Manoj Srivastava

Mesophase formation behavior in petroleum residues

Mesophase pitch is an important starting material for making a wide spectrum of industrial and advanced carbon products. It is produced by pyrolysis of petroleum residues. In this work, mesophase formation behavior in petroleum residues was studied to prepare environmentally- benign mesophase pitches, and the composition of petroleum residues and its influence on the mesophase formation was investigated. Two petroleum residues, i.e., clarified oil s (CLO-1, CLO-2) obtained from fluid catalytic cracking units of different Indian petroleum refineries, were taken as feed stocks. A third petroleum residue, aromatic extract (AE), was produced by extraction of one of the CLO-1 by using N-methyl pyrrolidone solvent. These petroleum residues were thermally treated at 380°C to examine their mesophase formation behavior. Mesophase pitches produced as a result of thermal treatment were characterized physico-chemically, as well as by instrumental techniques such as Fourier-transform infrared spectroscopy, nuclear magnetic resonance, X-ray diffraction and thermogravimetry/derivative thermogravimetry. Thermal treatment of these petroleum residues led to formation of a liquid-crystalline phase (mesophase). The mesophase formation behavior in the petroleum residues was analyzed by optical microscopy. Mesophase pitch prepared from CLO-2 exhibited the highest mesophase content (53 vol%) as compared to other mesophase pitches prepared from CLO-1 and AE.

Fullerenes: Synthesis, separation, characterization, reaction chemistry, and applications -- A review

The recently discovered third allotrope of carbon, the fullerenes, are a subject of very active research, particularly for chemists. They have a closed-cage structure, made by interlocking pentagonal and hexagonal panels, and are the only soluble form of carbon. In this review an attempt has been made to summarize ongoing fullerene research. The review covers methods of fullerene production and separation, mechanisms leading to closed-cage structure formation, structural characterization, reaction chemistry, and applications of this novel material. The emerging directions of research are also discussed.

Structural characterization of petroleum based feedstocks for carbon black production

Abstract Some selected petroleum based feedstocks have been characterized by 1H and 13C NMR spectroscopy for their possible use as carbon black feedstock (CBFS). Feedstocks studied are pyrolysis tars, clarified oils, aromatic extracts and vacuum residue. Analysis of average structural NMR parameters show that pyrolysis tars because of their being highly aromatic in character (high BMCI) are the most suitable feedstock for carbon black. Aromatic extracts rank the next. Clarified oils of Indian refinery origin needs further processing due to middle distillate mode refining severity.

Clarified Oil from Fluid Catalytic Cracking as an Additional Source of Group II Base Oil Components

Abstract Clarified oil (CLO) from a commercial fluid catalytic cracking unit was subjected to solvent extraction followed by solvent dewaxing and adsorption chromatography to analyze its various components for different end-use applications. The clarified oil was first solvent extracted using N-methyl pyrrolidone (NMP) to produce paraffinic rich raffinate (68.9 wt% yield). The raffinate thus obtained was dewaxed using methyl isobutyl ketone (MIBK) to get an oil of pour point 0°C. This dewaxed oil was then subjected to adsorption chromatography to determine group II base oil potential through yield v/s viscosity index (VI) curve. The results revealed that clarified oil has an actual potential of around 27.1 wt% of group II base oil components, suggesting that clarified oil can be used as an additional source of feed for production of group II base oil. This article also describes the potential of other components in clarified oil such as slack wax (24.2 wt%), aromatics (31.1 wt%), and low VI oil (17.6 wt%).

