Carbonization of methylene-bridged aromatic oligomers—Effect of alkyl substituents

Ida, Takashi; Akada, Katsumi; Okura, Tetsuo; Miyake, Mikio; Nomura, Masakatsu

doi:10.1016/0008-6223(94)00148-s

Cited by 4 publications

(1 citation statement)

References 10 publications

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“…However, because of the aromatization of naphthenic structures and formation of oxygen-containing functional groups during the air blowing process, at the early stage of carbonization, not only is the carbonization reactivity enhanced due to low thermal stability of oxygen-containing functional groups, but also the lack of naphthenic hydrogens neutralizes active free radicals, resulting in rapidly increasing viscosity of the reaction medium and then hinder the formation and coalescence of mesophase structures. In addition, the biphenyl-type structure induced by dissociation of −CO– or −O–C–O– influences the planarity of PAH molecules due to the free rotation of the C–C single bond to reduce the steric hindrance between aromatic rings. , As a result, the mesophase formation and development of as-prepared pitch are restricted by air blowing treatment.…”

Section: Resultsmentioning

confidence: 99%

Structural Modification of Petroleum Pitch Induced by Oxidation Treatment and Its Relevance to Carbonization Behaviors

et al. 2017

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Structural modifications of petroleum pitch and its subfractions induced by mild air-blowing modification have been monitored by elemental analysis, average molecular weight, Fourier transform infrared spectrometer (FTIR), 1 H nuclear magnetic resonance ( 1 H NMR), and carbon residue. Combined with the investigation into carbonization behaviors of asprepared oxidized pitch, the relationship between oxidized modification and carbonization behaviors has also been discussed. With the air blowing treatment process, average molecular weight and oxygen content grow rapidly in the petroleum etherinsoluble fraction of the air-blown pitch in comparison with those of corresponding petroleum ether-soluble fractions, which gradually enlarges the distinction in carbonization reactivity and mutual solubility between these two subfractions. As a result, although the yield of carbonized residue is dramatically increased from 36.1 wt % to 64.5 wt % during the direct thermal carbonization process, the air blowing treatment produces an adverse effect on mesophase development of oxidized pitches, leading to the optical texture index (OTI) significantly decreasing from 35.9 to 0.6. While adding the hydrogen-donor aromatic oil (HAO) into the air-blown pitches is able to effectively improve the mutual compatibility among the solvent subfractions via H-transfer reactions and dilution effect, consequently contributing to mesophase development during the co-carbonization process accompanied by increasing OTI value of mesophase residues to about 65, except 33.6 of the PP25-HAO mixture, simultaneously the co-carbonization process still maintains the relatively high carbonized residue yield between 42.1 and 61.8 wt %. Hence, a possible combined process including air blowing modification and subsequent co-carbonization process can obtain mesophase products with high residue yield and excellent anisotropic texture by controlling the degree of oxidation and selecting compatible co-carbonization additives.

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Section: Resultsmentioning

confidence: 99%