Molecular Weight Measurement of UG8 Asphaltene Using APCI Mass Spectroscopy

Cunico, Robert L.; Sheu, Eric Y.; Mullins, Oliver C.

doi:10.1081/lft-120038719

Cited by 66 publications

(60 citation statements)

References 17 publications

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“…A lot of analytical tools have been used to determine molecular weights of asphaltenes (Bergmann et al, 2002;Cunico et al, 2002;Hugley et al, 2002;Speight et al, 1985). However, results interpretations are often difficult and critical since results are strongly dependent on the methodology and experimental conditions (Herod et al, 2000;Nali and Manclossi, 1995;Vasquez and Mansoori, 2000).…”

Section: Introductionmentioning

confidence: 96%

Size Exclusion Chromatography: Characterization of Heavy Petroleum Residues. Application to Resid Desulfurization Process

Merdrignac

Truchy

Robert

et al. 2004

Petroleum Science and Technology

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Size exclusion chromatography (SEC) is still the only of the existing analytical methods that can easily and routinely provide information on relative asphaltene molecular weight distributions. However, molecular weight characterization still suffers from several physicochemical drawbacks such as association of molecular units, adsorption on column material and lack of appropriate standards, which are not always underlined in the petrochemical literature where SEC is used as a routine analytical tool. Thus, the resulting molecular weight distribution can be either overestimated or underestimated depending on the chosen experimental conditions: sample concentration, solvent, temperature, type of column packing. In order to ORDER REPRINTS further reduce these artefacts, the influence of the above operating parameters has been studied on Arabian petroleum asphaltenes. Our results show that the obtained bimodal profiles are mainly due to association-dissociation phenomena rather than the co-existence of two distinct molecular populations of low and high molecular weights. Based on these results, samples from pilot plants were studied. We will show that SEC enables to differentiate asphaltenes from different source rocks and to follow feed and effluent evolutions during hydroconversion process. Even though this technique should be only used on a relative basis to compare molecular weight distributions at given analytical conditions, it was revealed to be very useful for the understanding of main hydroconversion reaction pathways.

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Section: Introductionmentioning

confidence: 96%

Size Exclusion Chromatography: Characterization of Heavy Petroleum Residues. Application to Resid Desulfurization Process

Merdrignac

Truchy

Robert

et al. 2004

Petroleum Science and Technology

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“…41 Electrospray ionization is suitable for ionizing polar constituents of asphaltenes with a high heteroatom content, while atmospheric pressure chemical ionization (APCI) and atmospheric pressure photo ionization are more suitable for ionizing the nonpolar constituents. 37,[42][43]44 A variety of additional desorption/ionization methods have been utilized for asphaltene analysis, such as matrix-assisted laser desorption/ionization, 14 field desorption/field ionization, 45 and laser-induced acoustic desorption/electron ionization. 39 In this work, positive ion mode APCI doped with carbon disulfide (CS 2 ) was used to evaporate and ionize six petroleum asphaltene samples of different geographical origins in a linear quadrupole ion trap (LQIT) mass spectrometer.…”

Section: Introductionmentioning

confidence: 99%

Structural Comparison of Asphaltenes of Different Origins Using Multi-stage Tandem Mass Spectrometry

et al. 2015

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In this work, six petroleum asphaltene samples of different geographical origins were studied using atmospheric pressure chemical ionization (APCI) in positive ion mode in a linear quadrupole ion trap mass spectrometer (LQIT). APCI doped with carbon disulfide reagent was selected as the ionization method as it has been previously demonstrated to generate stable molecular ions with no fragmentation for asphaltene molecules. The mass spectra measured using this approach revealed the apparent molecular weights (MWs) of the molecules in the asphaltene samples. The results show that petroleum asphaltenes from the American continent, Europe and China have similar apparent molecular weight distributions, ranging from 200 up to 1450 Da, with slightly different apparent average MWs ranging from 570 to 700 Da. Further, molecular ions with eight randomly selected mass-to-charge ratios (m/z) ranging from m/z 500 up to m/z 808 were isolated for each asphaltene sample and subjected to collisionally activated dissociation (CAD) at the same collision energy to examine their structures. The CAD mass spectra (MS 2 experiment) provided information on the maximum total number of carbons in the alkyl chains and the smallest possible size of the aromatic cores in the ionized molecules. Additionally, MS 3 experiments were performed to investigate the fragmentation patterns of the fragment ions generated in the MS 2 experiments. The results obtained support the island structural model for these asphaltenes. Moreover, molecules of greater MWs are shown to have more carbons in alkyl chains (ranging from 17 to 41) but the minimum core size is fairly constant.

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“…Recent atmospheric pressure photo ionization (APPI-MS) mass spectroscopy and atmospheric pressure chemical ionization (APCI-MS) mass spectroscopy measurements showed excellent agreement with all previous measurements cited above. [21,22] The world's highest resolution mass spectrometer employs electrospray ionization -Fourier transform ion cyclotron resonance mass spectroscopy (ESI-FT-ICR-MS). Studies of heavy Venezuelan crude oils find asphaltene molecular weights consistent with all the above results.…”

Section: Asphaltene Molecular Structurementioning

confidence: 99%

Molecular Structure and Aggregation of Asphaltenes and Petroleomics

Mullins

Sheu²

2005

Proceedings of SPE Annual Technical Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractTremendous strides have been made recently in asphaltene science. Many advanced analytical techniques have been applied recently to asphaltenes elucidating many asphaltene properties. The inability of certain techniques to provide correct asphaltene parameters has also been clarified. Longstanding controversies have been resolved. For example, molecular structural issues of asphaltenes have been resolved, in particular, asphaltene molecular weight is now known. The primary aggregation threshold has recently been established by a variety of techniques. Characterization of asphaltene interfacial activity has advanced considerably. The hierarchy of asphaltene aggregation has emerged into a fairly comprehensive picture -essentially in accord with the Yen model with the additional inclusion of certain constraints. Crude oil and asphaltene science is now poised to develop proper structure-function relations that are the defining objective of the new field -Petroleomics. The purpose of this paper is to review of these developments in order to present a more clear and accessible picture of asphaltenes -especially considering that the asphaltene literature is a bit opaque.

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Molecular Weight Measurement of UG8 Asphaltene Using APCI Mass Spectroscopy

Cited by 66 publications

References 17 publications

Size Exclusion Chromatography: Characterization of Heavy Petroleum Residues. Application to Resid Desulfurization Process

Size Exclusion Chromatography: Characterization of Heavy Petroleum Residues. Application to Resid Desulfurization Process

Structural Comparison of Asphaltenes of Different Origins Using Multi-stage Tandem Mass Spectrometry

Molecular Structure and Aggregation of Asphaltenes and Petroleomics

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