PARTITIONING OF ALKYLPYRIDINES BETWEEN SHALE-DERIVED MIDDLE DISTILLATE FUEL AND WATER

A nitrogen-rich shale-derived middle distillate fuel was selected for the study of the partitioning of alkyl pyridines with water of pH 5. This particular middle distillate fuel, was found to contain acid extractable compounds composed mainly, about 90%, of alkyl substituted pyridines. The pyridine content of the extracts was determined by combined capillary column GC/HS. The partitioning was observed to be acid dependent.     

FUEL INSTABILITY STUDIES: THE SYNTHESIS OF LONG CHAIN ALKYL SUBSTITUTED INDOLES

ABSTRACT

The reactions that are responsible for fuel instability are complex and not well understood. GC/MS analysis of many different middle distillate and fuel oils showed that substituted indoles were always present in both the fuel itself and in the sediments formed by these fuels. The alkyl chain length of substitution of indoles found in fuels varies with distillation range. Indoles found in the middle distillate fraction have an average alkyl chain length of one to eight carbons while in fuel oils, the alkyl side chain can be up to twelve or fourteen carbons in length. Commercially, only short chain alkyl substituted indoles are available. This paper presents our results for the synthesis of long alkyl chain substituted indoles to be used for instability studies.     

FUEL INSTABILITY STUDIES: REACTION OF POLAR NITROGEN HETEROCYCLES DERIVED FROM A STABLE SHALE FUEL

Abstract

The degradation of middle distillate fuels with increasing time in storage is a continuing problem. Model systems have defined both the scope and the chemical types of molecules that are Implicated in fuel deterioration. To gain insight into a real fuel system, nitrogen-rich extracts have been isolated from a marginally stable shale derived middle distillate fuel and added as a dopant to a stable base fuel in order to induce instability reactions. Alkyl substituted pyridines, tetrahydro-quinolines, quinolines, and indoles were the prevalent classes of compounds present in the extract. The effects of this added extract were examined in terms of sediment formation and peroxide number under accelerated storage stability test conditions. The activity of the extract in inducing fuel instability was correlated with its nitrogen heterocylic composition.     

THE SYNTHESIS OF A REACTIVE PYRIDINE INTERMEDIATE FOR FUEL INSTABILITY STUDIES

ABSTRACT

Pyridine compounds have been found in significant concentration in middle distillate fuels. These compounds have been implicated in fuel instability reactions and could also be involved in color body formation. Few pyridine compounds are commercially available and those that are available are relatively simple in structure. We report the synthesis of a reactive pyridine intermediate, l-carbethoxy-2-cyano-1,2-dihydropyridine, that could be used for a wide range of further pyridine compound synthesis including pyridines, and many other alkyl derivatives. This particular compound has been reported, but in very low yield. This reported improved synthetic procedure give yields in excess of 90%.     

Nitrogen Compound Determination and Distribution in Three Source Fuels by GC/MS

Abstract

Three middle distillate fuels from Kenya, Kuwait, and Sweden were studied for the identification and comparison of their nitrogen content. The organic nitrogen compounds were isolated by mild acid extraction, and three extracts were obtained from each source fuel: a basic nitrogen extract in methylene chloride (BNC), a nonbasic nitrogen extract in methylene chloride (NBNC), and a nonbasic nitrogen extract in methanol (NBNC). The major constituents of each extract were determined by gas chromatography/mass spectrometry (GC/MS). The largest number of nitrogen compounds of the BNC extracts were pyridines and pyrroles in the Kuwait fuel, indoles and pyrroles in the Swedish fuel, and pyrroles and quinolines in the Kenya fuel. The Kenya fuel had carbazoles present in the BNC extract, whereas, the other two fuels didn’t have this compound. The predominant organic nitrogen compounds in the NBNC extracts in methylene chloride for Kuwait and Kenya were tetrahydroquinolines and quinolines, respectively. The analysis of the NBNC extracts in methanol showed the following prevalent organic nitrogen compounds: indoles for Kuwait, quinolines for Sweden, and pyrroles for Kenya. All three fuels had short chain alkyl substituted indoles. Kenya had the lowest nitrogen content, followed by Kuwait and Sweden.     

