The exhaust gas-purifying catalyst of the invention includes a noble metal, and crystallites that form CZ composite metal particles which serve as a carrier supporting the noble metal and contain at least zirconium (Zr) and cerium (Ce). The CZ composite oxide particles (crystallites) further contain crystal growth-suppressing fine particles which are fine metal particles comprising primarily a metallic element M that melts at 1,500° C. or above and which suppress crystal growth by the CZ composite oxide particles. The content of the metallic element M included in the CZ composite oxide particles, expressed in terms of the oxide thereof, is 0.5 mol % or less of the total oxide.

The invention relates to a process for treating a catalyst for alkane oxidative dehydrogenation and/or alkene oxidation, which catalyst is a mixed metal oxide catalyst containing molybdenum, vanadium and niobium, wherein the process comprises: contacting the catalyst with a gas mixture comprising an inert gas and oxygen (O.sub.2), wherein the amount of oxygen is of from 10 to less than 10,000 parts per million by volume (ppmv), based on the total volume of the gas mixture, at an elevated temperature.

The invention relates to a process for treating a catalyst for alkane oxidative dehydrogenation and/or alkene oxidation, which catalyst is a mixed metal oxide catalyst containing molybdenum, vanadium and niobium, wherein the process comprises: contacting the catalyst with a gas mixture comprising an inert gas and oxygen (O.sub.2), wherein the amount of oxygen is of from 10 to less than 10,000 parts per million by volume (ppmv), based on the total volume of the gas mixture, at an elevated temperature.

Provided are a Nb-doped nickel oxide-zirconia composite catalyst, and a method for preparing the same. An excellent methane modification reaction is performed by doping a nickel oxide site with niobium, so that alcohol may be prepared at low costs.

Provided are a Nb-doped nickel oxide-zirconia composite catalyst, and a method for preparing the same. An excellent methane modification reaction is performed by doping a nickel oxide site with niobium, so that alcohol may be prepared at low costs.

A catalyst composition comprises an acrolein-oxidizing catalyst comprising a mixed metal oxide catalyst of general formula (1):

MoV.sub.aA.sup.1.sub.bA.sup.2.sub.cA.sup.3.sub.dO.sub.m  (I)

in which A.sup.1 comprises at least one element selected from the group consisting of W and Cu; A.sup.2 comprises at least one element selected from the group consisting of Sb, Fe, and Nb; A.sup.3 comprises at least one element selected from the group consisting of Y, Ti, Zr, Hf, Ta, Cr, Mn, Re, Ru, Co, Rh, Ir, Ni, Pd, Pt, Ag, Au, Zn, B, Al, Ga, In, Ge, Sn, Si, Te, Pb, P, As, Bi, Se, rare earth elements, alkaline elements, and alkaline earth elements; a ranges from 0.01 to 1.0; b ranges from 0.01 to 1.5; c ranges from 0 to 1.5; d ranges from 0 to 1.0; and m is dependent on the oxidation state of the other elements. The catalyst composition further comprises a finishing catalyst comprising a mixed metal oxide catalyst of general formula (II):

MoV.sub.wNb.sub.xX.sup.1.sub.yX.sup.2.sub.zO.sub.n  (II)

in which X.sup.1 comprises at least one element selected from the group consisting of Te and Sb; X.sup.2 comprises at least one an element selected from the group consisting of Y, Ti, Zr, Hf, Nb, Ta, Cr, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Ag, Au, Zn, B, Al, Ga, In, Ge, Sn, Pb, P, As, Bi, Se, rare earth elements and alkaline earth elements; w ranges from 0.01 to 1.0; x ranges from 0.01 to 1.0; y ranges from 0.01 to 1.0; z ranges from 0 to 1.0; and n is depended on the oxidation state of the other elements. The finishing catalyst does not contain W or Cu, and has an X-ray diffraction pattern showing an orthorhombic phase as the major crystal phase with main peaks with 2θ at 6.7°, 7.8°, 22.1°, and 27.2°. The acrolein-oxidizing catalyst has a different chemical composition than the finishing catalyst. A process for producing acrylic acid is also disclosed.

