Modified carrier, complex oxide catalyst and process for preparation of acrylic acid

Abstract

A modified carrier carrying on at least a part of an inert carrier surface an oxide which is represented by the formula (1): X a Y b Z c O d (wherein X is at least an element selected from alkaline earth metals; Y is at least an element selected from Si, Al, Ti and Zr; Z is at least an element selected from Group IA elements and Group IIIb elements of the periodic table, B, Fe, Bi, Co, Ni and Mn; and O is oxygen; a, b, c and d denote the atomic ratios of X, Y, Z and O, respectively, where a=1, 0<b≦100, 0≦c≦10, and d is a numerical value determined by the extents of oxidation of the other elements) is provided. A catalyst formed with the use of this modified carrier carrying a complex oxide containing Mo and V is useful as a vapor-phase catalytic oxidation catalyst, and is particularly suitable as a catalyst for preparing acrylic acid through vapor phase catalytic oxidation of acrolein.

1 . A modified carrier which is characterized by carrying on at least a part of an inert carrier surface an oxide expressed by the formula (1): 
       X a Y b Z c O d   (1) (wherein X is at least an element selected from alkaline earth metals; Y is at least an element selected from a group consisting of silicon, aluminum, titanium and zirconium; Z is at least an element selected from a group consisting of Group IA elements and Group IIIB elements of the periodic table, boron, iron, bismuth, cobalt, nickel and manganese; and O is oxygen; a, b, c and d denote the atomic ratios of X, Y, Z and O, respectively, and where a=1, 0<b≦100 and 0≦c≦10, and d is a numerical value determined by the extents of oxidation of the other elements).    
     
     
         2 . A modified carrier as described in    claim 1   , in which the inert carrier is selected from a group consisting of silica, alumina, silica-alumina, silicon carbide, silicon nitride, titanium dioxide and zirconium oxide.  
     
     
         3 . A complex oxide catalyst which is characterized by supporting a complex oxide containing molybdenum and vanadium on the carrier as described in    claim 1   .  
     
     
         4 . A complex oxide catalyst as described in    claim 3   , in which the complex oxide containing molybdenum and vanadium is a complex oxide which is expressed by the following general formula (2): 
       Mo e V f W g Cu h A i B j O k   (2) (where Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper, A is at least an element selected from a group consisting of antimony, niobium and tin; B is at least an element selected from a group consisting of phosphorus, tellurium, lead, arsenic and zinc, and O is oxygen; e, f, g, h, i, j and k denote atomic ratios of Mo, V, W, Cu, A, B and O, where a=12, 2≦f≦15, 0≦g≦10, 0<h≦6, 0≦i≦6, 0≦j≦5, and k is a numerical value determined by the extents of oxidation of the other elements).    
     
     
         5 . A process for preparing acrylic acid through oxidation of acrolein at vapor phase with molecular oxygen or a molecular oxygen-containing gas in the presence of a catalyst, which is characterized in that the complex oxide catalyst of    claim 3    or    4    is used as the catalyst.