Arno de Klerk

University of Alberta

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James H. Gary

Colorado School of Mines

Glenn E. Hwerk

Louisiana State University

Mark J. Kaiser

Louisiana State University

Natalia Montoya Sánchez

University of Alberta

Vinay Prasad

University of Alberta

Glaucia H. C. Prado

University of California, Davis

Reinier J. J. Nel

Sasol (South Africa)

Muhammad N. Siddiquee

King Fahd University of Petroleum and Minerals

Cibele Melo Halmenschlager

University of Alberta

Joy H. Tannous

United Arab Emirates University

Cooperative Institutions

University of Alberta

Sasol (South Africa)

Alberta Hospital Edmonton

University of KwaZulu-Natal

University of Kentucky

Universidade Estadual de Campinas (UNICAMP)

Imperial College London

University of Pretoria

Cardiff University

United States Geological Survey

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Effect of Solvents on Persistent Free Radical Content in the Absence of Reactions

Energy & Fuels (2022)

Joy H. Tannous Diana Tulegenova Arno de Klerk

The impact of a solvent environment on persistent free radical concentrations at ambient conditions was studied by electron spin resonance spectrometry. The analyte selected was Canadian oil-sand-derived bitumen due to its high persistent free radical content. The ability of 54 different solvents to produce a homogeneous 5 wt % solution of bitumen was evaluated. The influence of solvents on the free radical content in bitumen was determined exclusively for solvents that were capable of quantitatively dissolving the bitumen. These were compounds in the classes of alkynes, mono- and bicyclic benzene-derivatives, and heteroatom-containing compounds containing nitrogen, oxygen, sulfur, and chlorine. It was found that a shift in the g-factor of bitumen occurred when the solvent was changed. The shift was attributed to the radical–solvent interaction that is affected by the polarity of the solvent and reflected in the solvent dipole moment property. The change in the free radical concentration was independent of changes in g-factor and was not correlated with any of the following solvent properties: molecular weight, dipole moment, dielectric constant, refractive index, density, and viscosity. There was a relationship between the free radical concentration in bitumen and the ionization potential of sulfur-containing and diaromatic hydrocarbon solvents. It was concluded that the bulk liquid properties that affected the electronic environment of the free radical species, resulting in a shift in g-factor, were not related to the bulk liquid properties that affected the dissociation equilibrium and resulted in a change in the free radical concentration.

Heteroatom

10.1021/acs.energyfuels.2c00300

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Citations (10)

Fischer–Tropsch Syncrude: To Refine or to Upgrade?

Vincenzo Calemma Arno de Klerk

This chapter contains sections titled: Synopsis Introduction Wax Hydrocracking and Hydroisomerization Olefin Dimerization and Oligomerization References

Fischer–Tropsch process

Upgrade

10.1002/9783527656837.ch14

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Citations (3)

Refining Technology Selection

Arno de Klerk

This chapter contains sections titled: Introduction Hydrotreating Addition and Removal of Oxygen Alkene Conversion Alkane Conversion Residue Conversion Fischer–Tropsch Refining Technology Selection References

Refining (metallurgy)

Alkane

Alkene

Fischer–Tropsch process

10.1002/9783527635603.ch16

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Citations (2)

Integration of Fischer–Tropsch and Oilsands Bitumen Production Processes

Energy & Fuels (2016)

Arno de Klerk

Oilsands bitumen production facilities need heat, water, and hydrogen to recover and upgrade bitumen. Hydrogen is usually derived from synthesis gas, which also provides an opportunity for Fischer–Tropsch synthesis. Heat, process, and product integration benefits were pointed out in the literature, and the literature was reviewed. New integration opportunities were identified, as well as technical aspects that should be considered in such integration. Heat integration of air separation and the impact of Fischer–Tropsch technology selection on the quality of heat integration were discussed. Integration of water management and the potential use of the Fischer–Tropsch aqueous products for bitumen recovery, demetalation, viscosity reduction, and pH management were described. Limited opportunity for integration of gas cleaning was found. Process integration during primary product separation, as well as various strategies to derive more benefit from gaseous products, was outlined. Gaseous product processing strategies that were described include the use of tail gas olefin oligomerization, improved hydrogen recovery, and opportunities related to froth treatment, such as deasphalting, that were of a more speculative nature. The lack of current understanding related to coprocessing Fischer–Tropsch wax with bitumen was highlighted. Lastly, an improvement was shown in the distillation profile of diluted bitumen produced with Fischer–Tropsch products when compared to typical industrial dilution with naphtha or natural gas condensate.

Fischer–Tropsch process

Naphtha

Refinery

10.1021/acs.energyfuels.6b01924

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Citations (5)

Benzene Reduction in a Fuels Refinery: An Unconventional Approach

Energy & Fuels (2008)

Arno de Klerk Reinier J. J. Nel

The benzene content of motor-gasoline is regulated by fuel specifications that are becoming increasingly stringent. Acid catalyzed alkylation of benzene by olefins in commonly found refinery units was explored as a low cost benzene reduction strategy. Cofeeding benzene to aliphatic alkylation, etherification, and olefin oligomerization processes were evaluated. Benzene can be alkylated in a sulfuric acid-based aliphatic alkylation unit at 5 °C, but significant disruption of the aliphatic alkylation reaction occurs if the feed contains more than 3% benzene. No benzene alkylation was found during reaction at 90 °C in an acidic resin based etherification process, since the alcohol is the proton carrier. When the same process was operated as an olefin oligomerization process (no alcohol in feed), alkylation proceeded. Benzene was also successfully alkylated during H-ZSM-5 based oligomerization (180–280 °C, 4 MPa), but the pore constrained geometry of the zeolite resulted in <5% alkylation selectivity with a hexene feed. Catalysts with a more open pore structure should rather be considered for the industrial application of benzene alkylation in an oligomerization process. Alkylation of benzene by cofeeding it to a solid phosphoric acid catalyzed oligomerization process (220 °C, 3.8 MPa, and benzene to olefin ratio in the range 1:6−6:1) was successful.

