摘要:
A composite having ultra-fine gold particles uniformly and strongly immobilized in a deposited state on a metal oxide is obtained by preparing a solution containing the metal oxide as a carrier and a gold compound, adjusting the pH value of the solution to a specific level thereby inducing precipitation and deposition of gold hydroxide or gold on the carrier and, when the precipitate is in the form of gold hydroxide, further, firing the precipitate. The ultra-fine gold particles immobilized on metal oxides are useful as a catalyst for reduction and oxidation, in sensor elements for flammable gases, and as an electrode catalyst.
摘要:
An ultra-fine gold particle-immobilized oxide is produced by a method which comprises adding an alkali compound to an aqueous solution containing a gold compound and a water-soluble metal salt thereby giving rise to a coprecipitate in the aqueous solution, separating the coprecipitate from the aqueous solution, and calcining the separated coprecipitate. This method is characterized by allowing the presence of a carboxylic acid or a carboxylate in the aqueous solution from the beginning or after the occurrence of the coprecipitate.
摘要:
An ultra-fine gold particle-immobilized alkaline earth metal compound having ultra-fine gold particles immobilized on an alkaline earth metal compound is useful as a catalyst or as an inflammable gas sensor. This compound is produced by (1) adding an aqueous solution of a gold compound dropwise to an aqueous solution containing an alkaline earth metal compound and having a pH value kept in the range of 7 to 11 thereby inducing immobilization of gold hydroxide on the compound, separating from the solution the gold hydroxide-immobilized compound, and calcining the separated compound at a temperature in the range of 80.degree. to 800.degree. C., (2) by adding a reducing agent to an aqueous solution of an alkaline earth metal having a gold compound dissolved therein, (3) by adding carbon dioxide gas or an acidic aqueous solution to an aqueous solution containing a gold compound and an alkaline earth metal compound thereby inducing immobilization of gold hydroxide on the alkaline earth metal compound, separating from the solution the gold hydroxide-immobilized compound, and calcining the separated compound at a temperature in the range of 100.degree. to 800.degree. C., or (4) by coprecipitating a gold compound and an alkaline earth metal and calcining the coprecipitate at a temperature in the range of 80.degree. to 800.degree. C.
摘要:
A humidity detection material includes oxide of at least one metal selected from the group consisting of Mg, Ca, Mn, Fe, Co, Ni, and Cu. The metal oxide is preferably in the form of a porous material. The metal oxide is formed preferably in the form of a thin film on a transparent substrate. The humidity detection material is contacted with water vapor in the presence of a gas such as air, and the optical absorbance of the humidity detection material is measured to detect the humidity. The humidity can be detected by an optical method.
摘要:
A catalyst for the hydrogenation of CO and CO.sub.2 consists essentially of a metal oxide and gold. Synthesis of methanol and hydrocarbons by hydrogenation of CO and CO.sub.2 comprises establishing contact between a gaseous mass consisting of CO, CO.sub.2, and hydrogen and a catalyst consisting essentially of a metal oxide and gold.
摘要:
A material having ultrafine gold particles immobilized thereon consists essentially of at least one support selected from the group consisting of metal oxides, metal sulfides, and carbonaceous substances and ultrafine gold particles having a maximum particle diameter of 250 angstroms and deposited on the support with strong interaction. The material exhibits high activity as a catalyst for the oxidation of carbon monoxide to carbon dioxide. It is produced by causing a vaporized organic gold complex to contact at least one support selected from the group consisting of metal oxides, metal sulfides, and carbonaceous substances in an atmosphere of reduced pressure thereby inducing adsorption of the vapor of organic gold complex on the support and then heating the product of the adsorption to a temperature in the range of 100.degree.-700.degree. C.
摘要:
A catalyst composite having gold or a mixture of gold with a catalytic metal oxide deposited on a carrier is produced by immersing a carrier in an aqueous solution containing a water-soluble salt of gold or water-soluble salts respectively of gold and other catalytic metal and urea and/or acetamide thereby allowing a precipitate to be deposited on the carrier and then firing the carrier holding the deposited precipitate thereon.
摘要:
A catalyst for the catalytic combustion of hydrogen, comprising a composite oxide of silver and cobalt and/or manganese. The catalyst permits hydrogen to be burnt safely at low temperatures.
摘要:
There are provided a third-order nonlinear optical material comprising a film formed on the surface of a transparent substrate and consisting essentially of an oxide of a metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni and Cu; and a third-order nonlinear optical material of the type as described above wherein the film additionally contains a metal selected from the group consisting of Au, Ag and Cu in the form of particles dispersed therein and having a particle size of at most 500 nm.
摘要:
The present invention provides a method for effectively suppressing the deactivation of a gold nanoparticle catalyst by removing both carbon dioxide and water from a gas to be treated, thereby effectively removing carbon monoxide over a long period of time. The present invention relates to a catalyst for removing carbon monoxide having a carbon dioxide and water remover and a gold nanoparticle catalyst in which gold particles with an average particle diameter of 25 nm or less are supported on a metal oxide; and a method for removing carbon monoxide from a gas containing carbon monoxide, having a step of treating a gas containing carbon monoxide with the carbon dioxide and water remover and the gold nanoparticle catalyst in which gold particles with an average particle diameter of 25 nm or less are supported on a metal oxide.