Interactions of H2O and O2 with char during gasification in mixed atmosphere analyzed by isotope tracer method and in-situ DRIFTS. (1st April 2023)

• Record Type: Journal Article
• Authors: Zhao, Deng; Shu, Shiqin; Zhao, Jianlong; Liang, Yongxiang; Wang, Huashan; Liu, Hui; Li, Lina; Wang, Daolei
• Is Part Of: Fuel. Volume 337(2023)
• Publication Date: 2023-04-01
• Subjects: Gasification -- Synergy -- Isotope -- In-situ FTIR -- Molecular dynamics; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.127173
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: Presence of H2 O inhibited the O2 -char reaction in mixed-gas atmosphere. O2 played a significant role in promoting H2 O-char reaction during gasification. In the mixed atmosphere, O2 inhibited the curling of char structure caused by H2 O. Free H radicals from H2 O occupied the active sites and inhibited O2 -char reaction. Abstract: The interactions of char with H2 O and O2 were important for describing the synergistic mechanism of char gasification in H2 O/O2 atmosphere. The gases produced during gasification in specific atmospheres were tracked by isotope-labeled oxygen tracing experiment. The interactions of H2 O with char and O2 with char during gasification in H2 O and O2 atmospheres were separately studied. This helped to explore the interactions between H2 O and char and O2 and char during the gasification in mixed-gas atmosphere. It was found that H2 O inhibited oxidation of char during gasification, whereas O2 promoted the char-H2 O reaction in mixed atmosphere. The overall gasification reactivity in mixed-gas atmosphere was determined by superimposing the effects of O2 on char-H2 O reactions and the effects of H2 O on O2 -char reactions. This could also explain the reason for the influence of H2 O on the overall changes in reactivity, based on O2 concentration. The interactive mechanisms during char gasification with H2 O and O2 atmospheres were investigated by in-situ DRIFTS experiment and molecular dynamics simulation. In the H2 O/O2 atmosphere, H2 O was more likely to promote the curling of char structure. The free H radicals obtained in the decomposition of H2 O molecules consumed the active sites of reaction between char and O2 and decreased its reactivity. Oxygen could inhibit the curling of the char structure caused due to water and promote the formation of OH radicals. This in turn, promoted the cracking of aromatic rings, increased the number of sites for reaction between char and H2 O, and improved the gasification of char in H2 O. In case of mixed-gas atmosphere, the interactions between isotope decoupled single reactions could provide new understanding.