FUEL INSTABILITY STUDIES: THE SYNTHESIS OF LONG CHAIN ALKYL SUBSTITUTED INDOLES

The reactions that are responsible for fuel instability are complex and not well understood. GC/MS analysis of many different middle distillate and fuel oils showed that substituted indoles were always present in both the fuel itself and in the sediments formed by these fuels. The alkyl chain length of substitution of indoles found in fuels varies with distillation range. Indoles found in the middle distillate fraction have an average alkyl chain length of one to eight carbons while in fuel oils, the alkyl side chain can be up to twelve or fourteen carbons in length. Commercially, only short chain alkyl substituted indoles are available. This paper presents our results for the synthesis of long alkyl chain substituted indoles to be used for instability studies.     

Nitrogen Compound Distribution of Refined Middle Distillate Fuels

Abstract

Three middle distillate fuels originating from New Zealand, Venezuela, and Texas were studied to determine the nitrogen compound distribution in each fuel. Organo-nitrogen compounds in the fuels were isolated by mild acid extraction followed by silica gel adsorption. The extraction scheme yielded three extracts for each fuel—a basic nitrogen extract in methylene chloride, a non-basic nitrogen extract in methyl alcohol, and a non-basic nitrogen extract in methylene chloride. The major constituents of each extract were identified by gas chromatography/mass spectrometry (GC/MS).     

FUEL INSEVHELETY 2: ORGANO-SUIHJR HYEKDEERDXIDE REACTIONS

Abstract

Instability in middle distillate fuels continues to be a problem. Instability is usually defined in terms of sediment formation and increases in peroxide species. There is a growing body of evidence that heteroatomic species, organo-sulfur, nitrogen and oxygen compounds are intimately involved in this deposition process. This is a two part review of the recent literature on middle distillate fuel instability as related to these heteroatomic species.     

FUEL INSTABILITY 1: ORGANO-SULFUR HYDROPEROXIDE REACTIONS

ABSTRACT

Instability in middle distillate fuels continues to be a problem. Instability is usually defined in terms of sediment formation and increases in peroxide species. There is a growing body of evidence that heteroatomic species, organo-sulfur, nitrogen and oxygen compounds are intimately involved in this deposition process. This is a two part review of the recent literature on middle distillate fuel instability as related to these heteroatomic species.     

FUEL INSTABILITY STUDIES: REACTION OF POLAR NITROGEN HETEROCYCLES DERIVED FROM A STABLE SHALE FUEL

The degradation of middle distillate fuels with increasing time in storage is a continuing problem. Model systems have defined both the scope and the chemical types of molecules that are Implicated in fuel deterioration. To gain insight into a real fuel system, nitrogen-rich extracts have been isolated from a marginally stable shale derived middle distillate fuel and added as a dopant to a stable base fuel in order to induce instability reactions. Alkyl substituted pyridines, tetrahydro-quinolines, quinolines, and indoles were the prevalent classes of compounds present in the extract. The effects of this added extract were examined in terms of sediment formation and peroxide number under accelerated storage stability test conditions. The activity of the extract in inducing fuel instability was correlated with its nitrogen heterocylic composition.     

The Instability of Storage of Middle Distillate Fuels: A Review

Abstract

The author reviews the research studies that have been so far carried out and reported in the literature on the stability of middle distillate fuels. The emphasis is mainly given to understand the stability of diesel fuels. It has been divided into five principle sections: (a) Introduction, (b) Methods for Determination of Fuel Stability, (c) Mechanism of Degradation, (d) Composition of Total Gum, and (e) Current Status of Methods to Improve Fuel Stability. The introduction provides information of in-stabilization of distillate fuel that depends on the various blending streams of middle distillates in the introduction part. In the second section the author elaborate the methods so far used to determine the instability of middle distillate fuels. The third section serves the elaborated mechanism of degradation, the role of chemical composition of distillate fuels, and the responsible components in distillate fuels that impart in degradation of distillate fuels. The fourth section comprises the composition of material formed during degradation and the fifth section of reveals the current status of methods used to improve the stability. In combination, these five sections would provide a ready reference source of data available in the literature on diesel fuel stability.     

