Abstract: A catalyst body including a catalytic material containing an alkali metal and/or an alkaline earth metal, a carrier carrying the catalytic material, and a method of manufacturing the catalyst body are provided. The carrier has a cordierite binder phase and aggregate phases dispersed in the cordierite binder phase.

Abstract: This invention relates to ?-SiC foam parts with a specific surface area preferably equal to at least 5 m2/g and with at least two zones A and B with a different cellular porosity distribution, wherein the parts were made by chemical transformation of a porous precursor medium comprising at least two blocks A? and B?, each having a different cellular porosity distribution, and in that the at least two zones A and B are derived from the chemical transformation of the two blocks A? and B?. This foam, optionally after deposition of an active layer, may be used as a filter medium in cartridges designed for the purification of exhaust gases. The invention also relates to manufacturing processes for preparing such a filter medium.

Abstract: The photocatalyst based on a composite WO3—SiC/TiO2 semiconductor and subjected to radiation whose wavelength is at least partly less than 400 nm gives1 photocatalytic oxidation of volatile organic compounds and leads to their total mineralisation into CO2 and H2O. The process for the photocatalytic purification of industrial, agricultural or domestic gaseous effluent may be conducted at room pressure and temperature. Its conversion rate is high and stable.

Abstract: Disclosed herein is a catalyst composition comprising a halide of a Group Ib element and an inert powder. Disclosed herein too is a composition comprising a reaction product of a halide of a Group Ib element, an inert powder and mercury. Disclosed herein too is a method comprising injecting a catalyst composition comprising a halide of a Group Ib element and an inert powder into an emissions stream of a thermoelectric power plant; converting an elemental form of mercury present in the emissions stream into an oxidized form, an amalgamated form and/or a particulate bound form of mercury; and collecting the oxidized form, the amalgamated form and/or the particulate bound form of mercury prior to the entry of the emissions stream into the atmosphere.

Abstract: A catalyst assembly comprising a substrate, nanofilaments which have a nanometer-size diameter and are formed on the substrate, and particles which have a nanometer-size diameter, at least one of the nanofilaments and the particles having a catalytic function, is provided to use a catalyst more efficiently and to provide a catalytic function more efficiently. Interstices between the nanofilaments serve as distribution channels of a reactive gas, and the reactive gas spreads sufficiently not only around the ends of nanofilaments but also inside a catalyst assembly. A combination of nanofilaments and particles enables dispersion of a catalyst at a distance of not more than about 100 nanometers.

Abstract: A catalyst for the preparation of dimethyl carbonate from urea and methanol having a composition on weight base of: active component of from 20 to 50 wt %, and carrier of from 80 to 50 wt %, and prepared by equal-volume spraying and impregnating method is disclosed. The method for the synthesis of dimethyl carbonate can be carried out in a catalytic rectification reactor, said method comprising: (1) dissolving urea in methanol to form a methanol solution of urea; and (2) feeding the methanol solution of urea and methanol counter-currently into the reaction zone, wherein the reaction is carried out at conditions including reaction temperature of from 120° C. to 250° C., reaction pressure of from 0.1 MPa to 5 MPa, kettle bottom temperature of from 70° C. to 210° C., stripping section temperature of from 70° C. to 250° C., rectifying section temperature of from 70° C. to 280° C., and reflux ratio of from 1:1 to 20:1.

Abstract: The silicon carbide-based catalytic body of the present invention comprises: a porous body of given shape comprising a first bonded structure formed by bonding a large number of silicon carbide particles as an aggregate to each other in a state that a large number of fine pores are present, and a catalyst containing an alkali metal and/or an alkaline earth metal, loaded on the porous body, characterized in that the catalyst is loaded via a crystalline coating film comprising an oxide and formed on at least part of the surfaces of the silicon carbide particles forming the first bonded structure. In the catalytic body, the catalyst such as NOx occlusion catalyst or the like, loaded thereon can maintain its activity over a long period.

Abstract: The invention is a catalyst formed by covering each surface of particles in a ceramic support with an alumina thin film and holding an active catalyst component with the surface of the thin film, which is large in the pore size and porosity and small in the pressure loss irrespectively of forming the alumina thin film on the surface and is produced, for example, by immersing the ceramic support in an aluminum-containing metallic compound, preliminarily firing, immersing in hot water, drying, firing and finally holding the active catalyst component on the alumina thin film on the surface of the support.

