Evaluations of the benefits of using a mixed MEA/MDEA solvent for CO 2 capture in terms of the heat requirement for solvent regeneration, lean and rich loadings, CO 2 production, and solvent stability were performed by comparing the performance of aqueous 5 kmol/m 3 MEA with that of an aqueous 4:1 molar ratio MEA/MDEA blend of 5 kmol/m 3 total amine concentration as a function of the operating time. The tests were performed using two pilot CO 2 capture plants of the International Test Centre for CO 2 Capture (ITC), which provided two different sources and compositions of flue gas. The University of Regina CO 2 plant (UR unit) processes flue gas from the combustion of natural gas while the Boundary Dam CO 2 plant (BD unit) processes flue gas from a coal-fired electric power station. The results show that a huge heat-duty reduction can be achieved by using a mixed MEA/MDEA solution instead of a single MEA solution in an industrial environment of a CO 2 capture plant. However, this benefit is dependent on whether the chemical stability of the solvent can be maintained.

At present, carbon dioxide (CO 2 ) is the largest contributor among greenhouse gases. This article addresses the potential application of photocatalysis to the reduction of CO 2 emissions from industrial flue gas streams. Not only does this process remove CO 2 , but it can also convert CO 2 into other chemical commodities such as methane, methanol, and ethanol. In addition, the photocatalytic process can consume less energy than conventional methods by harnessing solar energy. Given these advantages, photocatalysis is an attractive alternative for CO 2 capture. This article reviews the principle of photocatalysis; existing literature related to photocatalytic CO 2 reduction; and the effects of important parameters on process performance, including light wavelength and intensity, type of reductant, metal-modified surface, temperature, and pressure. Finally, we discuss various system configurations for UV and solar photocatalytic reactors. The advances in photocatalysis technology indicate a promising application potential for significant reductions of CO 2 emissions and a positive impact on climate change effects.

The reboiler heat duty for regeneration of aqueous single and blended alkanolamines used in the carbon dioxide (CO 2 ) absorption process was evaluated experimentally in a bench-scale gas stripping and solvent regeneration system under atmospheric pressure. The evaluation was done for a number of alkanolamines, including monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and 2-amino-2-methyl-1-propanol (AMP), and the mixtures of MEA-MDEA, DEA-MDEA, and MEA-AMP. The experimental results of heat duty were compared with industrial data available in the literature and subsequently correlated with process parameters. The results indicate that the reboiler heat duty is dependent upon CO 2 loading of lean and rich solutions, alkanolamine type and concentration, and composition of blended alkanolamines. MEA requires the highest reboiler heat duty, followed by DEA and MDEA. The reboiler heat duties of blended alkanolamines are between the heat duties of their parent alkanolamines.

The present study provides comprehensive information on the effects of process parameter variations on the corrosion behavior of carbon steel in CO2 absorption systems using aqueous amine solutions. The process parameters of interest are amine type, concentration of the amine solutions, solution temperature, CO2 loading, and oxygen content. An electrochemical testing technique was used for determining the system corrosiveness in terms of polarization behavior and corrosion rate. The experimental results suggest that the corrosion behavior is considerably sensitive to the variations in the process parameters. Increases in amine concentration, solution temperature, CO2 loading, and oxygen content accelerate the corrosion rate in the systems. In addition, different amine types yield different degrees of the system corrosiveness. Comparisons of the corrosiveness among single amine systems as well as between mixed amine systems and their precursors are also presented.