Experiments and DFT study on modified CaO-based adsorbents for enhanced CO 2  capture

Zhixin Li,Mengxiang Fang,Qinhui Wang,Yi Feng

doi:10.5802/crchim.79

Abstract

CaO-based adsorbents for carbon capture represent a promising technology for reducing carbon emission. In this study, we prepare metal oxide-doped multifarious CaO-based adsorbents using the hydration method. We investigate the effect of various working conditions, such as temperature and carbonation time, on different adsorbents in a fixed-bed reactor under multiple carbonation–calcination cycles. We examine the behavior of different metal oxides-doped synthetic adsorbents using density functional theory calculation based on experiments. The results prove that 5 wt% ZrO2-doped adsorbents show excellent CO2 adsorption efficiency, which reaches up to 38.4% after 20 carbonation–calcination cycles at 700 °C with 15 vol% CO2. The adsorbents doped with other metal oxides are also useful for CO2 capture to varying degrees. The adsorption energy of CO2 molecules on modifiequationed adsorbents is higher than that on pure CaO, especially for Zr, where the adsorption energy reached 2.37 eV. The calculation results are in good agreement with the experimental data.

Highlights

Fossil fuels are essential to modern society, as they are one of the most important contributors to world’s energy consumption
We evaluated the performance of modified adsorbents after multiple carbonation–calcination cycles
The performance of the modified adsorbents under various working conditions was studied and the results show that the modified calcium-based adsorbent doped with 5 wt% ZrO2 has excellent CO2 adsorption capacity

Summary

Introduction

Fossil fuels are essential to modern society, as they are one of the most important contributors to world’s energy consumption. Their excessive use is leading to a sharp increase in CO2 emissions, which creates many environmental concerns, such as the “greenhouse effect”. A CaO-based carbon capture technology is considered promising for carbon emission reduction, and it is studied here in detail. The circulatory system contains a reactor to capture CO2 and a calcination furnace for regenerating CaO-based adsorbents [2,3,4]. Calcination may bring about deformation and sintering of particles of the adsorbent [5,6]. After multiple carbonation–calcination cycles, the adsorption effequationiciency of calcium-based adsorbents decreased significantly [7,8]

Methods

Results

Conclusion