Multi-metal oxide catalyst for gas-phase partial oxidation of aromatic hydrocarbons, e.g. for phthalic anhydride production, contains silver, vanadium, a phosphorus group element and optionally other metals

摘要

Multi-metal oxides based on silver, vanadium and optionally other metal(s) also contain phosphorus, arsenic, antimony and/or bismuth. Multi-metal oxides consisting essentially of compounds of formula Aga-cQbMcV2Od.eH2O (I), in which a = 0.3-1.9; Q = phosphorus, arsenic, antimony and/or bismuth; b = 0.001-0.3; M = lithium, sodium, potassium, rubidium, cesium, thallium, magnesium, calcium, strontium, barium, copper, zinc, cadmium, lead, chromium, gold, aluminum, iron, cobalt, nickel and/or molybdenum; c = 0-0.5; (a-c) = not less than 0.1; d = a number determined by the valency and occurrence of elements other than oxygen; e = 0-20. The powder X-ray patterns of these oxides (I) show diffraction lines at lattice plane separations (d) of 15.23 ! 0.6, 12.16 ! 0.4, 10.68 ! 0.3, 3.41 ! 0.04, 3.09 ! 0.04, 3.02 ! 0.04, 2.36 ! 0.04 and 1.80 ! 0.04 Angstrom . Independent claims are also included for: (a) a method for the production of (I) by heating a suspension of vanadium pentoxide in a liquid with a solution of silver salt and the element Q or a compound of Q, optionally with the addition of a compound of M; (b) pre-catalysts for the production of shell catalysts for the partial gas-phase oxidation of aromatic hydrocarbons with molecular oxygen-containing gas, comprising an inert, non-porous support coated with one or more layers of (I); (c) shell catalysts for the above application, made from (I) and an inert support, in which the catalytically active material in the shell(s) contains 30-100 wt% silver-vanadium bronze(s) with an Ag:V atom ratio of 0.15-0.95 and a BET surface of 2-100 m2/g; (d) a process for the production of aldehydes, carboxylic acids and/or anhydrides by partial oxidation of aromatic hydrocarbons (see above) using shell catalysts as in (c) in the presence or absence of other shell catalysts for this application containing vanadium pentoxide and anatase as active components (which are, if present, used in a combined catalyst bed).