Catalysts for the oxidative dehydrogenation of hydrocarbons

A method for preparing a nonstoichiometric rare earth oxycarbonate catalyst having a disordered and/or defect structure, wherein said catalyst, when used for the oxidative dehydrogenation of a lower hydrocarbon at a pressure above about 100 psig, has a selectivity of at least about 40% to at least one higher hydrocarbon and/or lower olefin, said method comprising:

• (1) forming a catalyst precursor by combining at least one rare earth compound including at least one rare earth element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm and oxygen with at least one cocatalyst compound including at least one metal selected from the group consisting of Fe, Mn, W, and Mo to provide a mixture, treating the mixture with water and/or an organic compound that contains a hydroxyl group;
• drying the treated mixture;
• and calcining the treated mixture at a temperature in the range of about 300° C. to about 1000° C. in an atmosphere containing oxygen;
• and
• (2) forming said catalyst by (a) pressurizing the catalyst precursor to a pressure of at least about 100 psig with a flowing gas that contains at least one hydrocarbon and oxygen, and (b) heating the catalyst precursor at one or more temperatures within a temperature range of about 300° C. to about 700° C., wherein oxygen conversion occurs.

A method for preparing a nonstoichiometric rare earth oxycarbonate catalyst having a disordered and/or defect structure and a surface area greater than about 20 m2/g, wherein said catalyst, when used for the oxidative dehydrogenation of a lower hydrocarbon at a pressure above about 100 psig, has a selectivity of at least about 40% to at least one higher hydrocarbon and/or lower olefin, said method comprising:

• (1) treating at least one finely divided solid rare earth compound comprising at least one rare earth element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm and oxygen with water and an organic acid to form an aqueous mixture such that the final pH of the aqueous mixture has a substantially constant value in the range of about 2 to about 6;
• (2) drying the aqueous mixture to a substantially dry state such that the treated rare earth compound does not form a foamed material;
• and
• (3) calcining the treated rare earth compound in a flowing atmosphere containing oxygen at a temperature in the range of about 300° C. to about 600° C. to provide a nonstoichiometric rare earth oxycarbonate catalyst.