Novel method for investigation of a K–Mg-based CO2 sorbent for sorption-enhanced water–gas shift reaction. (March 2016)

• Record Type: Journal Article
• Authors: Byun, Chang Ki; Kwon, Soon Jin; Im, Hyo Bin; Ahn, Hee Sung; Ryu, Ho Jung; Yi, Kwang Bok
• Is Part Of: Renewable energy. Volume 87:Part 1(2016)
• Page Start: 415
• Page End: 421
• Publication Date: 2016-03
• Subjects: Precombustion CO2 capture -- K–Mg-based sorbent -- Reaction mechanism -- Hydrogen production -- Sorption enhanced water gas shift reaction; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2015.10.020
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: CO2 sorption reactions at 20 bar and two different temperatures (i.e., 180 and 220 °C) using a K–Mg-based CO2 sorbent were carried out in a custom-designed high-pressure thermogravimetric analyzer (pressurized bubbling fluidized bed reactor on a scale) coupled with a gas chromatograph. The experimental apparatus, including the thermogravimetric analyzer, was custom-designed to measure weight changes caused by either CO2 sorption or water sorption or both. Analysis of the CO2 sorption reaction revealed that water sorption takes place rapidly with a moderate CO2 sorption rate at the early stage of the reaction. Then, the reaction migrates to CO2 sorption with simultaneous water desorption. Therefore, the mechanism of the CO2 sorption reaction is assumed to consist of fast hydration of K2 CO3 and MgO, formation and decomposition of KHCO3, and finally carbonation of Mg(OH)2 resulting in MgCO3 as the main product. K2 CO3 is assumed to provide an efficient pathway for CO2 and water to travel into the core region of the sorbent via a reversible reaction between K2 CO3 and KHCO3 . Graphical abstract: Highlights: Water and CO2 consumed by K–Mg based sorbent were measured simultaneously. Confirmed that fast water absorption by K–Mg-sorbent takes place prior to CO2 sorption. K2 CO3 behaves as stepping stones for CO2 and H2 O to pass through MgO layers. Amorphous MgCO3 is produced in CO2 sorption reaction of K–Mg based sorbent.