Experimental analysis and evaluation on the CO2 adsorption performance of modified CaO-based adsorbents doped with high aluminum cement in different reactors

Abstract

CaO-based carbon capture system is a very promising technology to reduce carbon emissions. In this work, modified CaO-based adsorbents doped with high aluminum cement were prepared by hydration method. The effect of operating variables on the performance of modified CaO-based adsorbents in different reactors was studied, including different proportions of high aluminum cement, carbonation temperature and time. The results showed the adsorbent doped with 5 wt.% high aluminum cement had best CO2 capture capability in all reactors. After 20 carbonation-calcination cycles, the adsorption efficiency of modified CaO-based adsorbent doped with 5 wt.% high alumina cement was around 50.8% at 700 °C in the bubbling fluidized bed reactor, 34.5% at 700 °C in the fixed bed, 23.2% at 750 °C in the TGA reactor, respectively. It was found that the adsorption efficiency of modified adsorbent had obvious advantages in the bubbling fluidized bed. In addition, the effect of carbonation temperature and CO2 concentration on reaction kinetic for adsorbent was investigated. The results showed that the activation energy of modified CaO-based adsorbent doped with 5 wt.% high alumina cement in the rapid reaction stage and reaction diffusion stage was 40.3 KJ/mol and 120 KJ/mol, respectively. The time required to complete the carbonation reaction was shortened from 25 min to 6 min from fixed bed reactor to small bubbling fluidized bed reactor. This work provides a comprehensive study for the adsorption performance of low-cost CaO-based adsorbents in different reactors.