No abstract

No abstract

The high energy consumption of CO2-loaded solvent regeneration is the biggest impediment for the real application of the amine-based CO2 capture process. To lower the energy requirement, three Fe promoted SO4 2–/ZrO2 supported on MCM-41 (SZMF) catalysts with different iron oxide content (5%, 10%, and 15%) were synthesized and applied for the rich monoethanolamine solution regeneration process at 98 °C. Results reveal that the use of SZMF hugely enhanced the CO2 desorption performances (i.e., desorption factor) by 260–388% and reduced the heat duty by about 28–40%, which is better than most of the reported catalysts for this purpose. The eminent catalytic activities of SZMF are related to their enhanced ratio of Brønsted to Lewis acid sites, weak acid sites, basic sites, and high dispersed Fe3+ species. Meanwhile, the addition of SZMF for CO2 desorption shows a promotional effect on its CO2 absorption performance, and SZMF presents an excellent cyclic stability. A possible mechanism is suggested for the SZMF catalyzed CO2 desorption process. Results of this work may provide direction for future research and rational design of more efficient catalysts for this potential catalyst-aided CO2 desorption technology.

Over the past decade, amine-loaded solid adsorbents for capturing CO2 from power plants have been widely studied. Various nitrogen (N) sources have been used for this purpose, and the current range of adsorbents, referred to here as N-functionalized solid adsorbent (NFSAs), are the subject of this review. The main synthesis methods of NFSAs are described and recent progress in the field discussed. Criteria for improving NFSA performance are highlighted with reference to a variety of solid supports, providing guidance on the selection of highly efficient, inexpensive adsorbents. A thorough assessment of adsorption mechanisms and factors influencing the adsorption process is given. The review concludes by exploring future research and development opportunities, as well as pathways for commercializing NFSAs.

In this work, Diethanolamine (DEA) was considered as an activator to enhance the CO2 capture performance of Monoethanolamine (MEA). The addition of DEA into MEA system was expected to improve disadvantages of MEA on regeneration heat, degradation, and corrosivity. To understand the reaction mechanism of blended MEA‐DEA solvent and CO2, 13C nuclear magnetic resonance (NMR) technique was used to study the ions (MEACOO‐, DEACOO–, MEA, DEA, MEAH+, DEAH+, normalHnormalCnormalO3−, normalCnormalO32−) speciation in the blended MEA‐DEA‐CO2‐H2O systems with CO2 loading range from 0 to 0.7 mol CO2/mol amine at the temperature of 301 K. The different ratios of MEA and DEA (MEA: DEA = 2.0:0, 1.5:0.5, 1.0:1.0, and 0:2.0) were studied to comprehensively investigate the role of DEA in the system of MEA‐DEA‐CO2‐H2O. The results revealed that DEA performs the coordinative role at the low CO2 loading and the competitive role at high CO2 loading. Additionally, the mechanism was also proposed to interpret the reaction process of the blended solvent with CO2. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2515–2525, 2018

A strategy for decreasing the viscosity variation in the process of CO2 capture by amino-functionalized ionic liquids (ILs) through the formation of intramolecular hydrogen bond was reported. Different with the dramatic increase in viscosity during CO2 uptake by traditional amino-functionalized ILs, slight increase or even decrease in viscosity was achieved through introducing a N or O atom as hydrogen acceptor into amino-functionalized anion, which could stabilize the active hydrogen of produced carbamic acid. Quantum chemical calculations and spectroscopic investigations demonstrated that the formation of intramolecular hydrogen bond between introduced hydrogen acceptor and carbamic acid was the key to avoid the dramatic increase in viscosity during the capture of CO2 by these amino-functionalized ILs.

The formation of bicarbonate ions in an amine solution during CO 2 absorption results in lowering the heat duty for amine solvent regeneration in the CO 2 capture process because bicarbonate breakdown needs the lowest energy input to release CO 2 . In this study, bicarbonate formation was conducted for two mixed solvents consisting of tertiary amines (1DMA2P (1 M) or MDEA (1 M)) blended with MEA in order to determine both formation rate and capacity of bicarbonate ions as compared to MEA alone. The amines and concentrations used in the study were MEA (5 M), MEA−MDEA (5:1 molar ratio, 6 M total), and MEA−1DMA2P (5:1 molar ratio, 6 M total) at various CO 2 loadings. The formation of bicarbonate ions was evaluated using 13 C NMR technique at 293.15 K. The results show that for the single tertiary amine system higher concentrations of bicarbonate ions were formed for MDEA than for 1DMA2P for the same CO 2 loading. The results for the blended amine systems showed that bicarbonate ions were generated at CO 2 loadings lower with MEA alone than with MEA−1DMA2P generating bicarbonate ions at a CO 2 loading (0.34 mol CO 2 /mol amine) lower than that with MEA−MDEA (0.38 mol CO 2 /mol amine). Thus, as an additive in MEA, 1DMA2P has a better potential than does MDEA to generate bicarbonate ions at a leaner CO 2 loading with the attendant lowering of the regeneration energy.

The molecular weights (MWs) of hyaluronic acid (HA) in extracellular matrix secreted from both vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) play crucial roles in the cardiovascular physiology, as HA with appropriate MW influences important pathways of cardiovascular homeostasis, inhibits VSMC synthetic phenotype change and proliferation, inhibits platelet activation and aggregation, promotes endothelial monolayer repair and functionalization, and prevents inflammation and atherosclerosis. In this study, HA samples with gradients of MW (4 × 10, 1 × 10, and 5 × 10 Da) were prepared by covalent conjugation to a copolymerized film of polydopamine and hexamethylendiamine (PDA/HD) as multifunctional coatings (PDA/HD-HA) with potential to improve the biocompatibility of cardiovascular biomaterials. The coatings immobilized with high-MW-HA (PDA/HD-HA-2: 1 × 10 Da; PDA/HD-HA-3: 5 × 10 Da) exhibited a remarkable suppression of platelet activation/aggregation and thrombosis under 15 dyn/cm blood flow and simultaneously suppressed the adhesion and proliferation of VSMC and the adhesion, activation, and inflammatory cytokine release of macrophages. In particular, PDA/HD-HA-2 significantly enhanced VEC adhesion, proliferation, migration, and functional factors release, as well as the captured number of endothelial progenitor cells under dynamic condition. The in vivo results indicated that the multifunctional surface (PDA/HD-HA-2) created a favorable microenvironment of endothelial monolayer formation and functionalization for promoting reendothelialization and reducing restenosis of cardiovascular biomaterials.