SCM-36 zeolite nanosheets applied in the production of renewable p-xylene from ethylene and 2,5-dimethylfuran

Abstract

Zeolites as solid acid materials have played important roles in industrial catalysis. The attempts to obtain new zeolite framework structures and related chemical compositions have never stopped, and may expand the application thereof. Using renewable bioderived molecules as starting feedstocks would be of great help in building a more circular carbon cycle. However, zeolites have only shown limited efficiency in the conversion or production of bioderived chemicals. In this work, we report on the synthesis of a new aluminosilicate zeolite named SCM-36 (Sinopec Composite Material No. 36) using tetramethylammonium hydroxide (TMAOH) with the presence of hexadecylpyridinium bromide hydrate (C16PyBr) or octyltrimethylammonium chloride (OTMAC). The pore opening of this new zeolite material is about 0.6 nm, which is consistent with the size of 10 to 12 membered ring channel. SCM-36 possesses a nanoflower-like morphology with a thickness of ~20 nm. The SiO2/Al2O3 molar ratio of the SCM-36 material is ranging from 21.2 to 36.6, with most Al incorporated into the zeolite framework structure. The acid strength of SCM-36 is not strong, as confirmed by various techniques, including NH3-TPD, pyridine FT-IR, ex-situ confocal fluorescence microscopy and in-situ UV-Vis micro-spectroscopy. In the catalytic conversion of bio-derived 2,5-dimethylfuran (DMF) and ethylene into para-xylene (PX), H-SCM-36 zeolite showed better performance than the more traditional zeolites. The highest selectivity towards PX reached a value of ~93%. Besides, SCM-36 zeolite showed remarkable recyclability in the reaction.