Carbon Dioxide Capture by Aqueous Piperazine

Background The conventional process for CO2 absorption/stripping uses aqueous amines such as monoethanolamine (MEA). Piperazine has previously been identified as a very reactive amine. It is an attractive alternative to MEA because it reacts with CO2 thirty times faster than MEA. However, piperazine is a solid at ambient temperature that has a limited soubility in water. Furthermore, the boiling point of liquid piperazine is less than that of MEA, so it is expected to have a greater volatility than MEA. Therefore, aqueous piperazine by itself has not received any known commercial usage in CO2 absorption/stripping, because it is perceived to be too volatile and cannot be used at concentrations that provide high capacity for CO2 absorption.

Invention Description A new solvent composition has been identified for piperazine to capture CO2 from coal-fired flue gas, hydrogen, or natural gas. When combined with advanced stripper configurations, this solvent produces a large capacity for CO2 absorption with very fast rates of absorption at a high heat of absorption. The energy requirement should be reduced by 10 to 30 percent from conventional 30% MEA solvents.

The reactive amine will be three to ten times more expensive than MEA; but, unlike MEA, it will not degrade thermally, nor does it react quickly with oxygen in the presence of dissolved iron.

Benefits

Net energy consumption should be reduced by 10 to 30%. Piperazine is more stable than MEA, thereby reducing secondary environmental impact and makeup rates. Piperazine solutions absorb CO2 20% to 100% faster than MEA. Piperazine can be recovered in a thermal reclaimer by evaporation.

Market Potential/Applications As concerns of global climate changes spark initiatives to reduce carbon dioxide emissions, its economic removal from gas streams becomes increasingly important. Removal by absorption/striping is a commercially promising technology, as it is well suited to sequester CO2 from gas streams produced by coal-fired power plants. This process can be expensive, potentially increasing the cost of electricity by 50%; therefore, technology improvements to reduce operating cost, such as the use of the aqueous piperazine described herein, are desirable.

Development Stage Proof of concept

Inventor(s): Gary T. Rochelle

Type of Offer: Licensing



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