CO2Capture by Carbon Aerogel–Potassium Carbonate Nanocomposites

Guang Yang,Hirofumi Kanoh,Hongchao Luo,Tomonori Ohba

doi:10.1155/2016/4012967

Guang Yang, Hirofumi Kanoh + Show 2 more

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https://doi.org/10.1155/2016/4012967

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Abstract

Recently, various composites for reducing CO2emissions have been extensively studied. Because of their high sorption capacity and low cost, alkali metal carbonates are recognized as a potential candidate to capture CO2from flue gas under moist conditions. However, undesirable effects and characteristics such as high regeneration temperatures or the formation of byproducts lead to high energy costs associated with the desorption process and impede the application of these materials. In this study, we focused on the regeneration temperature of carbon aerogel–potassium carbonate (CA–KC) nanocomposites, where KC nanocrystals were formed in the mesopores of the CAs. We observed that the nanopore size of the original CA plays an important role in decreasing the regeneration temperature and in enhancing the CO2capture capacity. In particular, 7CA–KC, which was prepared from a CA with 7 nm pores, exhibited excellent performance, reducing the desorption temperature to 380 K and exhibiting a high CO2capture capacity of 13.0 mmol/g-K2CO3, which is higher than the theoretical value for K2CO3under moist conditions.

Highlights

Carbon dioxide (CO2) is the principal greenhouse gas
In the present study, we focus on impregnating K2CO3 into the nanopores of carbon aerogels (CAs) prepared by pyrolysis of a dried organic aerogel followed by carbonation, leading to the formation of vitreous black monoliths with highly crosslinked micropores and mesopores [12, 13]
The isotherms of the composites are categorized as type IV (IUPAC classification) with hysteresis between the adsorption and desorption branches

Summary

Introduction

Carbon dioxide (CO2) is the principal greenhouse gas. It has been continuously released into the environment through the burning of fossil fuels and has led to global warming and anthropogenic climate change, such as droughts, desertification, permafrost melt, inundation, rising sea levels, and ecosystem disruption, and it is expected to substantially affect the future of mankind. The atmospheric CO2 concentration was 384 ppm in 2007 and is expected to reach 550 ppm by 2050; mitigating the atmospheric CO2 concentration is critical for protecting our environment [1, 2] With both high CO2 capture capacity and low cost, alkali metal carbonates (M2CO3, M = K, Na) have been recognized as potential sorbents for CO2 sorption according to the following reaction [3]: M2CO3 (s) + H2O (g) + CO2 (g) 󴀘󴀯 2MHCO3 (s) (1). To solve problems such as the slow reaction rate of bicarbonate formation and high energy consumption during regeneration, researchers have extensively investigated various composites containing alkali metal carbonates [5,6,7,8]. The CO2 capture ability of K2CO3 nanocrystals incorporated into mesopores of CAs is studied from the viewpoint of lowering the regeneration temperature while achieving high selectivity and high capture capacity

Experimental Section

Results and Discussion

Conclusion