Abstract: This invention provides a process for producing hydrogen peroxide through catalytic reaction of oxygen with hydrogen in an aqueous medium in the presence of a platinum group metal catalyst, in which an organic solvent having only limited solubility with water and less hydrogen peroxide-dissolving ability compared to that of water is caused to be concurrently present in the reactor, and oxygen and hydrogen are catalytically reacted in an aqueous medium in the presence of a water- and organic solvent-insoluble, hydrophilic platinum group metal catalyst, under a low reaction pressure, to form high concentration aqueous hydrogen peroxide solution within a short time.

Abstract: The present invention provides a process for producing hydrogen peroxide by reacting oxygen and hydrogen in a reaction medium catalytically using, as a catalyst, a tin-modified platinum group metal supported on a carrier. In the process using said catalyst, the presence of halogen and acid in reaction medium is unnecessary unlike the prior art methods, and hydrogen peroxide of high concentration can be produced efficiently. Thus, the present process has no restriction for reactor material as seen the prior art methods and further allows for easy purification of produced hydrogen peroxide.

Abstract: A method of cleaning under high temperature and high pressure and cleaning equipment to be used in a cleaning process now being employed in such industrial fields as the electronics industry centering around the semiconductor industry and the optical machine industry. The high temperature/high pressure cleaning equipment has at least a compressing pump, a heating device, a nozzle, and piping, and, in the cleaning equipment to inject high temperature/high pressure water from a nozzle to the matter to be cleaned, functions to inject high temperature/high pressure ultrapure water from the nozzle to the matter to be cleaned. Cleaning is carried out by injecting ultrapure water having a relative resistance of 17.0 M/l-cm or more when converted at 25.degree. C. to a matter to be cleaned.

Abstract: A method for producing a high concentration of hydrogen peroxide by reacting oxygen and hydrogen directly in a neutral reaction medium that contains a promoter comprising a halogen containing compound, which halogen containing compound contains at least one halogen other than fluorine, at a reaction temperature in the range of from 0.degree. to 50.degree. C. and at a reaction pressure in the range of from 3 to 150 kg/cm.sup.2 .multidot.G in the presence of a platinum group metal catalyst supported on a catalyst carrier containing a heteropolyacid that has been made insoluble in water or a platinum group metal catalyst supported on a catalyst carrier comprising activated carbon that is supporting a heteropolyacid.

Abstract: In cleaning a semiconductor substrate with a basic aqueous solution of hydrogen peroxide, it is an object to prevent metal impurities adhering to the substrate surface. A cleaning solution of a semiconductor substrate which comprises a basic aqueous solution of a hydrogen peroxide containing a chelating agent having at least two phosphonic acid groups. Preferred chelating agent is 1,2-propylenediamine tetra(methylene phosphonic acid) in amount of 1 ppb to 1000 ppm, together with 0.1 to 20% by weight of hydrogen peroxide and, optionally, 0.1 to 10% by weight of ammonia. Even if the cleaning solution is contaminated with metal impurities, characteristics of semiconductor elements prepared from a substrate are stabilized since no metal impurities adhere on the substrate surface.

Abstract: Oxygen and hydrogen are catalytically reacted in an acidic reaction medium in the presence of a platinum group metal catalyst to prepare hydrogen peroxide using as a carrier for the platinum group metal catalyst a composite oxide containing cerium. The process need not halogen ions in the acidic reaction medium and enables preparation of hydrogen peroxide in high concentration on an industrial scale advantageously.

Abstract: The present invention offers a piping system for supplying ultra-pure water, which comprises a circulation tank to store primary pure water from a primary pure water producing unit, a pump for sending the primary pure water from said circulation tank, an outward pipe, one end of which is connected to a final purifying unit to purify primary pure water from said pump to ultra-pure water, a plurality of connection pipes, each end of which is connected to the other end of said outward pipe, a branching pipe connected between the middle of said connection pipe and the ultra-pure water using unit and having a branching valve to adjust the water quantity, and a return pipe connected between the other end of said connection pipe and said circulation tank, characterized in that means for controlling the output of said pump is provided to keep the water pressure at constant level by detecting the water pressure in said outward pipe, thereby supplying a constant quantity of ultra-pure water to the ultra-pure water usin