Abstract: A wall-flow filter (10) for an exhaust system of a combustion engine comprises: a plurality of channels (4,6,8) in honeycomb arrangement, wherein at least some of the channels (6) are plugged (12) at an upstream end and at least some of the channels (4,8) not plugged at the upstream end are plugged (14) at a downstream end; an oxidation catalyst (16) on a substantially gas impermeable zone at an upstream end of the channels (4,8) plugged at the downstream end; and a gas permeable filter zone (22) downstream of the oxidation catalyst for trapping soot, characterised in that in an exhaust system, preferably a diesel exhaust system, the oxidation catalyst is capable of generating sufficient NO2 from NO to combust the trapped soot continuously at a temperature less than 400° C.

Abstract: A diesel (compression ignition) engine having combustion management means and an exhaust gas aftertreatment system without an NOx trap, which system includes a platinum group metal (PGM) catalyst liable to be poisoned by fuel sulphur to cause significant degradation of catalyst performance, which engine is fuelled, at least intermittently, by a diesel fuel containing such levels of sulphur as to cause poisoning of the catalyst, wherein the combustion management means is effective to modulate the air/fuel ratio (?) to 0.95, preferably 0.90, or richer for a time which is in aggregate sufficient to cause release of significant quantities of sulphur-containing species from the catalyst or catalyst components, whereby the catalyst is regenerated.

Abstract: A cost-effective solution to removing particulates from diesel, especially light-duty diesel engines incorporates an oxidation catalyst (2) effective to convert NO in the exhaust from the engine to NO2 and a particulate trap (4) which traps no more than 85% by weight of the particulate, optionally by permitting gas to by-pass the trap.

Abstract: An improved system for treating the aftertreatment of exhaust gases, especially from diesel engines, comprises a first catalyst (20) effective to oxidise hydrocarbons, a second catalyst (22) effective to convert NO to NO2, a trap (24) for particulates, on which particulates may combust with the NO2, and optionally a NOx absorption material (26).

Abstract: A system and method for the control of emissions from a diesel engine exhaust, comprises a catalyst (14) to convert NO to NO2, a filter (16) to trap soot and hold it for combustion with the NO2, and a NOx absorber (28), with means to regenerate the NOx absorber by injecting reductant or other reactant (injector 18) upstream of the absorber, and at least during regeneration, passing the exhaust gases leaving the absorber through a three-way catalyst (30).

Abstract: An exhaust gas treatment system (8) for a diesel engine (10) having a NOx absorber (28) charged with solid absorbent for absorbing NOx from a diesel exhaust gas and means (18) for introducing intermittently into the exhaust system CO upstream of said absorber (28) whereby the solid absorbent is regenerable by contact with the CO-enriched gas. A process for treating NOx in a diesel exhaust gas comprises absorbing the NOx in a solid absorbent and regenerating the absorbent by contacting it with CO-enriched gas.

Abstract: A method of reducing at least one atmospheric oxidising pollutant, such as ozone, with a reducing agent comprises contacting the reducing agent with the at least one atmospheric oxidising pollutant, wherein the reducing agent comprises a precious metalfree trap material, such as a zeolite, including at least one trapped atmospheric reducing pollutant, e.g. a hydrocarbon, whereby as the at least one atmospheric oxidising pollutant is reduced the at least one trapped atmospheric reducing pollutant is oxidised.

Abstract: A wall-flow filter (10) for an exhaust system of a combustion engine comprises: a plurality of channels (4,6,8) in honeycomb arrangement, wherein at least some of the channels (6) are plugged (12) at an upstream end and at least some of the channels (4,8) not plugged at the upstream end are plugged (14) at a downstream end; an oxidation catalyst (16) on a substantially gas impermeable zone at an upstream end of the channels (4,8) plugged at the downstream end; and a gas permeable filter zone (22) downstream of the oxidation catalyst for trapping soot, characterised in that in an exhaust system, preferably a diesel exhaust system, the oxidation catalyst is capable of generating sufficient NO2 from NO to combust the trapped soot continuously at a temperature less than 400° C.

Abstract: A system for treating exhaust gases including NO, nitrogen and particulate matter comprises: a catalyst for generating NO2 from the NO; a plasma generator for generating at least one of: (1) NO2 from the NO or nitrogen or both; and (2) ozone; and a filter for trapping a desired proportion of the particulate matter which is combusted with at least one of NO2 or ozone. Methods for increasing levels of NO2 in an exhaust system to combust trapped particulate matter involve oxidising NO to NO2 over an oxidation catalyst at an optimum temperature range and using a plasma generator to generate NO2 from NO or N2. Reducing exhaust gas emissions is achieved by trapping the particulate matter and combusting it by reaction with NO2.

Abstract: A wall-flow filter for an exhaust system of a combustion engine comprises: a plurality of channels in honeycomb arrangement, wherein at least some of the channels are plugged at an upstream end and at least some of the channels not plugged at the upstream end are plugged at a downstream end; an oxidation catalyst on a substantially gas impermeable zone at an upstream end of the channels plugged at the downstream end; and a gas permeable filter zone downstream of the oxidation catalyst for trapping soot, in that in an exhaust system, preferably a diesel exhaust system, the oxidation catalyst, which preferably includes a platinum group metal, is capable of generating sufficient NO2 from NO to combust the trapped soot continuously at a temperature less than 400° C.

