence of excess O 2 , using a reactant mixture containing NO 1000 ppm, C 3 H 6 1000 ppm, O 2 5%. The effectiveness of the cobalt catalysts in the SCR process depends strongly on the type of support, metal loading and calcination temperature. The presence of barium oxide in the alumina network is effective in the stabilization on the surface of dispersed Co 2+ ions which are active and selective for NO reduction in excess of O 2 . Clusters of cobalt oxide, present as Co 3 O 4 in the alumina samples calcined at 500 °C, are active mainly for C 3 H 6 combustion.

Electrochemical reduction of CO2 on defect-rich Bi derived from Bi2S3 with enhanced formate selectivity

Abstract: A sulphide-derived bismuth catalyst, synthesised from a one-pot hydrothermal reaction followed by electrochemical reduction, exhibits excellent performance for converting CO2 into formate in an aqueous bicarbonate medium with high activity, selectivity and durability. The maximum faradaic efficiency of 84.0% for formate formation was achieved at an overpotential of 670 mV. A detailed study reveals that the lattice defects associated with the sulphide-derived Bi rather than residual sulphur are likely to engender a positive effect on the catalytic reduction of CO2.