摘要:
A composition is described that includes a perovskite of the formula LaMO3, where M is at least one element selected from among iron, aluminum or manganese, in the form of particles dispersed on an alumina or aluminum oxyhydroxide substrate, wherein after calcination at 700° C. for 4 hours, the perovskite is in the form of a pure crystallographic phase, and in that the size of the perovskite particles does not exceed 15 nm. The described composition can be used in the field of catalysis.
摘要:
A composition is described that includes a perovskite of the formula LaMO3, where M is at least one element selected from among iron, aluminium or manganese, in the form of particles dispersed on an alumina or aluminium oxyhydroxide substrate, wherein after calcination at 700° C. for 4 hours, the perovskite is in the form of a pure crystallographic phase, and in that the size of the perovskite particles does not exceed 15 nm. The described composition can be used in the field of catalysis.
摘要:
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%.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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%.
摘要:
A composition is described that includes oxides of zirconium, cerium and another rare earth different from cerium, having a cerium oxide content not exceeding 50 wt % and, after calcination at 1000° C. for 6 hours, a maximal reducibility temperature not exceeding 500° C. and a specific surface of at least 45 m2/g. The composition can be prepared according to a method that includes continuously reacting a mixture that includes compounds of zirconium, cerium and another rare earth having a basic compound for a residence time not exceeding 100 milliseconds, wherein the precipitate is heated and contacted with a surfactant before calcination.
摘要:
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.
摘要:
A composition is described that includes oxides of zirconium, cerium and another rare earth different from cerium, having a cerium oxide content not exceeding 50 wt % and, after calcination at 1000° C. for 6 hours, a maximal reducibility temperature not exceeding 500° C. and a specific surface of at least 45 m2/g. The composition can be prepared according to a method that includes continuously reacting a mixture that includes compounds of zirconium, cerium and another rare earth having a basic compound for a residence time not exceeding 100 milliseconds, wherein the precipitate is heated and contacted with a surfactant before calcination.