Evaluation of the CO2 absorption capacities of solid sorbents

• Main Authors: Gwo-Yuan Shiau, 蕭國源
• Other Authors: Shin-Min Shih
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/94590150410045358712

碩士 === 國立臺灣大學 === 化學工程學研究所 === 88 === A thermogravimetric technique was employed to evaluate the CO2 absorption capacities of solid sorbents（silicate minerals, Ca(OH)2, Mg(OH)2, K2CO3, Na2CO3, CaSiO3）. The reactivities of six silicate minerals, wollastonite, olivine, talc, serpentine, orthoclase, albite, toward CO2 were measured. Their reactions with CO2（101.3kPa） proceeded extremely slow at high temperature（100~850℃） without water existed. The carbonation rate was faster in humid CO2 at low temperature（25~100℃） and the rate increased with increasing relative humidity and surface area of minerals. The conversions for four hours reaction per unit specific surface area of mineral are：olivine＞serpentine＞albite＞orthoclase＞wollastonite＞talc. At high temperature, Ca(OH)2 reacted with CO2 rapidly, whereas CaSiO3 reacted slowly, and Mg(OH)2 was inert to CO2. Under humid and low temperature conditions, the carbonation rates and the final conversions of Ca(OH)2 and Mg(OH)2 both increased with increasing relative humidity. The time reaching the final conversions was reduced with increasing relative humidity. The reaction with CO2 would occur only at relative humidities above 10% RH for Ca(OH)2 and above 30% RH for Mg(OH)2.The reaction of Ca(OH)2 or Mg(OH)2 was chemical controlled and was well described by the surface coverage model. The carbonation rates of K2CO3 and Na2CO3 under humid and low temperature conditions were increased with increasing relative humidity. The carbonation rates were constant until the sorbents were completely, indicated that the reaction of K2CO3 or Na2CO3 was controlled by chemical and the sorbent grain had the shape of plate. The one hour CO2 captures per unit of sorbent are：Ca(OH)2＞K2CO3＞Mg(OH)2＞Na2CO3＞CaSiO3.