Abstract: The invention relates to an aqueous colloidal dispersion of a compound of cerium and at least one other element M chosen from among the rare earths other than cerium; titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminium, gallium and zirconium.

Abstract: The invention concerns an aqueous colloidal dispersion of the aqueous colloidal nanometric type wherein the mean colloidal particle diameter is not more than 6 nm, said dispersion comprising: (1) at least a metal M compound, said metal M being a majority metal in the dispersion, selected among the group consisting of aluminium, zirconium and metals or the periodic table whereof the atomic number is between 22 and 31; and (2) at least a complexing agent having a pKs(M) (cologarithm of the dissociation constant of the complex formed by the complexing agent and the cation of said metal M) more than 2. The invention also concerns the method for preparing said dispersion. The resulting dispersion can in particular be used for preparing anti-UV filters, in catalysis, or as reinforcement of polymeric or mineral matrices.

Abstract: The invention concerns a method for preparing a controlled mesoporous or mesostructured material, heat stable and at least partly crystallised, said method comprising steps which consist in: (A) forming an initial dispersion comprising: (1) at least partly crystalline colloidal particles of nanometric dimensions, whereof at least 50% of the population has a mean diameter ranging between 1 and 40 nm, and (2) a texturizer; (B) concentrating the resulting dispersion so as to obtain a solid by texturization and gradual aggregation of the colloidal particles; and (C) eliminating the texturizer in the resulting solid. The invention also concerns the partly crystalline and heat stable mesostructured products obtained by said method. The invention further concerns mesostructured materials, at least partly crystalline and heat stable, consisting essentially of a cerium, zirconium and/or titanium oxide. Said materials can be used in particular in catalysis.

Abstract: Process for preparing mineral particles in the form of colloids in aqueous dispersion of controlled size from a precursor, comprising: a) the step of putting the said precursor, which is a mineral salt of a metal cation, into aqueous solution; b) the complexation of the product obtained in a) with at least one water-soluble block copolymer having at least one complexing anionic hydrophilic block and at least one stabilizing nonionic hydrophilic block; and c) the partial or complete hydrolysis of the said precursor in order to obtain controlled growth of the mineral particles in the form of an aqueous dispersion. Use of said colloids, especially as reinforcing fillers for a polymer.

Abstract: An agent for removing heavy metals from an aqueous effluent, including at least one compound selected from a silicate or aluminosilicate compound such as an alkali-metal silicate or aluminosilicate, and a carbonate compound such as an alkali-metal carbonate; a sulphur compound; and optionally a carrier, particularly a clay carrier. The agent may also be used to stabilize such metals. Said agent is useful for removing or stabilizing heavy metals, including mercury, that are contained in the water used for scrubbing flue gases from waste incinerators, particularly for household refuse or industrial waste.

Abstract: The present invention relates to an aqueous suspension comprising: A) silica and/or alumina particles, and B) a compound of overall formula (I): Al(OH)a(SO4)b(SiOx)c(Y)d  (I)  with: a between 0.1 and 2, b between 0.3 and 1.5, c between 0 and 0.1, d greater than 0.05, Y chosen from alkali metals and alkaline earth metals, x between 2 and 4, and its derivatives, the said compound (B) being present in the suspension at a concentration of at least 1.65 mol/l, expressed as moles of aluminium issued from the said compound. Another subject-matter of the invention is a process useful for the preparation of the said suspension and its use in the field of cement pastes, mortars and concretes and in particular as setting and hardening accelerating agent for cements.

Abstract: Storage-stable sols are comprised of a colloidal dispersion of at least one compound of an acidic metal cation, Mn+, for example, cerium (IV) and/or iron (III), in an organic phase which comprises an organic liquid medium and an organic acid. The title sols are conveniently prepared via the phase transfer of colloidal particulates from a counterpart aqueous colloidal dispersion.

Abstract: In a first embodiment of the invention, a colloidal dispersion of a cerium compound is characterised in that it has a pH of at least 4 and a conductivity of at most 5 mS/cm. In a second embodiment, the colloidal dispersion is characterised in that it has a pH of more than 5. In a third embodiment, the colloidal dispersion is characterised in that the colloids have a carbon content such that the carbon/cerium mole ratio is at Least 0.01 and in that the pH is greater than 5.A process for the preparation of these dispersions is characterised in that a first colloidal dispersion is used as a starting material, with a pH which is lower than the pH of the dispersion which is to be prepared, and the pH of the first dispersion is raised while reducing the ionic strength. For the third embodiment, an organic acid is added to the starting dispersion.

Abstract: An agent for recovering heavy metal cations from an aqueous effluent, including a silicate or aluminosilicate type compound, e.g. an alkali metal silicate or aluminosilicate, and a carbonate type compound, e.g. an alkali metal carbonate, and preferably a carrier such as a lay. The agent may also form a cation stabilizer. Said agent is useful for removing or stabilizing heavy metal cations in the water used for cleaning flue gases from waste incineration, particularly household refuse and industrial waste incineration.

