Carbon dioxide was absorbed into non-aqueous solvents such as methanol, ethanol, n-propanol, n-butanol, ethylene glycol, propylene
glycol, and propylene carbonate, and into water in a stirred semi-batch tank with a planar gas-liquid interface at 298 K and
101.3 kPa. Triethanoamine (TEA) was used as a reactant with carbon dioxide. The reaction rate constants of the reaction between
carbon dioxide and TEA were estimated by the mass transfer mechanism, which was accompanied by a fast pseudo-first-order reaction.
An empirical correlation between the reaction rate constants and the solubility parameter of the solvent is presented. In
non-aqueous solutions of TEA, dissolved carbon dioxide is expected to react with solvated TEA to produce an ion pair. 相似文献
Gas absorption rates in a laminar liquid jet were measured for carbon dioxide in methyl- diethanolamine (MDEA) solutions. It was found that for the short contact times (<0.012s) of these absorption experiments there is only a small effect of any reaction between carbon dioxide and MDEA. Solubilities and molecular diffusivities for carbon dioxide in aqueous MDEA are estimated from measurements with nitrous oxide. The absorption rate data are described well using the solubilities and diffusivities measured in this work. Solubilities were measured over the temperature range 15 to 35°C and for MDEA concentrations up to 40%. Diffusion coefficients and viscosities were measured over the same temperature range and MDEA concentrations up to 20%. 相似文献
Carbon dioxide was absorbed into aqueous polyethylene oxide (PEO) solution containing N-methyldiethanolamine (MDEA) in a flat-stirred vessel to investigate the effect of non-Newtonian rheological behavior of PEO
on the chemical absorption rate of CO2, where the reaction between CO2 and MDEA was assumed to be a first-order reaction with respect to the concentration of CO2 and MDEA, respectively. A unified correlation equation containing the Deborah number, which reflects the viscoelastic properties
of a non-Newtonian liquid, was used to obtain the volumetric liquid-side mass transfer coefficient of carbon dioxide in aqueous
PEO solution. The elastic properties of PEO accelerated the absorption rate of CO2 compared with that of a Newtonian liquid based on the same values of viscosity. 相似文献
A stirred cell gas-liquid contactor was used to investigate the kinetics of the reaction between carbon dioxide and methyldiethanolamine (MDEA) in aqueous solutions. Experiments were conducted over the temperature range 15–35°C and for MDEA concentrations from 0.85 to 1.70 g mol/l. The kinetic data support a previously proposed mechanism in which MDEA acts as a homogeneous catalyst for CO2 hydrolysis. The second-order rate constant was found to have a value of 2/47 l/g mols at 25°C, in good agreement with existing literature values. The second-order rate constant is correlated well by the Arrhenius expression 相似文献
Abstract The tertiary araine methyldiethanolamine (MDEA) is finding increasing application as a chemical solvent for selective absorption of hydrogen sulfide from gases containing hydrogen sulfide and carbon dioxide. Gas streams of this type include some natural gases, synthetic gases from coal and heavy oil gasification and tail gases from sulfur plants. Selectivity for H2S is needed either to enrich Glaus sulfur plant feed in H2S or to remove only H2S when CO2 removal is not necessary or economic. For the absorption of hydrogen sulfide into MDEA, the reaction which occurs can be considered to be instantaneous while carbon dioxide undergoes a second-order reaction with MDEA. In this work, the simultaneous absorption of two gases into a liquid containing a reactant with which both gases react is modelled using the film theory. Physical properties and kinetic rate parameters used in the model have been measured in our laboratory. The model is used to study the effect of process variables on the selectivity of MDEA for H2S over C02. The simultaneous absorption of H2S and CO2 gases into aqueous MDEA is studied experimentally using a continuous stirred tank absorber. Experimental absorption rates are compared to predictions based on a multicomponent mass transfer model. The average deviations of the theoretical calculations from the experimental results are 10.2% and 12.9% for C02 and H2S, respectively. 相似文献
A rigorous model for absorption of carbon dioxide into aqueous N-methyldiethanolamine (MDEA) based on the assumption of reversible reactions and the simplified model with a pseudo-first order irreversible reaction hypothesis were employed to compare with experimental data. The experimental absorption rates were obtained from a characterized double stirred-cell absorber with a planar gas-liquid interface. It was demonstrated that the numerical solution of the rigorous model provides a better prediction for the absorption rate of carbon dioxide into aqueous MDEA solution than that of the simplified model. Only in the case of absorption experiments carried out at a low carbon dioxide partial pressure (p < 20 kpa) and low amine concentration (MDEAtotal < 1000 mol/m3), the assumption of pseudo-first order irreversible reaction is reasonable. 相似文献
Solubility data of methane in ethylene glycol and 1-4 butylene glycol and carbon dioxide in ethylene glycol and 1-2 propylene glycol in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide have been measured in the temperature range (303–423) K at pressures up to 14 MPa. Henry's law constant of each solute in the studied solvent at saturation pressure is given. The experiments were performed in an autoclave type phase equilibrium apparatus using the total pressure method. For mixtures containing carbon dioxide and ethylene glycol no influence was observed. For mixtures containing carbon dioxide and 1-2 propylene glycol it was observed salting-out effect at 303.2 K and 323.2 K and salting-in effect at the remaining temperatures. For mixtures containing methane and ethylene glycol or 1-4 butylene glycol salting-in effect was observed. 相似文献
