Rakesh Sarin

Studies on Guizotia abyssinica L. oil: Biodiesel synthesis and process optimization

Guizotia abyssinica seeds, a common bird feedstock, have been explored for the potential of biodiesel synthesis. The oil was extracted from the seeds by solvent extraction and composition of G. abyssinica oil was examined. The reaction parameters for biodiesel synthesis have been optimized. Temperature, oil: methanol ratio, catalyst type and catalyst concentration were found to have significant role on ester conversion. According to this study, the maximum yield of ester (98.7%) can be obtained with optimized sodium methoxide catalyst dosage (0.6%) at an operational temperature of 65 degrees C. Methyl ester of G. abyssinica oil was also studied for its oxidation stability and low temperature properties. Further, the synthesized product was blended in diesel at 5-20% ratios and evaluated for physico-chemical properties.

Terminalia belerica Roxb. seed oil: A potential biodiesel resource

Terminalia belerica seeds, collected from Indian forests, were explored as an alternate bioresource for biodiesel synthesis. The oil yield of T. belerica seed is about 31% (dry weight basis). The fatty acid profile of T. belerica seed oil shows predominance of oleic acid (C(18:1)) glycerides (61.5%) along with linoleic (18.5%) and palmitic (11.6%) glycerides. Oil was extracted and evaluated for physico-chemical properties vis-a-vis jatropha, sunflower, soybean and rapeseed oil. T. belerica oil was transesterified with methanol in the presence of sodium methoxide catalyst. The physico-chemical properties of synthesized methyl ester were compared to jatropha, sunflower, soybean and rapeseed methyl esters as per ASTM D-6751 specification of biodiesel. Synthesized T. belerica methyl ester was also blended in diesel at 5-20% ratios and evaluated for key physico-chemical properties as per IS 1460 specification and found to meet in properties evaluated as per specific standards. The study revealed the possibility of T. belerica seed oil as potential resource of biodiesel.

Biodiesel surrogates : Achieving performance demands

Synthesis of surrogate molecules is particularly useful for generating in sight of structural-activity relationships, understanding processes and improving the performance. In order to improve upon the physico-chemical properties of biodiesel, methyl, ethyl, isopropyl and n-butyl esters of beta-branched fatty acid have been synthesized, initiating from beta-branched alcohols. Beta-branched alcohols upon oxidation gave corresponding acids, which were converted to their esters. The synthesized esters have substantially better oxidative stability, exhibited by Rancimat oxidation induction period of more than 24 h. The cloud point of synthesized esters is < -36 degrees C, pour point is < -42 degrees C and CFPP is < -21 degrees C, which is substantially better than fatty acid methyl esters. Besides achieving the objective of better oxidative stability and improved low temperature properties, the synthesized surrogate esters have viscosity in the range of 4.2-4.6 cSt at 40 degrees C, meeting the international diesel and biodiesel standards. The cetane number of synthesized esters is 62-69, which is much better than diesel and biodiesel. The blends of the synthesized esters in diesel at 5% and 10% meet Indian standards of diesel.

Synthesis and performance evaluation of O, O-dialkylphosphorodithioic disulphides as potential antiwear, extreme-pressure and antioxidant additives

Abstract The ashless antiwear/EP additives based on phosphorodithioic acids are preferred to their heavy metal complexes, due to operational problems and enviromental restrictions being enforced in many countries. Four O, O-dialkylphosphorodithioic disulphides with varying alkyl chain length from C5 to C10 have been synthesized and their antiwear, EP and antioxidant performance examined vis-a-vis a commercial ZDDP in a mineral base oil. The synthesized products have been found to exhibit appreciable antiwear and antioxidant properties and mild EP performance, which are comparable to that of commercial ZDDP.

Additive-additive interactions : search for synergistic FM-EP-AW composition

Abstract A recent trend and need is towards formulating energy efficient lubricants as fuel efficiency has become a critical component of industrys operating efficiency. However, compatibility of friction modifiers (FM) with existing additives, specially surface-active types, needs to be examined beforehand. The effect of oil-soluble commercial organomolybdenum compounds on the extreme pressure (EP) and antiwear (AW) properties of most commonly used S-containing EP/AW agents has been investigated on a four-ball machine. While mostly complementary and exclusory interactions were observed in some cases graded response was also noticed. Based on this extensive study, involving three oil-soluble organomolybdenum FM and four EP/AW agents of varying chemistries, the most synergistic FM-AW-EP combination was identified. The selected combination, when incorporated into a fully formulated industrial gear oil formulation, resulted in marked enhancement in EP/AW properties and a substantial improvement in frictional characteristics.

