Absorption of Carbon Dioxide into Aqueous Colloidal Silica Solution

Abstract

On the basis of experimental data for carbon dioxide absorption into aqueous nanometer sized colloidal silica solution as a non‐Newtonian fluid, a dimensionless correlation for volumetric liquid‐side mass transfer coefficient (k_La) of CO₂ in the flat‐stirred vessel was proposed. In addition to ordinary liquid properties and operating parameters such as impeller size and speed in the vessel, Deborah number, which is defined as the product of the characteristic material times of the liquid and agitation speed in the flat‐stirred vessel and represents the viscoelastic behavior of non‐Newtonian fluid, was used to present unified expressions for k_La in Newtonian as well as non‐Newtonian liquid. The values of k_La in the aqueous colloidal silica solution were reduced due to elasticity of the solution.     

Absorption of Carbon Dioxide into Aqueous Xanthan Gum Solution Containing Monoethanolamine

Abstract

Carbon dioxide was absorbed into the aqueous xanthan gum (XG) solution in the range of 0–0.151 wt% containing monoethanolamine (MEA) of 0–2 kmol/m³ in a flat‐stirred vessel with the impeller of 0.05 m and agitation speed of 50 rpm at 25°C and 0.101 MPa to measure the absorption rate of CO₂. The volumetric liquid‐side mass transfer coefficient (k_La_L) of CO₂ decreased with increasing XG concentration, and was correlated with the empirical formula having the rheological behavior of XG solution. The chemical absorption rate of CO₂ was estimated by the film theory using the values of k_La_L and physicochemical properties of CO₂ and MEA. The aqueous XG solutions made the rate of absorption of CO₂ accelerated compared with the Newtonian liquid based on the same viscosity of the solution.     

Chemical Absorption of Carbon Dioxide into Aqueous Solution of Potassium Threonate

Carbon dioxide was absorbed into aqueous solution of potassium threonate (PT) at different concentrations of PT and CO₂, and temperatures in the range of 0.1–1.0 kmol/m³, 10.1–101.3 kPa, and 293-313 K, respectively, using a stirred semi-batch vessel with a planar gas-liquid interface. Both the reaction order and rate constant were determined from gas absorption rates under the fast pseudo-first-reaction regime. The reaction was found to be first order with respect to both CO₂ and PT, and its activation energy has been found to be 40.6 kJ/mol. From a comparison of the reaction kinetics by the overall reaction scheme with those by the elementary reaction scheme based on the zwitterions mechanism, the overall reaction between CO₂ and PT has been found to be equivalent to the formation of zwitterions.     

Chemical Absorption of Carbon Dioxide into Glycidyl Methacrylate Solution with Tetrabutylammonium Bromide

Abstract

Absorption of carbon dioxide was carried out in a semi‐batch stirred tank of glycidyl methacrylate solution with tetrabutylammonium bromide as a catalyst at 101.3 kPa. The measured rate of absorption of carbon dioxide was used to obtain the reaction kinetics by the mass transfer mechanism accompanied by the chemical reaction, which was consisted of two elementary reactions. An empirical correlation formula between the reaction rate constants and the solubility parameters of the solvents, such as toluene, N‐methyl‐2‐pirrolidinone, and dimethyl sulfoxide, was presented.     

Chemical Absorption of Carbon Dioxide into Aqueous PEO Solution of Monoethanolamine

Abstract

Carbon dioxide was absorbed into aqueous polyethylene oxide (PEO) solution containing monoethanolamine (MEA) in a flat‐stirred vessel to investigate the effect of non‐Newtonian rheological behavior of PEO on the rate of chemical absorption of CO₂, where the reaction between CO₂ and MEA was assumed to be a first‐order reaction with respect to the molar concentration of CO₂ and MEA, respectively. The liquid‐side mass transfer coefficient (k_L), which was obtained from the dimensionless empirical equation containing the properties of viscoelasticity of the non‐Newtonian liquid, was used to estimate the enhancement factor due to chemical reaction. PEO with elastic property of non‐Newtonian liquid made the rate of chemical absorption of CO₂ accelerate compared with Newtonian liquid based on the same viscosity of the solution.     

