Premium
Aluminophosphates for CO 2 Separation
Author(s) -
Liu Qingling,
Cheung Ngo Chuen Ocean,
GarciaBennett Alfonso E.,
Hedin Niklas
Publication year - 2011
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201000256
Subject(s) - adsorption , molecular sieve , zeolite , calcination , selectivity , crystallization , chemistry , desorption , hydrothermal circulation , langmuir , hydrothermal synthesis , chemical engineering , organic chemistry , catalysis , engineering
The pressure‐swing adsorption method for carbon dioxide capture would ideally be facilitated by adsorbents with a high capacity and a high selectivity for CO 2 . Several aluminophosphates with 8‐ring window apertures (AlPO 4 ‐17, AlPO 4 ‐18, AlPO 4 ‐53, and AlPO 4 ‐25) were synthesized by hydrothermal crystallization, calcined, and their CO 2 uptake and CO 2 /N 2 selectivity were studied. CO 2 and N 2 uptake was determined for pressures up to 101 kPa at 273 and 293 K. Langmuir and Toth adsorption models were used to describe the adsorption isotherms. The CO 2 and N 2 uptakes strongly indicated that the squeezed 8‐ring windows of certain aluminophosphates can sieve CO 2 from a CO 2 and N 2 gas mixture. Both AlPO 4 ‐53 and AlPO 4 ‐25 exhibited a remarkably higher uptake of CO 2 compared to N 2 . The hydrophilicity of the AlPO 4 materials was investigated by means of water adsorption, and the results showed that all of the tested aluminophosphates were less water sensitive than a benchmark zeolite (13X). In particular, AlPO 4 ‐53 and AlPO 4 ‐25 showed a very low degree of water uptake with up to 20–30 % relative humidity. Determination of cyclic adsorption and desorption confirmed the relatively hydrophobic nature of the aluminophosphates, which render them less energy costly for the regeneration of adsorbents.