Lower alkane oxidative dehydrogenation catalysts and a process for producing olefins

Abstract

The invention provides catalysts for oxidative dehydrogenation of lower alkanes, said catalysts being suitable for use in vapor phase oxidative dehydrogenation of C 2 -C 5 lower alkanes in the presence of molecular oxygen to produce corresponding olefins and characterized by having a composition expressed by a general formula (I) below: Mn α E 1 β E 2 γ O x   (I) (in which Mn denotes manganese, and O, oxygen; E 1 is at least one element selected from the group consisting of P, As, Sb, B, S, Se, Te, F, Cl, Br, I, Nb, Ta, W, Re and Cu; E 2 is at least one element selected from the group consisting of Cr, Fe, Co, Ni, Ag, Au, Zn, Tl, Sn, Pb, Bi, Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Y, La, Ce, Nd and Sm; and α, β, γ and x denote atomic numbers of Mn, E 1 , E 2 and oxygen, respectively, where when α=1, β=0.01-10, γ=0-5, and x is a numerical value determined by the state of oxidation of those elements other than oxygen). When these catalysts are used in reactions for oxidizing and dehydrogenating C 2 -C 5 alkanes with molecular oxygen at vapor phase, corresponding olefins can be produced at high yield.

1 . Oxidative dehydrogenation catalysts for lower alkanes, said catalysts being suitable for use in vapor phase oxidative dehydrogenation of C 2 -C 5  lower alkanes in the presence of molecular oxygen to produce corresponding olefins and characterized by having a composition expressed by a general formula (I) below:  
       Mn α E 1   β E 2   γ O x   (I)  (in which Mn denotes manganese, and I, oxygen; E 1  is at least one element selected from the group consisting of P, As, Sb, B, S, Se, Te, F, Cl, Br, I, Nb, Ta, W, Re and Cu; E 2  is at least one element selected from the group consisting of Cr, Fe, Co, Ni, Ag, Au, Zn, Tl, Sn, Pb, Bi, Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Y, La, Ce, Nd and Sm; and α, β, γ and x denote atomic numbers of Mn, E 1 , E 2  and oxygen, respectively, where when α=1, β=0.01-10, γ=0-5, and x is a numerical value determined by the state of oxidation of those elements other than oxygen).    
     
     
         2 . The catalysts as described in    claim 1   , in which, referring to the general formula (I), when α=1, β=0.02-2 and γ=0-1.  
     
     
         3 . The catalysts as described in    claim 1    or    2   , in which S as E 1  is added in the form of sulfate ion (SO 4   2− ).  
     
     
         4 . The catalysts as described in    claim 3   , in which the sulfate ion is added in the form of a sulfate.  
     
     
         5 . The oxidative dehydrogenation catalysts as described in any one of claims  1 - 4 , in which the preparation process of the catalysts includes drying at temperatures not higher than 300° C. only, and does not include firing at high temperatures exceeding 300° C.  
     
     
         6 . A process for producing olefins which comprises oxydizing and dehydrogenating C 2 -C 5  lower alkanes in the presence of molecular oxygen at vapor phase to produce corresponding olefins, characterized in that a catalyst as described in    claim 1    is used.  
     
     
         7 . A process for producing unsaturated aldehyde and unsaturated acid from lower alkane which comprises oxidizing an olefin which has been obtained through vapor-phase oxidative dehydrogenation of C 2 -C 5  lower alkane in the presence of molecular oxygen using a catalyst as described in    claim 1   , at vapor phase in the presence of oxygen to produce unsaturated aldehyde and unsaturated acid.  
     
     
         8 . A process for producing unsaturated acid from lower alkane, which comprises oxidizing at vapor phase the unsaturated aldehyde as obtained according to    claim 7    in the presence of molecular oxygen to produce unsaturated acid.