Hydrotreating Chemistry of Model Products from Bioprocessing of Carbazoles

and, David C. Bressler; Gray, Murray R.

doi:10.1021/ef010284o

Cited by 15 publications

(5 citation statements)

References 18 publications

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“…stainless steel tubing and Swagelok fittings. Similar microreactors have been used in previous studies. – All reactors were built by the Chemical and Materials Engineering Department Machine Shop and were constructed using similar methods. Microreactors modified with either a thermocouple or a pressure gauge were used to assess the internal reactor conditions .…”

Section: Methodsmentioning

confidence: 99%

Pyrolytic Decarboxylation and Cracking of Stearic Acid

Maher

Kirkwood

Gray

et al. 2008

Ind. Eng. Chem. Res.

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101

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The primary objective of this work was to study the pyrolytic conversion of fatty acids to produce deoxygenated, liquid hydrocarbon products for use as renewable chemicals or fuels. Stearic acid (n-octadecanoic acid) was chosen as a model compound for the free fatty acids liberated through the hydrolysis of beef tallow. Batch pyrolysis of stearic acid was conducted over a range of temperatures and times, and the reaction products were extracted and identified through gas chromatography and mass spectrometry. Under mild conditions, n-heptadecane was the main product, with concurrent production of CO 2 , showing that decarboxylation was likely the first reaction to occur. Distinct series of n-alkanes and 1-alkenes developed and shifted to lower carbon numbers with increased temperature and time, consistent with hydrocarbon cracking reactions. Eventually, the series decomposed to aromatics, insoluble solids, and unidentified low-molecular-weight species. Semiquantitative analysis of the chromatographic data confirmed the predominance of n-heptadecane in the product mixture, the development and decomposition of the aliphatic species, the selectivity for n-alkanes over 1-alkenes, and the shift in product distribution toward lower carbon numbers. This work demonstrates the feasibility of producing liquid hydrocarbons through the pyrolysis of free fatty acids hydrolyzed from lipid feeds.

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Section: Methodsmentioning

confidence: 99%

Pyrolytic Decarboxylation and Cracking of Stearic Acid

Maher

Kirkwood

Gray

et al. 2008

Ind. Eng. Chem. Res.

Self Cite

101

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“…For example, Bressler and Gray (419) showed that the biodegradation of CARs yielded products that can be readily hydroprocessed using conventional techniques. For example, Bressler and Gray (419) showed that the biodegradation of CARs yielded products that can be readily hydroprocessed using conventional techniques.…”

Section: Vi5 Biodenitrogenationmentioning

confidence: 99%

Hydrodenitrogenation of Petroleum

Furimsky¹,

2005

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A high level of hydrodenitrogenation (HDN) is required to achieve a desirable conversion of other hydroprocessing reactions. This results from a strong adsorption of nitrogen-containing compounds on catalytic sites that slows down the hydrogen activation process and hinders the adsorption of other reactants. Studies on model compounds and real feeds indicate that less than 50 ppm of nitrogen in the feed can poison catalytic sites. Kinetic studies determined adsorption constants of various nitrogen-containing compounds and concluded that at least four different catalytic sites are required to interpret experimental observations in contrast with a dual site site ffi concept, which only considered two sites. The advancements in experimental techniques allowed identification of products formed during very early stages of hydrodenitrogenation. These results confirmed that the removal of the amino group from saturated amines, as the last step in hydrodenitrogenation, is governed by the type of carbon to which the amino group is attached rather than the number of hydrogen atoms attached to carbon in a and b position to nitrogen Performance of conventional Co(Ni)Mo(W)/Al 2 O 3 catalysts during hydrodenitrogenation was enhanced by combination with various additives and by replacing the traditionally used g-Al 2 O 3 support with novel supports. Catalytic functionalities could be modified by using different precursors of active metals and varying conditions during preparation. Progress has been made in the development of catalysts possessing a high selectivity for hydrodenitrogenation. In this case, the nonconventional catalysts based on the carbides and nitrides of transition metals exhibited high activity and selectivity. Noble metal sulfides alone or supported on different supports were active for HDN as well. Feedstocks used for catalyst evaluation included model compounds and mixtures of model compounds as well as real feeds. The challenges in the development of catalysts for hydrodenitrogenation of heavy feeds containing asphaltenes and metals have been identified.In general, compared to Q, conversions were little affected by a methyl (Me) on the aromatic ring, while being lower for Me on the N-ring, except for 2-MeQ. It is evident that Me substitution in the 2-position had little effect on HDN over the NiMoP/Al 2 O 3 catalyst, whereas it actually enhanced the HDN rate over the CoMo/Al 2 O 3 catalyst. For both catalysts the HDN rate was suppressed in 6-MeQ and particularly in 3-MeQ and 4-MeQ. The distribution of N-containing intermediates was influenced by the ring substitution and the type of catalyst. This suggests that several factors influence the overall HDN mechanism of Qs. This should be kept in mind while analyzing differences in the networks proposed by different authors.The preceding discussion on the HDN of Q mostly referred to conventional catalysts. A number of studies on the HDN of Q were conducted over unconventional catalysts. For example, 3-and 4-MeQs were more reactive than Q over the unsupported Zr,...

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“…One alternate approach to remove unwanted heterocyclic compounds is to use bacterial cells or enzymes as biocatalysts . The difference from biodesulfuration, to date, is that no bacterial isolates efficient for biodenitrogenation have been reported . The previous methods are efficient for the removal of basic nitrogen compounds, but none of them seemed to be efficient or selective enough to remove neutral nitrogen compounds such as indole 1 and carbazole 2 .…”

Section: Introductionmentioning

confidence: 99%

Novel Methodology toward Deep Desulfurization of Diesel Feed Based on the Selective Elimination of Nitrogen Compounds

Macaud

Sévignon

Favre‐Réguillon

et al. 2004

Ind. Eng. Chem. Res.

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π-Acceptor molecules covalently attached on hydrophilic support were used to selectively remove neutral nitrogen heterocyclic compounds from diesel feed by a charge transfer mechanism. Functionalized hydrophilic polymers can effectively adsorb nitrogen heterocyclic compounds with a high selectivity toward sulfur heterocyclic compounds from model and real feed. The results showed that charge transfer processes coupled with an ion-exchange process to selectively remove basic nitrogen compounds are efficient enough to produce denitrogenated feed in high yield. This study was conducted to determine whether trends in hydrodesulfurization (HDS) activity with lower sulfur content were mainly the result of lower reactivity of hindered sulfur compounds or due to nitrogen species inhibition. The inhibition effects of nitrogen compounds on HDS at conditions commonly used in the hydrotreatment of gas oil feedstocks has been experimentally determined. This study suggests that the selective removal of nitrogen compounds from gas oil strongly enhanced the deep desulfurization.

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Hydrotreating Chemistry of Model Products from Bioprocessing of Carbazoles

Cited by 15 publications

References 18 publications

Pyrolytic Decarboxylation and Cracking of Stearic Acid

Pyrolytic Decarboxylation and Cracking of Stearic Acid

Hydrodenitrogenation of Petroleum

Novel Methodology toward Deep Desulfurization of Diesel Feed Based on the Selective Elimination of Nitrogen Compounds

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