Abstract: A catalyst for exhaust gas purification includes (1) a monolithic carrier having passages and (2) palladium-loaded alumina obtained by immersing alumina in a palladium solution and then firing the resulting alumina and loaded on the monolithic carrier as a catalyst layer. In the catalyst, the catalyst layer loaded on the partition walls of the passages of the monolithic carrier has a thickness of 5 to 100 &mgr;m and the palladium/alumina (Pd/Al2O3) weight ratio in the catalyst layer is 0.03 to 0.30. This catalyst is a Pd-only catalyst improved in hydrocarbon purifiability during the cold start of engine.

Abstract: A reformer is disposed in the flow path of a reactant fluid. The reformer includes an electrically heatable heater unit of honeycomb structure, in the upstream of the flow path of a reactant fluid, and a catalyst unit of honeycomb structure capable of generating hydrogen from a reactant fluid containing an organic compound or carbon monoxide, by catalysis, in the downstream of the above heater unit. The heater unit and catalyst unit satisfy the following relationship: Cell density of the heater unit≦Cell density of the catalyst unit. The reformer improve efficiency for production of hydrogen and reduce CO as the by-product.

Abstract: A reformer includes two or more catalyst units in the flow path, capable of generating hydrogen from a reactant fluid containing an organic compound or carbon monoxide, by catalysis. In the reformer, at least two of the catalyst units satisfy the following relationship: Heat capacity of the upstream-side catalyst unit≦Heat capacity of the downstream-side catalyst unit. The reformer is improved in the relationship between these catalyst units with respect to heat capacity. This improvement leads to improvement of the reformer in safety, heating characteristics during the start-up period, efficiency of hydrogen production and reduction in production of CO as the coproduct.

Abstract: A catalyst body is obtained by loading, on a carrier, a catalyst layer containing an alkali metal and/or an alkaline earth metal, wherein at least one kind of alkali metal and/or alkaline earth metal is allowed to be present in the carrier and/or between the carrier and the catalyst layer. With this catalyst body, the deterioration of the carrier caused by the alkali metal, etc. is prevented effectively and the long-term use has been made possible.

Abstract: The invention is directed to a filter made of a porous ceramics sintered body has a honeycomb structure having a large number of through channels partitioned by partition walls and passing through along an axial direction. When a ratio of a pore volume having a diameter of 30 &mgr;m or more to a total pore volume, measured by a method of mercury penetration, of the filter is P1(%) and a thickness of said partition wall is T (&mgr;m), these satisfy the relationship defined by the following formula: P1×10≦T. In case of this filter, one may produce it relatively easily on a large scale without adjustment requiring the change of the properties of material for a filter, and the filter can flexibly cope with various uses.

Abstract: A ceramic-made filter for capturing the particulates present in the exhaust gas discharged from diesel engines, wherein a ceramic particles layer made of heat-resistant ceramic particles is formed on a filter by coating, the heat-resistant ceramic particles having a BET specific surface area of 300 m2/g or less. In this ceramic-made filter, the melting of the filter caused by the ash remaining and accumulating after the particulates captured by the filter have been burnt, can be prevented easily without using a large system or the like.

Abstract: A system for exhaust gas purification disposed in the exhaust pipe of an internal combustion engine, includes (1) an adsorbent comprising a monolithic carrier and (2) an adsorbent component having a hydrocarbon adsorptivity, loaded on the carrier, and a catalyst comprising a monolithic carrier and a catalyst component loaded on the carrier, having a purifiability for the harmful substances present in the exhaust gas emitted from the engine. The catalyst is provided downstream of the adsorbent in the flow direction of the exhaust and it can remove the hydrocarbons generated during engine cold gas. The adsorbent has a sectional shape satisfying the following relation: 1.2≦(major axis)/(minor axis)≦6.5 This system enables the desorption of hydrocarbons from the adsorbent in a longer time and can remove the hydrocarbon generated during engine cold start at a higher purification ratio.

