Abstract: A monolithic membrane-type filtration structure for filtering liquids, includes a support formed of a porous inorganic material of permeability Ks, the support having a tubular overall shape with a main axis, an upstream base, a downstream base, a peripheral wall delimiting an internal part and a plurality of passages parallel to the main axis of the support, formed in the internal part of the support, a membrane of permeability Km and of mean thickness tm covering the internal surface of the passages; the external hydraulic diameter of the structure satisfying the relationship Øf=?×[A+B×log10 (Ks×tm/Km)]; in which ? is a coefficient between 0.85 and 1.15, and A=?21570×entint2?18.6×Dh+19.0×eint?2.5×eext+0.1244 B=?11760×Dh×eint+9.7×eint+3.1×eext+0.04517. Dh is the mean hydraulic diameter of the passages, eint is the minimum thickness of the internal walls between the passages, eext is the minimum thickness of the peripheral wall of the filter.

Abstract: A monolithic membrane-type filtration structure for filtering liquids, includes a support formed of a porous inorganic material of permeability Ks, the support having a tubular overall shape with a main axis, an upstream base, a downstream base, a peripheral wall delimiting an internal part and a plurality of passages parallel to the main axis of the support, formed in the internal part of the support, a membrane of permeability Km and of mean thickness tm covering the internal surface of the passages; the external hydraulic diameter of the structure satisfying the relationship Øf=?×[A+B×log10 (Ks×tm/Km)]; in which ? is a coefficient between 0.85 and 1.15, and A=?21570×entint2?18.6×Dh+19.0×eint?2.5×eext+0.1244 B=?11760×Dh×eint+9.7×eint+3.1×eext+0.04517. Dh is the mean hydraulic diameter of the passages, eint is the minimum thickness of the internal walls between the passages, eext is the minimum thickness of the peripheral wall of the filter.

Abstract: A tangential filter for filtration of a fluid includes a support element, wherein, along a transverse plane perpendicular to the central axis of the support element a) the support element includes in its central portion only inner channels that do not share a common wall with its outer surface, the inner channels having a substantially equivalent hydraulic diameter, b) the support element includes peripheral channels, including at least first and second adjacent peripheral channels, each of the two channels sharing a common wall with the outer surface, c) the ratio of the hydraulic diameter of the first channel to the hydraulic diameter of the second channel is greater than or equal to 1.1, d) the number of peripheral first channels is greater than or equal to the number of peripheral second channels, e) the second channel has a hydraulic diameter substantially identical to the hydraulic diameter of the inner channels.

Abstract: A membrane filter includes a plurality of honeycomb ceramic filtering elements, each element including a plurality of parallel ducts separated by walls and open on a face for introduction of the liquid to be filtered, an interstitial volume between the filtering elements, a filtration membrane positioned on the inner surface of the walls of the ducts, wherein the filtering elements are joined together by a curable material that forms after curing a sleeve in the form of a single part joining together, by sealing, all of the filtering elements separated the interstitial volume, the sleeve having a thickness e between 1% and 10% of the length of the filter, and the curable material being present in the open porosity and through the entire thickness of each porous wall forming the elements, over a minimum non-zero height h.

Abstract: A tangential filter for filtration of a fluid includes a support element, wherein, along a transverse plane perpendicular to the central axis of the support element a) the support element includes in its central portion only inner channels that do not share a common wall with its outer surface, the inner channels having a substantially equivalent hydraulic diameter, b) the support element includes peripheral channels, including at least first and second adjacent peripheral channels, each of the two channels sharing a common wall with the outer surface, c) the ratio of the hydraulic diameter of the first channel to the hydraulic diameter of the second channel is greater than or equal to 1.1, d) the number of peripheral first channels is greater than or equal to the number of peripheral second channels, e) the second channel has a hydraulic diameter substantially identical to the hydraulic diameter of the inner channels.