超重力反应器中甘氨酸钠吸收混合气体中CO_2的实验研究

CO2减排已经成为国际关注的热点问题。近年来,化学吸收法以其效率高、适应范围广、技术成熟等优点,逐渐占据主导地位。采用甘氨酸钠溶液为吸收剂,在超重力反应器中进行了CO2吸收实验,考察了转速、吸收液温度、吸收液浓度、气液比等对CO2吸收率的影响。结果表明:CO2的吸收率随着转速的增加而上升,当转速达到1000 r?min?1后,吸收率基本趋于稳定;CO2的吸收率随着吸收液温度的升高而升高,在90℃时可以达到83%以上;在实验范围内,CO2的吸收率随吸收液浓度的增加略有增加,随气液比的增加而逐渐降低并趋于稳定。     

Chemical Absorption of Carbon Dioxide into Aqueous Colloidal Silica Solution with Diethanolamine

Abstract

The chemical absorption rate (R_A) of CO₂ was measured into the aqueous nanometer sized colloidal silica solution of 0–31 wt% and diethanoleamine of 0–2 kmol/m³ in the flat‐stirred vessel with the impeller size of 0.034 m and its agitation speed of 50 rev/min at 25°C and 0.101 MPa, and compared with the values estimated from the model based on the film theory accompanied by chemical reaction. The value of the volumetric liquid‐side mass transfer coefficient (k_La) of CO₂, which was used to estimate the value of R_A, was obtained by the empirical correlation formula presenting the relationship between k_La and the rheological behavior of the aqueous colloidal silica solution. The value of R_A in the aqueous colloidal silica solution was decreased by the reduction of k_La due to the elasticity of the solution.     

活化甲基二乙醇胺溶液吸收CO2的动力学

采用圆盘塔在常压、温度３０～７０℃、ＭＤＥＡ（甲基二乙醇胺）浓度１．７５～４．２１ｋｍｏｌ／ｍ３、哌嗪浓度０．０４１～０．２１ｋｍｏｌ／ｍ３条件下，研究了活化ＭＤＥＡ吸收ＣＯ２的动力学。动力学数据证实了ＣＯ２与哌嗪之间进行着拟一级均匀［４］活化反应机理，其吸收速率可由并行拟一级快速可逆反应吸收来表示：　式中：ｋｐ＝２．９８×１０（１１）ｅｘｐ（－６４２４／Ｔ），表观活化能为５３．４１ｋＪ／ｍｏｌ。     

加压下二氧化碳在氯化钠水溶液中的溶解度

采用气液逆流双循环的溶解度测定装置测定了不同温度、不同压力、不同含盐浓度下ＣＯ２在ＮａＣｌ水溶液中的溶解度数据。应用改进的ＰＴ方程,并提出ＣＯ２和Ｈ２Ｏ交互作用参数与温度的新关系式,用于ＣＯ２在水以及ＮａＣｌ水溶液中溶解度的计算并获得满意的结果。     

Absorption of Carbon Dioxide into Ionic Liquid of 2-Hydroxy Ethylammonium Lactate

Abstract

Absorption of carbon dioxide into organic solvents such as DMA, NMP, DMSO, and DMF with the 2-hydroxy ethylammonium lactate (HEAL) ionic liquid was investigated using a batch stirred tank with a plane of gas-liquid interface in a range of 0–2.0 kmol/m³ of HEAL and 298–318 K at 101.3 kPa. The absorption of CO₂ was analyzed with the film model accompanied by the zwitterion mechanism of CO₂ with HEAL. The proposed model fits the experimental data of the enhancement factor due to the ready, chemical absorption of CO₂ in different solvents, temperatures, and HEAL concentrations. The reaction rate constant of CO₂ with HEAL was correlated linearly with the solubility parameter of the solvent.     