Abstract: The invention relates to the use of barium sulphide or strontium sulphide for the removal of heavy metals in industrial acidic solutions.The invention is applicable to the purification of contaminated acids, in particular of spent battery acid, or of industrial solutions of titanyl sulphate.

Abstract: In a first embodiment, the present invention concerns a colloidal dispersion of a cerium compound, characterised in that it has a CeO.sub.2 concentration of between 500 and 700 g/l and a conductivity of at most 50 mS/cm. In a second embodiment, the colloidal dispersion is characterised in that it has a CeO.sub.2 concentration of more than 700 g/l.A process for the preparation of the dispersion of the invention is characterised in that a starting suspension or dispersion is treated by dialysis or with a cationic resin and an anionic resin.Colloidal dispersions of the invention can be used in automobile post combustion catalysis, in cosmetics, in lubrication, in ceramics or as an anticorrosion agent.

Abstract: Gaseous effluents containing oxygen and no greater than 2% by volume of sulfur dioxide, SO.sub.2, for example those emanating from facilities for the industrial-scale production of sulfuric acid, are converted into useful solutions of ammonium or of alkali or alkaline earth metal bisulfites, by first absorbing such gaseous effluent in a solution of ammonium or of an alkali or alkaline earth metal sulfite and bisulfite, at a pH ranging from 5 to 7, and, secondly, contacting the solution thus produced with an acidic reagent, advantageously a gaseous feedstream containing oxygen and greater than 2% by volume of sulfur dioxide, the O.sub.2 / SO.sub.2 ratio by volume thereof being less than 5.

Abstract: Storage-stable sols are comprised of a colloidal dispersion of Ce (IV) values in an aqueous medium, and optionally colloidal particulates of a cation of a metal M, with said colloidal dispersion being "supersaturated" in [OH.sup.- ] ions.

Abstract: A novel cerium (IV) compound, well adopted for the production of aqueous colloidal sols therefrom, has the general formula (I):Ce (Me).sub.x (OH).sub.y (NO.sub.3).sub.z (I)wherein M is an alkali metal an ammonium radical; x ranges from 0.01 to 0.2; y is a number such that y=4-z+x; and z ranges from 0.4 to 0.7.

Abstract: Preparing a novel cerium (IV) compound, well adopted for the production of aqueous colloidal sols therefrom, has the general formula (I): ##STR1## wherein M is an alkali metal or a quaternary ammonium radical; t ranges from 0.1 to 0.3; n is 0 or 1; x ranges from 0.1 to 0.7; y is a number such that y=4+t-x-z; and z ranges from 0.3 to 0.6.

Abstract: A novel cerium (IV) material, well adopted for the production of aqueous colloidal sols therefrom, has the general formula (I):Ce(M).sub.t (CH.sub.3 --CH.sub.2 ].sub.n COO.sup.-).sub.x (OH.sup.-).sub.y (NO.sub.3.sup.-).sub.z (I)whereein M is an alkali metal or a quaternary ammonium radical; t ranges from 0.1 to 0.3; n is 0 or 1; x ranges from 0.1 to 0.7; y is a number such that y=4+t-x-z; and z ranges from 0.3 to 0.6.

Abstract: Morphologically improved cerium oxide particulates having low sulfur content, useful, e.g., as catalyst/catalyst supports, and having a B.E.T. specific surface of at least 130 m.sup.2 /g measured at a temperature ranging from 400.degree. C. to 500.degree. C., are prepared by reacting an aqueous solution of cerium (IV) salt with an aqueous solution of sulfate ions to precipitate a basic ceric sulfate, filtering the precipitate which results, washing and optionally drying said precipitate, and thence calcining same.

Abstract: Provided is a ceric oxide having a specific surface of at least 85 m.sup.2 /g after calcination between 350.degree. and 550.degree. C., and being further characterized in that it has a pore volume of at least 0.15 cm.sup.3 /g and a median pore diameter greater than 50 .ANG.. The ceric oxide is prepared by destabilizing an aqueous colloidal dispersion of a cerium (IV) compound by the addition of base thereto, separating the precipitate which results and subjecting it to a heat treatment.

Abstract: Novel cerium (IV) compounds having the Formula (I):Ce(OH).sub.x (NO.sub.3).sub.y, pCeO.sub.2.nH.sub.2 O (I)can be directly dispersed in water to produce unique colloidal dispersions thereof.

Abstract: Morphologically improved cerium oxide particulates useful, e.g., as catalysts/catalyst supports, and having a B.E.T. specific surface of from 100 to 130 m.sup.2 /g, measured at a temperature ranging from 400.degree. C. to 450.degree. C., are prepared by hydrolyzing an aqueous solution of a cerium (IV) salt in an acidic medium, filtering the precipitate of hydrolysis which results, washing and optionally drying said precipitate, and thence calcining same.