Process for the selective preparation of acetic acid using a molybdenum and palladium based catalytic oxide

Abstract

The present invention relates to a process for the selective preparation of acetic acid from a gaseous feed comprising ethane, ethylene or mixtures thereof plus oxygen at elevated temperature, which comprises bringing the gaseous feed into contact with a catalyst comprising the elements Mo, Pd, X and Y in gram atom ratios a:b:c:d in combination with oxygen Mo a Pd b X c Y d   (I) where the symbols X and Y have the following meanings: X is one or more elements selected from the group consisting of: Cr, Mn, Nb, Ta, Ti, V, Te and/or W, in particular Nb, V and W; Y is one or more elements selected from the group consisting of: B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Cu, Rh, Ir, Au, Ag, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, TI and U, in particular Ca, Sb, Te and Li. The present invention further provides a catalyst for the selective preparation of acetic acid comprising the elements Mo, Pd, X and Y in the gram atom ratios a:b:c:d in combination with oxygen. The process can be illustrated by the following reaction scheme,

1. An industrial large scale process for the selective preparation of acetic acid from a gaseous feed comprising ethane, ethylene or mixtures thereof plus oxygen at elevated temperature, which comprises bringing in a reactor the gaseous feed into contact with a catalyst comprising the elements Mo, Pd, X and Y in gram atom ratios a:b:c:d in combination with oxygen
   Mo a Pd b X c Y d   (I)  
 
       where the symbols X and Y have the meanings:
 X is one or more elements selected from the group consisting of Cr, Mn, Nb, Ta, Ti, V, Te and W;  
 Y is one or more elements selected from the group consisting of B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag, Au, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, Tl and U;  
 the indices a, b, c and d are the gram atom ratios of the corresponding elements, where a=1; b>0; c>0; and d= 0.05-2  d=0-2.    
 
     
     
       2. The process as claimed in  claim 1 , wherein X and/or Y are a plurality of elements, where, if desired, the indices c and d assume different values for different elements and wherein the sum of the gram atomic ratios of all elements of Y is 0-2. 
     
     
       3. The process as claimed in  claim 1 , wherein the temperature is in the range from 200 to 500° C. 
     
     
       4. The process as claimed in  claim 1 , wherein the pressure in the reactor is in the range from 1 to 50 bar. 
     
     
       5. The process as claimed in  claim 1 , wherein b is in the range from 0.0001 to 0.5. 
     
     
       6. The process as claimed in  claim 1 , wherein said gaseous feed comprises ethane mixed with at least one further gas. 
     
     
       7. The process as claimed in  claim 6 , wherein the further gas fed in is nitrogen, oxygen, methane, carbon monoxide, carbon dioxide, ethylene and/or water vapor. 
     
     
       8. The process as claimed in  claim 1 , wherein the catalyst comprises at least one of the following compositions in combination with oxygen:
 Mo 1.00 V 0.25 Nb 0.12 Pd 0.0005    
 Mo 1.00 V 0.25 Nb 0.12 Pd 0.0004    
 Mo 1.00 V 0.25 Nb 0.12 Pd 0.0003    
 Mo 1.00 V 0.36 Nb 0.03 Sb 0.01 Ca 0.01 Pd 0.0005    
 Mo 1.00 V 0.50 Nb 0.15 Te 0.2 Pd 0.0002    
 Mo 1.00 V 0.25 Nb 0.3 W 0.2 Pd 0.0003    
 Mo 1.00 V 0.25 Nb 0.3 Sb 0.1 Pd 0.0004 .  
 
     
     
       9. The process as claimed in  claim 1 , wherein the catalyst is mixed with a support material or is fixed on a support material. 
     
     
       10. The process as claimed in  claim 1 , wherein the selectivity of the oxidation reaction to acetic acid is ≧60%, at an ethane conversion of ≧4%. 
     
     
       11. A catalyst for the selective oxidation of ethane, ethylene or mixtures thereof plus oxygen, comprising the elements Mo, Pd, X and Y in gram atom ratios a:b:c:d in combination with oxygen
   Mo a Pd b X c Y d   (I)  
 
       where the symbols X and Y have the meanings:
 X is one or more elements selected from the group consisting of Cr, Mn, Nb, Ta, Ti, V, Te and W;  
 Y is one or more elements selected from the group consisting of B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag, Au, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, Tl and U;  
 the indices a, b, c and d are the gram atom ratios of the corresponding elements, where a=1; b>0; c>0; and d= 0.05-2  d=0-2.