Deep-desulfurization of the petroleum diesel using the heterogeneous carboxyl functionalized poly-ionic liquid

摘要

Highlights ? Carboxyl functionalized poly-ionic liquid (CFPIL) has been synthesized. ? Highly efficient protocol has developed for the removal of sulfur from the model oil. ? Oxidative desulfurization has achieved 100% with moderate conditions. ? Easy work up and recyclability of CFPIL has been reported. Acidic carboxyl functionalized poly(ionic liquid) (CFPIL) has been synthesized and characterized by various techniques like FT-NMR, Fourier transform infrared spectroscopy (FTIR). In this work, deep oxidative desulfurization of model oil (thiophene dissolved in iso-octane) by CFPIL catalyst was carried out in presence of 30 wt% H₂O₂ solution as an oxidant. The effects of the hydrogen peroxide, amount of CFPIL, temperature-time and recyclability are scrutinized systematically. It was found that the effective molar proportion of H₂O₂ to sulfur was 4:1 at 70?°C in 180?min with 0.6?g catalyst, removing 100% thiophene from model oil. This method has shown high efficiency for the removal of thiophene, which is difficult to remove from the oil than benzothiophene and dibenzothiophene. Additionally, an oxidative desulfurization mechanism has been proposed according to the experimental results. This catalytic system by CFPIL offers advantages such as higher efficiency, low amount of ionic liquid, simple work up for separating oil from the catalyst and ease of recycling. This protocol inclines to show that diesel fuels in industry can be purified to sulfur-free or ultra-low sulfur fuels by further deep oxidative desulfurization with CFPILs after hydrodesulfurization.