Catalyst composition and process for the selective oxidation of ethane and/or ethylene to acetic acid

Abstract

An oxide catalyst composition comprising the elements molybdenum, vanadium, niobium and titanium and a process for making the catalyst composition. A process for the selective oxidation of ethane and/or ethylene and/or ethylene to acetic acid using the catalyst composition. The catalyst composition provides high selectivity to acetic acid with reduced selectivity to ethylene.

1 - 26 . (canceled)  
   
   
       27 . A catalyst composition for the oxidation of ethane and/or ethylene to acetic acid, which composition consists of in combination with oxygen the elements molybdenum, vanadium, niobium and titanium according to the empirical formula:  
       Mo a W b Ti c V d Nb e Y f   (I)  wherein Y is one or more elements selected from the group consisting of: Cr, Ta, B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Zr, Hf, Ni, P, Pb, Si, Sn, Tl, U, Re, Te, La, Au and Pd;    a, b, c, d, e and f represent the gram atom ratios of the elements such that:    0<a≦1; 0-≦b<1 and a+b=1;    0.05<c≦2;    0<d≦2;    0<e≦1; and    0≦f≦2.    
   
   
       28 . A catalyst composition as claimed in  claim 27  wherein formula (I) is selected from the group consisting of Mo a W b Ti c V d Nb e Y f ; Mo a Ti c V d Nb e Y f ; Mo a W b Ti c V d Nb e  and Mo a Ti c V d Nb e .  
   
   
       29 . A catalyst composition as claimed in  claim 27  or  claim 28  wherein 0.01<a≦1, 0.1<d≦2 and e is selected from the group consisting of 0.01<e≦1, 0.01≦e<0.5 and 0<e≦0.5 and f is selected from the group consisting of 0.01≦f≦2, 0≦f≦0.5 and 0.01≦f≦0.5.  
   
   
       30 . A catalyst composition as claimed in  claim 27  wherein Y is selected from the group consisting of Bi, Ca, Ce, Cu, K, P, La and Te.  
   
   
       31 . A catalyst composition as claimed in  claim 27  having the formula Mo 1.00 V 0.529 Nb 0.124 Au 0.0012 Ti 0.331 O x  or Mo 1.00 V 0.529 Nb 0.124 Ti 0.331 O x     —    wherein x is a number which satisfies the valencies of the elements in the composition for oxygen.  
   
   
       32 . A catalyst composition according to  claim 27  in which the catalyst composition has a substantial absence of noble metals.  
   
   
       33 . A catalyst composition according to  claim 27  wherein the catalyst composition is a supported catalyst.  
   
   
       34 . A catalyst composition according to  claim 33  wherein the support is selected from the group consisting of silica, alumina, a titanium-containing support, titania, titanosilicates, zirconia, silicon carbide and mixtures thereof.  
   
   
       35 . A catalyst composition according to  claim 34  wherein the support is selected from silica, a titanium-containing support and mixtures thereof.  
   
   
       36 . A process for the preparation of the catalyst compositions according to  claim 27  comprising the steps of: 
 (a) forming a mixture comprising molybdenum, vanadium, niobium, titanium, optionally tungsten and optionally Y, in a solution;    (b) drying the mixture to form a dried solid material; and    (c) calcining the dried solid material to from the catalyst composition.    
   
   
       37 . A process according to  claim 36  wherein the mixture is formed by mixing compounds and/or complexes of each of the metals in a suitable solvent.  
   
   
       38 . A process according to  claim 37  wherein the solvent is water.  
   
   
       39 . A process according to  claim 38  wherein the mixture is a solution in water having a pH in the range from 1 to 12.  
   
   
       40 . A process according to  claim 39  wherein the pH is from 2 to 8.  
   
   
       41 . A process according to  claim 39  or  claim 40  wherein the temperature of the solution is from 20° to 100° C.  
   
   
       42 . A process according to  claim 36  wherein the drying of the mixture comprises spray-drying.  
   
   
       43 . A process according to  claim 36  wherein the calcining comprises heating the dried solid to a temperature of from 200 to 550° C. for a period of from 1 minute to 24 hours.  
   
   
       44 . A process according to  claim 36  wherein a support material or precursor thereof is added to the mixture in step (a) or step (b).  
   
   
       45 . A process for the selective production of acetic acid from a gaseous mixture comprising ethane and/or ethylene which process comprises contacting the gaseous mixture with a molecular oxygen-containing gas at elevated temperature in the presence of a catalyst composition as claimed in  claim 27  or as prepared by the process of  claim 36 .  
   
   
       46 . A process according to  claim 45  in which ethane and optionally ethylene is oxidised to acetic acid.  
   
   
       47 . A process according to  claim 45  in which the gaseous mixture is contacted with the molecular oxygen-containing gas in the presence of water.  
   
   
       48 . A process according to  claim 45  wherein the process is a fixed bed or fluidised bed process.  
   
   
       49 . A process according to  claim 45  wherein the selectivity to acetic acid is at least 50 mol %.  
   
   
       50 . A process according to  claim 49  wherein the selectivity to acetic acid is at least 60 mol %.  
   
   
       51 . A process according to  claim 45  in which ethylene is produced and the selectivity to ethylene is less than 30 mol %.  
   
   
       52 . A process according to  claim 51  wherein the selectivity to ethylene is less than 20 mol %.