Abstract: A method of producing a catalyst carrier. The method comprises contacting a silicon-containing ceramic material with a solution of an aluminum containing metal compound, firing the resulting material, immersing the material in hot water and, again firing the material.

Abstract: An object of the present invention is to realize low pressure loss and high purification performance in a constitution in which a primary catalyst component and co-catalyst component are loaded onto a ceramic support that allows catalyst components to be loaded directly. According to the present invention, a primary catalyst component in the form of a catalyst precious metal and a co-catalyst component in the form of an oxygen occluding component are loaded on the surface of a honeycomb-shaped ceramic support, including the inner surfaces of pores. As a result of the large loaded amount of co-catalyst component entering inside the pores, the loaded amount of co-catalyst component on the cell wall surfaces is reduced, thereby making it possible to inhibit increases in pressure loss. In addition, since the primary catalyst component and co-catalyst component are in close proximity to each other, catalyst performance is improved.

Abstract: The present invention discloses nanowires for use in a fuel cell comprising a metal catalyst deposited on a surface of the nanowires. A membrane electrode assembly for a fuel cell is disclosed which generally comprises a proton exchange membrane, an anode electrode, and a cathode electrode, wherein at least one or more of the anode electrode and cathode electrode comprise an interconnected network of the catalyst supported nanowires. Methods are also disclosed for preparing a membrane electrode assembly and fuel cell based upon an interconnected network of nanowires.

Abstract: Catalysts have been discovered that are useful in hydrogenation reactions, and particularly for the selective hydrogenation of acetylene and/or methyl acetylene (MA) and/or propadiene (PD) in light olefin-rich feedstreams. These catalysts can selectively hydrogenate acetylene with less selectivity to making oligomers (green oil) as compared with existing commercial catalysts, particularly palladium catalysts. These catalysts are non-palladium catalysts, and have three different constituents that are metal or metal-based components. The metal of the first constituent may be nickel or platinum, the metal of the second constituent may be from Groups 1–10, and the metal of the third constituent may be from Groups 11–12, where the Groups are of the Periodic Table of Elements (new IUPAC notation).

Abstract: A catalyst carrier which comprises particles of a silicon-containing ceramic material. Each of these particles is covered by a film of alumina on which a noble metal is carried.

Abstract: A method for converting light hydrocarbons (e.g. methane or natural gas) to synthesis gas employs a silicon carbide-supported catalyst that catalyzes a net partial oxidation reaction. Certain preferred catalysts include a catalytically active metal disposed on a silicon carbide support.

Abstract: Catalysts for the water gas shift reaction contain a variety of late transition metals. The catalytic compositions contain a late transition metal carried on a support which is a carbide, nitride, or mixed carbide nitride of a group 6 metal such as molybdenum, tungsten, and mixtures thereof. The late transition metal includes ruthenium, cobalt, nickel, palladium, platinum, copper, silver, or gold. The water gas shift reaction may be catalyzed by contacting a gaseous stream containing carbon monoxide and water with such a solid catalyst composition. In some embodiments, the catalysts are several times more active than known commercial catalysts for the water gas shift reaction.

Abstract: Provided is a catalyst formulation which exhibits extended catalyst life. The formulation comprises a mixture of a ceramic foam material uniformly interspersed between the solid catalyst particles, with the volume percent of ceramic material in the mixture preferably ranging from 20 to 60 volume %. The catalyst formulation is particularly applicable to solid catalyst particles comprised of a phosphoric acid impregnated substrate, and is particularly useful for processes such as catalytic hydrocarbon condensation processes.

Abstract: There are provided a high-strength zirconia-containing inorganic fiber having excellent alkali resistance, oxidation resistance, catalyst function and/or catalyst-carrying function and a process for the production thereof. The zirconia-containing inorganic fiber is a fiber which is formed of a composite oxide phase comprising a first phase mainly formed of a silica component or silicon carbide and a second phase formed of zirconia, and it is characterized in that the ratio of Zr slopingly increases toward the surface layer of the fiber.

Abstract: A catalyst for the selective oxidation of hydrogen has been developed. It comprises an inert core such as cordierite and an outer layer comprising a lithium aluminate support. The support has dispersed thereon a platinum group metal and a promoter metal, e.g. platinum and tin respectively. This catalyst is particularly effective in the selective oxidation of hydrogen in a dehydrogenation process.

