Abstract
Pyrolysis oil derived from waste tires consists of sulfur content in the range of 7000 to 9000 ppm. For use in diesel engines, its sulfur content must be lowered to 10 to 15 ppm. Though conventional hydrodesulfurization is suitable for the removal of sulfur from tire pyrolysis oil, its high cost provides an avenue for alternative desulfurization technologies to be explored. In this study, oxidative desulfurization (ODS), a low-cost technology, was explored for the desulfurization of tire pyrolysis oil. Two categories of titanium-incorporated mesoporous supports with 20 wt% loaded heteropoly molybdic acid catalyst (HPMo/Ti-Al2O3 and HPMo/Ti-TUD-1) were developed and tested for ODS of tire pyrolysis oil at mild process conditions. Catalysts were characterized by X-ray diffraction, BET-N2 physisorption, and X-ray photoelectron spectroscopy (XPS). The incorporation of Ti into Al2O3 and TUD-1 frameworks was confirmed by XPS. The surface acidity of catalysts was studied by the temperature-programmed desorption of NH3 and pyridine FTIR analyses. HPMo/Ti-Al2O3 and HPMo/Ti-TUD-1 catalysts contained both Lewis and Brønsted acid sites. The presence of titanium in catalysts was found to promote the ODS activity of phosphomolybdic acid. The Ti-TUD-1-supported catalysts performed better than the Ti-Al2O3-supported catalysts for the ODS of tire pyrolysis oil. Hydrogen peroxide and cumene peroxide were found to be better oxidants than tert-butyl hydroperoxide for oxidizing sulfur compounds of tire pyrolysis oil. Process parameter optimization by the design of experiments was conducted with an optimal catalyst along with the catalyst regeneration study. An ANOVA statistical analysis demonstrated that the oxidant/sulfur and catalyst/oil ratios were more significant than the reaction temperature for the ODS of tire pyrolysis oil. It followed the pseudo-first-order kinetics over HPMo/Ti-TUD-1.
Highlights
The wide-angle XRD spectra depicted in Figure 2 show the fingerprint of Keggintype phosphomolybdic acid in the Heteropolymolybdic acid (HPMo)/Ti-TUD-1 type catalysts [35]
These Keggin ion peaks are absent in the HPMo/Ti-Al2 O3 catalysts
Ti-Al2 O3 support are known to interact with phosphomolybdic acid and depolymerize the polyoxometallate (Keggin) anion [36]
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Comprises C6 –C24 hydrocarbons with a calorific value of around 42 MJ/kg, which is comparable to that of crude oil (42–47 MJ/kg) [4,6] It can be used as fuel in cement kilns, thermal power plants, industrial boilers, and vehicles [7,8,9]. Pyrolysis oil needs to be desulfurized for its commercial use as fuel [10].compounds. Is one of species from tire pyrolysis oil under mild process conditions. It is one of the low-cost cost alternative desulfurization methods and does not require hydrogen. Doustkhah et al.organosilica [12] synthesized new type of and catalyst by merging periodic performance mesoporous with aaluminosilica investigated its catalytic mesoporous organosilica with aluminosilica investigated its catalytic for the oxidation of DBT.
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