(25a) Evolution and Revolution: Process Innovations In Aromatics Technology

When AIChE was founded, there was already a substantial market for aromatic compounds such as benzene and phenol, which were primarily recovered as byproducts of coal gasification. The demand for aromatics and their derivatives increased enormously in the second half of the twentieth century as new polymers were commercialized. The invention of catalytic cracking and later catalytic naphtha reforming made available cheaper benzene, toluene and xylenes (BTX) from petroleum feedstocks and laid the foundation for petroleum refiners to enter the aromatics business.

The production of aromatics from petroleum feedstocks has followed a pattern of “punctuated equilibrium”, with periods of steady increase in yields and plant sizes followed by radical breakthroughs that dramatically improved process economics. The successful commercialization of separation processes such as Sulfolane and Parex allowed desired compounds such as benzene and paraxylene to be recovered at higher purity and higher recovery. At the same time, new zeolite catalysts enabled the isomerization of xylenes and toluene disproportionation and transalkylation, allowing aromatics producers to tailor the yields of products to better match the market demand.

Aromatics production continues to evolve. In the past decade, new processes have been commercialized to allow aromatics production from cheaper feedstocks such as light hydrocarbons (Cyclar) and heavier feedstocks such as light cycle oil (LCO-X). The construction of bigger, more heat-integrated complexes is also driving continued innovation as we move into AIChE's second century.