Low pressure gas release hydrothermal and peroxide treatment of odh catalyst

Abstract

The preparation of an oxidative dehydrogenation catalyst comprising Mo, V, Nb and Te using a hydrothermal step. In some embodiments, the activity and reproducibility of the catalyst is improved by conducting the hydrothermal step while permitting gaseous products to leave the reactor. In some instances a condenser may be upstream of the outlet of the reactor.

What is claimed is: 
     
         1 . A process for the synthesis of a catalyst for the oxidative dehydrogenation of ethane, the process comprising:
 preparing an aqueous slurry comprising Mo, V, Nb, and Te salts, wherein:
 the molar ratio of Mo to V is from 1:0.4 to 1:0.8, 
 the molar ratio of Mo to Nb is from 1:0.15 to 1:0.25, and 
 the molar ratio of Mo to Te is from 1:0.15 to 1:0.25; 
   heating the aqueous slurry with agitation and simultaneous removal of a gaseous byproduct species produced during the reaction to provide a precatalyst;   recovering, drying, and calcining the precatalyst to provide the catalyst; and   treating the catalyst with hydrogen peroxide.   
     
     
         2 . The process of  claim 1 , wherein heating the aqueous slurry comprises heating the slurry to a temperature from 120° C. to 150° C. 
     
     
         3 . The process of  claim 2 , wherein heating the aqueous slurry with agitation and simultaneous removal of a gaseous byproduct species produced during the reaction to provide a precatalyst further comprises subjecting the slurry to a pressure up to 10 psig (68.9 kPag) above atmospheric. 
     
     
         4 . The process of  claim 3 , wherein the pressure is from 1 psig to 8 psig (6.89 kPag to 55.1 kPag). 
     
     
         5 . The process of  claim 1 , wherein the gaseous species are removed from the reactor using one or more methods selected from gas absorption, gas adsorption, membrane separation, and chemicals transformation. 
     
     
         6 . The process of  claim 1 , wherein:
 the molar ratio of Mo to V is from 1:0.4 to 1:0.8,   the molar ratio of Mo to Nb is from 1:0.08 to 0.20, and   the molar ratio of Mo to Te is from 1:0.15 to 1:0.20.   
     
     
         7 . The process of  claim 1 , further comprising washing the precatalyst with water or an aqueous oxalate solution. 
     
     
         8 . The process of  claim 7 , further comprising grinding the precatalyst. 
     
     
         9 . The process of  claim 8 , further including calcining the catalyst in an inert atmosphere at a temperature from 200° C. to 650° C. for a time from 1 to 20 hours. 
     
     
         10 . The process of  claim 9 , wherein:
 the molar ratio of Mo to V is from 1:0.4 to 1:0.8,   the molar ratio of Mo to Nb is from 1:0.08 to 0.20, and   the molar ratio of Mo to Te is from 1:0.15 to 1:0.20.   
     
     
         11 . The process of  claim 1 , wherein the catalyst is treated with 2.25 mL of 30% H 2 O 2  in water per 1 g of catalyst. 
     
     
         12 . The process of  claim 11 , wherein:
 the molar ratio of Mo to V in the catalyst is from 1:0.12 to 1:0.19, as determined by PIXE;   the molar ratio of Mo to Te in the catalyst is from 1:0.14 to 1:0.16, as determine by PIXE; and   the molar ratio of Mo to Nb in the catalyst is 1 to 0.15, as determine by PIXE.   
     
     
         13 . A catalyst comprising Mo, V, Te, and Nb prepared according to the process of  claim 1 . 
     
     
         14 . A process for the oxidative dehydrogenation of a mixed feed comprising ethane and oxygen, the method comprising passing the mixed feed over a catalyst comprising Mo, V, Te, and Nb, wherein the catalyst is prepared according to the process of  claim 1 .