The present disclosure relates to methods of preparing sols of titanium dioxide nanoparticles that are photoactive, neutral, and in a substantially concentrated form. The methods particularly provide for concentrated sols in light of washing and dewatering under low cation concentrations and utilizing rapid peptizing through addition of the filter case to the peptizing agent. Concentrated acid may be utilized to maintain high TiO.sub.2 concentration while still avoiding precipitation of the colloidal TiO.sub.2. Concentrated photoactive, neutral titanium dioxide sols are also provided as well as compositions thereof and photoactive coatings formed therewith.

Colloids comprising inorganic nanocrystals dispersed in a molten salt or a liquid metal are provided. The molten salt may comprise an ion which is a Lewis acid or a Lewis base in the presence of the inorganic nanocrystals. Solid composites formed from the colloids are also provided. Methods of using the colloids as media for inducing chemical transformations using the inorganic nanocrystals are also provided.

This invention relates to azirconium solution or sol comprising: (a) zirconium, (b) nitrate, acetate and/or chloride ions, and (c) one or more complexing agents being an organic compound comprising at least one of the following functional groups: an amine, an organosulphate, a sulphonate, a hydroxyl, an ether or a carboxylic acid group, wherein the molar ratio of components (a):(b) is 1:0.7 to 1:4.0, the molar ratio of components (a):(c) is 1:0.0005 to 1:0.1, and the pH of the zirconium solution or sol is less than 5. The invention also relates to a process for preparing a zirconium solution or sol, the process comprising the steps of: (a) dissolving a zirconium salt in nitric, acetic and/or hydrochloric acid, and (b) adding one or more complexing agents to the resulting solution, the one or more complexing agents being an organic compound comprising at least one of the following functional groups: an amine, an organosulphate, a sulphonate, a hydroxyl, an ether or a carboxylic acid group, and (c) heating the solution or sol to a temperature of at least 75? C. In addition, the invention relates to products formed from the zirconium solution or sol or obtainable by the process.

This invention relates to a cerium-zirconium based mixed oxide having: (a) a Ce:Zr molar ratio of 1 or less, and (b) a cerium oxide content of 10-50% by weight, wherein the composition has (i) a surface area of at least 18 m.sup.2/g, and a total pore volume as measured by N.sub.2 physisorption of at least 0.11 cm.sup.3/g, after ageing at 1100? C. in an air atmosphere for 6 hours, and (ii) a surface area of at least 42 m.sup.2/g, and a total pore volume as measured by N.sub.2 physisorption of at least 0.31 cm.sup.3/g, after ageing at 1000? C. in an air atmosphere for 4 hours. The invention also relates to a catalytic system comprising the cerium-zirconium based mixed oxide, as well as to a process 10 for treating an exhaust gas from a vehicle engine comprising contacting the exhaust gas with the cerium-zirconium based mixed oxide. In addition, the invention relates to a process for preparing a cerium-zirconium based mixed hydroxide or mixed oxide as claimed in any preceding claim, the process comprising the steps of: (a) dissolving a zirconium salt in an aqueous acid, (b) adding one or more complexing agents to the resulting solution, the one or more complexing agents being an organic compound comprising at least one of the following functional groups: an amine, an organosulphate, a sulphonate, a hydroxyl, an ether or a carboxylic acid group, (c) heating the solution or sol formed in step (b), (d) adding a cerium salt, and adding a sulphating agent either before or after the addition of the cerium salt, and (e) adding a base to form a cerium-zirconium based mixed hydroxide.

The present invention describes a fluid which is suitable for the decontamination of heat engines which can carry out both the catalytic reduction of oxides of nitrogen (NOx) contained in exhaust gases and assist in the regeneration of the particulate filter (PF), said fluid being in the form of a stable suspension of colloidal particles, these colloidal particles being dispersed in an aqueous solution containing at least one reducing agent or at least one precursor of a reducing agent for NOx. The invention also describes several embodiments for the preparation of said fluid.

A zirconia nanoparticle material includes a zirconia nanoparticle and a carbonate coordinated on a surface of the zirconia nanoparticle. The carbonate is 1 to 10 parts by weight of the zirconia nanoparticle.

The invention relates to an apparatus and methods for producing liquid colloids such as suspensions of nanoparticles, in which liquid feedstock materials are reacted on a reaction surface of a rotatable plate. The apparatus has a first plate (101) mounted for rotation about a rotation axis (102), the first plate (101) providing a reaction surface (103) having a concave portion; first (106) and second (107) inlet lines arranged to introduce respective first and second liquid feedstock materials to the reaction surface (103); and a collection unit (110) arranged to collect a reaction product formed from reaction of the liquid feedstock materials as a liquid colloid ejected from an outer edge of the plate (101).

Aqueous and substantially crystalline iron oxide nanoparticle dispersions and processes for making them are disclosed. The nanoparticle size and size distribution width are advantageous for use in a fuel additive for catalytic reduction of soot combustion in diesel particulate filters. Nanoparticles of the aqueous colloid are transferred to a substantially non-polar liquid comprising a carboxylic acid and one or more low-polarity solvents. The transfer is achieved by mixing the aqueous and substantially non-polar materials, forming an emulsion, followed by a phase separation into a substantially metal-free remnant polar phase and a substantially non-polar organic colloid phase. A method for rapid and substantially complete transfer of non-agglomerated nanoparticles to the low polarity phase in the presence of an organic amine, and a rapid phase separation of the substantially non-polar colloid from a remnant aqueous phase, are provided.

A method of making cerium dioxide nanoparticles includes: a) providing an aqueous reaction mixture having a source of cerous ion, a source of hydroxide ion, a nanoparticle stabilizer, and an oxidant at an initial temperature no higher than about 20 C.; b) mechanically shearing the mixture and causing it to pass through a perforated screen, thereby forming a suspension of cerium hydroxide nanoparticles; and c) raising the initial temperature to achieve oxidation of cerous ion to eerie ion and thereby form cerium dioxide nanoparticles having a mean diameter in the range of about 1 nm to about 15 nm. The cerium dioxide nanoparticles may be formed in a continuous process.

Disclosed are novel aqueous aluminum complex compositions and methods of making and using them. The novel compositions comprise very low halide content, even when made from aluminum chlorohydrate. The compositions find use in the production of zeolites, coatings, abrasives, binders, and refractories; and in the treatment of wastewater for example. The methods of making the novel compositions include passing a first aqueous aluminum complex composition through an anion exchange column or otherwise contacting the first composition with the anion exchange resin to provide a second aqueous aluminum complex composition that is different from the first aqueous aluminum complex composition. Also disclosed are methods of making zeolites and aqueous silica-alumina compositions from the novel aqueous aluminum complex compositions.