Abstract: A honeycomb filter is composed mainly of silicon carbide or of metallic silicon and silicon carbide; the filter being formed by bonding a plurality of honeycomb segments each of which has a plurality of through-holes being partitioned by porous partition walls. The filter is plugged alternately at the exhaust gas inlet face and exhaust gas outlet face of honeycomb segments. Each two adjacent honeycomb segments are contacted with each other at each a portion of their sides facing each other. They are bonded with each other at least at part of each portion of said sides other than the contacted portion through a bonding material having a strength lower than that of a basal body of honeycomb segment. Thus, the thermal stresses generated among the respective portions constituting the filter is reduced. The generation of cracks, etc. can be also prevented considerably.

Abstract: Catalyst particles having a higher activity and capable of showing activities for a plurality of kinds of material are provided. The catalyst particles of the invention comprise base particles that consist of one kind of single material fine particles or two or more kinds of solid solution fine particles having primary particle diameters of a nanometer order, and a surface coating layer made of one or more kind of noble metal, or an oxide of noble metal, that covers at least a part of the surface of the base particles 1 to a thickness of one to thirty single atom layers.

Abstract: A method for converting light hydrocarbons (e.g. methane or natural gas) to synthesis gas employs a silicon carbide-supported catalyst that catalyzes a net partial oxidation reaction. Certain preferred catalysts include a catalytically active metal disposed on a silicon carbide support.

Abstract: A catalyst useful for the production of olefins from alkanes via oxidative dehydrogenation (ODH) is disclosed. The catalyst includes a silicon carbide support. The catalyst may optionally include a base metal, metal oxide, or combination thereof. A base metal is herein defined as a non-Group VIII metal, with the exception of iron, cobalt and nickel. Suitable base metals include Group IB-VIIB metals, Group IIIA-VA metals, Lanthanide metals, iron, cobalt and nickel. Suitable metal oxides include alumina, stabilized aluminas, zirconia, stabilized zirconias (PSZ), titania, ytteria, silica, niobia, and vanadia. Additionally, the catalyst may optionally include a Group VIII promoter. Suitable Group VIII promoters include Ru, Rh, Pd, Os, Ir, and Pt.

Abstract: A catalyst for the selective oxidation of hydrogen has been developed. It comprises an inert core such as cordierite and an outer layer comprising a lithium aluminate support. The support has dispersed thereon a platinum group metal and a promoter metal, e.g. platinum and tin respectively. This catalyst is particularly effective in the selective oxidation of hydrogen in a dehydrogenation process.

Abstract: A silicon carbide-based porous material containing silicon carbide particles (1) as an aggregate and metallic silicon (2), wherein the average particle diameter of the silicon carbide-based porous material is at least 0.25 time the average particle diameter of the silicon carbide particles (1), or the contact angle between the silicon carbide particles (1) and the metallic silicon (2) is acute, or a large number of secondary texture particles each formed by contact of at least four silicon carbide particles (1) with one metallic silicon (2) are bonded to each other to form a porous structure. This silicon carbide-based porous material can be sintered, in its production, at a relatively low firing temperature and, therefore, can be provided at a low production cost, at a high yield and at a low product cost.

Abstract: Provided is a catalyst formulation which exhibits extended catalyst life. The formulation comprises a mixture of a ceramic foam material uniformly interspersed between the solid catalyst particles, with the volume percent of ceramic material in the mixture preferably ranging from 20 to 60 volume %. The catalyst formulation is particularly applicable to solid catalyst particles comprised of a phosphoric acid impregnated substrate, and is particularly useful for processes such as catalytic hydrocarbon condensation processes.

Abstract: A modified carrier carrying on at least a part of an inert carrier surface an oxide which is represented by the formula (1): XaYbZcOd (wherein X is at least an element selected from alkaline earth metals; Y is at least an element selected from Si, Al, Ti and Zr; Z is at least an element selected from Group IA elements and Group IIIb elements of the periodic table, B, Fe, Bi, Co, Ni and Mn; and O is oxygen; a, b, c and d denote the atomic ratios of X, Y, Z and O, respectively, where a=1, 0<b≦100, 0≦c≦10, and d is a numerical value determined by the extents of oxidation of the other elements) is provided. A catalyst formed with the use of this modified carrier carrying a complex oxide containing Mo and V is useful as a vapor phase catalytic oxidation catalyst, and is particularly suitable as a catalyst for preparing acrylic acid through vapor phase catalytic oxidation of acrolein.

