p-Xylene is a major commodity chemical and precursor in the production of the most widely used polyester, polyethylene terephthalate (PET). Due to the rapid growth in the global market of PET (6-8% per year), its replacement with a renewable feedstock is highly desirable, and there are ongoing research and development efforts to produce p-xylene from biomass feedstocks. Diels-Alder cycloaddition of 2,5-dimethylfuran (DMF) and ethylene with subsequent dehydration of the cycloadduct intermediate to produce renewable p-xylene is an attractive reaction pathway for its production from biomass feedstocks. To date, the most selective catalysts reported are acidic zeolites with large micropores (7.5 Å), which primarily catalyze the dehydration reaction. However, they also catalyze the formation of alkylated and oligomerized byproducts (Figure 1). Due to these side reactions, the highest yield to p-xylene previously achieved was 75%. In this talk, we report that phosphorous-containing siliceous zeolites can selectively catalyze the dehydration reaction from the furan-ethylene cycloadduct to p-xylene, without catalyzing reactions producing alkylated and oligomerized products. In particular, the phosphorous-containing zeolite Beta (P-BEA) and hierarchical self-pillared pentasil, P-SPP, are active, stable and selective catalysts for this reaction with an unprecedented p-xylene yield of 97%. This catalytic behavior is distinct from that of Al-containing zeolites and establishes a commercially attractive process for renewable p-xylene production.

Renewable p-xylene from 2,5-dimethylfuran and ethylene using phosphorus-containing zeolite catalysts

254th National Meeting (2017)

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