Aqueous co2 absorbent comprising 2-amino-2-methyl-1-propanol and 3-aminopropanol or 2-amino-2-methyl-1-propanol and 4-aminobutanol

Abstract

An aqueous CO2 absorbent comprising a combination of 2-amino-2-methyl-1-propanol (AMP) and 3-aminopropanol (AP), or AMP and 4-aminobutanol (AB), is described. A method for capturing CO2 from a CO2 containing gas using the mentioned absorbent, and the use of a combination of AMP and AP, or a combination of AMP and AB are also described.

Description

TECHNICAL FIELD[0001]The present invention relates to an improved method for capturing of CO2 from a combustion gas, and to an improved amine absorbent for CO2.BACKGROUND ART[0002]Capture of CO2 from a mixture of gases in an industrial scale has been known for decades, i.e. for separation of natural gas and CO2 from sub terrain gas wells to give natural gas for export and CO2 for return to the sub terrain structure.[0003]The growing concern on environment and the greenhouse effect of CO2 from combustion of fossil fuels has caused a growing interest in CO2 capture from major points of emission of CO2 such as thermal power plants, in so called Post Combustion CO2 capture[0004]Even if power plants represent the largest point sources for CO2 emissions, other industries like steelworks and cement plants can utilize similar technologies for CO2 capture.[0005]U.S. Pat. No. 5,618,506, and EP 0 558 019, both to The Kansai Electric Power Co., Inc., and Mitsubishi Jukogyo Kabushiki Kaisha, and...

AI Technical Summary

Benefits of technology

[0020]It has surprisingly been found that a CO2 absorbent comprising AMP and AP, or AMP and AB, is far less prone to oxidative degradation than other well known “standard” absorbents, such as MEA alone or MEA in combination with AMP. Additionally, the present absorbent is far less corrosive, both in laboratory tests and in a pilot plant. Liberation of ions into the absorbent caused by corrosion is known to increase the oxidative degradation of amines. Accordingly, as the present absorbent is less corrosive to the parts in the plant, less ions are liberated into the absorbent adding to the inherent resistance towards oxidative degradation for the present amine absorbent.

Problems solved by technology

Capture of CO2 is, however, an energy demanding process, as the binding of CO2 to the absorbent is an exothermal reaction and the regeneration is an endothermal reaction.

This heat demand is a major operating cost for a plant for CO2 capture.

Amines are also prone to degradation and are corrosive in the environment where they are used.

Degradation is unwanted, both as degradation inactivates the absorbent and causes a need for make-up filling of amine into the plant, as potentially large amounts of waste products are produced, and as the long term operation will be more dependent of a reclaimer unit to recover usable amines bound to degradation products (so called Heat Stable Amine Salts).

This implies a risk for emissions of volatile amine components or degradation products to the environment.

Nitrosamines formation is limited by avoiding the use of secondary amines and by limiting solvent degradation.

Corrosion is of concern both as it is detrimental for important parts of the plant and may reduce the life expectancy thereof, or cause a requirement for more expensive construction elements, and as products of corrosion, such as Fe-ions, may be detrimental to the absorbent by causing higher degree of degradation.

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