Abstract: CO promoter particles for an FCC unit comprising transition alumina and containing at least 3% cerium oxide and from 2 to 8% lanthanum oxide.

Abstract: Materials containing vanadium values which are leachable by water are treated to reduce the leachability of vanadium to minimum practical values, thereby rendering the material suitable for disposal as landfill. Vanadium is insolubilized by adding a polyvalent metal salt which is capable of dissolving in water to form an acidic solution from which polyvalent metal cations are precipitated at a pH of 5, the polyvalent cations having a valence of +3 or higher or being a divalent metal that is oxidizable to a valence of +3 or higher. The salt-treated mixture is then neutralized by a base. The vanadium may be contained in a solid such as, for example, a spent cracking catalyst or a spent sorbent used in the upgrading of petroleum feedstock by selective vaporization or it may be contained in liquid material.