Exhaust gas purification catalyst on which influence of iron compound has been suppressed

Abstract

An exhaust gas purification catalyst is provided which contains titanium oxide as a main component and an oxide of one element or two or more elements selected from the group consisting of tungsten (W), molybdenum (Mo), and vanadium (V) as an active component, wherein the exhaust gas purification catalyst contains phosphoric acid or a water soluble phosphoric acid compound so that the atomic ratio of phosphorus (P) to a catalytically active component represented by the following formula is more than 0 and 1.0 or less; P/catalytically active component (atomic ratio)=number of moles of P/(number of moles of W+number of moles of Mo+number of moles of V).

1 . An exhaust gas purification catalyst containing titanium oxide as a main component and an oxide of one element or two or more elements selected from the group consisting of tungsten (W), molybdenum (Mo), and vanadium (V) as an active component, wherein the catalyst contains phosphoric acid or a water soluble phosphoric acid compound so that the atomic ratio of phosphorus (P) to a catalytically active component represented by the following formula is 0.2 to 1.0;
 P/catalytically active component (atomic ratio)=number of moles of P/(number of moles of W+number of moles of Mo+number of moles of V).   
     
     
         2 . An exhaust gas purification catalyst, wherein the catalyst according to  claim 1  is supported on a metal substrate. 
     
     
         3 . A method of purifying exhaust gas, wherein the catalyst according to  claim 1  is used for purification of exhaust gas including nitrogen oxide and ashes containing a Fe component. 
     
     
         4 . A method of producing an exhaust gas purification catalyst, comprising: adding an oxide or an oxo-acid salt of one element or two or more elements selected from the group consisting of tungsten (W), molybdenum (Mo), and vanadium (V) to titanium oxide; adding water; and kneading followed by drying and calcination, wherein phosphoric acid or a water soluble phosphoric acid compound is added to the oxide or the oxo-acid salt for a reaction so that the atomic ratio of P to a catalytically active component represented by the following formula is 0.2 to 1.0;
 P/catalytically active component (atomic ratio)=number of moles of P/(number of moles of W+number of moles of Mo+number of moles of V).   
     
     
         5 . A method of producing an exhaust gas purification catalyst, comprising: adding an oxide or an oxo-acid salt of one element or two or more elements selected from the group consisting of tungsten (W), molybdenum (Mo), and vanadium (V) to titanium oxide; adding water; kneading followed by drying and calcination; and immersing the resultant in a solution that is prepared separately in advance by adding phosphoric acid or a water soluble phosphoric acid compound to an oxide or an oxo-acid salt of one element or two or more elements selected from the group consisting of tungsten (W), molybdenum (Mo), and vanadium (V) to be reacted so that the atomic ratio of P to a catalytically active component represented by the following formula is 0.2 to 1.0;
 P/catalytically active component (atomic ratio)=number of moles of P/(number of moles of W+number of moles of Mo+number of moles of V). 
 
     
     
         6 . A method of purifying exhaust gas, wherein the catalyst according to  claim 2  is used for purification of exhaust gas including nitrogen oxide and ashes containing a Fe component.