Single crystalline phase catalyst

A process for preparing an orthorhombic phase mixed metal oxide catalyst, said process comprising:

• (a) admixing compounds of elements A, V, N and X and at least one solvent to form a solution,
• wherein A is at least one element selected from the group consisting of Mo and W, N is at least one element selected from the group consisting of Te, Se and Sb, and X is at least one element selected from the group consisting of Nb, Ta, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pt, Bi, B, In, Ce, As, Ge, Sn, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Hf, Pb, P, Pm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Au, Ag, Re, Pr, Zn, Ga, Pd, Ir, Nd, Y, Sm, Tb, Br, Cu, Sc, Cl, F and I,
• wherein A, V, N and X are present in such amounts that the atomic ratio of A:V:N:X is a:b:c:d, and
• wherein, when a=1, b=0.01 to 1, c=0.01 to 1 and d=0.01 to 1;
• (b) admixing a seeding effective amount of an orthorhombic phase mixed metal oxide seed, substantially free of hexagonal phase mixed metal oxide, with said solution to form a seeded solution,
• (c) removing said at least one solvent from said seeded solution to form a catalyst precursor;
• and
• (d) calcining said catalyst precursor to obtain said orthorhombic phase mixed metal oxide catalyst.