383940 Tuning Acid-Base Properties of Znxzryoz for Ethanol-to-Isobutene Conversion
With environment deterioration from global warming and the depletion of fossil resources, the fundament research on fuel production has been being shifted, focusing on the sustainable production of bio-fuels. As the most natural abundant renewable resource, biomass has been considered one of the most promising ones with the potential to replace petroleum in production of chemicals and liquid transportation fuels.1-4 Isobutene is an important industrial intermediate, which has been widely used for the production of fuel additives (e.g. MTBE, ETBE and isooctane), butyl polymers, antioxidants, tert-butylamine, and tert-butanol et al.3 Currently, isobutene is mainly produced by steam cracking of fossil resource. With the increasing demand/wide application of isobutene and the dwindling reserve of fossil fuel, it is highly demanded to explore sustainable techniques for isobutene production. We developed a new ZnxZryOz catalyst with balanced acid-base pairs, on which a cascade reaction from bio-ethanol to isobutene has been achieved via acetone intermediate.5-6 In this work, the effects of catalyst composition, reaction temperature, residence time, steam to carbon ratio, and ethanol molar fraction on isobutene yield have been studied. Isobutene yield as high as 79% was achieved with an ethanol concentration of 8.3% at 475 °C over Zn1Zr8Oz. Further durability and regeneration tests showed that the catalyst shows very slow deactivation via coke formation with isobutene yield maintained above 75% for more than 10 hours, and that the catalysts activity can be fully recovered after calcination in air at 550 °C for 2.5 hours. Characterizations such as XRD, TGA, Nitrogen sorption, and in situ FTIR techniques have been employed to correlate structure to the performance of the catalysts. Especially, the effect surface acid-base property on the reaction of reactant (e.g., ethanol) and possible intermediate (i.e., acetone) has been investigated and correlated.
1. Liu, C.; Wang, H.; Karim, A. M.; Sun, J.; Wang, Y., Chem. Soc. Rev., DOI: 10.1039/c3cs60414d (2014).
2. Serrano-Ruiz, J. C.; Luque, R.; Sepulveda-Escribano, A., Chem. Soc. Rev. 40, 5266 (2011).
3. van Leeuwen, B.; van der Wulp, A.; Duijnstee, I.; van Maris, A.; Straathof, A., Appl. Microbiol. Biotechnol. 93, 1377 (2012).
4. Sun, J.; Wang, Y., Acs Catal. 4, 1078 (2014).
5. Sun, J.; Zhu, K.; Gao, F.; Wang, C.; Liu, J.; Peden, C. H. F.; Wang, Y., J. Am. Chem. Soc. 133, 11096 (2011).
6. Liu, C.; Sun, J.; Smith, C.; Wang, Y., Appl. Catal., A 467, 91 (2013).