Method for oxidatively dehydrogenating alkanes

A method of oxidatively dehydrogenating an alkane to form an olefin, comprising:

• contacting the alkane with a catalyst, an oxidant, and an inert gas in a reactor to oxidatively dehydrogenate the alkane to the olefin;
• wherein the catalyst comprises:
• a hierarchical silica composite;
• and
• an active catalytic material impregnated on the hierarchical silica composite, the active catalytic material comprising
• nickel, nickel oxide, and/or nickel and iron mixed metal oxide, and
• at least one cation dopant selected from the group consisting of Nb5+, Al3+, Ti4+, Ta5+, and Bi5+ and/or oxides thereof;
• wherein the hierarchical silica composite is a stereoregular MCM-41 ordered arrangement of uniformly-sized mesopores with diameters in a range of 10-50 nm and mesopore walls having a thickness of 3 to about 5 nm;
• a stereoregular ZSM-5 ordered arrangement of uniformly-sized micropores with diameters of less than 2 nm located within the mesopore walls of the stereoregular MCM-41;
• and
• wherein the hierarchical silica composite has a silane coating that coats at least a portion of a surface of the hierarchical silica composite,
• wherein the active catalytic material is incorporated into a lattice of the hierarchical silica composite by isomorphous substitution,
• wherein the dopant is located inside the mesopores of the hierarchical silica composite,
• wherein an amount of the dopant is in a range of 10-20 wt. %,
• wherein an amount of the hierarchical silica composite is in a range of 15-70 wt. %, and
• wherein an amount of the active catalytic material is in a range of 5-7.5 wt. %, all of which are relative to the total weight of the catalyst.