Girish C. Joshi

Crystallization behaviour of n-paraffins in Bombay-High middle-distillate wax/gel☆

Abstract The crystallization behaviour of n-paraffins in the waxes obtained from the middle distillate of Bombay-High crude oil has been studied using X-ray diffractometry and photomicrography. The effects of solvents and of a pour-point depressant additive on the lattice properties of the waxes have been investigated and the mechanisms of gel formation and additive action have been studied. The correlations between wax crystal structure and morphology have been discussed.

Fe(III)-EDTA mediated autoxidation of 2,6-Di-t-butylphenol and substituted hydroquinones by molecular oxygen

Abstract Fe(III)-EDTA in aq. MeOH offers a simple environmentally acceptable synthetic tool to oxidize 2,6-di- t -butylphenol to 3,3′,5,5′-tetra- t -butyl-4,4′-diphenoquinone by molecular oxygen with 100% selectivity and several alkyl-substituted hydroquinones to their quinones, in excellent yields, under mild conditions.

Oxidation of Sulphides by Molecular Oxygen - Aldehyde System in the Absence of Metal Catalyst

Abstract Molecular Oxygen/2-methylpropanal system provides a simple, efficient, and environmentally acceptable synthetic tool to convert sulphides to sulphones in near quantitative yields and to sulphoxides in high selectivity and good yields under ambient conditions. +Presented at the Int. Conf. on Org. Syn. (ICOS-10) at IISc, Bangalore, (India), December 11-16, 1994

Wax deposition of Bombay high crude oil under flowing conditions

Abstract The wax deposition rate of Bombay high crude oil under flowing conditions in a horizontal pipe was studied at different flow rates and at different temperature differentials between the oil and the cold surface. The deposition was found to increase asymptotically with time and reach a final fluctuating value. The time to obtain equilibrium deposition varied with test conditions. A mathematical equation correlating the flow rate and temperature differential with the equilibrium deposition was also developed.

Influence of waxes on the flow properties of Bombay high crude

Waxes present in crude oil are considered to be responsible for its poor flow properties. Bombay high crude is very waxy and has a pour point of + 30 °C. The influence of nature and concentration of waxes on some of the flow properties, namely pour point, plastic viscosity and yield stress, of dewaxed Bombay high crude have been determined. The hard wax components present in the crude do not appear to significantly influence the low temperature rheology of the crude oil, but do contribute to sludge formation.

Stability of cracked naphthas from thermal and catalytic processes and their additive response. Part II. Composition and effect of olefinic structures

Abstract Olefinic concentrates were separated from two naphthas, one from fluid catalytic cracking (FCC) and one thermal crackate, using column chromatography. The composition and structure of the olefins were determined by a combination of analytical techniques. FCC naphthas contain relatively higher levels of conjugated dienes. The monoolefins are highly branched. The thermal crackates have higher levels of α-olefins and abound in mono-, di-, tri- and conjugated cyclic olefins. Stability tests on these olefinic concentrates blended in low-S,N straight-run naphtha showed that cyclic olefins are very active gum formers. Representative commercial antioxidants (hindered phenols and phenylenediamines) both gave good responses to different olefin concentrate test blends. Hindered phenols had a marginally better effect.

Stability of cracked naphthas from thermal and catalytic processes and their additive response. Part I. Evaluation of stability and additive response

Abstract Olefinic naphthas derived from fluid catalytic cracking (FCC) or thermal cracking units are increasingly being used in high-octane motor gasoline with growing concern for resulting fuel quality. Hindered phenols and substituted arylamines are the two classes of antioxidants generally used for improving the stability of gasoline. The olefin types in cracked naphthas depend strongly on the process from which they are derived and hence are expected to show different responses with different antioxidants. However, systematic information on this aspect of antioxidant action is non-existent in the literature. Using two representative commercial antioxidants from each class with representative naphthas (FCC, visbreaking and coker), it was found that phenolic antioxidants gave a better response with thermally cracked naphthas. With amine-type antioxidants no clear preference could be observed.

Gum forming olefinic precursors in motor gasoline a model compound study

Abstract The source of the cracked components in motor gasoline are generally (Fluid Catalytic Cracking) FCC and thermal cracking naphthas incorporated in the gasoline pool. The FCC olefins are predominant in iso structures, while thermal cracking naphthas obtained from visbreaking and coking operations contain substantial amounts of cyclic structures. The contribution of various olefinic structures present in these naphthas are likely to vary. The gum forming tendencies of different types of olefinic structures have been studied by taking model compounds in a known sample matrix through potential gum measurements under accelerated test conditions. Peroxide number values have also been determined on aged sample. Cyclic and dicyclic structures have been found to contribute maximum, towards gum formation tendencies. Branching generally increase the gum formation. However, position of branching plays an important role besides the double bond. Synergistic effect of dienes with straight chain and branched olef...

Thermal properties of some petroleum waxes in relation to their composition

Phase transition temperatures and associated energies for petroleum waxes of different melting point were measured by differential scanning calorimetry. The analysis of the results showed that the existence of a solid-solid phase transition is dependent on the composition of the wax and the transition energies are related to the solid state properties of the waxes.

Metal phthalocyanine catalyzed oxidation of organic substrates with dioxygen - Aldehyde system

Metal phthalocyanines have been found to catalyze the oxidation of sulphides to sulphones at room temperature by molecular oxygen (1 atm) in the presence of isobutyraldehyde as sacrificial aldehyde. Among the metal phthalocyanines studied those of Fe(II), Mn(II) and Co(II)tetrasulphonato- showed excellent activity, followed by VO, while those of Ni(II) and Cu(II) were found to be least active for sulfide oxidation. Mn(II)phthalocyanine catalyzed epoxidation of olefins with molecular oxygen - isobutyraldehyde systems is also reported.