Abstract: A catalyst for exhaust gas purification is capable of purifying the hydrocarbons, nitrogen oxides and carbon monoxide present in the exhaust gas discharged from an internal combustion engine. The catalyst has a monolithic carrier and a catalyst layer containing Pd, Ba and a heat-resistant inorganic oxide, formed on the carrier. The amount of Pd supported on monolithic carrier is 100-300 g per ft3 of monolithic carrier (3.53×10−3 to 1.06×10−2 g per cc of monolithic carrier), the amount of Ba supported on monolithic carrier is 0.010-0.060 g per cc of monolithic carrier in terms of BaO, and the weight ratio of Pd and Ba as expressed as BaO is 1:2 to 1:10. This catalyst for exhaust gas purification is superior particularly in hydrocarbon purification for a low-temperature fuel-rich exhaust gas (such as exhaust gas emitted during cold start) of automobile.

Abstract: A honeycomb structure having, in the axial direction, a number of through-channels separated by partition walls, which honeycomb structure contains refractory particles and a vitreous component and is porous. Although the honeycomb structure contains refractory particles such as silicon carbide particles or the like, it can be produced at a relatively low firing temperature; therefore, the honeycomb structure has a low production cost and a high yield and can be provided at a low price.

Abstract: The present invention provides a ceramic filter to be used at a high temperature, and it contains a substance having preferential reactivity with an ash component contained in materials captured by the ceramic filter and not removed by a high temperature treatment such as combustion over the principal component of the ceramic filter; the reaction between said ash component being not removed by a high temperature treatment such as combustion of the filter and remaining accumulated and the filter component to cause melting of the filter being suppressed to attain a long period of service.

Abstract: A ceramic structure obtained by combining a plurality of sintered ceramic material segments (3a, 3b) having a thermal expansion coefficient of 3.0×10−6/° C. or more and integrating them, in which ceramic structure thermal impact-relieving zones (5a, 5b) capable of releasing the thermal impact applied are provided between the segments (3a, 3b) and the widths of the thermal impact-relieving zones (5a, 5b) in the sectional direction of the ceramic structure are various. This ceramic structure is capable of sufficiently release the thermal impact applied, without significantly reducing the effective sectional area of the structure or the overall strength of the structure, and can have the universality capable of coping with various applications and various materials.

Abstract: A catalyst for exhaust gas purification is capable of purifying the hydrocarbons, nitrogen oxides and carbon monoxide present in the exhaust gas discharged from an internal combustion engine. The catalyst has a monolithic carrier and a catalyst layer containing Pd, Ba and a heat-resistant inorganic oxide, formed on the carrier. The amount of Pd supported on monolithic carrier is 100-300 g per ft3 of monolithic carrier (3.53×10−3 to 1.06×10−2 g per cc of monolithic carrier), the amount of Ba supported on monolithic carrier is 0.010-0.060 g per cc of monolithic carrier in terms of BaO, and the weight ratio of Pd and Ba as expressed as BaO is 1:2 to 1:10. This catalyst for exhaust gas purification is superior particularly in hydrocarbon purification for a low-temperature fuel-rich exhaust gas (such as exhaust gas emitted during cold start) of automobile.

Abstract: A reformer includes two or more catalyst units in the flow path, capable of generating hydrogen from a reactant fluid containing an organic compound or carbon monoxide, by catalysis. In the reformer, at least two of the catalyst units satisfy the following relationship: Heat capacity of the upstream-side catalyst unit≦Heat capacity of the downstream-side catalyst unit. The reformer is improved in the relationship between these catalyst units with respect to heat capacity. This improvement leads to improvement of the reformer in safety, heating characteristics during the start-up period, efficiency of hydrogen production and reduction in production of CO as the coproduct.

Abstract: A reformer is disposed in the flow path of a reactant fluid. The reformer includes an electrically heatable heater unit of honeycomb structure, in the upstream of the flow path of a reactant fluid, and a catalyst unit of honeycomb structure capable of generating hydrogen from a reactant fluid containing an organic compound or carbon monoxide, by catalysis, in the downstream of the above heater unit. The heater unit and catalyst unit satisfy the following relationship: Cell density of the heater unit≦Cell density of the catalyst unit. The reformer improve efficiency for production of hydrogen and reduce CO as the by-product.