A catalyst composition comprises an acrolein-oxidizing catalyst comprising a mixed metal oxide catalyst of general formula (1):

MoV.sub.aA.sup.1.sub.bA.sup.2.sub.cA.sup.3.sub.dO.sub.m  (I)

in which A.sup.1 comprises at least one element selected from the group consisting of W and Cu; A.sup.2 comprises at least one element selected from the group consisting of Sb, Fe, and Nb; A.sup.3 comprises at least one element selected from the group consisting of Y, Ti, Zr, Hf, Ta, Cr, Mn, Re, Ru, Co, Rh, Ir, Ni, Pd, Pt, Ag, Au, Zn, B, Al, Ga, In, Ge, Sn, Si, Te, Pb, P, As, Bi, Se, rare earth elements, alkaline elements, and alkaline earth elements; a ranges from 0.01 to 1.0; b ranges from 0.01 to 1.5; c ranges from 0 to 1.5; d ranges from 0 to 1.0; and m is dependent on the oxidation state of the other elements. The catalyst composition further comprises a finishing catalyst comprising a mixed metal oxide catalyst of general formula (II):

MoV.sub.wNb.sub.xX.sup.1.sub.yX.sup.2.sub.zO.sub.n  (II)

in which X.sup.1 comprises at least one element selected from the group consisting of Te and Sb; X.sup.2 comprises at least one an element selected from the group consisting of Y, Ti, Zr, Hf, Nb, Ta, Cr, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Ag, Au, Zn, B, Al, Ga, In, Ge, Sn, Pb, P, As, Bi, Se, rare earth elements and alkaline earth elements; w ranges from 0.01 to 1.0; x ranges from 0.01 to 1.0; y ranges from 0.01 to 1.0; z ranges from 0 to 1.0; and n is depended on the oxidation state of the other elements. The finishing catalyst does not contain W or Cu, and has an X-ray diffraction pattern showing an orthorhombic phase as the major crystal phase with main peaks with 2θ at 6.7°, 7.8°, 22.1°, and 27.2°. The acrolein-oxidizing catalyst has a different chemical composition than the finishing catalyst. A process for producing acrylic acid is also disclosed.

A method for producing a catalyst for unsaturated carboxylic acid synthesis is proposed. The method includes: obtaining a dried product by drying and heat-treating a starting material mixed liquid in which supply source compounds of respective catalyst component elements are integrated; and forming a catalyst precursor by supporting powder to be supported on a carrier in the form of a particle aggregate. The powder to be supported is either the dried product or obtained from the dried product. The method further includes calcining the catalyst precursor to form the catalyst. The mass loss rate of the powder to be supported at 300° C. is less than 5 percent by mass, and the difference between the mass loss rate of the powder at 370° C. and the mass loss rate of the powder at 300° C. is not less than 1 percent by mass and not more than 6 percent by mass.

A method for producing a catalyst for unsaturated carboxylic acid synthesis is proposed. The method includes: obtaining a dried product by drying and heat-treating a starting material mixed liquid in which supply source compounds of respective catalyst component elements are integrated; and forming a catalyst precursor by supporting powder to be supported on a carrier in the form of a particle aggregate. The powder to be supported is either the dried product or obtained from the dried product. The method further includes calcining the catalyst precursor to form the catalyst. The mass loss rate of the powder to be supported at 300° C. is less than 5 percent by mass, and the difference between the mass loss rate of the powder at 370° C. and the mass loss rate of the powder at 300° C. is not less than 1 percent by mass and not more than 6 percent by mass.

Mixed metal oxide catalysts having an amorphous content of not less than 40 wt. % are prepared by calcining the catalyst precursor fully or partially enclosed by a porous material having a melting temperature greater than 600° C. in an inert container including heating the catalyst precursor at a rate from 0.5 to 10° C. per minute from room temperature to a temperature from 370° C. to 540° C. under a stream of pre heated gas chosen from steam and inert gas and mixtures thereof at a pressure of greater than or equal to 1 psig having a temperature from 300° C. to 540° C. and holding the catalyst precursor at that temperature for at least 2 hours and cooling the catalyst precursor to room temperature.