Catalytic activity of heteropoly tungstate catalysts for ethanol dehydration reaction: Deactivation and regeneration

• Published in: Catalysis today 2021-04, Vol.366, p.123-132
• Main Authors: Verdes, Orsina, Sasca, Viorel, Popa, Alexandru, Suba, Mariana, Borcanescu, Silvana
• Format: Article
• Language: English
• Subjects: Coke formation deactivation; Ethanol conversion; Heteropoly compound; Palladium
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2019.12.040

[Display omitted] •Dehydration of ethanol was studied over silica-supported HPCs between 200 and 350 C°.•The XP spectra show that Pd doped HPAs consists of Cs3PW crystallites coated with Pd0.25 P W layers.•The value of Brönsted acidity has a significant impact on the coke formation.•Pd and SBA-15 improves the catalytic activity by reducing the catalysts deactivation.•After air regeneration, the catalysts regain the catalytic activity for o short time. The pure and palladium doped 12-tungstophosphoric acid - H3PW12O40 (HPW) and its cesium salts CsxH3-xPW12O40 (x = 1, 2, 2.25 and 2.5) were prepared and characterized by thermal analysis, FTIR, XRD, BET and XPS methods. In this paper were determined the optimal reaction temperature and the effect of palladium on the coke content during the dehydration of ethanol in the temperature range of 200−350 °C. Above 300 °C, a strong deactivation of the catalysts was caused by coke formation. The catalytic tests demonstrate that by supporting the HPW and PdyPW (y = 0.15, 0.2 and 0.25) on mesoporous molecular sieve SBA-15 the catalytic activity in ethanol dehydration reaction was improved. Palladium doping of HPW/SBA-15 significantly decreases the formation of coke deposit. The formation of coke during the ethanol dehydration does not affect the Keggin structure which led us to conclude that such catalysts can be regenerated in air and regain their catalytic activity for a short time.