Structural Evaluation of Coal Tar Pitch by Multiple Techniques
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Structural Evaluation of Coal Tar Pitch by Multiple Techniques Zhilei Wanga, Yugao Wanga,*, Zeshi Niua, Jun Shena,**, Yanxia Niua, and Wei Zhaob a College
of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024 China b Key Laboratory of Coal Processing and Efficient Utilization, Ministry of Education, China University of Mining and Technology, Xuzhou, Jiangsu, 221116 China e-mail: *[email protected]; **[email protected] Received May 21, 2020; revised August 08, 2020; accepted September 18, 2020
Abstract—Coal tar pitch (CTP) is an important heavy carbon resource. Its effective utilization largely depends on the full structural evaluation of CTP. In this paper, the CTP from Shanxi Datuhe coal tar distillation plant was adopted as the sample (DCTP). Multiple analytical equipments including X-ray diffractometer spectrometer, solidstate 13C nuclear magnetic resonance spectrometer, and X-ray photoelectron spectrometer were used to directly characterize DCTP, and DCTP was further catalytically oxidized over ruthenium ion. The typical characteristics of structures in DCTP were investigated by combining the two methods. It was demonstrated that aromatic structures dominated in DCTP, in which the aromaticity was up to 95 %. Specifically, aromatic structures were abundant in peri-condensed aromatic structures, poor in cata-condensed aromatic structures, but short of polyaryl structures. There were about 4 rings in each aromatic cluster, and the aromatic clusters were lowly substituted by a few methyl side chains. Furthermore, the nitrogen and sulfur atoms mainly existed in the heterocyclic ring, while the oxygen one was principally in Car‒O group. Keywords: coal tar pitch, structural evaluation, direct characterization technology, catalyzed oxidation by ruthenium ion
DOI: 10.1134/S0965544121010059 is far away to reveal the structural features of CTP only using single analytical equipment. The combination of different analytical techniques is needed in order to get enough and comprehensive structural information on CTP. Based on the fast-developing modern instrumental analysis technology, solid samples can be directly, comprehensively and conveniently analyzed without complicated processing. X-ray diffractometer (XRD) can analyze the microcrystalline structure of the solid sample, providing aromatic structural information [9–11]. The solid-state 13C nuclear magnetic resonance spectrometer (SS 13C NMR) is widely adopted to study the carbon skeleton structure of coal and its derivatives [12–14], which could reveal the type and distribution of the organic carbons in CTP. Despite the low content of oxygen, nitrogen, and sulfur in CTP, these heteroatoms are the indispensable fraction in the overall molecular structure of CTP, and they can be analyzed by X-ray photoelectron spectrometers (XPS) [15, 16]. Therefore, these characterization techniques are helpful to gain insights into the structural features of the whole CTP.
INTRODUCTION Coal tar pitch (CTP) is a main product during the
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