Abstract: To reduce the number of particles in an exhaust gas (A), in particular in the exhaust gas (A) from an internal-combustion engine, sulfur dioxide SO2 which is contained in the exhaust gas (A) is at least partially catalytically oxidized, in the presence of ammonia NH3 in a catalytic converter system having a catalytic activity which increases in the direction of flow, to form sulfur trioxide SO3. The simultaneous presence of sulfur trioxide SO3 and ammonia NH3 in the exhaust-gas stream which is brought about in this way results in an agglomeration of the small and very small particles and reduction in the number thereof.

Abstract: The invention relates to a catalytic converter and a method for cleaning the exhaust gas from an internal combustion engine which is operated with excess air. The catalytic converter has an active material made from the oxides TiO2, V2O5, CaO and SiO2, as well as WO3 and/or MoO3. An active material of this type has the property of using the SCR method to reduce to equal extents the levels of nitrogen oxides and hydrocarbons. The CO oxidation activity of a material of this type can be increased by metering in elements selected from the group consisting of Pt, Pd, Rh, Ru and Ir in any desired inorganic form.

Abstract: A process for regenerating a catalyst, in particular a plate-type or honeycomb catalyst, which has been at least partially deactivated by catalyst poisons, is described. The catalyst is treated with a gaseous reducing agent and with a polyfunctional complex-forming agent, so that the catalyst poisons are removed.

Abstract: A process for producing a catalyst body includes providing titanium dioxide, tungsten trioxide, vanadium pentoxide, aluminum oxide, and/or silicon oxide for the catalyst body. A kneadable and/or shapable compound is processed to form a shaped body by extrusion or by coating of a support body. The shaped body is dried and is calcined to form an active compound. The calcined shaped body is artificially aged by a final heat treatment at a temperature higher than the calcination temperature to produce a catalyst body having a high resistance to deactivation at high temperatures. The starting materials include from 65 to 95% by weight of titanium dioxide, 2 to 30% by weight of tungsten trioxide, 0 to 2% by weight of vanadium pentoxide, preferably, less than 1.5%, 0.1 to 10% by weight of aluminum oxide, and 0.1 to 10% by weight of silicon dioxide. The final heat treatment is done is at 660 to 700° C., drying is at 20 to 100° C. prior to calcination, and calcination is at 400° C. to less than 700° C.

Abstract: A method for cleaning diesel engine exhaust gas is described. The exhaust gas is passed over a catalytic converter with an active material which contains (% by weight) 70-95% TiO2, 2-10% WO3 and/or MoO3, 0.1-5% V2O5, 0.1-8% CaO, 0.1-8% Al2O3, 0.1-5% B2O3 and 0.1-10% SiO2. A reducing agent for a reduction of nitrogen oxides is metered into the exhaust-gas stream upstream of the catalytic converter.

Abstract: A process is provided for the catalytic removal of polycyclic aromatic nitro, nitroso and/or amino compounds from the exhaust gas of a combustion system, in particular a diesel engine. The exhaust gas is brought into contact with a catalytic converter which includes a catalytically active material that contains titanium dioxide, at a temperature of from 150 to 600° C. The polycyclic aromatic compounds are oxidized at the catalytic converter through the use of oxygen to form nitrogen oxides, carbon dioxide and water.

Abstract: A process for catalytic removal of a pollutant from a combustion installation exhaust gas includes calculating, from operationally relevant parameters of the installation, a pollutant concentration using a predetermined characteristic diagram. A predetermined quantity of a reagent is introduced into the exhaust per unit time as a function of the calculated pollutant concentration, the reagent reacting with the pollutant at a catalytic converter. Operating states of the installation with substantially constant pollutant emission levels are determined. The pollutant concentration during an operating state of the installation with a substantially constant pollutant emission level is determined with a sensor and only a pollutant concentration from the installation in a steady operating state is used to correct the diagram. The pollutant concentration from the installation is calculated with the diagram in a non-steady operating state.

Abstract: An exhaust system for an internal combustion with a catalytic converter connected to the exhaust pipe for cleaning the engine exhaust gas in the presence of a reducing agent also includes a condensation water collector into which the exhaust gases are diverted prior to reaching the catalytic converter. The collector condenses moisture in the exhaust gas to produce liquid water condensate that is held in a reservoir. The water condensate is combined with a reactant capable of forming a reducing agent and the aqueous solution of the reactant is introduced into the exhaust gas upstream of the catalytic converter.

