The kinetic performance of a novel amine solvent blend BEA-AMP was compared with MEA and blended MEA-MDEA in the presence and absence of a solid acid catalyst (HZSM-5) in the desorber column of a bench-scale pilot plant. In addition, a total of seven solid base catalysts were screened using a semibatch reactor to select the one that is most suitable as catalyst for amine-based CO 2 absorption. The selected solid base catalyst, K/MgO, was placed in the absorber of the pilot plant. Overall, three absorber-desorber catalytic scenarios were evaluated: blank−blank, blank-HZSM-5, and K/MgO-HZSM-5. For the blank−blank and blank-HZSM-5 scenarios, the novel solvent (4 M BEA-AMP) outperformed 5 M MEA and 7 M MEA-MDEA blend despite BEA-AMP having the lowest molarity. The rates of absorption and desorption for the blank−blank (noncatalytic) scenario for BEA-AMP were 14.8 and 38.4 mol/m 3 min, respectively. For the blank-HZSM-5 system, the rates were 18.1 and 45.6 mol/m 3 min, respectively. Absorption and desorption rates of 29.7 and 62.4 mol/m 3 min, respectively, were obtained for the K/MgO-HZSM-5 system. These results reveal higher rates of absorption and desorption with the inclusion of solid base and solid acid catalysts to the amine-based CO 2 capture process. The results show that in the presence of the amine, the electron-rich anion species in K/ MgO easily attack the dissolved CO 2 . This interaction ties the CO 2 molecules to the surface of the catalyst, making them readily available for nitrogen atom of the amine in the CO 2 absorption process. This process is facilitated because of the large pore size of K/MgO. With the desorber catalyst, easier proton donation by HZSM-5 results in weakening the N−C bond in carbamate, which thereby causes CO 2 to break away.

The performance of a novel bi-blend butylethanolamine (BEA)–2-amino-2-methyl-1-propanol (AMP) solvent developed from an earlier work using a semi-batch method was validated in a bench-scale CO2 capture pilot plant in terms of its CO2 capture performance criteria compared to the benchmark 7 M monoethanolamine (MEA)–methyldiethanolamine (MDEA) solvent blend. Also, the synergistic benefits provided by placement of a solid acid catalyst (HZSM-5) in the desorber column and a solid base catalyst (K/MgO) used for the first time in the CO2 absorber column were evaluated. In addition, a process method was developed to use the pilot plant to determine, for the first time, the intrinsic heat of CO2 desorption from BEA–AMP and MEA–MDEA blends (or any solvent), without making any assumptions and/or reference to the heat of CO2 absorption. The results showed that all of the performance parameters for the novel 4 M BEA–AMP bi-blend were tremendously better than those of the 7 M MEA–MDEA bi-blend for both catalytic and non-catalytic runs, even though the molarity of the 7 M MEA–MDEA bi-blend was much higher, thereby showing the superiority of the BEA–AMP bi-blend solvent. The placement of catalysts in both absorber and desorber columns led to a synergistic benefit in the overall absorption and desorption processes. The heat of desorption has been proven not to be equal to the heat of absorption as a result of their having different conditions of CO2 loading and product species. The results of the heat duty term clearly demonstrate that the desorber catalyst (HZSM-5) worked mainly in reducing the heat of the CO2 desorption component for both solvent systems. This work further demonstrates that the reported results are just the apparent heat of CO2 desorption, which reflects the actual amount of external energy required to make up the theoretical heat of CO2 desorption needed to break the amine–CO2 bonds. Therefore, part of the energy needed for CO2 desorption is provided by HZSM-5 through proton donation. The Lewis base catalyst led to a tremendous improvement in the CO2 absorption process through electron donation during the rate-determining step.

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