Abstract: Catalyst particles having a higher activity and capable of showing activities for a plurality of kinds of material are provided.

Abstract: A process and catalyst for the partial oxidation of paraffinic hydrocarbons, such as ethane, propane, naphtha, and natural gas condensates, to olefins, such as ethylene and propylene. The process involves contacting a paraffinic hydrocarbon with oxygen in the presence of a catalyst under autothermal process conditions. The catalyst comprises a Group 8B metal and, optionally, a promoter metal, such as tin or copper, supported on a fiber monolith support, preferably a ceramic fiber mat monolith. In another aspect, the invention is a process of oxidizing a paraffinic hydrocarbon to an olefin under autothermal conditions in the presence of a catalyst comprising a Group 8B metal and, optionally, a promoter metal, the metals being loaded onto the front face of a monolith support. An on-line method of synthesizing and regenerating catalysts for autothermal oxidation processes is also disclosed. This divisional case covers the catalyst composition and the method of preparing an olefin using the catalyst.

Abstract: A carbon fiber fabric having large specific surface area is made using a rayon precursor, and a catalyst is fixed on the fabric by impregnation or by cationic exchange. The carbon fiber fabric has pores with a mean size lying in the range 0.3 nm to 3 nm, a carbon content greater than 99%, and a high density of functional groups per unit area which favors the dispersion of metal catalyst in the form of fine particles and which is good for highly selective catalytic reactions in fine chemistry.

Abstract: The invention relates to a catalyst for cleaning the exhaust gases from internal combustion engines, especially diesel engines, comprising a monolithic body having longitudinally extending, open throughchannels coated with a surface-enlarging washcoat layer which contains one or more catalytically active precious metals. In order to reduce the tendency of the catalyst to oxidize and absorb (be enriched with) sulphur dioxide, the washcoat layer of the catalyst is based on silicon carbide and is substantially free from aluminum oxide. A method for preparing the catalyst, the use of the catalyst, as well as an exhaust gas cleaning system and a motor vehicle equipped with the catalyst, are also disclosed.

Abstract: The invention relates to the catalytic activity and selectivity of microporous, amorphous glasses of mixed metal oxides and the application thereof in the form of shape selective, heterogeneous catalysts. Microporous, amorphous mixed metal oxides (glasses) can be formed by polycondensation of soluble metal compounds. These new materials show a temperature stability up to 800° C. These amorphous glasses shown in heterocatalytic reactions selective oxidation, hydrogenation, hydrocracking and condensation catalysis.

Abstract: This invention relates to a preparation process of a catalyst which comprises a noble metal and a metal as catalysis promoter in combination with an alkali or alkaline earth metal compound, supported on the outer surface of a carrier. The preparation process comprises impregnating the carrier with a solution containing an oxidative state noble metal as the main catalyst and an oxidative state metal as catalysis promoter, reducing the oxidative state metals into the metallic state in gaseous phase with a gaseous reducing agent under certain temperature, pressure, moisture and gas concentration, then impregnating the reduced carrier with a solution of an alkali or alkaline earth metal compound. The metal components-supporting catalyst prepared by the process according to the present invention has a high surface area and exhibits high catalytic activity, which leads to increase the catalytic efficiency and life of this heterogeneous catalyst.

Abstract: Silicon carbide foam useful as a catalyst support has a BET specific surface area of at least 5 m2/g, and a compression strength exceeding 0.2 MPa. The foam is prepared by impreganting an organic foam with a suspension of silicon in a resin containing a cross-linking agent, incompletely cross-linking the resin, carbonizing the foam and resin, and carburizing the silicon.

Abstract: The invention relates to a method of producing a catalyst comprising a porous support and a catalytically active metal deposited thereon comprising the steps of treating the porous support with a solution of a salt of the catalytically active metal and a reducing agent to achieve electroless deposition of the catalytically active metal on the support. The invention also relates to a catalyst obtainable by the method and a process of producing hydrogen peroxide.

