Lime-Based Sorbents for High-Temperature CO2 Capture—A Review of Sorbent Modification Methods

Vasilije Manovic,Edward J Anthony

doi:10.3390/ijerph7083129

Vasilije Manovic, Edward J Anthony

Open Access

https://doi.org/10.3390/ijerph7083129

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Abstract

This paper presents a review of the research on CO2 capture by lime-based looping cycles undertaken at CanmetENERGY’s (Ottawa, Canada) research laboratories. This is a new and very promising technology that may help in mitigation of global warming and climate change caused primarily by the use of fossil fuels. The intensity of the anticipated changes urgently requires solutions such as more cost-effective technologies for CO2 capture. This new technology is based on the use of lime-based sorbents in a dual fluidized bed combustion (FBC) reactor which contains a carbonator—a unit for CO2 capture, and a calciner—a unit for CaO regeneration. However, even though natural materials are cheap and abundant and very good candidates as solid CO2 carriers, their performance in a practical system still shows significant limitations. These limitations include rapid loss of activity during the capture cycles, which is a result of sintering, attrition, and consequent elutriation from FBC reactors. Therefore, research on sorbent performance is critical and this paper reviews some of the promising ways to overcome these shortcomings. It is shown that reactivation by steam/water, thermal pre-treatment, and doping simultaneously with sorbent reforming and pelletization are promising potential solutions to reduce the loss of activity of these sorbents over multiple cycles of use.

Highlights

It is widely accepted that climate change is being exacerbated by increasing atmospheric concentrations of greenhouse gases, and this is a key problem that requires urgent solutions
About a third of global CO2 emissions come from the burning of fossil fuels in electricity production
We have intensely investigated spent sorbent reactivation by steam, sorbent pretreatment at elevated temperatures, and doping/pelletization with commercial calcium aluminate cements

Summary

Introduction

It is widely accepted that climate change is being exacerbated by increasing atmospheric concentrations of greenhouse gases, and this is a key problem that requires urgent solutions. About a third of global CO2 emissions come from the burning of fossil fuels in electricity production. Reduction of such emissions may significantly decrease total emissions of greenhouse gases. One possible approach is the capture of CO2 from flue gas followed by its sequestration in geological formations [1,2,3]. The purpose of CO2 capture is to produce a concentrated stream of CO2, preferably at high pressure, so that it can readily be transported to a storage site. In principle, the entire gas stream containing low concentrations of CO2 could be transported and injected underground, the energy requirements and other associated costs generally make this approach impractical

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