Hydrocarbon Addition Reactions during Low-Temperature Autoxidation of Oilsands Bitumen

Siddiquee, Muhammad N.; Klerk, Arno de

doi:10.1021/ef501694s

Cited by 25 publications

(64 citation statements)

References 24 publications

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“…8 The GC-MS analyses were performed using an Agilent 78820A GC coupled with an Agilent 5977E mass spectrometer. The products were separated on an HP-5 30 m × 0.25 mm × 0.25 μm column.…”

Section: Methodsmentioning

confidence: 99%

“…A systematic study of hydrocarbon addition reactions was performed, 8 which confirmed the formation of addition products and the particularly deleterious impact of molecules containing five-membered aliphatic rings. However, oilsands bitumen does not consist of just hydrocarbons; it also contains sulfur, nitrogen, and oxygen.…”

Section: Introductionmentioning

confidence: 92%

“…9 The heteroatoms can be found in aliphatic and aromatic heterocyclic molecules. The study of addition reactions due to low temperature oxidation of hydrocarbons 8 was therefore extended to heterocyclic compounds.…”

Section: Introductionmentioning

confidence: 99%

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Heterocyclic Addition Reactions during Low Temperature Autoxidation

Siddiquee

Klerk

2015

Energy Fuels

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Low temperature air oxidation affects many aspects of the fuels business: weathering, storage stability, hardening, and fouling. Addition reactions taking place during the autoxidation of different heterocyclic compound classes were studied at 130°C. This investigation reports on the conversion, product selectivity, nature of addition products, and plausible mechanisms that would explain the observations subsequent to the oxidation of indole, 2,3-dihydroindole, quinoline, benzofuran, 2,3-dihydrobenzofuran, and thianaphthene. Of these, indole is known to be prone to oxidative addition. Among the five-membered heterocyclic compounds, the propensity to form oxidative addition products increased in the order: S ≪ O < N. Addition took place mainly through C−C bond formation. In comparison to hydrocarbons, it was surprising to find that indole and 2,3-dihydroindole were less prone to oxidative addition than the five-membered naphtheno-aromatic hydrocarbon analogues indene and indan. On the basis of the work, some implications for low temperature oxidation processes, and free radical processes in general, are discussed.

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“…8 The GC-MS analyses were performed using an Agilent 78820A GC coupled with an Agilent 5977E mass spectrometer. The products were separated on an HP-5 30 m × 0.25 mm × 0.25 μm column.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

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Heterocyclic Addition Reactions during Low Temperature Autoxidation

Siddiquee

Klerk

2015

Energy Fuels

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“…2, 3, 4). Oxidation may also give rise to addition reactions [19], particularly in materials that are rich in naphtheno-aromatics, such as the asphaltenes feed. Thus, the polarity, solubility parameter and molecular mass of the molecules were likely increased by oxidation.…”

Section: Discussionmentioning

confidence: 99%

Low-temperature oxidative asphaltenes liquefaction for petrochemicals: fact or fiction?

Sánchez

Klerk

2016

Appl Petrochem Res

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Asphaltene is the heavy and heteroatom-rich fraction of petroleum that is rejected during a solvent deasphalting process. In patent literature there are claims that state that this material can be converted into an aromatic petrochemical feedstock by oxidative liquefaction at low temperature. To evaluate the validity of these claims, asphaltenes from an industrial solvent deasphalting process were oxidized with dry and water-saturated air at temperatures in the range 45-100°C. Infrared spectroscopy of the oxidized product confirmed that oxygen was incorporated as C=O and C-O. Under all experimental conditions studied little oxidative degradation was observed that would lead to the production of a petrochemical feedstock. Nevertheless, some observations of scientific value were made about the low-temperature conversion of asphaltenes. During autoxidation with dry air, the n-pentane-insoluble fraction increased. On the contrary, when oxidation was conducted with water-saturated air, the formation of additional n-pentane-insoluble material was suppressed. Mild heating of asphaltenes under nitrogen atmosphere also caused the n-pentane-insoluble content to increase. Spectroscopic evidence showed that esters are formed during oxidation at *100°C. The temperature dependence of this reaction was explained and a possible reaction pathway for cycloalkane to ester conversion was presented. Ester selectivity was determined by the competition between hydrogen abstraction and b-scission of the alkoxy radical.

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“…5,13,14 Secondary oxidation products (oxidized multiple times), and in some cases addition products (dimerized/ oligomerized), are also generated. 15 Oxidation proceeds via a free radical mechanism, which is well studied and reviewed in literature. 5,13,14 Alkyl free radicals (R˙) are formed (initiation) during the induction period, but initiation has no appreciable effect on product selectivity.…”

Section: Introductionmentioning

confidence: 99%