Structure of Maya Asphaltene−Resin Complexes through the Analysis of Soxhlet Extracted Fractions

Douda, J.; Llanos, M. E.; Alvarez, Regina; Navarrete, J.

doi:10.1021/ef034057t

Cited by 42 publications

(30 citation statements)

References 24 publications

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“…The FTIR bands assignment for asphaltene samples (measured with a Shimadzu FTIR-8900 spectrometer equipped with a ZnSe internal reflection element) are summarized in Table 1. The spectra show common features of asphaltenes (18)(19)(20), namely, a peak around 3050 cm -1 corresponding to aromatic double bonds, and peaks around 2930 (very strong) and 2850 corresponding to CH 3 and CH 2 groups (aliphatic C-H stretching). A band at 3080 cm -1 also appears, probably related with the presence of amino groups.…”

Section: Asphaltene Extractionmentioning

confidence: 97%

Properties of Venezuelan Asphaltenes in the Bulk and Dispersed State

2006

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High oil prices have renewed the interest not only in new sources of energy but also in using more efficiently the available oil reserves, which are mostly of the heavy or bituminous type. Many of the problems associated with processing of heavy crude oils come from asphaltenes, roughly defined as fractions which are soluble in aromatic solvents such as toluene and benzene and insoluble in alkanes such as pentane or heptane (1,2). This scientifically vague definition makes difficult a precise characterization of asphaltenes, which composition and structure depends on the source and it is therefore a matter of discussion. In general, the chemical structure consists of an aromatic nucleus with several benzenic rings surrounded by alkyl chains and heteroatoms (1) .However, it is difficult to estimate a precise molecular weight due to association among molecules (3). The behavior of asphaltenes in solution has also 563 JOS

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Section: Asphaltene Extractionmentioning

confidence: 97%

Properties of Venezuelan Asphaltenes in the Bulk and Dispersed State

2006

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“…The chemical structure and physicochemical properties of petroleum and its subfractions are not fully understood; nevertheless, many analytical approaches have given, until now, some valuable indications. They have been employed alone or coupled (for example, using MS, NMR, FT‐IR or UV‐vis or using them all together) 2–17. Elemental analysis is also a test usually considered when an analysis on petroleum is performed.…”

Section: Introductionmentioning

confidence: 99%

“…In another recent paper, Bolaños et al 11 compared field desorption (FD)‐MS, electron ionization (EI)‐MS and FT‐IR data on an asphaltene–resin complex sample fractionated by Soxhlet extraction. Asphaltene and maltene compositions and structural information were obtained, indicating how aromaticity, presence of heteroatoms, polarity and functional groups influence either the external surface or the inner part of the asphaltene micelle.…”

Section: Introductionmentioning

confidence: 99%

Laser desorption/ionization techniques in the characterization of high molecular weight oil fractions. Part 1: asphaltenes

Rizzi¹,

Cosmina

Flego

et al. 2006

J. Mass Spectrom.

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The molecular weight distribution of the asphaltene fractions of two types of crude oils from two different Italian fields (samples 1 and 2) was investigated. The analytical tools used to perform these analyses were matrix assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) mass spectrometry. After observing that the use of the matrix (as well as the addition of Ag+) did not improve the quality of the data compared to that obtained in LDI conditions, all further measurements were performed with the latter technique. Operating under usual conditions of laser power and delay time, a very low resolution was observed, showing only macroscopic differences between the two samples in the molecular weight distribution of the different components. An accurate study on the possible reasons of this undesirable behavior indicates that it can originate from space charge phenomena occurring either in the ion source region or during the flight. A valid parameterization of the delay time and the laser power allowed higher quality spectra to be obtained. Surface-enhanced laser desorption ionization (SELDI) measurements were also performed using normal phase (silica) as the sample holder surface. Under these conditions, better results are obtained, proving that the sample-surface interaction is important to achieve, by means of laser irradiation, a homogeneous set of product ions. Both asphaltene samples were fractionated in five subfractions by gel-permeation chromatography (GPC) to obtain a better separation of the molecular weight distributions; the related spectra confirmed these findings. By using different approaches, relevant and reproducible differences between the asphaltene fractions of the two oil samples were observed.

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“…It enables the release of analyte molecules which are trapped within structures of complex samples [1]. It can also improve analytical selectivity.…”

Section: Introductionmentioning

confidence: 99%