Regenerating the catalytic activity of a spent catalyst

A method of regenerating the catalytic activity of a spent catalyst comprising nickel, said spent catalyst being:

• (a) a spent steam reforming catalyst comprising a support, in which the nickel content is 5-20 wt % Ni and the support is an oxide comprising aluminium, zirconium, magnesium, calcium, lanthanum, yttrium, and/or cerium, and wherein the spent catalyst is provided in the form of tablets or pellets,
• or
• (b) a spent steam reforming catalyst in which the nickel content is 5-20 wt % Ni, said spent steam reforming catalyst being a structured catalyst comprising a macroscopic structure, wherein said macroscopic structure is formed by a metallic material and at least partly supported by a refractory oxide support;
• said method comprising the steps of:
• i) contacting the spent catalyst with a nitric acid solution, in which the nitric acid solution is at least 60 wt % HNO3, and adding one or more organic acids;
• ii) heat-treating the spent catalyst at a suitable temperature for reacting nickel with nitric acid, said suitable temperature being in the range 50-100° C., and subsequently drying the spent catalyst at 100-125° C.;
• and
• iii) calcining and reducing the spent catalyst, in which the calcining is conducted in air at 500-1300° C. for 1-4 hours, and the reducing is conducted in the presence of hydrogen at 400-600° C. for 2-4 hours,
• wherein the tablets or pellets of spent catalyst (a) are spherical, oblong, cylindrical, multilobe, ring-shaped, or any combinations thereof;
• wherein the macroscopic structure of spent catalyst (b) is a monolith;
• and
• wherein the shape of the spent catalyst (a) or the macroscopic structure of the spent catalyst (b) is preserved during the regenerating method.