Abstract: A process for producing a catalyst body includes providing titanium dioxide, tungsten trioxide, vanadium pentoxide, aluminum oxide, and/or silicon oxide for the catalyst body. A kneadable and/or shapable compound is processed to form a shaped body by extrusion or by coating of a support body. The shaped body is dried and is calcined to form an active compound. The calcined shaped body is artificially aged by a final heat treatment at a temperature higher than the calcination temperature to produce a catalyst body having a high resistance to deactivation at high temperatures. The starting materials include from 65 to 95% by weight of titanium dioxide, 2 to 30% by weight of tungsten trioxide, 0 to 2% by weight of vanadium pentoxide, preferably, less than 1.5%, 0.1 to 10% by weight of aluminum oxide, and 0.1 to 10% by weight of silicon dioxide. The final heat treatment is done is at 660 to 700° C., drying is at 20 to 100° C. prior to calcination, and calcination is at 400° C. to less than 700° C.

Abstract: A process for catalytic removal of a pollutant from a combustion installation exhaust gas includes calculating, from operationally relevant parameters of the installation, a pollutant concentration using a predetermined characteristic diagram. A predetermined quantity of a reagent is introduced into the exhaust per unit time as a function of the calculated pollutant concentration, the reagent reacting with the pollutant at a catalytic converter. Operating states of the installation with substantially constant pollutant emission levels are determined. The pollutant concentration during an operating state of the installation with a substantially constant pollutant emission level is determined with a sensor and only a pollutant concentration from the installation in a steady operating state is used to correct the diagram. The pollutant concentration from the installation is calculated with the diagram in a non-steady operating state.

Abstract: A process is provided for the catalytic removal of polycyclic aromatic nitro, nitroso and/or amino compounds from the exhaust gas of a combustion system, in particular a diesel engine. The exhaust gas is brought into contact with a catalytic converter which includes a catalytically active material that contains titanium dioxide, at a temperature of from 150 to 600° C. The polycyclic aromatic compounds are oxidized at the catalytic converter through the use of oxygen to form nitrogen oxides, carbon dioxide and water.

Abstract: An exhaust-gas cleaning installation and a process for the catalytic reduction of a pollutant level in exhaust gas from a combustion system are provided for solving the problem of exact metering of reagent in regulated diesel catalytic converters. The metering of the reagent is linked to operationally relevant parameters of the combustion system through the use of a functional relationship and the functional relationship is corrected through the use of pollutant measurement. The pollutant measurement and, if appropriate, the correction, are carried out by an exhaust-gas testing installation which does not form part of the exhaust-gas cleaning installation.

Abstract: An exhaust gas laden with nitrogen oxides is subjected to a catalytic oxidation in an oxidizing catalyst. The exhaust gas is subsequently brought into contact with water and oxygen or air in a mixing device. This results in an exhaust gas freed of nitrogen oxides and in an aqueous solution. In a reaction vessel, the aqueous solution is reacted with a nitrogen-containing reducing agent, in particular with urea ((HN2)2CO), in an acidic aqueous medium under reducing conditions. The gas occurring at the same time is discharged through a discharge line.

Abstract: A method for cleaning diesel engine exhaust gas is described. The exhaust gas is passed over a catalytic converter with an active material which contains (% by weight) 70-95% TiO2, 2-10% WO3 and/or MoO3, 0.1-5% V2O5, 0.1-8% CaO, 0.1-8% Al2O3, 0.1-5% B2O3 and 0.1-10% SiO2. A reducing agent for a reduction of nitrogen oxides is metered into the exhaust-gas stream upstream of the catalytic converter.

Abstract: A process for regenerating a catalyst, in particular a plate-type or honeycomb catalyst, which has been at least partially deactivated by catalyst poisons, is described. The catalyst is treated with a gaseous reducing agent and with a polyfunctional complex-forming agent, so that the catalyst poisons are removed.