Abstract: The present invention relates to a porous aluminum hydrate, to a process for preparing same and to the use of same as intermediate in the preparation of an alumina or of a mixed oxide based on aluminum, on cerium and on zirconium. The invention also relates to the alumina obtained from the aluminum hydrate.

Abstract: The present invention relates to a mixed oxide of aluminium, of zirconium, of cerium, of lanthanum and optionally of at least one rare-earth metal other than cerium and lanthanum that makes it possible to prepare a catalyst that retains, after severe ageing, a good thermal stability and a good catalytic activity. The invention also relates to the process for preparing this mixed oxide and also to a process for treating exhaust gases from internal combustion engines using a catalyst prepared from this mixed oxide.

Abstract: The present invention relates to an alumina with a particular pore profile and good thermal stability. This alumina is also characterized in that it has a high bulk density. The alumina has, after calcining in air at 1100° C. for 5 hours: a pore volume in the range of pores with a size of between 5 nm and 100 nm which is between 0.50 and 0.75 mL/g, more particularly between 0.50 and 0.70 mL/g; and a pore volume in the range of pores with a size of between 100 nm and 1000 nm which is less than or equal to 0.20 mL/g, more particularly less than or equal to 0.15 mL/g, or even less than or equal to 0.10 mL/g.

Abstract: The present invention relates to an alumina with a particular pore profile and good thermal stability. This alumina is also characterized in that it has a high bulk density. The alumina has, after calcining in air at 1100° C. for 5 hours: a pore volume in the range of pores with a size of between 5 nm and 100 nm which is between 0.50 and 0.75 mL/g, more particularly between 0.50 and 0.70 mL/g; and a pore volume in the range of pores with a size of between 100 nm and 1000 nm which is less than or equal to 0.20 mL/g, more particularly less than or equal to 0.15 mL/g, or even less than or equal to 0.10 mL/g.

Abstract: The invention relates to a novel method of preparing silicas and to highly-structured silicas having the following characteristics: a specific surface area CTAB (SCTAB) of between 40 and 525 m2/g; a specific surface area BET (SBET) of between 45 and 550 m2/g; an object size distribution width Ld ((d84?D16)/d50), which is measured by XDC particle size analysis after deagglomeration with ultrasound, of at least 0.91; and a pore-size distribution such that ratio V(d5?d50)/V(d5?d100) is at least 0.66. The invention also relates to the use of said silicas as polymer reinforcing fillers.

Abstract: The present invention relates to a porous aluminum hydrate, to a process for preparing same and to the use of same as intermediate in the preparation of an alumina or of a mixed oxide based on aluminum, on cerium and on zirconium. The invention also relates to the alumina obtained from the aluminum hydrate.

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 present invention relates to a mixed oxide of aluminium, of zirconium, of cerium, of lanthanum and optionally of at least one rare-earth metal other than cerium and lanthanum that makes it possible to prepare a catalyst that retains, after severe ageing, a good thermal stability and a good catalytic activity. The invention also relates to the process for preparing this mixed oxide and also to a process for treating exhaust gases from internal combustion engines using a catalyst prepared from this mixed oxide.

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: A dispersion includes an apolar organic phase, at least one amphiphilic agent, and solid objects based on particles of an iron compound in crystallized form of small size.

Abstract: The composition according to the invention 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, characterized in that 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 composition according to the invention can be used in the field of catalysis.

Abstract: Thermal and/or acoustic insulation materials based on dried precipitated silica, having a total pore volume of from 1 to 5 cm3/g and optionally containing reinforcing fillers and/or opacifying agents, are prepared by: (A) filtering an aqueous dispersion D containing precipitated silica particles in a filter press, whereby a compacted filter cake is obtained; and then (B) drying the filter cake in the compacted state as obtained after step (A).

Abstract: The composition of the invention is based on oxides of zirconium, cerium, niobium and tin in proportions by weight of oxide of between 5% and 50% for cerium oxide, 5% and 20% for niobium oxide, 1% and 10% for tin oxide and the remainder being zirconium oxide. The composition may be used in a catalytic system for an SCR-type process for treating a gas that contains nitrogen oxides (NOx).

Abstract: Precipitated silicas including clusters of large primary silica particles having at the surface thereof small primary silica particles, have a specific surface area CTAB (SCTAB) ranging from 60 to 400 m2/g; a cluster average size d50, as measured by XDC grading after ultrasound deagglomeration, such that d50 (nm)>(6214/SCTAB (m2/g)+23; a pore volume distribution such that V(d5-d50)/V(d5-d100)>0.906?(0.0013×SCATB (m2/g)); and a pore size distribution such that Mode (nm)>(4166/SCTAB (m2/g))?9.2; such silicas are useful reinforcing fillers for polymers.

Abstract: A diene rubber composition for tires based on at least (i) one diene elastomer, (ii) one reinforcing inorganic filler and (iii) one coupling agent which provides the bonding between the inorganic filler and the elastomer. The inorganic filler comprises at least one silica capable of being obtained by the preparation process of the type comprising the reaction of a silicate with an acidifying agent, whereby a silica suspension is obtained, followed by the separation and the drying of this suspension. The reaction of the silicate with the acidifying agent is carried out according to the following successive stages: (i) an aqueous suspension of precipitated silica, exhibiting a pH of between 2.5 and 5.3, is brought into contact (mixing) with acidifying agent and silicate, in such a way that the pH of the reaction medium is maintained between 2.5 and 5.3, (ii) silicate is added to the reaction medium obtained, so as to increase the pH of the reaction medium up to a value of between 4.7 and 6.3.

Abstract: Thermal and/or acoustic insulation materials based on dried precipitated silica, having a total pore volume of from 1 to 5 cm3/g and optionally containing reinforcing fillers and/or opacifying agents, are prepared by: (A) filtering an aqueous dispersion D containing precipitated silica particles in a filter press, whereby a compacted filter cake is obtained; and then (B) drying the filter cake in the compacted state as obtained after step (A).

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 composition according to the invention 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, characterized in that 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 composition according to the invention can be used in the field of catalysis.

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 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.