(113d) Isomerization Inhibition During the Production of Renewable p-Xylene From the Cycloaddition of 2,5-Dimethylfuran and Ethylene

To reduce dependence on non-renewable resources, investigation into the catalytic conversion of sugars aims to produce renewable building block chemicals. The processes for the production of renewable chemicals from sugars are generally derived through the saccharification of biopolymers (e.g., cellulose, hemicellulose). One renewable chemical, p-xylene (used in the production of PET plastics), is currently a research area of great interest [1,2]. In previous work, the conversion of 2,5-dimethylfuran (DMF) and ethylene to p-xylene by a two-step reaction (Diels-Alder cycloaddition followed by dehydration), demonstrated a 75% yield of p-xylene [1].  This cycloaddition/dehydration is the final step in a four step process for the production of green chemicals that consists of: glucose isomerization to fructose, fructose dehydration to hydroxymethylfurfural (HMF), reduction of HMF to 2,5-dimethylfuran, and cycloaddition/dehydration of DMF to p-xylene.

In this work, multiple analytical and reaction engineering techniques have been used to gain a fundamental understanding of the DMF to p-xylene process. The competitive binding of DMF over p-xylene to the acid sites located in the super and sodalite cages of H-Y faujasite has been examined using diffuse reflectance infrared spectroscopy (DRIFTS). ²⁷Al-NMR has shown the existence of these Brønsted acid sites after reaction. Thermogravimetric analysis (TGA) has also been used and indicates that DMF molecules can be adsorbed to Brønsted acid sites at a reaction temperature of 300 °C, while p-xylene will be completely desorbed. The combined utilization of DRIFTS, ²⁷Al-NMR, and TGA, in addition to isomerization inhibition reaction experiments, has allowed us to elucidate the source of p-xylene isomerization inhibition during the production of renewable aromatics from furans.

References

[1]  Williams, C. L.; Chang, C.-chih; Do, P.; Nikbin, N.; Caratzoulas, S.; Vlachos, D. G.; Lobo, R. F.; Fan, W.; Dauenhauer, P. J. ACS Catalysis 2012, 2, 935-939

[2] N. Nikbin, P.T. Do, S. Caratzoulas, R.F. Lobo, P.J. Dauenhauer, D.G. Vlachos, "A DFT study of the acid-catalyzed conversion of 2,5-dimethylfuran and ethylene to p-xylene," Journal of Catalysis, 2013, 297, 35-43