Ethylene production via catalytic ethanol dehydration by 12-tungstophosphoric acid@ceria-zirconia

Abstract

The use of renewable raw materials as feedstocks for important industrial chemicals presents a challenge to the scientific community in its pursuit of sustainability. The necessary tasks include the revision of significant processes such as the ethanol-to-olefin process (ETO), and our goal was the production of ethylene. We chose 12-tungstophosphoric acid (HPW) supported on ceria-zirconia mixed oxide (Ce0.8Zr0.2O2, CZ) as a promising catalyst. The structural properties of different loadings of HPW (5–45 wt%) and different support preparation methods were examined, in addition to their activities in the gas-phase dehydration of ethanol. The maintenance of the Keggin structure was proved by infrared spectroscopy (FT-IR), 31P solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) and X-ray diffraction (XRD). Scanning electron microscopy (SEM) images showed a gradual increase in the formation of agglomerates by the HPW coating on the support surface. The reaction products were followed by mass spectra in the interval of 200–400 °C. Multiple catalysts reached 100% ethanol conversion and selectivity for ethylene at low temperatures (200, 250 and 300 °C). A double effect of the support was observed: to disperse the HPW, improving its original low surface area, and to probably facilitate the coke burning process. Tests to determine the lifetime of catalysts (e.g., 26.4% HPW/CZ) performed in a pulsed microreactor coupled to a GC system showed at least 70 h of activity at 300 °C temperature, which demonstrated the potential of these catalysts.