Abstract:
The invention relates to a method of structuring a catalyst on a support, characterised in that it comprises the following stages: depositing of a layer of catalyst on the support; annealing of the structure thus created to obtain a fractionation of the layer of catalyst in the shape of drops; etching of the fractionated layer of catalyst to adjust the density of the catalyst drops. The invention also relates to a method of carbon nanotube growth on the catalyst drops present on the structure obtained according to the method of structuring. Finally, the invention relates to a device comprising a cathode and an anode, the cathode comprising a layer of carbon nanotubes made according to the method of nanotube growth. No figures.
Abstract:
A method of making a catalyst with monolayer or sub-monolayer metal by controlling the wetting characteristics on the support surface and increasing the adhesion between the catalytic metal and an oxide layer. There are two methods that have been demonstrated by experiment and supported by theory. In the first method, which is useful for noble metals as well as others, a negatively-charged species is introduced to the surface of a support in sub-ML coverage. The layer-by-layer growth of metal deposited onto the oxide surface is promoted because the adhesion strength of the metal-oxide interface is increased. This method can also be used to achieve nanoislands of metal upon sub-ML deposition. The negatively-charged species can either be deposited onto the oxide surface or a compound can be deposited that dissociates on, or reacts with, the surface to form the negatively-charged species. The deposited metal adatoms can thereby bond laterally to the negatively-charged species as well as vertically to the oxide surface. Thus the negatively-charged species serve as anchors for the metal. In the second method, a chemical reaction that occurs when most metals are deposited on a fully hydroxylated oxide surface is used to create cationic metal species that bind strongly both to the substrate and to metallic metal atoms. These are incorporated into the top layer of the substrate and bind strongly both to the substrate and to metallic metal atoms. In this case, these oxidized metal atoms serve as the anchors. Here, as in the previous method, nanoislands of catalytic metal can be achieved to increase catalytic activity, or monolayers or bilayers of reactive metal can also be made.
Abstract:
A photocatalytic material, which exhibits photocatalytic activity when exposed to visible light, the material containing Ti—O—N containing nitrogen in lattices of titanium oxide crystal.
Abstract:
A photocatalytic material having titanium oxide crystals and anions X incorporated therein, which is prepared by at least one of a method comprising substituting anions X for some of the oxygen sites of titanium oxide crystals, a method comprising doping anions X between lattices of a titanium crystal and a method comprising doping grain boundaries of titanium oxide, or a combination of these method. The photocatalytic material has acquired a new energy level formed in a band gap of titanium oxide, which results in its exhibition of a photocatalytic activity by absorbing visible lights. The photocatalytic material can thus exhibit a satisfactory photocatalytic activity under sunlight and also in a room with a fluorescent lamp.
Abstract:
A porous clay composite having fine metal particles deposited substantially only on surfaces of inorganic particles which are intercalated between layers of an expandable clay is obtained. After the expandable clay is expanded with a solvent into an expanded clay, the inorganic particles are intercalated between the layers of the expanded clay. The inorganic particles have photo-semiconducting property, that is, a plurality of carriers such as electrons and holes are released from the inorganic particles by irradiation of a light such as ultraviolet light. A solution including metal ions is mixed with the inorganic particles intercalated clay to form a mixed solution thereof. Subsequently, the light is irradiated to the mixed solution to deposit the fine metal particles substantially only on the inorganic particles which are intercalated between the layers of the expanded clay, so that the porous clay composite is formed in the mixed solution. The porous clay composite including the mixed solution is dried by a supercritical drying or a carbon dioxide extractive drying, etc., so as not to disrupt a porous structure thereof. When a metal having oxidation/reduction catalysis is used as the fine metal particles, the porous clay composite functions as an excellent oxidation/reduction catalyst.
Abstract:
A surface modified catalyst of the type comprising at least two mechanically mixed elements forming active catalyst sites at the boundaries of such elements. The surface-modified catalyst is formed by irradiating a catalyst compound, which is preferably hopcalite (copper-manganese), at an energy level sufficient to cause molecular dispersion of the copper molecules and increase the number of active sites. One or more additional elements may be added to the surface-modified catalyst, e.g. lithium and yttrium, to affect the reaction properties and temperature stability.
Abstract:
The invention relates to metal microaggregates.The monodisperse of the invention are non-noble metal microaggregates in a monodispersed form in a solid or liquid medium and of a size uniformly less than 5 nm. They are obtained by irradiation of a metal salt or a mixture of salts, by means of an ionizing radiation source, by dissolving a non-noble metal salt or a mixture of metal salts, at least one of which is a non-noble metal, in an appropriate solvent, in the presence of an oxidizing radical scavenger and a surfactant and/or a support, and then by carrying out irradiation.Application is for catalysis of various reactions, in particular the photoreduction of water into hydrogen.
Abstract:
A process and apparatus for the transportation and heating of granulated materials, particularly of solid particles of catalyst used for hydrocarbon conversion which must be activated or regenerated. The process comprises moving a bed of catalyst particles on travelling bands or floor plates passing through an elongate chamber and eventually inclined to the axis. The bands are subjected to vibrations imparting to said bed an unidirectional motion, and said bed on said bands being exposed to heating by means of electromagnetic radiations of a wave length range from 0.38 .mu.m to 50 mm.
Abstract:
This invention relates to a new manner of carrying out chemical reactions by injection of selected forms of energy into the reaction zone by novel means. By applying this principal, many new processes result with application in a large number of different industries. The new process is generally capable of operation at room temperatures, which has advantages in the creation of certain sensitive products including uniformly doped semi-conductors, new catalysts, pure gases, high purity materials of any kind, controlled coatings, new polymers, combustion enhancement, difficult separation, petroleum refinery operations, and carrying out any reaction in which the injection of specific energy types is helpful.
Abstract:
Photocatalytic methods are disclosed for the preparation of metallized powders. Specifically, such methods include the photodeposition of platinum, copper and other metals on TiO.sub.2 powder and other semiconductor powders. The powders thus prepared are particularly useful as catalysts.