Abstract: The present invention provides: a fixed-bed shell-and-tube reactor, which can stably produce an aimed product for a long period when a solid particulate material such as a catalyst is packed and used for each substance; and its usage. The fixed-bed shell-and-tube reactor comprises a plurality of reaction tubes that are packed with a solid particulate material and arranged in parallel, wherein the solid particulate material is weighed so as to be uniform volume, and is packed in each reaction tube in a packing time of not shorter than 30 seconds per liter.

Abstract: The present invention provides: a fixed-bed shell-and-tube reactor, which can stably produce an aimed product for a long period when a solid particulate material such as a catalyst is packed and used for each substance; and its usage. The fixed-bed shell-and-tube reactor comprises a plurality of reaction tubes that are packed with a solid particulate material and arranged in parallel, wherein the solid particulate material is weighed so as to be uniform volume, and is packed in each reaction tube in a packing time of not shorter than 30 seconds per liter.

Abstract: The present invention provides: a fixed-bed shell-and-tube reactor, which can stably produce an aimed product for a long period when a solid particulate material such as a catalyst is packed and used for each substance; and its usage. The fixed-bed shell-and-tube reactor comprises a plurality of reaction tubes that are packed with a solid particulate material and arranged in parallel, wherein the solid particulate material is weighed so as to be uniform volume, and is packed in each reaction tube in a packing time of not shorter than 30 seconds per liter.

Abstract: In the production of maleic anhydride by the contact of a raw material gas containing an aliphatic hydrocarbon of not less than 4 carbon atoms and molecular oxygen with a vanadium-phosphorus oxide catalyst, the raw material gas is caused to allow presence therein of nitrogen and an inert gas possessing a thermal conductivity of not less than 800 (10−4Wm−1K−1) at 700 K. The gas formed by the oxidation reaction is allowed to contact an absorbent to effect recovery of the produced maleic anhydride. Maleic anhydride is recovered from produced oxidation reaction gas separated from a remained oxidation reaction gas after recovering maleic anhydride, and the saparated inert gas is circulated to the reaction zone. The catalyst capable of producing maleic anhydride with a high yield can be obtained by activating the vanadium-phosphorus oxide catalyst with the gas composition containing an inert gas possessing a thermal conductivity of not less than 800 (10−4Wm−1K−1) at 700 K.

Abstract: A vanadium-phosphorus oxide having an X-ray diffraction spectrum (Cu--K.alpha.) showing main peaks of the diffraction angle 2.theta.(.+-.0.2.degree.) at 18.5.degree., 23.0.degree., 28.4.degree., 29.9.degree., and 43.1.degree. and having the intensity ratio of the peaks of the diffraction angle 2.theta.(.+-.0.2.degree.) at 23.0.degree. and 28.4.degree. in the following range0.3.ltoreq.I (23.0)/I (28.4).ltoreq.0.7wherein I (23.0) and I (28.4) respectively represent the intensities of the peaks of the diffraction angle 2.theta.(.+-.0.2.degree.) at 23.0.degree. and 28.4.degree., a method for the production of the oxide, a catalyst for use in a vapor phase oxidation formed of the oxide, and a method for the partial vapor phase oxidation of a hydrocarbon.

Abstract: A process for producing methacrylic acid, which comprisesfilling a plurality of catalysts of different activities into a plurality of reaction zones which have been formed in each of the reaction tubes of a fixed bed multi-tubular reactor by dividing said reaction tube into two or more portions in the direction of tubular axis, so that the activity of catalyst is higher as the reaction zone is closer to the outlet of the reaction tube, andintroducing into the reaction zones containing the catalysts at least one compound selected from methacrolein, isobutyl aldehyde and isobutyric acid to oxidize the at least one compound with molecular oxygen or a molecular oxygen-containing gas.

Abstract: A catalyst for the production of methacrylic acid composed of an inert carrier and a catalytically active substance. The catalytically active substance layer being composed of oxides represented by the following formula (I)Mo.sub.a P.sub.b a.sub.c B.sub.d C.sub.e D.sub.f O.sub.x (I)where Mo represents molybdenum, P represents phosphorus, A represents at least one element selected from arsenic, antimony, germanium, bismuth, zirconium, cerium and selenium, B is at least one element selected from copper, iron, chromium, nickel, maganese, cobalt, tin, silver, zinc, palladium, rhodium and tellurium, C represents at least one element selected from vanadium, tungsten and niobium, D represents at least one element selected from alkali metals, alkaline earth metals and thallium, and O represents oxygen, a, b, c, d, e, f and x respectively represent the atomic ratios of Mo, P, A, B, C, D and O, and when a=12, b=0.5-4, c=0-5, d=0-3, e=0-4, and f=0.