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Examining the molecular entanglement between VO complexes and their matrices in atmospheric residues by ESR

Author:
Cui, Qingyan, Nakabayashi, Koji, Ma, Xiaoliang, Ideta, Keiko, Miyawaki, Jin, Marafi, Abdulazim M. J., Al-Mutairi, Adel, Park, Joo-Il, Yoon, Seong-Ho, Mochida, Isao
Source:
RSC advances 2017 v.7 no.60 pp. 37908-37914
ISSN:
2046-2069
Subject:
asphaltenes, resins, solvents, temperature, toluene
Abstract:
The VO complexes in atmospheric residues (ARs) and their maltene, resin and asphaltene fractions have been investigated using ESR to examine the effects of the surrounding matrices, measurement temperature, pre-heat-treatment of AR as well as addition of toluene on the electron structure and mobility of the VO ion. The B parameter calculated on the basis of the ESR spectrum has been found to be a good index to reflect the molecular entanglement between the VO complexes and their matrixes in ARs and their fractions, and to indicate the effects of the measurement temperature, pre-heat-treatment as well as the solvent on such interactions. The B parameter value for the VO complexes decreases in the order of asphaltenes > AR ≈ resins > maltenes, implying that the constraint on the mobility of the VO complexes in the samples decreases in the same trend. Increasing temperature, pre-heat-treatment and the addition of toluene reduce the B parameter value, thus, favoring the mobility of the VO complexes in the ARs and their fractions. It can be ascribed to the change in the peripheral environment of the VO complexes surrounded by the matrix molecules. A comprehensive understanding of such molecular entanglement between the VO complexes and their matrixes in ARs may give some important hints to improve the hydrodemetallization performance of AR.
Agid:
6420549