Abstract: Catalyst support in granular form with a SiC&bgr; crystallite base and a high specific surface area having improved mechanical characteristics. The porosity of the support is between 0.001 and 1 um in size and the crystallinity of the support is determined by: a full width at half maximum of diffraction X rays, corresponding to plane [2 2 0] of the SiC&bgr; crystallites, of between 0.15 and 0.60°, angle 2&thgr; of Bragg's law; and a bidimensional peak height [1 0] corresponding to directions [1 0] normalized by the integrated intensity of the peak of plane [2 2 0] of between 0.15 and 0.40.

Abstract: A catalytic structure is formed by first partially embedding discrete, non-conductive particles into the surface of an aluminum substrate. Nodules of a catalyst metal are then electrodeposited onto the surface between the embedded particles. The non-conductive particles control the distribution of the electrodeposited nodules. The aluminum substrate may be anodized after embedding the particles and the particles themselves may possess catalytic activity thereby providing a dual catalyst structure.

Abstract: A mixed metal oxide MoVLaPdNbXO catalytic system (wherein X=Al, Ga, Ge and/or Si) providing higher selectivity and space time yield of acetic acid at low pressure and low temperature in a single stage oxidation of ethane with a molecular oxygen-containing gas and steam.

Abstract: A process is provided for the catalytic removal of sulfur compounds, such as hydrogen sulfide and sulfur dioxide, out of a gas by contacting the gas with catalyst composition containing a silicon carbide support and a catalyst component, such as a salt or elemental state of a metal, such as titanium, zirconium, yttrium, lanthanum, uranium, lead, molybdenum, iron, cobalt, copper, nickel, zinc and cadmium and an oxide of a metal, such as uranium, lead, calcium, magnesium and cadmium. The process may be conducted at a temperature above or below the dew point of sulfur.

Abstract: A method of producing an acoustic baffle/catalyst foam support material and the resultant material. A polyurethane open cell foam material is provided having a density between 10-100 ppi. The polyurethane foam is infiltrated with a resin material to produce an impregnated foam. The impregnated foam is pyrolized to form a carbon skeleton forming a carbon foam. The carbon foam skeleton is coated with one or more of the following group of materials to a relative density of five to thirty five (5-35) percent, the group of materials being SiC, Si.sub.3 N.sub.4, MoSi.sub.2 or high temperature metal.

Abstract: An SiC film having an excellent strength and thermal characteristics. The SiC film is prepared by a CVD process (i.e. CVD-SiC fabrication) and has a thermal conductivity along the direction of the SiC crystal growth between 100 and 300 W/m.multidot.K, and an average grain diameter of the internal structure between 4 to 12 .mu.m. It is preferred that the ratio of the thermal conductivity along the direction of the SiC crystal growth to the thermal conductivity in the perpendicular direction is in a range of 1.10 to 1.40.

Abstract: SiC foam-based catalyst carrier in the form of a moulded part having walls reinforced with a SiC skin having mechanical characteristics higher than those of the foam, this skin allowing the carrier to be handled and used without damage.

Abstract: The present invention provides a catalyst and method for purifying exhaust gases, having superior performance of NOx purification to exhaust gases containing oxygen and nitrogen oxides, particularly superior performance of NOx elimination to exhaust gases from lean-bum engines with excess oxygen, and a wider effective temperature range of NOx elimination, and also superior heat resistance at high temperature, said catalyst for purifying exhaust gases comprises, as indispensable contents, iridium and alkaline metal loaded on a carrier which is at least one selected from metal carbide and metal nitride, or these and at least one element selected from the group consisting of alkaline earth metal elements and rare earth metal elements, and said method using these catalyst.

Abstract: The invention relates to a supported catalyst for gas-phase reactions having an inert support body and a surface coating comprisinga) at least 5% by weight of silicon carbide,b) from 5 to 90% by weight, calculated as oxide, of one or more titanium dioxide or zirconium oxide components or mixtures thereof,c) from 1 to 50% by weight, calculated as V.sub.2 O.sub.5, of one or more vanadium oxide components,d) from 0 to 10% by weight, calculated as oxide, of one or more compounds of elements of the 1st and 5th main groups of the Periodic Table, and also a process for its preparation and its use.

