Effects of Bromination-Dehydrobromination on the Microstructure of Isotropic Pitch Precursors for Carbon Fibers

Liang, Dingcheng; Liu, Deqian; Yang, Shuai; Lu, Changyu; Xie, Qiang; Liu, Jinchang

doi:10.3390/polym12123059

Cited by 13 publications

(7 citation statements)

References 26 publications

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“…The reaction time was started the moment the reactor was submerged in the oil bath, and in a typical experiment, the reaction time was set to 4 h. The silicone oil bath was placed on the Fisherbrand Isotemp hot plate, and the temperature of the oil bath was regulated through the temperature sensor attached to the hot plate, which was submerged into the oil bath during the reaction. In addition to the more limited extent of the bromination, two important differences in the debromination procedure between this work and others − can be pointed out: (i) lower debromination temperature and (ii) the use of a closed system. Both differences would decrease the extent of debromination that could be achieved during pretreatment, with more of the original bromine being retained in the product.…”

Section: Experimental Sectionmentioning

confidence: 80%

“…Autoxidation is routinely used to increase viscosity of road paving asphalt and is employed during oxidative stabilization of carbon fibers after melt spinning. Mild halogenation of asphaltenes also resulted in a higher viscosity product, and bromination–debromination has been used for the preparation of carbon fiber precursor materials. − …”

Section: Introductionmentioning

confidence: 99%

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Rigorous Deasphalting, Autoxidation, and Bromination Pretreatment Methods for Oilsands Bitumen Derived Asphaltenes to Improve Carbon Fiber Production

et al. 2021

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Carbon fiber production from asphaltenes was identified as a potential noncombustion process to add value to the n-pentane insoluble fraction of oilsands bitumen. Methods to pretreat the asphaltenes before melt spinning to improve its properties for carbon fiber production were investigated. Oilsands bitumen derived asphaltenes from an industrial npentane solvent deasphalting process served as raw material for this study. The material was characterized before and after pretreatment, and the melt spin properties were evaluated. Selected carbon fiber products were also oxidatively stabilized and carbonized to be characterized as carbonized carbon fibers. It was found that pretreatment by rigorous n-pentane and nheptane deasphalting, autoxidation (190−250 °C), and bromination with Br 2 (150−170 °C) followed by debromination (200 °C) had a minor impact on the CHNS elemental composition. At the same time, noticeable changes were found in the physical properties of the pretreated products with an increased softening point temperature for melt spinning. In most cases, the melt spin productivity was improved. The exception was the poorer melt spin productivity for n-heptane insoluble material, which was tentatively ascribed to a lack of lighter material to act as plasticizer. Variability in the fiber diameter of carbonized fibers was noticeably reduced by autoxidation as pretreatment even at the mildest conditions studied. Yet, despite the noted effects of pretreatment on physical properties and melt spin behavior, it was found that pretreatment did not cause a meaningful change in the tensile strength or Young's modulus of the carbonized fiber products compared to carbon fibers produced from the industrial asphaltenes without any pretreatment.

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Section: Experimental Sectionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Rigorous Deasphalting, Autoxidation, and Bromination Pretreatment Methods for Oilsands Bitumen Derived Asphaltenes to Improve Carbon Fiber Production

et al. 2021

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“…The details of the precursor preparation process are available in literature. [49][50][51][52][53][54] The scope of the current review is limited to the precursor preparation only, more specifically following the controlled autoxidation.…”

Section: Value-added Products (Carbon Fiber) From the Low-value Heavy...mentioning

confidence: 99%

Prospect of Controlled Autoxidation to Produce High‐Value Products from the Low‐Value Petroleum Fractions

Siddiquee

2024

The Chemical Record

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Substantial amounts of low‐value light petroleum fractions and low‐value heavy petroleum fractions, such as light naphtha, HVGO, and vacuum residue, are generated during the upgrading and refining of conventional and unconventional petroleum resources. The oil industry emphasizes economic diversification, aiming to produce high‐value products from these low petroleum fractions through cost‐effective and sustainable methods. Controlled autoxidation (oxidation with air) has the potential to produce industrially important oxygenates, including alcohols, and ketones, from the low‐value light petroleum fractions. The produced alcohols can also be converted to olefin through catalytic dehydration. Following controlled autoxidation, the low‐value heavy petroleum fractions can be utilized to produce value‐added products, including carbon fiber precursors. It would reduce the production cost of a highly demandable product, carbon fiber. This review highlights the prospect of developing an alternative, sustainable, and economic method to produce value‐added products from the low‐value petroleum fractions following a controlled autoxidation approach.

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“…It was proved experimentally that the components of the obtained brominated products do not change along with the increase in reaction time. 94,95 The bromination-debromination method can achieve the controlled synthesis of pitch precursors from molecular dimension and effectively control excessive polycondensation to produce a linear and crosslinked molecular structure, thus improving the melt-spinning properties of pitch precursors and the mechanical performance of the final carbon fibers.…”

Section: Bromination-debrominationmentioning

confidence: 99%

Mechanism and application of halogenation–dehalogenation in the development of pitch-based carbon fiber: A review

Liu

et al. 2023

Journal of Engineered Fibers and Fabrics

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Pitch-based carbon fiber, as one of the important engineering materials, has been widely used in aerospace, defense, sports, and other fields. In the long production process of pitch-based carbon fiber, the property of pitch precursor is significant for the mechanical performance of obtained carbon fiber. Thus, it is crucial to improve the property of pitch precursor by efficient means. Halogenation–dehalogenation is a newly developed method for the controllable synthesis of a pitch precursor from the molecular dimension, including fluorination–defluorination, chlorination–dechlorination, and bromination–debromination. This work reviewed the mechanism and application, as well as the advantages and disadvantages of each halogenation–dehalogenation method.

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Effects of Bromination-Dehydrobromination on the Microstructure of Isotropic Pitch Precursors for Carbon Fibers

Cited by 13 publications

References 26 publications

Rigorous Deasphalting, Autoxidation, and Bromination Pretreatment Methods for Oilsands Bitumen Derived Asphaltenes to Improve Carbon Fiber Production

Rigorous Deasphalting, Autoxidation, and Bromination Pretreatment Methods for Oilsands Bitumen Derived Asphaltenes to Improve Carbon Fiber Production

Prospect of Controlled Autoxidation to Produce High‐Value Products from the Low‐Value Petroleum Fractions

Mechanism and application of halogenation–dehalogenation in the development of pitch-based carbon fiber: A review

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