Abstract: The invention relates to a method for converting a gas into methane (CH4) which includes: a step of activating a catalytic material including praseodymium oxide (Pr6O11) associated with nickel oxide (NiO) and alumina (Al2O3), the respective proportions of which are, relative to the total mass of these three compounds: Pr6O11: 1 wt % to 20 wt %, NiO: 1 wt % to 20 wt %, and Al2O3: 60 to 98 wt %; and a step of passing a gas including at least one carbon monoxide (CO) over the activated catalytic material.

Abstract: Zirconium and yttrium oxide-based composition with a specific surface area of at least 12 m 2/g following calcination at 1000° C. for 10 hours. This composition is obtained via a method wherein a mixture of zirconium and yttrium compounds is precipitated with a base; the resulting precipitate-containing medium is heated; a compound selected from anionic surfactants, non-ionic surfactants, polyethylene glycols, carboxylic acids and the salts thereof and carboxymethylated fatty alcohol ethoxylate-type surfactants is then added to said precipitate, and, finally, the precipitate is calcined. Said composition can be used as a catalyst.

Abstract: The invention relates to a method for converting a gas into methane (CH4) which includes: a step of activating a catalytic material including praseodymium oxide (Pr6O11) associated with nickel oxide (NiO) and alumina (Al2O3), the respective proportions of which are, relative to the total mass of these three compounds: Pr6O11: 1 wt % to 20 wt %, NiO: 1 wt % to 20 wt %, and A12O3: 60 to 98 wt %; and a step of passing a gas including at least one carbon monoxide (CO) over the activated catalytic material.

Abstract: A composition based on cerium and niobium oxide in a proportion of niobium oxide of 2% to 20% is described. This composition can include zirconium oxide, optionally 50% of cerium oxide, 2% to 20% of niobium oxide, and at most 48% of zirconium oxide. Also described, is the use of the composition for treating exhaust gases.

Abstract: The invention relates to a method for converting a gas into methane (CH4) which includes: a step of activating a catalytic material including praseodymium oxide (Pr6O11) associated with nickel oxide (NiO) and alumina (Al2O3), the respective proportions of which are, relative to the total mass of these three compounds: Pr6O11: 1 wt % to 20 wt %, NiO: 1 wt % to 20 wt %, and A12O3: 60 to 98 wt %; and a step of passing a gas including at least one carbon monoxide (CO) over the activated catalytic material.

Abstract: The composition of the invention is based on oxides of cerium, of zirconium and of at least one rare earth metal other than cerium, with a cerium oxide content of greater than 50% by weight and it has, after calcination at 1000° C. for 4 hours, a specific surface area of at least 20 m2/g and an amount of mobile oxygen between 200° C. and 400° C. of at least 0.8 ml O2/g. It is prepared by a process in which, in a reactor, a mixture of compounds of cerium, of zirconium and of the other rare earth metal is reacted continuously with a basic compound with a residence time of the reaction medium in the mixing zone of the reactor of at most 100 milliseconds; the precipitate is heated then brought into contact with a surfactant before being calcined.

Abstract: The invention relates to a composition containing zirconium, cerium and yttrium oxides with a cerium oxide proportion of between 3% and 15%, and yttrium oxide proportions corresponding to the following conditions: 6% at most if the cerium oxide proportion is between 12% excluded and 15% included; 10% at most if the cerium oxide proportion is between 7% excluded and 12% included; 30% at most if the cerium oxide proportion is between 3% and 7% included; the balance consisting of zirconium oxide. The composition may optionally include an oxide of a rare earth selected from lanthanum, neodymium and praseodymium. The composition can be used for processing the exhaust gases of a vehicle.

Abstract: Compositions useful for treating the exhaust gases of diesel engines contain zirconium oxide, silicon oxide and at least one oxide of at least one element M selected from among titanium, aluminum, tungsten, molybdenum, cerium, iron, tin, zinc, and manganese, in the following mass proportions of these different elements: silicon oxide: 5%-30%; M-element oxide: 1%-20%; the balance being zirconium oxide; such compositions also have an acidity, as measured by the methylbutynol test, of at least 90% and are prepared by placing a zirconium compound, a silicon compound, at least one M-element compound and a basic compound in a liquid medium, thereby generating a precipitate, maturing the precipitate in a liquid medium and separating and calcining the precipitate.

Abstract: The present invention relates to compositions based on zirconium oxide and cerium oxide that exhibit a sufficiently high specific surface area after calcination and a low maximum reduction temperature of the oxide after calcination. Compositions of the present invention may be notably used in various catalytic systems, such as for the treatment of exhaust gases from internal combustion engines.

Abstract: Thermally stable, solid alumina-based compositions useful for the trapping of nitrogen oxides that are contained in gaseous fluids, notably in vehicular exhaust gases, are formed of alumina, cerium and a divalent metal M selected from among barium, strontium or an association of these two elements and which include at least 10% of the weight of element M expressed by weight of oxide in contrast to the total weight of the composition and also wherein the aluminate compound of the metal element M, i.e., MAl2O4, is absent and not detectable by X-ray diffraction of the composition, after calcination thereof with air at 700° C. for two hours.

