Catalytic cracking of a coal tar in a fluid bed reactor

A coal-derived tar from the Coal Technology Corporation's mild gasification process was catalytically cracked in a fluid bed reactor. Several commercial catalysts were tested and their effectiveness in decomposing tar and releasing sulfur was compared. The effects of process variables such as temperature and residence time were also tested. It was found that the Linde LZ-Y82 zeolite was the most effective catalyst tested in converting tar to coke and gases. LZ-Y82 was also the most effective catalyst in converting the sulfur compounds in the tar into hydrogen sulfide which can be removed by a sorbent. Other catalysts such as LZ-Y82/NiW, LZ-Y82/ZnTi, and Englehard's Sp2323 showed strong catalytic activity. LZ-Y3Z7, which is the LZ-Y82 catalyst impregnated with zinc, displayed less activity. LZ-Y82 cracked most effectively in the temperature range 500-530 degrees C.