THE SYNTHESIS OF A REACTIVE PYRIDINE INTERMEDIATE FOR FUEL INSTABILITY STUDIES

Pyridine compounds have been found in significant concentration in middle distillate fuels. These compounds have been implicated in fuel instability reactions and could also be involved in color body formation. Few pyridine compounds are commercially available and those that are available are relatively simple in structure. We report the synthesis of a reactive pyridine intermediate, l-carbethoxy-2-cyano-1,2-dihydropyridine, that could be used for a wide range of further pyridine compound synthesis including pyridines, and many other alkyl derivatives. This particular compound has been reported, but in very low yield. This reported improved synthetic procedure give yields in excess of 90%.     

DETERMINATION OF NITROGEN COMPOUND DISTRIBUTION FROM THREE SOURCE FUELS

ABSTRACT

As part of a world-wide survey of middle distillate fuel instability, three fuels were chosen for detailed GC/MS analysis. These fuels are identified by number and country of origin; FL-2577 was from Burnaby, British Columbia, Canada; FL-2599 was from Abamadj, Kuwait; and FL 2592 was from Chiba, Japan. The organo-nitrogen compounds in the three fuels were separated by mild acid extraction followed by silica gel absorption. This treatment yielded three fractions for each fuel; a basic nitrogen compounds fraction, BNC; a non-basic nitrogen compounds fraction in methylene chloride, mcl, NBNC-mcl; and a non-basic nitrogen compounds fraction in methanol, meoh, NBNC-meoh. The three fractions from each fuel were analyzed by combined capillary gc/ms. The organo-nitrogen compounds from each fraction were identified and quantitated.     

Nitrogen Compound Determination and Distribution in Three Source Fuels by GC/MS

Three middle distillate fuels from Kenya, Kuwait, and Sweden were studied for the identification and comparison of their nitrogen content. The organic nitrogen compounds were isolated by mild acid extraction, and three extracts were obtained from each source fuel: a basic nitrogen extract in methylene chloride (BNC), a nonbasic nitrogen extract in methylene chloride (NBNC), and a nonbasic nitrogen extract in methanol (NBNC). The major constituents of each extract were determined by gas chromatography/mass spectrometry (GC/MS). The largest number of nitrogen compounds of the BNC extracts were pyridines and pyrroles in the Kuwait fuel, indoles and pyrroles in the Swedish fuel, and pyrroles and quinolines in the Kenya fuel. The Kenya fuel had carbazoles present in the BNC extract, whereas, the other two fuels didn't have this compound. The predominant organic nitrogen compounds in the NBNC extracts in methylene chloride for Kuwait and Kenya were tetrahydroquinolines and quinolines, respectively. The analysis of the NBNC extracts in methanol showed the following prevalent organic nitrogen compounds: indoles for Kuwait, quinolines for Sweden, and pyrroles for Kenya. All three fuels had short chain alkyl substituted indoles. Kenya had the lowest nitrogen content, followed by Kuwait and Sweden.     

THE REACTION OF 3-METHYL INDOLE WITH para-ETHYLBENZENE SULFONIC ACID: FUEL INCOMPATIBILTY REACTIONS

ABSTRACT

Polar Heteroatomic species have been correlated with incompatibility reactions in middle distillate fuels. Instability is defined as the formation of filterable sediments and fuel insoluble gums. Heteroatoms (oxygen, nitrogen and sulfur) have been found to be greatly enriched in such sediments. Trace levels of certain organo-sulfur compounds, especially sulfonic acids in model fuel systems, have been found to significantly increase deposit formation. The effectiveness of organic amines as additives suggests that acid/base chemistry is also involved in the formation of deposits. This paper reports on a study of p-ethylbenzene sulfonic acid reacting with 3-methyl indole in model systems. A possible reaction mechanism and a proposed structure for the product is reported. The results of the model system are contrasted to results from previous actual fuel systems.     

