Understanding the Effect of Water on CO₂ Adsorption

Abstract

Carbon capture from large sources and ambient air is one of the most promising strategies to curb the deleterious effect of greenhouse gases. Among different technologies, CO2 adsorption has drawn widespread attention mostly because of its low energy requirements. Considering that water vapor is a ubiquitous component in air and almost all CO2-rich industrial gas streams, understanding its impact on CO2 adsorption is of critical importance. Owing to the large diversity of adsorbents, water plays many different roles from a severe inhibitor of CO2 adsorption to an excellent promoter. Water may also increase the rate of CO2 capture or have the opposite effect. In the presence of amine-containing adsorbents, water is even necessary for their long-term stability. The current contribution is a comprehensive review of the effects of water whether in the gas feed or as adsorbent moisture on CO2 adsorption. For convenience, we discuss the effect of water vapor on CO2 adsorption over four broadly defined groups of materials separately, namely (i) physical adsorbents, including carbons, zeolites and MOFs, (ii) amine-functionalized adsorbents, and (iii) reactive adsorbents, including metal carbonates and oxides. For each category, the effects of humidity level on CO2 uptake, selectivity, and adsorption kinetics under different operational conditions are discussed. Whenever possible, findings from different sources are compared, paying particular attention to both similarities and inconsistencies. For completeness, the effect of water on membrane CO2 separation is also discussed, albeit briefly.

A scalable metal-organic framework as a durable physisorbent for carbon dioxide capture

“…Nearly all classes of porous solids have potential as solid sorbents for CO 2 capture ( 1 – 3 , 7 – 10 ), including metal-organic frameworks (MOFs) ( 2 , 3 , 9 , 12 – 14 ), in which chemical building blocks, pore sizes and shapes, surface functionalities, and even degrees of order can be varied to optimize CO 2 capture ability. More robust MOFs ( 15 , 16 ), including ones that are stable in the presence of water ( 17 – 19 ) and steam ( 20 ), have been reported, although stability to wet acid gases is less common ( 21 – 23 ). For sorbent powder to be a usable material, it must be capable of formation in macroscopic shape for rapid mass transfer and thermal management, be durable in that form, and be available at scale (hundreds of thousands of tonnes) and reasonable cost ( 24 , 25 ).…”

Removal of carbon dioxide using zeolitic imidazolate frameworks: Adsorption and conversion via catalysis

“…The emission of gases is one of the most causes of global climate change. [1][2][3][4][5][6][7][8][9][10][11] Gases can be classified as incondensable inorganic gases (i.e., hydrogen (H 2 ), carbon dioxide (CO 2 ), carbon monoxide (CO), nitrogen (N 2 ), oxygen (O 2 ), and noble gases such as He-Kr) and condensable organic gases (i.e., methane (CH 4 ), ethane (C 2 H 6 ), and ethene (C 2 H 4 )). Greenhouse gases, for example, CO 2 and NO x , are mainly responsible for global climate changes.…”

“…Among these gases, CO 2 emission to the atmosphere from human activities such as breathing, industrial processes, and the burning of fossil fuels is one of the leading causes of global warming. [1][2][3][4][5][6][7][8][9][10][11] Thus, several methods were reported for CO 2 capture and utilization (CCU), including adsorption and sequestration. [12] Metal-organic frameworks (MOFs) are organicinorganic crystalline porous materials.…”

A Review on Removal of Carbon Dioxide (CO2) using Zeolitic Imidazolate Frameworks: Adsorption and Conversion via Catalysis

“…The changes in the climate temperature are irreversible, causing a real threat to the environment and humankind. The emission of gases is one of the most causes of global climate change [1][2][3][4][5][6][7][8][9][10][11] . Gases can be classified as incondensable inorganic gases (i.e., hydrogen (H2), carbon dioxide (CO2), carbon monoxide (CO), nitrogen (N2), oxygen (O2), and noble gases such as He-Kr) and condensable organic gases (i.e., methane (CH4), ethane (C2H6), ethene (C2H4)).…”

“…Greenhouse gases, e.g., CO2, and NOx, are mainly responsible for global climate changes. Among these gases, CO2 emission to the atmosphere from human activities such as breathing, industrial processes, and the burning of fossil fuels is one of the leading causes of global warming [1][2][3][4][5][6][7][8][9][10][11] . Thus, several methods were reported for CO2 capture and utilization (CCU), including adsorption and sequestration [12] .…”