Catalyst and process for conversion of hydrocarbons

In a hydrocarbon conversion process for converting a sulfur-containing hydrocarbon feedstock which comprises (1) contacting said feedstock with solid particles capable of promoting the conversion of said feedstock at hydrocarbon conversion conditions in at least one reaction zone to produce at least one hydrocarbon product and to cause deactivating sulfur-containing carbonaceous deposit to be formed on said solid particles, thereby forming deposit-containing particles;

• (2) contacting said deposit-containing particles with an oxygen-containing vaporous medium at conditions to combust at least a portion of said carbonaceous deposit in at least one regeneration zone to thereby regenerate at least a portion of the hydrocarbon conversion catalytic activity of said solid particles and to form a regeneration zone flue gas containing at least one sulfur-containing carbonaceous deposit combustion product;
• and (3) repeating steps (1) and (2) periodically, the improvement which comprises, circulating between said reaction zone and said regeneration zone in intimate admixture with said solid particles, a minor amount of discrete entities comprising at least one material capable of associating with sulfur trioxide at the conditions of step (2) and capable of disassociating with sulfur trioxide at the conditions of step (1), thereby associating at least a portion of said sulfur-containing combustion product with said discrete entities in said regeneration zone and disassociating at least a portion of said sulfur-containing combustion product from said discrete entities in said reaction zone to form H.sub.2 S which exits said reaction zone with said hydrocarbon product, provided that said discrete entities prior to introduction into said reaction zone-regeneration zone system are more attrition resistant than said solid particles.