Worldwide demand for purified terephthalic acid, the key raw material for polyester, is expected to double from 12 million tons per year in 1995 to 24 million tons per year in 2005. The raw material for making terephthalic acid, para-xylene, serves as the intermediate step between petroleum refining and end-use chemical markets. However, production of this feedstock is energy-intensive, relying either on adsorption or cryogenic crystallization for purification. This project will develop novel catalysts(s) and a simplified process for the reactive separation of commodity chemical para-xylene. The catalyst will selectively alkylate ethylbenzene and other xylene isomers, except para-xylene, and yield high purity para-xylene product in one reactive distillation step, where the feed is conventional pyrolysis gas or reformates from the refinery. The alkylated products, recovered from the bottom of the distillation column, could be separately treated to make other value added products or de-alkylated to ethylbenzene, ortho-and meta-xylene. Phase I will screen potential catalysts and alkylating agents to determine preferred alkylating agent(s), catalyst, or catalyst combination. Then, the preferred catalyst or catalyst combination will be optimized with respect to various catalyst designs and process variables.
Commercial Applications and Other Benefits as described by the awardee: The process should save the U.S. chemical industry about 105 trillion BTUs of energy in the year 2020. Although the chemical industry sector would be the primary users of this technology, its effect would be felt in almost every industrial sector, since many U.S. industries use polyester end products. The U.S. para-xylene manufacturers would be more competitive than foreign counterparts, and the nationâs dependence on imported fossil fuel would be reduced
