In a mixing structure with an injector 3 arranged 2 immediately after a bend 1a of an exhaust pipe 1, urea water 5 being injected by the injector 3 into the exhaust pipe 1 for mixing, a pipe diameter D.sub.p downstream of the bend 1a of the exhaust pipe 1 is large relative to a pipe diameter D.sub.e upstream of the bend.

A particulate filter for use in a vehicle engine exhaust is provided which includes a catalyst containing a mixture of nickel and copper. The catalyst is impregnated into the filter substrate, which is non-reactive with nickel and copper. When used in a vehicle exhaust gas treatment system, the catalyst on the filter improves soot burn-off at low temperatures, provides improved efficiency in reducing CO and NO.sub.x emissions over the use of conventional three-way-catalyst washcoats, and provides enhanced oxygen storage capacity (OSC) and water-gas-shift (WGS) functions.

Described are base metal catalysts that comprise a base metal material in an amount effective to generate an exotherm over a temperature range of 300 C. to 650 C. and to oxidize soot collected by a downstream particulate filter. The base metal catalysts are substantially free of platinum group metals. Emission treatment systems and methods of remediating nitrogen oxides (NO.sub.x), particulate matter, and gaseous hydrocarbons using base metal catalyst are also described.

Zero-PGM (ZPGM) catalyst materials including pseudo-brookite compositions for use in diesel oxidation catalyst (DOC) applications are disclosed. The disclosed doped pseudo-brookite compositions include A-site partially doped pseudo-brookite compositions, such as, Sr-doped and Ce-doped pseudo-brookite compositions, as well as B-site partially doped pseudo-brookite compositions, such as, Fe-doped, Co-doped, Ni-doped, and Ti-doped pseudo-brookite compositions. The disclosed doped pseudo-brookite compositions, including calcination at various temperatures, are subjected to a DOC standard light-off (LO) test methodology to assess/verify catalyst activity as well as to determine the effect of the use of a dopant in an A-site cation or a B-site cation within a pseudo-brookite composition. The disclosed doped pseudo-brookite compositions exhibit higher NO oxidation catalyst activities when compared to bulk powder pseudo-brookite, thereby indicating improved thermal stability and catalyst activity when using a dopant in an A-site cation or in a B-site cation within a pseudo-brookite composition.

Variations of ZPGM catalyst material compositions including doped CuMn spinel supported on doped zirconia support oxide are disclosed. The disclosed ZPGM catalyst compositions include a small substitution of Ni within the A-site or B-site cation of a CuMn spinel supported on doped zirconia support oxide, and produced by the incipient wetness (IW) methodology. Bulk powder ZPGM catalyst compositions are subjected to XRD analyses to determine the spinel phase formation and stability. Additionally, bulk powder ZPGM catalyst compositions are subjected to a steady-state isothermal sweep test to determine NO, CO, and THC conversion. The ZPGM catalyst material compositions including Ni-doped CuMn spinel supported on doped zirconia support oxide exhibit improved levels in NO and CO conversions, which can be employed in ZPGM catalysts for a plurality of TWC applications, thereby leading to a more effective utilization of ZPGM catalyst materials with high thermal and chemical stability in TWC products.

The present disclosure describes ZPGM catalyst material compositions having significantly high oxygen storage capacity for a plurality of TWC applications. The disclosed ZPGM catalyst material compositions include a CuMn spinel deposited on doped Zirconia support oxide. The disclosed ZPGM catalyst material compositions exhibit significant high OSC stability properties after fuel cut aging. The improved thermal stability and OSC properties of the disclosed ZPGM catalyst material compositions are determined by performing a standard isothermal oscillating OSC tests. Fresh and aged ZPGM catalyst material compositions are employed within the standard isothermal oscillating OSC test, over multiple reducing/oxidizing cycles at a temperature of about 575 C.

The present disclosure describes bulk powder Zero-PGM material compositions including a CuMn.sub.2O.sub.4 spinel structure supported on doped zirconia support oxides powders, including Ba, Sr, and Ti at different dopant loadings produced by different conventional synthetic methods. BET-surface area and XRD analysis are performed for a plurality of doped zirconia support oxides to compare the thermal stability, before and after deposition of CuMn spinel. Additionally, bulk powder ZPGM catalyst compositions are subjected to a steady-state isothermal sweep test to determine NO conversion capabilities. The selected support oxide material compositions are capable of providing increased surface areas for improved thermal stability leading to a more effective utilization of ZPGM catalyst materials with enhanced NO conversion and improved thermal stability for TWC applications.

Variations of coating processes of CuMnFe ZPGM catalyst materials for TWC applications are disclosed. The disclosed coating processes for CuMnFe spinel materials are enabled in the preparation ZPGM catalyst samples according to a plurality of catalyst configurations, which may include an alumina only washcoat layer coated on a suitable ceramic substrate, and an overcoat layer with or without an impregnation layer, including CuMnFe spinel and doped Zirconia support oxide, prepared according to variations of disclosed coating processes. Activity measurements are considered under variety of lean condition to rich condition to analyze the influence of disclosed coating processes on TWC performance of ZPGM catalysts for a plurality of TWC applications. Different coating processes may substantially increase thermal stability and TWC activity, providing improved levels of NO.sub.x conversion that may lead to cost effective manufacturing solutions for ZPGM-TWC systems.

A process for removing sulfur from a gas containing sulfur compounds as H2S, SO2, COS, CS2 . . . , in a quantity of up to 15% wt; particularly gases emanating from the Claus process: A first hydrogenation of the sulfur compounds into H2S, the hydrogenation gas being used to regenerate a deactivated bed of oxidation catalyst, both being carried out at 200-500 C. After sulfur removal, the resulting gas undergoes a second hydrogenation step and then a direct oxidation step, said step being operated under the dew point of sulfur to trap the formed sulfur in the catalyst. In the further cycle, the gas streams are switched so as to regenerate the catalyst in run which is deactivated.

The present invention relates to a particulate filter, which comprises a substrate, comprising a plurality of porous walls extending longitudinally to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a quantity of the channels are inlet channels that are open at the inlet end and closed at the outlet end, and a quantity of channels are outlet channels that are closed at the inlet end and open at the outlet end; and a layer of inorganic particles loaded on surfaces of the porous walls in the inlet channels and/or outlet channels, preferably in at least the inlet channels, wherein the inorganic particles have a D.sub.90 in the range of 5.0 to 14.0 microns.