Abstract: A catalyst support includes substantially spherical particles of a substantially homogeneous mixture of at least two compounds selected from the group consisting of refractory inorganic oxides, refractory inorganic carbides, refractory inorganic nitrides and mixtures thereof, wherein said particles have a surface area of at least about 30 m.sup.2 /g, an average pore diameter of at least about 150 .ANG., and a particle size of at least about 0.1 mm. The support may be used in a catalyst system to support a Group IVb and a Group VIII metal in a catalyst system useful for hydrogenation of carbon monoxide into C.sub.2 + hydrocarbons. A method is also provided for preparing the catalyst support and system.

Abstract: A catalyst support includes substantially spherical particles of a substantially homogeneous mixture of at least two compounds selected from the group consisting of refractory inorganic oxides, refractory inorganic carbides, refractory inorganic nitrides and mixtures thereof, wherein said particles have a surface area of at least about 30 m.sup.2 /g, an average pore diameter of at least about 150 .ANG., and a particle size of at least about 0.1 mm. The support may be used in a catalyst system to support a Group IVb and a Group VIII metal in a catalyst system useful for hydrogenation of carbon monoxide into C.sub.2 + hydrocarbons. A method is also provided for preparing the catalyst support and system.

Abstract: Silicon carbide fibers having a high mechanical strength at a high temperature, an excellent heat resistance and a uniform structure are produced by activating carbon fibers which have been produced by heat-treating organic carbon fibers such as cellulose, polyacrylonitrile or petroleum pitch, polyimide or phenol resin fibers in an oxidative gas atmosphere and carbonizing the heat-treating organic fibers in an inert gas, with an activating gas, for example, water vapor, to convert them to the activated porous carbon fibers having a specific surface area of 100 to 3,000 m.sup.2 /g, a length of 5 mm or more and a thickness of 5 to 100 .mu.m; reacting the activated porous carbon fibers with a silicon monoxide gas at a temperature of 800.degree. C. to 2,000.degree. C. under a reduced pressure of 10.sup.2 Pa or less to convert them to silicon carbide fibers having a length of 5 mm or more, without generating whiskers; and optionally the resultant silicon carbide fibers are heat-treated at a temperature of 800.

Abstract: A catalyst support includes substantially spherical particles of a substantially homogeneous mixture of at least two compounds selected from the group consisting of refractory inorganic oxides, refractory inorganic carbides, refractory inorganic nitrides and mixtures thereof, wherein said particles have a surface area of at least about 30 m.sup.2 /g, an average pore diameter of at least about 150 .ANG., and a particle size of at least about 0.1 mm. The support may be used in a catalyst system to support a Group IVb and a Group VIII metal in a catalyst system useful for hydrogenation of carbon monoxide into C.sub.2 + hydrocarbons. A method is also provided for preparing the catalyst support and system.

Abstract: A combustor for supporting the catalytic combustion of a gaseous carbonaceous fuel/air combustion mixture contains a catalyst zone in which is disposed a catalyst body comprising at least a first and a second catalyst member and further contains a downstream zone where homogeneous combustion occurs. Each catalyst member is comprised of a carrier body having a catalyst material deposited thereon. The first carrier is made of a silica-magnesia-alumina material comprised primarily of cordierite, mullite and corundum and the second carrier is made of a ceramic fiber matrix material comprising ceramic (alumina-boron oxide-silica) fibers in a silicon carbide matrix.

Abstract: A polymerization catalyst comprising a polycation complex (A) represented by the following Formula, [(CUHC).sub.n MX.sub.m ].sup.j+ .multidot.([Y].sup.-)j; [(CUHC): a cyclic unsaturated hydrocarbon group], more particularly, a polymerization catalyst comprising the reaction product of a transition metal compound and an ionic compound (b) capable of forming an ionic complex when reacted with a transition metal compound, and the above-mentioned compound (b), is disclosed.

Abstract: The invention concerns a process for preparing a silicon carbide foam consisting of attacking a polyurethane foam with an alkaline solution, impregnating it, after rinsing and drying, with a suspension of silicon powder in an organic resin, heating progressively to polymerise the resin, carbonising the polyurethane foam and resin, and finally carburising the silicon contained in the resin suspension by means of the carbon originating from the carbonisation of the foam and resin.The foams obtained are characterised by a high microporosity and a mesoporosity which is variable according to the carburising temperature.The invention finds an application in the manufacture of catalyst carriers for exhaust chambers and filters for diesel engines.