title: Synthesis, characterization, and CO(2) adsorptive behavior of mesoporous AlOOH-supported layered hydroxides.
abstract: A novel CO(2) solid sorbent was prepared by synthesizing and modifying AlOOH-supported CaAl layered double hydroxides (CaAl LDHs), which were prepared by using mesoporous alumina (γ-Al(2)O(3)) and calcium chloride (CaCl(2)) in a hydrothermal urea reaction. The nanostructured CaAl LDHs with nanosized platelets (3-30 nm) formed and dispersed inside the crystalline framework of mesoporous AlOOH (boehmite). By calcination of AlOOH-supported LDHs at 700 °C, the mesoporous CaAl metal oxides exhibited ordered hexagonal mesoporous arrays or uniform nanotubes with a large surface area of 273 m(2) g(-1) , a narrow pore size distribution of 6.2 nm, and highly crystalline frameworks. The crystal structure of the calcined mesoporous CaAl metal oxides was multiphasic, consisting of CaO/Ca(OH)(2), Al(2)O(3), and CaAlO mixed oxides. The mesoporous metal oxides were used as a solid sorbent for CO(2) adsorption at high temperatures and displayed a maximum CO(2) capture capacity (≈45 wt %) of the sorbent at 650 °C. Furthermore, it was demonstrated that the mesoporous CaAl oxides showed a more rapid adsorption rate (for 1-2 min) and longer cycle life (weight change retention: 80 % for 30 cycles) of the sorbent because of the greater surface area and increased number of activated sites in the mesostructures. A simple model for the formation mechanism of mesoporous metal oxides is tentatively proposed to account for the synergetic effect of CaAl LDHs on the adsorption of CO(2) at high temperature.
authors.affiliation: Department of Materials Sciences and Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu Taiwan 300, PR China.
authors.forename: Yen-Po
authors.initials: YP
authors.lastname: Chang
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Chen
authors.forename: Po-Hsueh
authors.initials: PH
authors.lastname: Chang
authors.forename: San-Yuan
authors.initials: SY
authors.lastname: Chen
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D060326:Chemistry Techniques, Synthetic; D006878:Hydroxides / Q000138:chemical synthesis* / Q000737:chemistry*; D007700:Kinetics; D016062:Porosity; D013696:Temperature
chemical_list: D006878:Hydroxides; D002245:Carbon Dioxide; D000536:Aluminum Hydroxide; C069471:aluminum oxide hydroxide; D000537:Aluminum Oxide