New systems have been developed for the measurement of effective interfacial area, a, by the chemical method which allow the use of hydrocarbon solvents, such as toluene, xylene, etc; polar solvents, such as benzyl alcohol, cyclohexanol, etc; and highly viscous solvents, such as diethylene glycol, polyethylene glycol, etc. In all the above cases, the reaction between carbon dioxide and selected amines is employed.Effective interfacial area and liquid-side mass transfer coefficient have been measured by the absorption of lean carbon dioxide and pure carbon monoxide/propylene, respectively, into cuprousamine solutions. Here, both water and polar substances, such as, pyridines, benzyl alcohol, isopropanol, etc. can be used. 相似文献
Absorption rate of CO2 into aqueous solution of N-methyldiethanolamine (MDEA) blended with di-ethanolamine (DEA) and piperazine (PZ) was studied and a kinetic model was established. It is shown that homogeneous activation mechanism could explain this absorption process. The absorption rate coefficients of carbon dioxide into MDEA aqueous solution blended with DEA, PZ or DEA+PZ were compared with each other. The results demonstrated that the different activation effect of DEA, PZ and DEA+PZ on the carbon dioxide absorption comes from the difference in CO2 combination rate, transport of PZ and DEA to MDEA and the regeneration rate of PZ and DEA. 相似文献
The absorption of H2S into aqueous methyldiethanolamine (MDEA) was studied experimentally over the temperature range 15 to 35°C and for MDEA concentrations from 10 to 25 wt% using a laminar liquid jet device and a stirred-cell absorber. The contact times ranged from 2 × 10-3 to 1 × 10-2 seconds for the jet absorber and from 6 to 38 seconds for the stirred-cell absorber. It was found that the absorption rate data for both devices could be modelled assuming an instantaneous reaction regime for the reaction between H2S and MDEA. The experimental results were interpreted to give an estimate for the diffusion coefficient of MDEA in water. Diffusion coefficient results are consistent for the two apparatuses. A lower bound for the second-order rate constant for the reaction between H2S and MDEA is estimated from the experimental data to be 1.4 × 1010cm3/g mole s at 25°C 相似文献
ABSTRACTEnvironmental concerns from global warming and climate change demand carbon dioxide separation from post-combustion gases. Important parameters are involved in choosing the suitable solvent for carbon dioxide separation, including the reaction rate of carbon dioxide and the solvent. In this paper, the kinetics of carbon dioxide (CO2) absorption in aqueous solutions of Monoethanolamine (MEA) + 1,3-Diaminopropane (DAP), a diamine containing two primary amino group, was developed. The measurements were performed in a stirred cell with a horizontal gas-liquid interface in the temperature range of 313.15–333.15 K and aqueous solutions of 10 wt% MEA + 5 wt% DAP and 12.5 wt% MEA + 2.5 wt% DAP. Experiments were conducted in an isothermal batch reactor with a horizontal gas-liquid interface under pseudo-first-order conditions, enabling the determination of the overall kinetic rate constant from the pressure drop method. Second-order reaction rate constants of CO2 absorption in amine solutions were estimated using the calculated initial absorption rate. It was found that the rate constants in MEA+ DAP solutions were greater than in MEA solutions which means that DAP increases the reaction rate. 相似文献
The chemical absorption of carbon dioxide by a laminar jet of ethylenediamine has been studied at 25.5°C under pseudo-first-order kinetic conditions. The reaction was found to be second-order with a rate constant of 1.0 x 105 1/g. mole sec. Equilibrium calculations at 18°C indicate that the partial pressure of carbon dioxide is very low, even over highly carbonated ethylenediamine solutions. The effects of amine concentration and carbonation ratio on the physical solubility and diffusivity of carbon dioxide in solution were inferred from corresponding results for nitrous oxide 相似文献
Carbon dioxide was absorbed into aqueous polyacrylamide (PAA) solution containing methyl-diethanolamine (MDEA) in a flat-stirred
vessel to investigate the effect of non-Newtonian rheological behavior of PAA on the rate of chemical absorption of CO2, where the reaction between CO2 and MDEA was assumed to be a first-order reaction with respect to the molar concentration of CO2 and MDEA, respectively. The liquid-side mass transfer coefficient (kL), which was obtained from the dimensionless empirical equation containing the viscoelasticity properties of a non-Newtonian
liquid, was used to estimate the enhancement factor due to chemical reaction. PAA with elastic property of non-Newtonian liquid
made the rate of chemical absorption of CO2 accelerate compared with a Newtonian liquid 相似文献
A series of modified zinc oxide catalysts were prepared and their catalytic activities were evaluated by the direct synthesis
of propylene carbonate from propylene glycol and carbon dioxide in the presence of acetonitrile, which acted as not only the
solvent but also the dehydrating reagent in the reaction. The reusability test indicated that the modified catalysts had the
high stability. Ammonium carbonate was added into the reaction to significantly elevate the selectivity of propylene carbonate. 相似文献