Shingo Kazama

Density functional theory study on carbon dioxide absorption into aqueous solutions of 2-amino-2-methyl-1-propanol using a continuum solvation model.

We used density functional theory (DFT) calculations with the latest continuum solvation model (SMD/IEF-PCM) to determine the mechanism of CO(2) absorption into aqueous solutions of 2-amino-2-methyl-1-propanol (AMP). Possible absorption process reactions were investigated by transition-state optimization and intrinsic reaction coordinate (IRC) calculations in the aqueous solution at the SMD/IEF-PCM/B3LYP/6-31G(d) and SMD/IEF-PCM/B3LYP/6-311++G(d,p) levels of theory to determine the absorption pathways. We show that the carbamate anion forms by a two-step reaction via a zwitterion intermediate, and this occurs faster than the formation of the bicarbonate anion. However, we also predict that the carbamate readily decomposes by a reverse reaction rather than by hydrolysis. As a result, the final product is dominated by the thermodynamically stable bicarbonate anion that forms from AMP, H(2)O, and CO(2) in a single-step termolecular reaction.

Cardo polyimide membranes for CO2 capture from flue gases

Publisher Summary This chapter discusses that cardo polyimide hollow fiber membranes were developed as an alternative to existing commercial amine absorption for CO2 capture from flue gases. To investigate the relationship between chemical structures and CO2 separation properties, various cardo polyimides were synthesized to measure CO2 separation properties and some chemical structure was found to give remarkable properties both in CO2 permeation and selectivity. An economic analysis was carried out for CO2 separation using the hollow fiber membrane followed by a liquefaction process. In the cost breakdown of CO2 separation with membrane, the electricity consumption of the vacuum pump, which induce a pressure difference between a feed side and a permeate side of a membrane, contributed 50% or more of the total cost. For further cost reduction, an application of membrane system to pressurized gas streams similar to CO2 removal from natural gas might be a promising way of reducing the cost of CO2 separation.

Development of CO2 Separation Membranes (1) Polymer Membrane

Publisher Summary Exhaust gas from thermal power plants, cement plants, and steel mills consists mostly of N 2 and CO 2 and thus technology to separate these gases is required. This chapter explains how to develop a membrane that provides excellent selectivity for CO 2 and is durable and heat resistant. Furthermore, CO 2 separation membranes need to be modular to cope effectively with the large volumes of exhaust gases from stationary sources. A new cardo type polymer membrane was developed keeping in mind the ongoing problem of global warming. The cardo type polymer has a molecular structure with a bulky loop form. The polymer shows the important characteristics of a high gas permeability and high solubility in organic solvents that provide hollow fiber membrane processability and heat stability derived from an aromatic structure. Since a cardo type polyimide showed the highest CO 2 /N 2 selectivity and CO 2 permeability during the screening of many newly synthesized cardo type polymers, it was selected and a structure function relationship analysis was conducted looking at CO 2 /N 2 selectivity and CO 2 permeability. A new cardo type polyimide structure for CO 2 separation was identified. Then, the wet spinning technology to produce an asymmetric hollow fiber membrane was developed and the membrane in module was incorporated. In addition to using bench-scale testing to obtain basic data for implementing the module, a 1,000MW coal combustion power plant was considered. The information obtained confirmed that in energy terms, the developed membrane separation method is superior to current methods.

Development of poly(amidoamine) dendrimer/poly(vinyl alcohol) hybrid membranes for CO2 separation

Abstract A novel hybrid membrane of poly(amidoamine) (PAMAM) dendrimer/cross-linked poly(vinyl alcohol) (PVA) was developed for the selective separation of CO2 from a mixture of CO2 and H2. PAMAM dendrimers were incorporated into a cross-linked PVA matrix to improve CO2 separation performance at elevated pressures. An organic metal compound di-isopropoxy-bis(triethanol aminato) titanium (Ti cross-linker) was selected as the PVA cross-linker. The characterization of PAMAM/cross-linked PVA hybrid membranes was conducted using Fourier transform infrared spectrometry/attenuated total reflectance (FTIR/ATR), wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS) spectra. Cross-linking of PVA with Ti cross-linker was confirmed by FTIR/ATR spectra. WAXD spectra showed that the relative crystallinity of PAMAM/PVA hybrid membrane decreased greatly when compared with PVA film. SAXS results indicated that PAMAM and PVA are compatible in the PAMAM/PVA hybrid membrane. To improve the CO2 separati...

Experimental study into carbon dioxide solubility and species distribution in aqueous alkanolamine solutions

We investigated the solubility of CO2 in aqueous solutions of alkanolamines at 40C and 120C over CO2 partial pressures ranging from a few kPa to 100 kPa to evaluate the potential for CO2 capture from flue gas. CO2 capacities were compared between monoethanolamine, N-ethyl ethanolamine and N-isopropyl ethanolamine. Speciation analyses were conducted in the alkanolamine solutions at different CO2 loadings by accurate quantitative 13 C nuclear magnetic resonance spectroscopy. N-isopropyl ethanolamine showed a large capacity for CO2 because of the formation of bicarbonate. However, we also found that at a lower CO2 loading a significant amount of carbamate was present in the aqueous N-isopropyl ethanolamine solutions.

Polymeric membranes composed of polystyrenes tethering amino acids for preferential CO 2 separation over H 2

Various N-tert-butoxycarbonyl (N-Boc) amino acids, such as glycine, valine, and serine, were combined to 4-chloromethylstyrene. The resulted monomers were readily polymerized to give polystyrenes tethering an amino acid by a conventional free radical polymerization technique. After deprotection of the N-Boc group with trifluoroacetic acid, the obtained polystyrene derivatives were soluble in ethanol and spin-coated on a commercial poly(ether sulfone) porous membrane to fabricate a composite membrane for CO2 separation over H2. The CO2 selective layer of synthesized PSt was ca. 200 nm thick, and the composite membranes showed preferential CO2 separation over H2, while parent polystyrene passed through H2 rather than CO2. Especially, the separation factor

Carbon dioxide and nitrogen transport properties of bis(phenyl)fluorene-based cardo polymer membranes

\alpha_{{{\text{CO}}_{ 2} /{\text{H}}_{ 2} }}

Facile fabrication of a novel high performance CO2 separation membrane: Immobilization of poly(amidoamine) dendrimers in poly(ethylene glycol) networks

was raised after alkaline treatment to form free primary amine on the terminus of graft chain. Serine tethered polystyrene showed the highest