Novel Impact of Wet Dosages of NMP in Extraction for Production of High BMCI Carbon Black Feedstocks

Abstract

In separation sciences, “Solvent Extraction” is one of the most important unit operations, a very widely used process, next only to distillation. In the petroleum refining industry, solvent extraction is commonly widely applied to produce a number of specialty products such as BTX, lube base oils, waxes, etc. There are many solvents used in various separation processes, like sulfolane, phenol, furfural, ketones, and N-methyl pyrollidone (NMP). NMP in particular is an environmentally benign, new generation solvent, which can be tailored for specific separations by using it in conjunction with small doses of water. In recent years, researchers are re-looking at the separation processes and their modifications to exploit these for producing high-value industrial products from low-value refinery streams. The present study deals with the production of high-quality carbon black feedstocks (CBFS) from clarified oils. The study shows the beneficial effect of using NMP in combination with different dosages of water as extraction solvent to extract low-value clarified oil, a cracked material from the FCC unit of an operating Indian refinery. In the present study, water ranging from 0.3 wt% to 10 wt% was used with NMP to produce aromatic extract of BMCI (Bureau of Mines Correlation Index) up to 146 through liquid-liquid equilibrium and mass transfer studies on clarified oil (CLO). The effect of solvent-to-feed ratio at constant temperature on solvent extraction was also studied. The addition of water in NMP alters the “selectivity” of solvent, which can be exploited for producing aromatic extracts of a wide range of BMCI for different end-use applications. The major users of such high BMCI extracts are carbon black and electrode pitch manufacturers. Regression analysis was also done to develop correlations between water percentage in NMP and targeted BMCI of aromatic extract. Presently, CLO is blended with fuel oil and sold as a very low value product in refinery. Since the demand of CBFS is increasing continuously and current short-fall in India is met through imports from China, Korea, and Japan, it is desirable that such studies are undertaken and will lead to production of high-value CBFS from low-value refinery streams through separation processes.