Lithium cationization can significantly extend the compositional range for analysis of petroleum components by positive electrospray ionization [(+) ESI], by accessing species that lack a basic nitrogen atom and, hence, are not seen by conventional (+) ESI that relies on protonation as the primary ionization mechanism. Here, various solvent compositions and lithium salts enabled us to optimize ionization by formation of lithium adducts ([M + Li]+), and the results are compared to production of [M + H]+ by conventional (+) ESI with formic acid. Lithium cationization (+) ESI Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of Athabasca bitumen heavy vacuum gas oil (475–500 °C) and North and South American crude oils demonstrates considerable improvement over protonation for production of ions from compounds belonging to SxOy (SO, SO2, SO3, SO4, S2O, S2O2, etc.) heteroatom classes. Those compounds exhibit much higher affinity for lithium cation than for proton and yield abundant [M + Li]+ ions. Li+ cationization thus opens a pathway for detection and characterization of SxOy class compounds that preferentially concentrate at the interface in oil/water emulsions.
Molecular characterization of asphaltenes by conventional analytical techniques is a challenge because of their compositional complexity, high heteroatom content, and asphaltene aggregate formation at low concentrations. Thus, most common characterization techniques rely on bulk properties or solution-phase behavior (solubility). Proposed over 20 years ago, the Boduszynski model proposes a continuous progression in petroleum composition (molecular weight, structure, and heteroatom content) as a function of the atmospheric equivalent boiling point. Although exhaustive detailed compositional analysis of petroleum distillates validates the continuum model, the available compositional data from asphaltene fractions supports the extension of the continuum model into the nondistillables only indirectly. Asphaltenes, defined by their insolubility in alkane solvents, accumulate in high-boiling fractions and form stable aggregate structures at low parts per billion (ppb) concentrations, far below the concentration required for most mass analyzers. Here, we present direct mass spectral detection of stable asphaltene aggregates at lower concentrations than previously published and observe the onset of asphaltene nanoaggregate formation by time-of-flight mass spectrometry (TOF–MS). We conclude that a fraction of asphaltenes must be present as nanoaggregates (not monomers) in all atmospheric pressure and laser-based ionization methods. Thus, those methods access a subset of the asphaltene continuum.
The findings of the present investigation titled, Influence of vermicompost, neem cake and biofertilizers on growth, yield and economics of Green gram (Vigna radiata L.), carried out during the kharif season of 2023 at the Baba Farid Institute of Technology's Crop Research Farm in Dehradun. It is situated between latitude 30.3436 and longitude 77.9367. The Shivalik hills and the lower Himalayas in the Indian states of Uttarakhand, Himachal Pradesh, and Haryana are home to the extraordinarily wide and lengthy valley known as the doon valley. The investigation was conducted in Randomized Block Design consisting of 10 treatment combinations with 3 replications and was laid out with the different treatments allocated randomly in each replication. Application of vermicompost (1.25t/ha) + neem cake (0.625 t/ha) + rhizobium (10 g/kg seed) + PSB (10 g/kg seed), recorded maximum plant height (45.44 cm), Number of branches per plant (6.08), number of nodules/plant (11.05), dry weight (g/plant) (6.57), no. of pods/plant (28.38), seeds per pod (10.13), test weight(g) (38.14), grain yield (1094.06 kg/ha), stover yield (1523.95 kg/ha) and biological yield (2618.01 kg/ha). Where the maximum gross return (101249.80 INR/ha), net return (76043.75 INR/ha) and B:C ratio (3.02) were also recorded with application of vermicompost (1.25 t/ha) + neem cake (0.625 t/ha) + rhizobium (10 g/kg seed) + PSB (10 g/kg seed).
Molecular characterization of sulfur-containing species in petroleum is important because sulfur-containing compounds are detrimental to the environment and the refining processes. In a recent report, the sulfur-containing compounds in a vacuum bottom residue (VBR) were methylated to enhance their detectability by electrospray ionization (ESI) mass analysis. The most abundant sulfur compounds exhibited relatively low double bond equivalents (4 < DBE < 12). Alternatively, atmospheric pressure photoionization (APPI) mass analysis can provide molecular characterization without chemical derivatization. Here, we compare the sulfur speciation of a petroleum vacuum bottom residue by ESI and APPI with a 9.4 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Even after methylation, ions produced by APPI extend to much higher DBE than by ESI. Moreover, analysis of the saturates and aromatics fractions of underivatized VBR by APPI shows comparable ionization efficiency across a broad DBE range. We conclude that methylation is hindered for high-DBE species (DBE > 20), so that methylation followed by ESI MS is not suitable for sulfur speciation of higher-boiling fractions from petroleum crude oil.