Abstract: A process for treating gas containing a NOx-specific reactant or NOx by contacting the gas with a solid absorbent comprises: removing the NOx-specific reactant from the gas using a solid absorbent comprising a nitroxy salt; or removing NOx from the gas using a solid absorbent comprising a basic material and intermittently regenerating the absorbent by the action of a NOx-specific reactant and stopping the action of the NOx-specific reactant while the absorbent contains nitroxy salt therby substantially preventing slip of NOx-specific reactant. The invention also comprises an exhaust system (10) for an international combustion engine including a NOx-trap (28), means (18) for injecting a NOx-specific reactant or a precursor of a NOx-specific reactant upstream of the NOx trap (28), whereby NOx stored on the NOx trap is reduced by the NH3 and the NOx trap is partially regenerated, thereby substantially preventing slip of NOx-specific reactant.

Abstract: A method of treating exhaust gases from a gasoline engine after cold-start using an exhaust gas aftertreatment system comprises adsorbing unburnt hydrocarbons (HC) from the engine exhaust gas with an HC trap, supplying heated ambient air to the exhaust gas stream downstream of the HC trap when the temperature of the HC trap is sufficient that trapped HC are desorbed therefrom and passing the air-enriched gas stream over a three-way catalyst (TWC). An exhaust gas aftertreatment system for a gasoline-fuelled engine (1) for performing the method according to the invention comprises a HC trap (5), a downstream secondary air injection point (8), means for supplying heated ambient air to the secondary air injection point (9), a TWC (7) downstream of the point of secondary air injection, and means in use for operating the heated air supply means when the temperature of the HC trap is sufficient that HC trapped thereon are desorbed therefrom.

Abstract: A process for treating exhaust gas from internal combustion engines wherein the combustion exhaust gas contains HC, CO, O2, soot and possibly NOx. In treating the combustion exhaust gas, HC is oxidized to COx and H2O: NO, if present, is oxidized to NO2 and soot is oxidized by reaction with NOx. In addition, NOx is generated by oxidizing ammonia and NOx is introduced into the exhaust gas upstream of the oxidization of soot by reaction with NOx.

Abstract: An exhaust system (8) for a diesel engine, which engine being operable in a plurality of modes including an idling mode, wherein the engine emits a relatively cool exhaust gas, and a running mode, wherein the engine emits a relatively hot exhaust gas, comprises a solid NOx absorbent (18), whereby NOx is absorbed by the NOx absorbent (18) during said idling mode and is desorbed and passed to atmosphere during said running mode and/or during acceleration from idling to running as the temperature of the exhaust gas increases, wherein during all modes the engine runs lean and the exhaust gas composition is lambda>1.

Abstract: A system and method for the after-treatment of exhaust gases from an internal combustion engine is provided. The system includes a first catalyst disposed downstream of the engine, through which the exhaust gases flow and which is effective to catalyze a shift reaction between carbon monoxide and water, or which is exhaust gas. The system also includes an oxygen source disposed between the first catalyst and a hydrocarbon trap, and downstream from all of those a three-way catalyst to catalytically oxidize hydrocarbons and carbon monoxide to reduce noxious emissions.

Abstract: A lean-burn gasoline engine including an exhaust system, which system has a first oxidation catalyst for oxidizing engine-derived, unburned hydrocarbons during &lgr;>1 conditions, and a NOx-trap downstream of the oxidation catalyst. Also included in one embodiment is by-pass means arranged between an upstream end and a downstream end of the oxidation catalyst and means for switching at least some exhaust gas flowing in the exhaust system to flow in the bypass during rich or stoichiometric running conditions, thereby substantially to prevent bypassed exhaust gas from contacting the oxidation catalyst. Included in the invention are methods of treating the exhaust gas streams with the apparati defined above.

Abstract: An exhaust gas treatment system (8) for a diesel engine (10) comprises a NOx absorber (28) charged with solid absorbent for absorbing NOx from a diesel exhaust gas and means (18) for introducing intermittently into the exhaust system CO upstream of said absorber (28) whereby the solid absorbent is regenerable by contact with the CO-enriched gas. A process for treating NOx in a diesel exhaust gas comprises absorbing the NOx in a solid absorbent and regenerating the absorbent by contacting it with CO-enriched gas.

Abstract: A system for treating exhaust gases including NO, nitrogen and particulate matter comprises: a catalyst for generating NO2 from the NO; a plasma generator for generating at least one of: (1) NO2 from the NO or nitrogen or both; and (2) ozone; and a filter for trapping a desired proportion of the particulate matter which is combusted with at least one of NO2 or ozone. Methods for increasing levels of NO2 in an exhaust system to combust trapped particulate matter involve oxidising NO to NO2 over an oxidation catalyst at an optimum temperature range and using a plasma generator to generate NO2 from NO or N2 at temperatures outside of the optimum range, or using the plasma generator an increased amount of particulate matter is generated, regardless of the catalyst temperature. Reducing exhaust gas emissions is achieved by trapping the particulate matter and combusting it by reaction with NO2.

Abstract: An oxidation catalyst for a light-duty diesel vehicle comprising a first upstream part (2) and a second downstream part (3) of high heat capacity relative to the first part, each part comprising a substrate and a catalyst support coated thereon. With this arrangement the diesel catalyst can reach light-off temperature more quickly and retain sufficient heat to maintain light-off temperature for substantially longer than conventional diesel catalyst arrangements.

Abstract: A process for treating an exhaust gas from a lean-burn internal combustion engine containing sulfur, oxides (SOx) and at least one other atmospheric pollutant selected from HC, CO, NO and soot, which gas being untreated or having undergone some chemical and/or catalytic treatment, comprises the steps of absorbing a sulfate-forming SOx component in a solid absorbent material, passing gas containing SO2 to atmosphere and periodically replacing the absorbent material. A system for carrying out the process comprises exhaust passage and a sulfate absorber (26) comprising a substrate supporting a solid material for absorbing a sulfate-forming component from SOx in the exhaust gas, which sulfate absorber is adapted to be replaceable.