Sulfur transfer process in catalytic cracking

Claim 1

In a process for cracking a sulfur-containing hydrocarbon feed in a cracking zone at cracking conditions by contact with a particulate cracking catalyst to produce C 3 + product liquids and gases, flue gas being formed and coke and sulfur deposited on said catalyst during cracking, the catalyst is transferred to a catalyst regeneration zone wherein it is contacted with an oxygen-containing gas and the coke and sulfur deposits gasified and removed from the catalyst by burning, and the coke-depleted catalyst is recycled to said cracking zone for contact with additional fresh feed hydrocarbon, the improvement comprising, contacting the sulfur-containing hydrocarbon feed in the cracking zone with a catalyst composition comprising an admixture of composite particles, a major component particle in concentration of greater than 50 percent, based on the total weight of the catalyst, constituted of a Group VIII noble metal composited on an aluminosilicate zeolite-containing refractory inorganic oxide support in concentration ranging from about 1 part to about 50 parts, per million parts by weight of total catalyst, for providing principally cracking and combustion promoting functions, and a minor component particle present in the admixture in concentration of less than 50 percent, based on the total weight of the catalyst, constituted of a Group II-A metal composited with a refractory inorganic oxide support in concentration ranging from about 1 percent to about 50 percent, based on the weight of the minor component particles, to crack said feed and promote combustion reactions, and then transferring the catalyst composition to the regeneration zone whereby sulfur is fixed on the minor component particles, sulfur dioxide is converted to sulfur trioxide and formed into a Group II-A metal sulfate thus suppressing the sulfur oxides emission which normally occurs with release of the regeneration zone flue gas, and then, recycling the catalyst composition to the reaction zone, whereby the Group II-A metal sulfate is reacted to form from said sulfate principally hydrogen sulfide which is released with the flue gases from the reaction zone.