Efficient solid reducing agent CaO/SiO2 hybrid composite for hydrogen fluoride elimination. (24th January 2019)

• Record Type: Journal Article
• Authors: Sohn, Jeong Sun; Rho, Seon-Gyun; Sohn, Jun Youn; Lim, Min-Hwa; Sadhasivam, T.; Lim, Hankwon; Ryi, Shin-Kun; Jung, Ho Young
• Is Part Of: Advanced composite materials. Volume 28(2019)Supplement 1
• Page Start: 65
• Page End: 77
• Publication Date: 2019-01-24
• Subjects: calcium oxide -- hydrophobic silica -- composite -- solid reducing agent -- HF elimination; Composite materials -- Periodicals; Reinforced plastics -- Periodicals; Electronic journals; 620.11805
• DOI: 10.1080/09243046.2018.1458484
• Languages: English
• ISSNs: 0924-3046

Abstract

Abstract : An advanced solid reducing agent, i.e., a CaO/SiO2 composite has been optimized to improve the hydrogen fluoride (HF; a green house gas) elimination in semiconductor-based industrial applications. To avoid the Ca(OH)2 formation and enhance the HF removal efficiency of CaO, the hydrophobic properties of silica (SiO2 ) have used as a catalyst materials to enhance the stability of CaO/SiO2 solid reducing agent in the present investigation. The novel composite structure based on CaO/SiO2 was prepared using various concentrations of hydrophobic nano-silica sol and Ca(OH)2 . The composite was characterized by contact angle goniometry, thermogravimetry analysis, and scanning electron microscopy. The water contact angle of the CaO/SiO2 composites significantly increased with increasing SiO2 content. In particular, angles of 61.6°, 73.7°, 84.8°, and 84.9° were obtained for SiO2 concentrations of 20, 40, 60, and 80 wt.%, respectively. These results suggest that the hydrophobic nature of the composites was improved with the addition of 60 and 80 wt.% of SiO2 . Moreover, the surface properties were measured using the nitrogen Brunauer–Emmett–Teller method for obtaining the weight ratios (wt.%) and calcinations times. The determined specific surface areas (SSAs) were 16.19, 27.25, 32.86, and 40.56 m 2 /g for 80:20, 60:40, 40:60, and 20:80 CaO/SiO2 composites, respectively. From the water contact angle and SSA analysis, the optimum hydrophobic nature of CaO/SiO2 composites for HF removal was achieved at a weight ratio of 40:60 (Ca(OH)2 /SiO2 ) at the calcination temperature of 650 °C. The perfluorinated compound (PFC) removal rate is 80 and 88% for a common regenerative catalytic system (RCS) catalyst and the CaO/SiO2 reaction-enhanced (RE)-RCS catalyst, respectively. In addition, higher amount of HF elimination is successfully achieved using CaO/SiO2 solid reducing agent. During the RE-RCS process, SiO2 acts as a catalyst to prevent the formation of Ca(OH)2 when CaO is exposed to water.