Nitrogen Compound Distribution in Refined Middle Distillate Fuels

Abstract

Three diverse middle distillate fuels from Mobile, Alabama, Jacksonville, Florida, and Kirachi, Pakistan were analyzed to quantify the organic nitrogen compound distribution in each. Organo-nitrogen compounds were isolated by a mild acid extraction followed by a silica-gel adsorption procedure. The extraction process yielded three extracts for each fuel: a basic nitrogen extract in methylene chloride, a nonbasic nitrogen extract in methylene chloride, and a nonbasic nitrogen extract in methanol. The major compounds in each extract were identified by gas chromatography/mass spectrometry (GC/MS).     

Removing Organic Nitrogen Compounds From Middle Distillate Fuels with a Catalyst Used as a Filtering Media

Abstract

Fuel storage instability reactions of middle distillate fuel continue to be of great interest to the Department of Defense. Unlike civilian fuel, military fuel typically remains in storage tanks for one or more years. As fuel is removed from these tanks, the tanks are subsequently filled with more recently purchased fuel. In many cases, the mixed fuel is not compatible, resulting in chemical sediment and sludge formation. This fuel incompatibility can result in chemical degradation reactions that form solids that will plug nozzles and filters and render the entire contents of the storage tank unusable. Previous research has shown that polar organic nitrogen functional groups are involved in fuel instability reactions. These organo-nitrogen compounds are difficult and expensive to completely remove during the refining process; hence, this investigation involved the removal of these compounds employing three heterogeneous catalyst systems and combinations of these systems as filtering media. An unstable fuel was treated separately with Sc₂O₃, Cu/Sc₂O₃, fullerene (F), a 1:1 ratio of Sc₂O₃:(F), and a 1:1 ratio of Cu/Sc₂O₃:(F). The composition of the filtrates after filtering with the different catalytic systems was analyzed by combined gas chromatography/mass spectrometry (GC/MS). The results of this study showed that after treating the fuel with the catalyst systems, the organic nitrogen compounds detected in the extract were 0.29% carbazoles, 18.2% indoles, and 1.0% for both pyrroles and tetrahydroquinolines, and neither pyridines nor quinolines were detected. This investigation showed that scandium oxide, which is a recycled catalyst, is capable of removing organic nitrogen compounds from fuels.     

MINIMIZATION OF THE RATE OF AMBIENT DIOXYGEN CONSUMPTION BY A COAL-DERIVED MIDDLE DISTILLATE

ABSTRACT

Rates of molecular oxygen consumption at 23°C and 1 atm O₂ by a coal-derived middle distillate containing cyclohexanol and other additives are reported. Significant inhibition of fuel oxidation was observed in the presence of 0.15% w/w benzylidene benzoylhydrazine, HBBz, but was not observed if the fuel had first been treated with pentane to precipitate gum and the predominant metals. Gum precipitated in the presence of HBBz had a higher S content than in its absence. Equilibria between HBBz, metals in the fuel and catalyst X (which may contain sulfur) are suggested to account for inhibition of fuel oxidation by HBBz.     

Soybean Biodiesel: Instability Reactions

Abstract

It has been suggested that renewable energy sources be considered as replacements for middle distillate ground transportation and marine fuels. It is vital for the operational considerations of these fuels to investigate the many positives and negatives of incorporating these renewable energy sources in such systems. In proposing such a replacement, considerations must be given to the many problems that could arise including fuel storage stability, fuel solubility, oxidative stability, and seawater stability. Contrary to air environments, water environments have a pH factor that has to be considered. United States Navy shipboard fuel tanks compensate for diminishing fuel by the addition of seawater to the fuel tank. It was found that this would lead to fuel instability problems such as filter stoppage and other serious engine damage. Studies were performed to determine what in the soybean-derived biodiesels led to the observed fuel degradation.     

JFTOT MODEL STUDIES: OXIDATION OF SELECTED MODEL ORGANOSULFUR COMPOUNDS IN DODECANE

Abstract

Active oxygen species such as peroxides can exert deleterious influences on middle distillate fuels. Because the oxidation of fuels is a complex process involving time, temperature, heteroatoms, hydroperoxides, and various other reactive species it is not well understood. Model studies provide a means for isolating some of these variables. This paper examines the oxidation of selected organosulfur compounds in a model fuel, dodecane, in a modified JFTOT apparatus. The results can be correlated to model studies at lower temperatures.