Method and apparatus for performance enhancement of the manifold catalyst in the automotive exhaust system

An exhaust gas treatment apparatus for converting at least hydrocarbons in an exhaust gas stream of an engine to innocuous substances, the apparatus defining a flow path for the exhaust gas stream and comprising:

• a trap means in a first gas flow zone of the flow path for adsorbing hydrocarbons in the exhaust gas stream at least during a cold-start period of engine operation and for desorbing the hydrocarbons in a subsequent period of engine operation;
• a downstream catalyst zone disposed in the flow path downstream from the trap means, and comprising a catalytic material effective at least for conversion of hydrocarbons to innocuous substances;
• air injection means for injecting air into the exhaust gas stream to facilitate the conversion of hydrocarbons in the downstream catalyst zone;
• and
• air heating means for heating the air before the air is injected into the exhaust gas stream, the air heating means comprising a heat exchanger comprising the first gas flow zone and a second gas flow zone disposed in mutual heat exchange relation with each other, and wherein the first gas flow zone comprises a part of the flow path, for transferring heat from the exhaust gas to the air before the air is injected into the exhaust gas stream.

An exhaust gas treatment apparatus for converting at least hydrocarbons in an exhaust gas stream of an engine to innocuous substances, the apparatus defining a flow path for the exhaust gas stream and comprising:

• trap means in the flow path for adsorbing hydrocarbons in the exhaust gas stream at least during a cold-start period of engine operation and for desorbing the hydrocarbons in a subsequent period of engine operation;
• a downstream catalyst zone disposed in the flow path downstream from the trap means, and comprising a catalytic material effective at least for conversion of hydrocarbons to innocuous substances;
• an upstream catalyst zone disposed in the flow path upstream of the trap means, the upstream catalyst zone comprising a catalytic material effective for the conversion of at least one of carbon monoxide, hydrocarbons, and nitrogen oxides to innocuous substances;
• air injection means for injecting air into the exhaust gas stream to facilitate the conversion of hydrocarbons in the downstream catalyst zone, wherein the air injection means is dimensioned and configured to inject air into the exhaust gas stream at a point upstream of the upstream catalyst zone;
• and
• air heating means for heating the air before the air is injected into the exhaust gas stream.

An exhaust gas treatment apparatus for converting at least hydrocarbons in an exhaust gas stream of an engine to innocuous substances, the apparatus defining a flow path for the exhaust gas stream and comprising:

• air heating means comprising a heat exchange catalyst member comprising a first flow gas zone and a second gas flow zone, the first gas flow zone comprising a catalytic material effective for the conversion of at least some pollutants in the exhaust gas stream to innocuous substances, the first gas flow zone comprising part of the flow path, and a second gas flow zone for disposing a gas in heat exchange relation with exhaust gas in the first gas flow zone;
• a downstream catalyst zone disposed in the flow path downstream from the first gas flow zone and comprising a catalyst effective at least for the conversion of hydrocarbons in the exhaust gas stream to innocuous substances;
• and
• air injection means, for flowing air through the second gas flow zone of the heat exchange catalyst member and for injecting the air into the flow path at a point upstream of the first gas flow zone.