Molybdenum dialkylphosphorodithioates: synthesis and performance evaluation as multifunctional additives for lubricants

Abstract Phosphorodithioate complexes of various metals are used as lubricant additives to impart anti-wear, anti-friction, anti-oxidant and extreme-pressure properties in lubricating oils. Four molybdenum dialkylphosphorodithioate (MoDTP) complexes with varying alkyl chain length from C5 to C10 have been synthesized and their anti-friction, anti-wear and anti-oxidant performance examined vis-a-vis a commercial MoDTP in a mineral oil, base oil and finished engine oil. The synthesized products have been found to exhibit appreciable anti-friction, anti-wear and anti-oxidant properties, which are comparable to that of commercial MoDTP.

Sulphur-phosphous components in gear oils: part 1, oxidation stability studies by 31P-NMR spectroscopic techniques

Abstract In the present investigations, the mechanism of oxidation stability of sulphur and phosphorus-based additives such as S-alkyl O,O-dialkyl phosphorodithioate, alkyl amine salt of dialkyl dithiophosphoric acid, dialkyl hydrogen phosphite and zinc dialkyl dithiophosphate used in lubricants has been studied by liquid and solid state 31 P/ l H-NMR spectroscopic techniques. These techniques have enabled to monitor the complex changes that occur during oxidation at different intervals during long duration oxidation tests and provide qualitative and quantitative information of products formed during degradation of S–P based additives. The nature of both soluble and insoluble products of decomposition has been /determined. The studies have revealed few important aspects regarding thermal stability of these additives. The ashless S-alkyl O,O-dialkyl phosphorodithioate have better thermal oxidative stability and retain their identity for longer period compared to other similar ashless additives and zinc dialkyl dithiophosphates. The loss of additives during oxidation is 12% in case of S-alkyl O,O-dialkyl phosphorodithioate compared to other mentioned additives (40–100%) during 64 h of heating at 165 °C in the presence of air and catalyst. The decomposed products are also solublised in case of S-alkyl O,O - dialkyl phosphorodithioate and dialkyl hydrogen phosphite, and small amount of solids are formed compared to other additives. During oxidation the main components are being converted into more complex insoluble polyphosphates. The nature of soluble and insoluble products of decomposition as a result of thermal degradation are similar irrespective of the types of additive used. The mechanism of degradation and subsequent composition and structure of products formed has been discussed in detail. These studies will facilitate correlation of the structure and performance of these additives in lubricants.

Phosphorus Components in Lubricants: Structure-Activity Relationship

Phosphorus components are probably the earliest known and most important additives for lubricant applications. Phosphites, phosphates, thiophosphates, metal dithiophosphates, and amine phosphates are examples of common phosphorus additives being used in the lubricant industry. However, due to environmental concerns and to help conserve catalyst life of catalytic converters, there is a trend to reduce the phosphorus content in lubricant formulations. In order to achieve this goal, different types of phosphorus components have been studied for their tribological properties.

Characterization of Metal Phthalocyanine Catalysts Using Field Desorption Mass Spectrometry

Abstract Metal phthalocyanines are a very important class of compounds due to their ability to activate oxygen, which enables them to become useful chemical reagents and largely-accepted catalysts for many chemical reactions. Phthalocyanines containing metals like iron, cobalt, manganese and vanadium are useful catalysts in many refinery processes. In the petroleum industry mercaptans are oxidized to disulfides by aerobic oxidation in an alkaline medium in the presence of a metal phthalocyanine. A number of analytical techniques have been explored to characterize metal phthalocyanines. In this article, we have for the first time successfully used field desorption mass spectrometry (FDMS) techniques for the characterization simple metal phthalocyanines and substituted metal phthalocyanines. For this purpose metal phthalocyanines were prepared in the laboratory and the conditions were optimized for the characterization of metal phthalocyanines containing cobalt, nickel, copper and zinc by FDMS. This technique was also successfully applied to characterize sulfato, nitro, and chloro substituted phthalocyanines. This technique has been found to be a useful tool for the characterization of phthalocyanines.