Investigation of the sulfonation mechanism by gas–liquid interfacial plasma under atmospheric pressure conditions. (25th August 2022)

• Record Type: Journal Article
• Authors: Deng, Siqi; Takeuchi, Nozomi; Hieda, Junko; Takahashi, Katsuyuki; Tachibana, Kosuke; Li, Oi Lun
• Is Part Of: Journal of physics. Volume 55:Number 34(2022)
• Publication Date: 2022-08-25
• Subjects: atmospheric-pressure plasma -- plasma modification -- carbon sulfonation -- gas–liquid interfacial plasma system; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/ac73c2
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Although sulfonated carbon catalysts are considered promising solid acid catalysts for cellulose conversion, most carbon sulfonation processes require concentrated sulfuric acid (18 M) at elevated temperatures. This work investigates a novel sulfonation mechanism for carbon acid catalysts via a gas–liquid interfacial plasma sulfonation system under atmospheric pressure conditions with a dilute sulfuric acid solution (1 M) at 38 °C, and the by-products of the plasma sulfonation process were investigated by in-situ and ex-situ diagnosis. The results show that a high gas temperature (>1050 K) around the plasma allows H2 SO4 droplet decomposition, and active species (OH, SO3, and HOSO2 ) generated at the gas–liquid interface were grafted on the defects of the carbon materials and subsequently formed sulfonic acid groups (0.36 mmol g −1 ) and total acid groups (4.16 mmol g −1 ) on the carbon network. This study aimed to provide significant insight into the understanding of the sulfonation mechanisms of an emerging plasma-based process for carbon acid catalysts, which is important for the further development of an environmentally friendly sulfonation process for acid catalysts for biomass conversion.