10.1021/ef7005996

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Citations (13)

A mechanism study of acid-assisted oxidative stabilization of asphaltene-derived carbon fibers

Carbon Trends (2021)

Desirée Leistenschneider Peiyuan Zuo Yuna Kim Zahra Abedi Douglas G. Ivey

The development of inexpensive carbon fiber precursors is necessary to meet the future demands of carbon fibers. This work shows how asphaltenes, which are obtained as a by-product in bitumen production, can play an important role as such inexpensive carbon fiber precursors. To synthesize carbon fibers from asphaltene, stabilization by means of oxidizing acids (HNO3 and H2SO4) was developed. Stabilization could not be achieved by a non-oxidizing acid (HCl). The reactions leading to fiber stabilization was investigated for nitric acid treatment, which led to oxidation and the incorporation of nitro-groups. Further thermal treatment caused an increase in C/H ratio that was related to decomposition of nitro-groups, which facilitated air oxidation and other reactions leading to the loss of volatile hydrogen-rich products, such as light hydrocarbons. Additionally, the influence of the acid concentration during treatment on fiber properties, such as fiber diameter, composition, tensile strength and elastic modulus, has been examined. The application of the acid treatment leads to carbon fibers with good tensile properties, with a tensile strength and elastic modulus of 811 MPa and 32.7 GPa, respectively. The overall yield of carbon fibers is 37 – 38 wt.%.

Oxidizing agent

Nitric acid

Asphaltene

Carbon fibers

10.1016/j.cartre.2021.100090

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Citations (29)

American Hydrocol Facility

Arno de Klerk

10.1002/9783527635603.ch7

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Citations (0)

Conversion of waste to sustainable aviation fuel via Fischer–Tropsch synthesis: Front‐end design decisions

Energy Science & Engineering (2022)

Natalia Montoya Sánchez Felix Link Garima Chauhan Cibele Melo Halmenschlager Hanan E. M. El‐Sayed

Abstract Front‐end design decisions for a process to produce sustainable aviation turbine fuel from waste materials were presented. The design employs distributed conversion of wastes to oils, which are then transported to a central facility for gasification, syngas cleaning, Fischer–Tropsch synthesis and refining, that is, a spoke ‐ and ‐ hub approach. Different aspects of the front‐end design, that is, the steps up to syngas cleaning, were evaluated. The evaluation employed a combination of case studies, calculations, experimental investigations, and literature review. The supply of sustainable aviation fuel (SAF) as a 50:50 mixture of waste‐derived and petroleum‐derived kerosene to meet the demand of an international airport (Pearson, Toronto) was employed as case study. The amount of raw material required made it impractical to make use of only one type of waste. Using the same set of assumptions, it was shown that in terms of cumulative transport distance required, a spoke ‐ and ‐ hub approach was twice as efficient as centralized processing only. Technologies for decentralized production of oils were assessed, and oils produced by pyrolysis and hydrothermal liquefaction (HTL) in pilot‐scale and larger facilities were procured and characterized. These oils were within the broader compositional space of pyrolysis oils and HTL oils reported in laboratory studies. The oil compositions were employed to study the impact of oil composition on entrained flow gasification. Thermodynamic equilibrium calculations of pyrolysis and HTL oil entrained flow gasification resulted in H 2 /CO ratios of syngas and O 2 consumption rates in a narrow range, despite the diversity of feeds. At the same time, to produce an equal molar amount of syngas (H 2 + CO), less HTL oil than pyrolysis oil was required as feed. Gas cleaning technologies were reviewed to ascertain types of contaminants anticipated after gasification, their removal effectiveness, and Fischer–Tropsch catalyst poisoning potential. Raw syngas cleaning requirements were comparable to that from coal gasification.

Hydrothermal liquefaction

Refinery

Fischer–Tropsch process

Kerosene

10.1002/ese3.1072

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Citations (27)

Impact of co-feeding cracked light products on visbreaking of vacuum residue deasphalted oil

Fuel (2021)

Joy H. Tannous Yuwei Yan Arno de Klerk

Naphtha

Pentane

Kerosene

Residue (chemistry)

Asphaltene

10.1016/j.fuel.2021.122182

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Citations (10)

Catalysis in the Refining of Fischer-Tropsch Syncrude

The Royal Society of Chemistry eBooks (2010)

Arno de Klerk Edward Furimsky

Fischer-Tropsch Synthesis (FTS) has been used on a commercial scale for more than eighty years. It was initially developed for strategic reasons because it offered a source of transportation fuels that was independent from crude oil. Unlike crude, Fischer-Tropsch synthetic crude is rich in olefins and oxygenates, while being sulphur and nitrogen free. Consequently, the catalysis involved in refining it is significantly different and only a few catalysts have been developed for the purpose. Until now, an account of this topic has been missing from the literature, despite mounting interest in the technology. This is the first book to provide a review and analysis of the literature (journal and patent) on the catalysis needed to refine syncrude to transportation fuels. It specifically highlights the impact of oxygenates and how oxygenates affect selectivity and deactivation. This aspect is also related to the refining of biomass derived liquids. Topics covered include: dimerisation / oligomerisation, isomerisation / hydroisomerisation, catalytic cracking / hydrocracking and hydrogenation, catalytic reforming, aromatic alkylation, etherification, dehydration, and some oxygenate and wax specific conversions.

Oxygenate

Fischer–Tropsch process

Refining (metallurgy)

10.1039/9781849732017

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Citations (128)