A novel approach is developed for desulphurization of fuels or organics without use of catalyst. In this process, organic and aqueous phases are mixed in a predefined manner under ambient conditions and passed through a cavitating device. Vapor cavities formed in the cavitating device are then collapsed which generate (in-situ) oxidizing species which react with the sulphur moiety resulting in the removal of sulphur from the organic phase. In this work, vortex diode was used as a cavitating device. Three organic solvents (n-octane, toluene and n-octanol) containing known amount of a model sulphur compound (thiophene) up to initial concentrations of 500 ppm were used to verify the proposed method. A very high removal of sulphur content to the extent of 100% was demonstrated. The nature of organic phase and the ratio of aqueous to organic phase were found to be the most important process parameters. The results were also verified and substantiated using commercial diesel as a solvent. The developed process has great potential for deep of various organics, in general, and for transportation fuels, in particular.
The present work, for the first time, describes the efficacy of the cavitation process and compares the cavitation yield for two types of cavitation devices-one employing linear flow for the generation of cavities and other employing vortex flow. The process involves preprogrammed mixing of the organic and aqueous phases, and can be carried out using simple mechanical cavitating devices such as orifice or vortex diode. The process essentially exploits in situ generation of oxidising agents such as hydroxyl radicals for oxidative removal of sulfur. The efficiency of the process is strongly dependent on the nature of device apart from the nature of the organic phase. The effects of process parameters and engineering designs were established for three organic solvents (n-octane, toluene, n-octanol) for model sulfur compound-Thiophene. A very high removal to the extent of 95% was demonstrated. The results were also verified using commercial diesel. The cavitation yield is significantly higher for vortex diode compared to the orifice. The process has potential to provide a green approach for
The harmful impact on the environment due to SO x emissions from fuels and increasingly strict norms over the years have amplified deep-desulfurization challenges, consequently enhancing attractiveness of adsorptive separations. The present work focuses on investigating metal modifications and process intensification using acoustic cavitation for improving sulfur removal behavior and selectivity. The proof of concept was elucidated using two model adsorbents: one commercial Shirasagi TAC adsorbent and another newer adsorbent derived from Cassia fistula biomass. Single- and double-metal modifications were studied using zinc, cobalt, nickel, and copper. An attempt was made to further improve the sulfur removal using process intensification using acoustic cavitation coupled with adsorption. The removal of three refractory sulfur compounds (viz. thiophene, benzothiophene, and dibenzothiophene) was studied, and the performance was compared for both single- and double-metal modifications apart from process intensification. In the case of TAC, a high capacity for sulfur removal, up to 23 mg S/g, was obtained, especially for dibenzothiophene. Process intensification using cavitation coupled with adsorption further improved sulfur removal to the extent of 100%, and for metal-modified TAC, a capacity increase up to 38 mg S/g for dibenzothiophene was obtained. The results indicate that the combined effect of metal modification and process intensification can substantially improve the sulfur-removal efficiency of carbon adsorbents.
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