Upgrading low value refinery streams into electrode grade petroleum pitch

Abstract Petroleum pitch is an excellent precursor for a number of advanced carbon materials such as carbon fibres, carbon molecular sieves, mesocarbon micro-beads, activated carbon spheres, needle coke etc. Some of the refinery streams have good potential for making pitches. These streams are the by-products of petroleum refining processes. Currently, these streams are being sold as low value ‘fuel oils.’ The present study has been carried out to examine the feasibility of making electrode grade impregnating pitches from aromatic extract of waxy distillates, a by-product of lube refining. Pitches were prepared by thermally induced polymerization and condensation of aromatic extracts obtained by solvent extraction of waxy distillates. It was found that, it is possible to produce quality-impregnating pitches from aromatic extracts. These pitches are of good quality having key properties like softening point (112–128°C), coking value (>45 wt%) and quinoline insolubles (<1 wt%), and are well comparable with Ashlands A-240 pitch which is used as impregnating pitch in graphite electrode plants world over. Average structural parameters (Har, α-Ph, β-CH2, γ-CH3 etc.) of these pitches have been computed from NMR spectra and used for comparison purpose. It appears that integration of pitch making process in refineries will improve the profitability by converting low value aromatic extracts into high priced petroleum pitches.

Comparison of Structural Properties of Pitches Prepared from Petroleum Refinery/Petrochemical Residues using NMR Spectroscopy

Several petroleum pitches have been prepared by thermal treatment of various petroleum-derived residues such as clarified oil, aromatic extract and pyrolysis tars. These pitches were characterized physico-chemically (softening point, coking value, QI, & TI) and instrumentally (NMR) and compared. Attempts have been made to correlate physico- chemical properties of petroleum residues and pitches with their NMR structural parameters through regression analysis. Studies on high temperature in-situ 1 H NMR analysis of pitches have also been carried out. Structural characterization of petroleum residues and pitches is very useful for screening of petroleum residues and optimization of process variables for tailoring pitch properties for different end-use applications.

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.

Employ NMP Extraction for Value Addition of Waxy Streams

Abstract With rising crude oil prices, coupled with tightening product specifications and environmental concerns, the refining industry will continue to see many changes during the times to come. In order to maintain/improve their margins, refiners are obliged to upgrade the low value streams into more profitable products. For upgrading the existing product slate, or manufacture of new products, huge investments are needed for new facilities. This involves logistic and proper evaluation of all the possible upgrading technologies and optimal processing schemes in order to arrive at the best option for a particular unit. This study deals with NMP extraction studies on two vacuum cuts; namely, pressible and heavy waxy distillates (PWD and HWD) for their up-gradation into raffinates of desired hydrocarbon composition and extracts of high aromaticity (BMCI). Solvent extraction studies were carried out on multistage extraction column in countercurrent mode. The water content in the solvent was optimized and kept the same for both the streams for ease of solvent recovery. The extraction conditions such as temperature, solvent-to-feed ratio, and water content in solvent were optimized for high quality raffinate and high quality aromatic extract (BMCI > 105). Studies reveal that the processing of PWD and HWD produces raffinate that could be used as feedstocks to solvent dewaxing/de-oiling unit for paraffin wax production. The high BMCI extract can be used as feed for high value industrial carbons such as pitches and needle coke. An added advantage of following this scheme is that the filtration rates of the NMP extracted PWD and HWD raffinates increase by ∼ 50% in comparison to that of raw distillates, thereby leading to capacity enhancement besides easy finishing of the wax. Moreover, withdrawal of about 25% of aromatic extracts from PWD and HWD feed stocks would lead to increase in capacity of the wax dewaxing/deoiling unit.

Evaluation of Different Packings in Lube Extraction System

Abstract Often the most cost effective way of enhancing mass transfer through improved mixing and settling of droplets in liquid-liquid extraction applied to lube systems is by way of using internals (packings). Although, such retrofits are generally performed to increase capacity, they also have been used to increase separation efficiency. Liquid extraction quite often proves to be an economical means of effecting a component separation. Packing material promotes mass transfer between the continuous and dispersed phases by forcing the phases to pass through interstices of the packings causing the dispersed phase droplets to follow a tortuous path through the packed bed. Most of the investigations in this direction have been carried out with respect to liquid and gas loadings. Commercial considerations have been the drivers to force the refineries and chemical plants to adopt new packings. However, there is room for carrying out R&D studies with respect to packings vis-à-vis lube extraction. An attempt has been made to initiate studies with relatively new generation packing, namely berl saddle, applied in lube systems, using N-methylpyrrolidone and comparing the findings with a standard conventionally employed packing (i.e., raschig rings). Preliminary studies indicate that the berl saddle performs better as compared to rasching rings in lube feed range (interneutral) taken from present studies.