Here, we present a case study on a Wyoming well with known asphaltene deposition issues as a result of natural depletion. Field deposits and crude oil from the same well were collected for analysis. Compositional differences between field deposits, lab-generated capillary deposits, and C7-precipitated asphaltenes were determined by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and all three samples show similar trends in composition, displayed as plots of aromaticity versus carbon number. An enrichment of highly condensed aromatic molecules for the field deposit is detected with both ultrahigh-resolution mass spectrometry and thermal cracking experiments and could predict asphaltene deposition. FT-ICR mass spectral analysis of solvent-extracted fractions suggest different deposition mechanisms for field deposits (slow deposition) compared to rapid precipitation in standard asphaltene preparation protocols that contain trapped maltenes.
Abstract A platform in the Campos Basin of Brazil experienced paraffin deposition issues in the inner-field flowline. The paraffin deposition rate was relatively low; however the deposited wax was hard and very sticky making pigging of the line difficult. Comprehensive advanced analyses and characterization of the crude oil and the deposit were conducted to determine the nature of the hardness and stickiness of the deposit. As part of the study, paraffin modifiers were tested to see their effect on the volume, hardness and stickiness of the deposit. The analysis on the deposit that was treated with the paraffin modifier showed a reduction in the components of the deposit that caused the hardness and stickiness of the deposit, resulting in a softer less sticky deposit that is easier to remove by pigging. FT-ICR MS analysis of the field deposit identifies an enrichment of the high molecular weight polar crude oil components that could be the reason for the stickiness of the deposit. Introduction Crude oils contain high molecular weight paraffin hydrocarbons that may precipitate out of the crude oil and form a waxy solid phase when the oil is cooled (due to heat loss to the surroundings) during production and transport operations. Resultant plugging of the pipelines and clogging of transport equipment can often be a challenging problem to control and remediate.1-5 Pigging is one method of removing paraffin deposits from the pipe wall, but pigging programs can be ineffective if the deposited paraffin is hard and sticky. This problem has been experienced by a platform in the Campos Basin of Brazil due to the hard and very sticky nature of the paraffin deposit. The pigging program for the inner-field flowline has been difficult and it is unclear if the pigging program is effective in removing all of the paraffin deposit. A better understanding of the oil composition and the paraffinic hydrocarbons present in the crude oils was sought in order to recommend chemical mitigation strategy. Crude oil sample from the field and paraffinic field deposits were collected for a comprehensive characterization with various analytical techniques, and the effect of wax crystal modifiers was qualitatively examined as potential remediation for deposition. Differential Scanning Calorimetry was employed to study the wax crystallization behavior of the crude oil and the deposit. Paraffinic hydrocarbon distribution of the fluids was characterized with High Temperature Gas Chromatography (HTGC). Efficacy of the wax crustal modifiers was evaluated with established Pour point and Cold Finger Deposition tests. Compositional information on the crude oil sample and the untreated paraffinic field deposit and the lab generated cold-finger deposits was further elucidated via high resolution Fourier transform ion cyclotron resonance mass spectrometry. Negative ion Electrospray Ionization (ESI) and Atmospheric Pressure Photoionization (APPI) coupled to 9.4T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS) were applied to attain extensive compositional knowledge of the fluids' hydrocarbon and hetroaromatic matrix.
Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) enables the direct characterization of complex mixtures without prior fractionation. High mass resolution can distinguish peaks separated by as little as 1.1 mDa), and high mass accuracy enables assignment of elemental compositions in mixtures that contain tens of thousands of individual components (crude oil). Negative electrospray ionization (ESI) is particularly useful for the speciation of the most acidic petroleum components that are implicated in oil production and processing problems. Here, we replace conventional ammonium hydroxide by tetramethylammonium hydroxide (TMAH, a much stronger base, with higher solubility in toluene) to more uniformly deprotonate acidic components of complex mixtures by negative ESI FTICR MS. The detailed compositional analysis of four crude oils (light to heavy, from different geographical locations) reveals that TMAH reagent accesses 1.5–6 times as many elemental compositions, spanning a much wider range of chemical classes than does NH4OH. For example, TMAH reagent produces abundant negative electrosprayed ions from less acidic and neutral species that are in low abundance or absent with NH4OH reagent. More importantly, the increased compositional coverage of TMAH-modified solvent systems maintains, or even surpasses, the compositional information for the most acidic species. The method is not limited to petroleum-derived materials and could be applied to the analysis of dissolved organic matter, coal, lipids, and other naturally occurring compositionally complex organic mixtures.
Precipitation of calcium naphthenate soaps from acidic crude oils poses significant operational challenges. Calcium naphthenate deposition in oil fields results from the interaction of a family of special polycyclic tetracarboxylic acids, known as ARN acids, with divalent metal ions (Ca2+) present in produced water. Calcium naphthenate scaling is being increasingly reported from oil fields in South America. We report detailed analyses of three field deposits from various crude-oil-producing fields in South America. All the field deposits were confirmed as calcium naphthenate scale via advanced analytical probes such as mass spectrometry and high-temperature gas chromatography. These field deposits consisted predominantly of polycyclic tetracarboxylic ARN acids. Presence of ARN acids was also validated in South American crude oils. Furthermore, low molecular weight ARN acids with a C70–C72 hydrocarbon skeleton were identified in all the calcium naphthenate field deposits as well as in the crude oil samples. Another interesting observation reported is the striking resemblance in the molecular signature of ARN acids from South America to those from West Africa.
Asphaltenes represent the most complex fraction of crude oil, consisting of a diverse range of species with varying sizes, solubilities, aggregation states, structural motifs, and heteroatom contents. In prior work, we identified differences between asphaltenes that deposit in subsea flowlines and those that settle in topside processing facilities. These differences were determined through a variety of techniques, including near-infrared absorbance, bulk elemental analyses, saturates, aromatics, resins, asphaltenes composition profiling, and sequential precipitation using alkanes of different carbon numbers (e.g., C5, C6, and C7). This study extends that research by using high-resolution mass spectrometry to identify molecular-level differences between flow-line and separator deposits. Recent advances in separation methods, such as extrography coupled with high-field Fourier transform ion cyclotron resonance mass spectrometry (21 T FT-ICR MS), have minimized the selective ionization effects of ultracomplex asphaltene samples, thereby enhancing our understanding of their molecular composition, including contributions from both island and archipelago structural motifs. In this work, the two deposit samples were fractionated by extrography and characterized by negative-ion electrospray ionization 21 T FT-ICR MS. Our results reveal significant molecular-level differences between the deposits. The flowline deposit is dominated by species with lower aromaticity and molecular weight, which suggests aggregation behaviors driven by hydrogen bonding and acid–base interactions. In contrast, the separator deposit contains highly aromatic species with higher carbon numbers, indicating a stronger tendency for aromatic stacking and, thus, aggregation. These findings imply that the molecular mechanisms driving subsea deposition differ from those responsible for topside settling. Understanding these distinctions can improve our ability to correlate laboratory results with field data and aid in the development of more effective asphaltene control chemicals.
ABSTRACT This paper summarizes the synthesis of some amino acid esters and their derivatives. The structural characteristics of these derivatives have been studied by IR, 1H and 13C NMR spectroscopy. Evaluation of their efficacy with respect to gum and sediment inhibition and dispersant characteristics in highly unstable distillate fuel blends has been carried out. The results of accelerated stability test have been discussed and it is inferred that while most of these derivatives are quite effective for stabilization of fuel, phenyl alanine dodecanoate and N-tert-dodecyl lysine dodecanoate are highly efficient in imparting stability and dispersant characteristics to the fuel employed for study. It has been concluded that structural parameters such as nature of substituents on the amino acid backbone and the type and length of alkyl chains profoundly influence the dispersant as well as stabilizing characteristics.
