Study on microcrystalline structure and model construction of semi-coke based on XRD, XPS, FTIR, 13C NMR, and HRTEM

• Published in: Journal of molecular structure 2025-04, Vol.1327, p.141264, Article 141264
• Main Authors: Liu, Yuxi, Yang, Zhiyuan, Qu, Shen, Li, Yinyan, Ju, Xiaoqian, Cui, Baolu, Du, Zhiye, Ali, Amir, Wang, Dechao, Chen, Zhiping, Zhou, Anning
• Format: Article
• Language: English
• Subjects: 13C NMR; HRTEM; Microcrystalline structure; Model construction; Semi-coke
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2024.141264

•The microcrystalline structure of semi-coke was analyzed.•The calculated aromatic carbon ratios of XRD, FTIR and 13C NMR were compared.•The lattice fringes with sizes of below 3 × 3 have high proportion.•A chemical and structural properties of structure met the experimental data. To efficiently utilize semi-coke as a carbon-based material, the molecular dimension characteristics and structure of semi-coke were studied based on XRD, XPS, FTIR, 13C NMR, and HRTEM in this paper. The XRD results show that the semi-coke has fewer side chain functional groups, and the aromatic carbon rate (fa) can be calculated to be 82.33 %. FTIR results show that the content of CH2 in semi-coke is higher than that of CH3, indicating that the side chain functional groups of char are less, which is consistent with the XRD results. At the same time, the aromatic carbon rate calculated by FTIR was 95.41 %. The occurrence forms of C, N, and O were analyzed by XPS, in which C mainly existed in the form of CC/CH, O mainly existed in the form of -C-O, and N mainly existed in the form of pyridine and pyrrole. The 13C NMR fitting results show that the carbon in the semi-coke mainly exists in the form of aromatic carbon and the aromatic carbon rate is 93.32 %. In addition, the ratio of aromatic bridgehead carbon to peri carbon (XBP) is 0.472. HRTEM results show that the lattice fringes in semi-coke are mainly composed of 1 × 1, 2 × 2, and 3 × 3. Finally, the model parameters are consistent with the experimental results, which provides a molecular theoretical basis for further study of semi-coke. [Display omitted]