Abstract: A hydrogenation catalyst for the production of hydrogen peroxide by the hydrogenation of anthraquinones in accordance with a hydrogen peroxide production process utilizing an anthraquinone method. The catalyst includes palladium supported on a carrier. The carrier comprises spherical silica particles, wherein at least 90 wt % of the silica particles have particle diameters of 10 to 100 .mu.m. The silica particles have an average particle diameter of 30 to 60 .mu.m and a pore volume of 0.4 to 1.0 ml/g. The catalyst has desirable activity, strength, service life and selectivity.

Abstract: A method for preparing hydrogen peroxide in accordance with an anthraquinone method, comprising hydrogenating at least one anthraquinone with a hydrogenation catalyst comprising palladium and at least one alkali metal, supported on a silica carrier, wherein the at least one alkali metal is in an amount of 0.1% to 5 wt % based on the weight of the silica carrier.

Abstract: A process for producing hydrogen peroxide by subjecting a working solution containing anthraquinones as the reaction medium, to reduction and oxidation alternately, which process is characterized in that (1) the anthraquinones as the reaction medium contained in the working solution are a mixture of an alkyl-substituted anthraquinone and an alkyl-substituted tetrahydroanthraquinone, (2) in the reduction step, the total amount of the alkyl-substituted tetrahydroanthraquinone in the working solution and part or the total amount of the alkyl-substituted anthraquinone in the working solution are reduced, and (3) in the working solution after the reduction step, the content of the alkyl-substituted anthrahydroquinone formed is kept higher than the content of the alkyl-substituted tetrahydroanthrahydroquinone formed.

Abstract: A humidity-sensing component composition includes a metallic oxide and a chalcogen oxyacid salt represented by a general formula A.sub.x B.sub.y O.sub.z where A is one of an alkali metal and an alkaline earth metal, B is one of sulphur, selenium, and tellurium, O is oxygen, x is 1 to 2, y 1 to 5, and z 2 to 7. The chalcogen oxyacid salt is blended by an amount of 0.01 to 99.99 mol % in the metallic oxide with the sum of the metallic oxide and the chalcogen oxyacid salt as a reference. The metallic oxide and the chalcogen oxyacid salt are sintered under an atmosphere of molecular oxygen.

Abstract: A regeneration method of a working solution is herein disclosed in which various by-products which do not participate in the production of hydrogen peroxide and which are present in the working solution in a hydrogen peroxide production process utilizing an anthraquinone method can efficiently be converted into anthraquinones effective as reaction media for the production of hydrogen peroxide.The present invention is concerned with (1) a regeneration method of a working solution wherein at least a part of the unreduced working solution is brought into contact with a catalyst mainly comprising a .gamma.-alumina at a temperature of 40 to 150.degree. C., and (2) another regeneration method of a working solution wherein the working solution is brought into contact with a catalyst mainly comprising a .gamma.-alumina at a temperature of 20 to 150.degree. C.