Effects of alkali and alkaline earth metals of inherent minerals on Fe-catalyzed coal pyrolysis. (1st January 2022)

• Record Type: Journal Article
• Authors: He, Renze; Deng, Jin; Deng, Xiaoling; Xie, Xiaoguang; Li, Yun; Yuan, Shenfu
• Is Part Of: Energy. Volume 238:Part C(2022)
• Publication Date: 2022-01-01
• Subjects: Coal -- Catalytic pyrolysis -- Fe catalyst -- Demineralization -- Alkali and alkaline earth metals; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2021.121985
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: In this work, the effects of alkali and alkaline earth metals (AAEM (K, Na, Ca and Mg)) on Fe (5 wt%) loaded-coal pyrolysis were conducted using the fixed-bed reactor at 700 °C with 0.1 MPa N2 . The coal was pretreated by HCl and HF aqueous solutions (De-2 coal). These effects were investigated with AAEM additive into Fe loaded De-2 coal. The results indicate that K, Na, Ca and Mg (0.1 wt%-1.5 wt%) enhanced the catalytic effect of Fe catalyst, leading to the high H2 selectivity ( 59.34 ml / g → 85.94 ml / g ), as well as the low yield toward CO2 ( 157.50 ml / g → 148.62 ml / g ), and the catalytic activity follows the order of Na ≈ K > Ca > Mg. Characterization results reveal that the inherent AAEM promote the reduction of Fe species and the dispersion of Fe particles. The reason for that was AAEM combined with oxygen-containing functional group generated C–O-AAEM and COO-AAEM, and released active oxygen sites to activate carbon sites, leading to Fe catalyst bound with active oxygen sites formed iron oxide and Fe-(O)–C on char surface. This study was helpful to understand the promotion mechanism of AAEM on Fe catalyzed coal pyrolysis. Graphical abstract: Image 1 Highlights: The existence of Si, Al in coal ash could not be beneficial to Fe-catalyzed coal pyrolysis. CO2 yield decreased with addition of alkali and alkaline earth metals in Fe-catalyzed demineralized coal pyrolysis. Alkali and alkaline earth metals promoted the dispersion of Fe particles and the reduction of Fe species.