Abstract: The composition is based on zirconium oxide and at least one additive selected from zirconium oxide and at least one additive chosen from praseodymium, lanthanum or neodymium oxides, has a specific surface of at least 29 m 2/g after calcination at 1000° C. during a period of 10 hours and is obtained by a method wherein a mixture of zirconium compounds and additive is precipitated with a base; the medium thus obtained, containing a precipitate, is heated and a compound chosen from anionic surfactants, non-ionic surfactants, polyethylene glycols, carboxylic acids and the salts thereof and surfactants such as the ethoxylates of caroboxymethyl fatty alcohols is added to the compound and the precipitate is calcinated; the composition can be used as a catalyst.

Abstract: A composition based on cerium, zirconium and tungsten is described. The composition has a content expressed as an oxide, of which cerium is from 5% to 30% of the composition, tungsten is from 2% to 17% of the composition, and the remainder of the composition is zirconium. After aging at 750° C. under an air atmosphere including 10% water, it has a two-phase crystallographic structure having a tetragonal zirconia phase and a monoclinic zirconia phase, with no presence of a crystalline phase including tungsten. The composition can be used as a catalyst, especially in an SCR process.

Abstract: The invention relates to a composition containing zirconium, cerium and yttrium oxides with a cerium oxide proportion of between 3% and 15%, and yttrium oxide proportions corresponding to the following conditions: 6% at most if the cerium oxide proportion is between 12% excluded and 15% included; 10% at most if the cerium oxide proportion is between 7% excluded and 12% included; 30% at most if the cerium oxide proportion is between 3% and 7% included; the balance consisting of zirconium oxide. The composition may optionally include an oxide of a rare earth selected from lanthanum, neodymium and praseodymium. The composition can be used for processing the exhaust gases of a vehicle.

Abstract: The invention relates to a method for treating a gas containing nitrogen oxides (NOx), in which an NOx-reduction reaction is carried out using a nitrogen-containing reducing agent, which invention is characterized in that the catalyst used for the reduction reaction is a catalytic system containing a composition comprising zirconium, cerium and niobium in the following percentages by weight, expressed in terms of the weight of oxide: 10-50% of cerium, 5-20% of niobium and the remainder consisting of zirconium.

Abstract: A composite oxide and a catalyst for purifying exhaust gas using the same are provided, which oxide has excellent heat resistance, including that a large specific surface area is maintained even when the composite oxide is used in a high temperature environment, and that, even after calcination at 800° C. for 2 hours, no AECeO3 phase is detected and increase in CeO2 crystallite size is inhibited. The composite oxide contains, in terms of oxides, 50 to 98 mass % of a cerium-containing element, the cerium-containing element consisting of Ce and at least one element selected from rare earth elements other than Ce and including Y, Zr, and A1, at 85:15 to 100:0 by mass, 1 to 30 mass % of an alkaline earth metal element, and 1 to 20 mass % silicon in terms of SiO2.

Abstract: A composite oxide and a catalyst for purifying exhaust gas using the same are provided, which oxide has excellent heat resistance, including that a large specific surface area is maintained even when the composite oxide is used in a high temperature environment, and that, even after calcination at 800° C. for 2 hours, no AECeO3 phase is detected and increase in CeO2 crystallite size is inhibited. The composite oxide contains, in terms of oxides, 60 to 98 mass % of a cerium-containing element, the cerium-containing element consisting of Ce and at least one element selected from rare earth elements other than Ce and including Y, Zr, and Si at 85:15 to 100:0 by mass, 1 to 20 mass % of an alkaline earth metal element, and 1 to 20 mass % aluminum in terms of AI2O3, wherein the composite oxide has properties of exhibiting a specific surface area of not smaller than 40 m2/g as measured by the BET method after calcination at 800° C.

Abstract: The composition of the invention is based on oxides of cerium, of zirconium and of at least one rare earth metal other than cerium, with a cerium oxide content of greater than 50% by weight and it has, after calcination at 1000° C. for 4 hours, a specific surface area of at least 20 m2/g and an amount of mobile oxygen between 200° C. and 400° C. of at least 0.8 ml O2/g. It is prepared by a process in which, in a reactor, a mixture of compounds of cerium, of zirconium and of the other rare earth metal is reacted continuously with a basic compound with a residence time of the reaction medium in the mixing zone of the reactor of at most 100 milliseconds; the precipitate is heated then brought into contact with a surfactant before being calcine.

Abstract: A method is described for treating a gas including nitrogen oxides (NOx). The method can include conducting a reduction reaction of the nitrogen oxides with a nitrogen reducing agent. Further described, is a catalyst used for the reduction reaction which is a catalytic system including a composition based on cerium oxide and including niobium oxide in a proportion by a mass of from 2% to 20%.

Abstract: Catalyst/catalyst support composition essentially consist of oxides of zirconium, cerium and lanthanum and of another rare earth selected from among yttrium, gadolinium and samarium, having a proportion of the lanthanum oxide and the oxide of the other rare earth of at least 15% and specific surfaces of at least 40 m2/g and at least 15 m2/g after calcination respectively for 4 hours at 1,000° C. and 10 hours at 1,150° C.; after calcination for 10 hours at 1,200° C. these have a surface of at least 7 m2/g and such surface is at least 5 m2/g for an embodiment in which after 10 hours of calcination at 1,150° C. the composition is in the form of a pure solid solution.

Abstract: The invention relates to a method for treating a gas containing nitrogen oxides (NOx), in which an NOx-reduction reaction is carried out using a nitrogen-containing reducing agent, which invention is characterized in that the catalyst used for the reduction reaction is a catalytic system containing a composition comprising zirconium, niobium in the following percentages by weight, expressed in terms of the weight of oxide: 10-50% of cerium, 5-20% of niobium and the remainder consisting of zirconium.