Catalyst for production of acrylic acid and process for production of acrylic acid using this catalyst

Abstract

An object of the present invention is to provide: a catalyst for production of acrylic acid which catalyst is so high active as to give a still higher selectivity of acrylic acid (which is the objective product) or a long-catalytic-life-time catalyst for production of acrylic acid which catalyst is so high active as to be able to give a high acrylic acid yield while suppressing the temperature rise of the oxidation reaction to a low one; and processes for production of acrylic acid using these catalysts. As a means of achieving this object, a catalyst according to the present invention for production of acrylic acid comprises an oxide and/or a composite oxide as an essential catalytic component, wherein the oxide and/or the composite oxide has a metal element composition shown by general formula (1): Mo a V b W c Cu d O x   (1) (wherein: 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); with the catalyst being characterized in that any of the vanadium, tungsten, and copper is maldistributed in the surface side or core side of the catalyst.

1 . A catalyst for production of acrylic acid, which comprises an oxide and/or a composite oxide as an essential catalytic component, wherein the oxide and/or the composite oxide has a metal element composition shown by the following general formula (I):
   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);
 wherein: the tungsten is maldistributed in the surface side of the catalyst; and/or the copper is maldistributed in the core side of the catalyst. 
 
   
   
       2 . (canceled) 
   
   
       3 . A catalyst according to  claim 1  for production of acrylic acid, which comprises both the catalytic component and a support as essential constitutional materials wherein the catalytic component is supported at least inside the support, or which is a molding that comprises the catalytic component as an essential constitutional material,
 wherein: the surface side of the catalyst refers to a surface layer portion of the catalyst and/or the neighborhood of this portion; and the core side of the catalyst refers to a central portion of the catalyst and/or the neighborhood of this portion.   
   
   
       4 . A catalyst for production of acrylic acid, which comprises an oxide and/or a composite oxide as an essential catalytic component, wherein the oxide and/or the composite oxide has a metal element composition shown by the following general 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);
 wherein: the vanadium is maldistributed in the surface side of the catalyst. 
 
   
   
       5 . (canceled) 
   
   
       6 . A catalyst according to  claim 4  for production of acrylic acid, which comprises both the catalytic component and a support as essential constitutional materials wherein the catalytic component is supported at least inside the support, or which is a molding that comprises the catalytic component as an essential constitutional material,
 wherein the surface side of the catalyst refers to a surface layer portion of the catalyst and/or the neighborhood of this portion.   
   
   
       7 . A catalyst for production of acrylic acid, which comprises an oxide and/or a composite oxide as an essential catalytic component, wherein the oxide and/or the composite oxide has a metal element composition shown by the following general formula (I):
   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);
 wherein: the copper is maldistributed in the surface side of the catalyst; and/or the tungsten is maldistributed in the core side of the catalyst. 
 
   
   
       8 . (canceled) 
   
   
       9 . A catalyst according to  claim 7  for production of acrylic acid, which comprises both the catalytic component and a support as essential constitutional materials wherein the catalytic component is supported at least inside the support, or which is a molding that comprises the catalytic component as an essential constitutional material,
 wherein: the surface side of the catalyst refers to a surface layer portion of the catalyst and/or the neighborhood of this portion; and the core side of the catalyst refers to a central portion of the catalyst and/or the neighborhood of this portion.   
   
   
       10 . A catalyst for production of acrylic acid, which comprises an oxide and/or a composite oxide as an essential catalytic component, wherein the oxide and/or the composite oxide has a metal element composition shown by the following general formula (I):
   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);
 wherein the vanadium is maldistributed in the core side of the catalyst. 
 
   
   
       11 . (canceled) 
   
   
       12 . A catalyst according to  claim 10  for production of acrylic acid, which comprises both the catalytic component and a support as essential constitutional materials wherein the catalytic component is supported at least inside the support, or which is a molding that comprises the catalytic component as an essential constitutional material,
 wherein the core side of the catalyst refers to a central portion of the catalyst and/or the neighborhood of this portion.   
   
   
       13 . A process for production of acrylic acid, wherein the catalyst as recited in  claim 1  for production of acrylic acid is used when acrylic acid is produced by catalytic gas phase oxidation of acrolein in the presence of molecular oxygen. 
   
   
       14 . A process for production of acrylic acid, wherein the catalyst as recited in  claim 4  for production of acrylic acid is used when acrylic acid is produced by catalytic gas phase oxidation of acrolein in the presence of molecular oxygen. 
   
   
       15 . A process for production of acrylic acid, wherein the catalyst as recited in  claim 7  for production of acrylic acid is used when acrylic acid is produced by catalytic gas phase oxidation of acrolein in the presence of molecular oxygen. 
   
   
       16 . A process for production of acrylic acid, wherein the catalyst as recited in  claim 10  for production of acrylic acid is used when acrylic acid is produced by catalytic gas phase oxidation of acrolein in the presence of molecular oxygen.