Abstract: A system for exhaust gas purification disposed in the exhaust pipe of an internal combustion engine, includes an adsorbent formed by loading, on a monolithic carrier, (1) a zeolite containing at least one kind of ion of an element having an electronegativity of 1.40 or more and (2) a catalyst material formed by loading at least one kind of noble metal selected from Pt, Pd and Rh on a heat-resistant inorganic oxide, and at least one loaded carrier formed by loading, on a monolithic carrier, a catalyst component having a purifiability for the harmful substances present in the exhaust gas emitted from the engine and/or an adsorbent component having an adsorptivity for the hydrocarbons also present in the exhaust gas, the loaded carrier being provided upstream of the adsorbent in the flow direction of the exhaust gas and having a total volume of 0.6 l or more.

Abstract: A catalyst for purification of exhaust gas includes a carrier, and a catalyst layer containing an alkali metal and/or an alkaline earth metal as an NOx-adsorbing component, the catalyst layer being loaded on the carrier, in which catalyst the carrier-composing material contains Si in an amount of 0.5 to 10.0% by weight as expressed as an oxide. Since the inclusion of Si can suppress the deterioration of the carrier caused by the alkali metal and/or the alkaline earth metal during the use of the catalyst, the catalyst can be used over a long period.

Abstract: A catalyst-adsorbent for purification of exhaust gases, comprising a monolithic carrier and a catalyst-adsorbent layer formed thereon, the catalyst-adsorbent layer comprising a catalyst for reduction of the carbon monoxide, hydrocarbons and nitrogen oxides emitted from internal combustion engines and an adsorbent for reduction of the hydrocarbons emitted during the cold start of said engines, the catalyst being composed mainly of catalyst particles each comprising a heat-resistant inorganic oxide and at least one noble metal selected from Pt, Pd and Rh, loaded thereon, the catalyst containing at least catalyst particles each comprising a heat-resistant inorganic oxide and 2-30% by weight, based on said oxide, of Pd loaded thereon, the adsorbent comprising adsorbent particles composed mainly of zeolite.

Abstract: A catalyst for exhaust gas purification includes (1) a monolithic carrier having passages and (2) palladium-loaded alumina obtained by immersing alumina in a palladium solution and then firing the resulting alumina and loaded on the monolithic carrier as a catalyst layer. In the catalyst, the catalyst layer loaded on the partition walls of the passages of the monolithic carrier has a thickness of 5 to 100 &mgr;m and the palladium/alumina (Pd/Al2O3) weight ratio in the catalyst layer is 0.03 to 0.30. This catalyst is a Pd-only catalyst improved in hydrocarbon purifiability during the cold start of engine.

Abstract: A catalyst body comprising a carrier and a catalyst layer containing an alkali metal and/or an alkaline earth metal, loaded on the carrier, which catalyst further contains a substance capable of reacting with the alkali metal and/or the alkaline earth metal, dominating over the reaction between the main components of the carrier and the alkali metal and/or the alkaline earth metal. With this catalyst body, the deterioration of the carrier by the alkali metal and/or the alkaline earth metal is prevented; therefore, the catalyst body can be used over a long period of time.

Abstract: A system for exhaust gas purification disposed in the exhaust pipe of an internal combustion engine, includes an adsorbent formed by loading, on a monolithic carrier, (1) a zeolite containing at least one kind of ion of an element having an electronegativity of 1.40 or more and (2) a catalyst material formed by loading at least one kind of noble metal selected from Pt, Pd and Rh on a heat-resistant inorganic oxide, and at least one loaded carrier formed by loading, on a monolithic carrier, a catalyst component having a purifiability for the harmful substances present in the exhaust gas emitted from the engine and/or an adsorbent component having an adsorptivity for the hydrocarbons also present in the exhaust gas, the loaded carrier being provided upstream of the adsorbent in the flow direction of the exhaust gas and having a total volume of 0.6 l or more.