Patent ID: 7378367

Claim:
A fixed-bed reactor catalyst for preparing acrylic acid, wherein the fixed-bed reactor catalyst is an eggshell type catalyst comprising: a) a support and a catalytic component supported on an outer support surface of the support; b) wherein said catalytic component includes a support surface side, an outer surface side, and a catalytic outer surface, wherein said catalytic outer surface is on said outer surface side; c) wherein said catalytic component comprises an oxide represented by the formula (1): Mo a V b W c Cu d O x (1) (wherein: Mo is molybdenum; V is vanadium; W is tungsten; Cu is copper; and O is oxygen; and a, b, c, d, and x denote atomic ratios of Mo, V, W, Cu, and O respectively; when a=12, then 1≦b≦14, 0≦c≦12, 0≦d≦10, and 0<c+d; and x is a numerical value determined by oxidation states of the elements); d) wherein: the tungsten is maldistributed in the outer surface side of the catalytic component; and/or the copper is maldistributed in the support surface side of the catalytic component; e) wherein in the case of tungsten: an outer surface side maidistribution ratio (Ma (%)) of said tungsten is more than 50% such that more than 50% of a total content of tungsten is found from a middle of the catalytic component to said catalytic outer surface; and f) wherein in the case of copper: a support surface side maldistribution ratio (Mc (%)) of said copper is more than 50% such that more than 50% of a total content of copper is found from a middle of the catalytic component to said support surface of the support.