277757 Catalytic Cycloaddition of Ethylene to Dimethylfuran for the Production of p-Xylene

Wednesday, October 31, 2012
Hall B (Convention Center )
Christopher L. Williams1, Chun-Chih Chang1, Phuong T. Do2, Nima Nikbin2, Stavros Caratzoulas3, Dionisios G. Vlachos4, Raul F. Lobo2, Wei Fan1 and Paul J. Dauenhauer1, (1)Chemical Engineering, University of Massachusetts Amherst, Amherst, MA, (2)Chemical Engineering, University of Delaware, Newark, DE, (3)Catalysis Center for Energy Innovation, University of Delaware, Newark, DE, (4)Chemical and Biomolecular Engineering, University of Delaware, Newark, DE

To reduce independence on non-renewable resources, we investigate the catalytic conversion of sugars to building block chemicals for biorenewable plastics. Glucose, the monomer of cellulose, can be converted to 2,5-dimethylfuran through fructose [1] after isomerization by catalysts such as Sn-BEA zeolite [2]. 2,5-Dimethylfuran can then be upgraded to p-xylene, a precursor of terephthalic acid, which is used in the production of plastic bottles (PET). In this work a renewable route to p-xylene from dimethylfuran and ethylene is investigated with zeolite catalysts.  Cycloaddition of ethylene and 2,5-dimethylfuran and subsequent dehydration to p-xylene has been achieved with 75% selectivity using H-Y zeolite and an aliphatic solvent at 300 °C.  Competitive side reactions include hydrolysis of dimethylfuran to 2,5-hexanedione, alkylation of p-xylene, and polymerization of 2,5-hexanedione. The observed reaction rates and computed energy barriers are consistent with a two-step reaction which proceeds through an oxabicyclic-adduct prior to dehydration to p-xylene.  Cycloaddition of ethylene and dimethylfuran occurs without a catalytic active site, but the reaction is promoted by confinement within microporous materials.  The presence of Brønsted acid sites catalyzes dehydration of the Diels-Alder cycloadduct (to produce p-xylene and water) and this ultimately causes the rate determining step to be the initial cycloaddition.  

[1] Román-Leshkov, Y.; Barrett, C. J.; Liu, Z. Y.; Dumesic, J. A. Nature 2007, 447, 982-5

[2] Moliner, M.; Román-Leshkov, Y.; Davis, M. E. Proceedings of the National Academy of Sciences of the United States of America 2010, 107, 6164-8

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