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Environmental Impact of Atmospheric Fugitive Emissions from Amine Based Post Combustion CO2 Capture

Moetaz I. Attalla, †Merched Azzi, Phil Jackson, †Dennys AngoveCentre for Energy Technology, CSIRO, Newcastle, NSW, Australia and †Centre for Energy Technology, CSIRO, Lucas Heights, NSW, Australia.

contact: Moetaz Attallaphone: (+61) 2 4960 6083email: moetaz.attalla@csiro.auweb: www.det.csiro.au

Introduction Global reductions in greenhouse gas emissions are now recognised as a priority for combating climate change. However, since coal and gas fired electricity

generation are likely to remain the largest sources of CO2 emissions for the foreseeable future, CO2 capture and storage is crucial technology if emission reductions are to be achieved.

Major projects are currently being undertaken globally to adapt and improve carbon dioxide gas separation technologies for CO2 post combustion capture (PCC) applications. The most mature technology for PCC is amine solvent-based chemical absorption/release of CO2. This technology is currently being applied at pilot scale and is likely to be the first technology successfully demonstrated and thereby reach commercial scale application.

If solvent based PCC technology is deployed at a commercial scale, potentially millions of tonnes of solvent will be used per annum. Hence, fugitive emissions of solvents and solvent degradation products (through oxidative and thermal degradation) will likely occur. Some potential environmental concerns associated with these emissions include:• Entrainment of the amine/ammonia with the treated flue gas and their associated atmospheric chemical reaction pathways (reactions with NOx, CO, O2)• Formation of ammonia and other amine degradation products such as formic acid, ethylamine, acetone etc., can be entrained with the flue gas to the atmosphere. In

particular, NH3 can enhance the formation of particulate matter in the atmosphere• Nitrosamines formation as a result of reaction between an amine and nitrogen oxide • The mounting evidence of the presence of amines in the particulate phase

It is also known that amines in the atmosphere can be oxidised by OH•, O3 and possibly by NO3• chemical reactions. In additions amines can react with nitrous acid (HONO) to produce nitrosamines which in turns can undergo photolysis to reproduce amine and NO.

To ensure the viability of this technology, it is crucial at this early stage of development that a thorough understanding of the potential environmental impacts of fugitive emissions on terrestrial, aquatic and atmospheric environments be investigated. However, at present, there is little understanding of the environmental impact of PCC technology.

The aim of the present work is to use controlled laboratory/ pilot scale experiments to determine the major chemical components emitted under different operation conditions. As well, the atmospheric photo-oxidation products of amines were studied in a smog chamber under ambient conditions.

In this paper we present data where we have estimated the chemical compositions of potential fugitive emissions in the flue gases from the CO2 capture system. Using the CSIRO smog chamber, the potential environmental impact of selected relevant compounds has been assessed in terms of their reactivities to produce secondary products. These secondary products were characterised to determine their potential health risk factors.

As a result of this study, a chemical reaction scheme will be generated. The new mechanism will be incorporated into air quality model that can be used to assess the potential impact of using amine solutions for CO2 capture. The results will be used to determine the trade-off between CO2 capture and local and regional air quality.

AcknowledgementsThis CSIRO Coal Portfolio research project has been funded by the Australian Government through the Asia Pacific Partnership on Clean Development and Climate initiative (APP).

Field program

Laboratory program

CSIRO PCC pilot plant deployed to power station

Loy Yang MEALake Munmorah NH3Tarong ??

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Top: IR spectral surface between 2000-900 cm-1 for the reaction between aqueous 30.00 % wt MEA and a gas stream of 1.702 L/mincontaining 13.04 % CO2; Bottom: CID of mass-selected oxalate anionat 10 eV collision energy. The peak at m/z 35 (H3O2

−) arises from acontaminant ion of mass m/z 89, most likely (H2O)4OH−. Oxalate hasbeen identified as one of the major MEA decomposition products.1The CID result suggests a major thermal decomposition pathway leadsto bicarbonate, the other major pathway to formate. Thus,oxalate slippage from a CO2 capture plant operating with MEAcould locally alter the biosphere pH; Left: HPLC-DAD and HPLC-MS+

traces for a controlled MEA oxidation experiment conducted in the lab-scale amine degradation apparatus, top far left.

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Merched Azzi(+61) 2 9710 6870merched.azzi@csiro.auwww.det.csiro.au

ATR-FTIR

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Realistic lab based data and analytical procedures:• Oxidation and thermal degradation experiments carried out under controlled laboratory conditions • Low limit-of-detection analytical procedures

Pilot plant samples from exhaust and liquor: • For long term operational data

Smog chamber simulations will be carried out to:• Identify the major pollutants produced by the photo-decomposition of the flue gas compounds of the absorber under

selected ambient conditions• Identify the major chemical reactions pathways responsible of the MEA oxidation• Develop the appropriate chemical mechanism required to simulate the oxidation of MEA

Airshed modelling to determine the potential environmental impact of using amine solution for CO2 capture:• Embedded the modified chemical mechanism into the airshed model• Simulate different atmospheric scenarios to assess the potential impact of the new CO2 capture process• Determine the trade off between CO2 capture and local and regional air quality

Solvent development work to mitigate environmental impact.

Current and Future Work

HPLC-MS

References1. Goff, G.S.; Rochelle, G.T. Ind. Eng. Chem. Res. 2004, 43, 6400.