CO 2 sorbents with scaffold-like Ca-Al layered double hydroxides as precursors for CO 2 capture at high temperatures

Po Hsueh Chang, Tai Jung Lee, Yen Po Chang, San-Yuan Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


A highly stable high-temperature CO 2 sorbent consisting of scaffold-like Ca-rich oxides (Ca-Al-O) with rapid absorption kinetics and a high capacity is described. The Ca-rich oxides were prepared by annealing Ca-Al-NO 3 layered double hydroxide (LDH) precursors through a sol-gel process with Al(O i P) 3 and Ca(NO 3 ) 2 with Ca 2+ /Al 3+ ratios of 1:1, 2:1, 4:1, and 7:1. XRD indicated that only LDH powders were formed for Ca 2+ /Al 3+ ratios of 2:1. However, both LDH and Ca(OH) 2 phases were produced at higher ratios. Both TEM and SEM observations indicated that the Ca-Al-NO 3 LDHs displayed a scaffold-like porous structure morphology rather than platelet-like particles. Upon annealing at 600 °C, a highly stable porous network structure of the CaO-based Ca-Al-O mixed oxide (CAMO), composed of CaO and Ca 12 Al 14 O 33 , was still present. The CAMO exhibited high specific surface areas (up to 191 m 2 g -1 ) and a pore size distribution of 3-6 nm, which allowed rapid diffusion of CO 2 into the interior of the material, inducing fast carbonation/calcination and enhancing the sintering-resistant nature over multiple carbonation/calcination cycles for CO 2 absorption at 700 °C. Thermogravimetric analysis results indicated that a CO 2 capture capacity of approximately 49 wt % could be obtained with rapid absorption from the porous 7:1 CAMO sorbents by carbonation at 700 °C for 5 min. Also, 94-98 % of the initial CO 2 capture capability was retained after 50 cycles of multiple carbonation/calcination tests. Therefore, the CAMO framework is a good isolator for preventing the aggregation of CaO particles, and it is suitable for long-term cyclic operation in high-temperature environments. Caught in a web: A Ca-Al layered double hydroxide-based scaffold-like network is synthesized in the presence of hexadecyl trimethyl ammonium bromide (CTAB) by using a sol-gel process with Al(O i P) 3 and Ca(NO 3 ) 2 as precursors. The calcined Ca-Al-NO 3 layered double hydroxides display rapid CO 2 absorption kinetics in addition to a long-term cyclic operation in a high-temperature environment.

Original languageEnglish
Pages (from-to)1076-1083
Number of pages8
Issue number6
StatePublished - 1 Jun 2013


  • carbon dioxide capture
  • high temperature
  • layered double hydroxides
  • mesoporous materials
  • metal oxides

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