木质素磺酸钠吸收烟道气中的SO2

本文就木质素磺酸钠溶液脱除烟道气中SO_2进行了实验研究。实验采用双搅拌气-液反应器,探讨了木质素磺酸钠的浓度、温度等因素对SO_2吸收的影响,并求取了化学吸收增强因子。结果表明,木质素磺酸钠能有效地脱除烟道气中的SO_2。     

Simultaneous Absorption of Carbon Dioxide and Sulfur Dioxide into Aqueous 1,8-Diamino-p-menthane

Abstract

Carbon dioxide and sulfur dioxide were simultaneously absorbed into aqueous 1,8-diamino-p-menthane (DAM) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–2.0 kmol/m³ of DAM, 0.01–0.12 mole fraction of CO₂, 0.001–0.012 mole fraction of SO₂, and 298-318 K. Absorption data of each gas in the CO₂-DAM and SO₂-DAM systems are obtained to verify their reaction regimes, based on film theory, respectively, which are used to analyze the simultaneous absorption mechanisms of CO₂ and SO₂ in the CO₂-SO₂- DAM systems. In the simultaneous absorption rate of CO₂ and SO₂ into DAM solution, the absorption of CO₂ belongs to the second-order reaction of finite rate and the absorption of SO₂ belongs to the instantaneous reaction regime.     

Simultaneous Absorption of Carbon Dioxide and Nitrogen Dioxide into Aqueous 2-amino-2-methy-1-propanol

Carbon dioxide and nitrogen dioxide were simultaneously absorbed into aqueous 2-amino-2-methyl-1-propanol (AMP) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–4.0 kmol/m³ of AMP, 0.03–0.3 atm of CO₂, 0.005–0.2 atm of NO₂, and 298–318 K. Absorption data of each gas in the CO₂-AMP and NO₂-AMP systems were obtained to verify their reaction regimes, based on film theory, respectively, which were then used to analyze the simultaneous absorption mechanisms of CO₂ and NO₂ in the CO₂-NO₂-AMP systems. The measured absorption rates of CO₂ and NO₂ were compared to those formulated by an approximate solution of the mass balances with simultaneous reactions.     

Simultaneous Absorption of Carbon Dioxide and Sulfur Dioxide into Aqueous 2-Amino-2-Methy-1-Propanol

Abstract

Carbon dioxide and sulfur dioxide were simultaneously absorbed into aqueous 2-amino-2-methyl-1-propanol (AMP) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–4.0 kmol/m³ of AMP, 0.03–0.3 mole fraction of CO₂, 0.005–2 mole fraction of SO₂, and 298–318 K. Absorption data of each gas in the CO₂-AMP and SO₂-AMP systems are obtained to verify their reaction regimes, based on film theory, respectively, which are used to analyze the simultaneous absorption mechanisms of CO₂ and SO₂ in the CO₂-SO₂-AMP systems. The measured absorption rates of CO₂ and SO₂ are compared to those formulated by an approximate solution of the mass balances with simultaneous reactions.     

Simultaneous Absorption of Hydrogen Sulfide and Carbon Dioxide into di-isopropanolamine Solution

The simultaneous absorption of hydrogen sulfide and carbon dioxide into di-isopropanolamine (DIPA) solution was investigated in a 183 cm long, 2.72 cm OD wetted-wall column at atmospheric pressure. The influence of liquid flow rate, gas flow rate, temperature and liquid concentration on the absorption rate, overall gas-phase mass transfer coefficient and selectivity factor were studied at a constant gas feed ratio. The results show that the absorption rate of CO₂ increases rapidly with increasing liquid flow rate (the Reynolds number of the turbulent liquid film ranges from 2600 to 4350) but increases moderately with increasing gas flow rate (G = 18-91 L/min), indicating that it is liquid-phase mass transfer controlled. In contrast, the absorption rate of H₂S increases very slowly with increasing liquid flow rate but increases rapidly with increasing gas flow rate, indicating that it is gas-phase mass transfer controlled. The absorption rate of CO₂ also increases with increasing temperature (26-80°C) but H₂S absorption rate decreases with increasing temperature. When the concentration of DIPA solution increases from 0.2 to 2.6 mol/L, the absorption rate of both CO₂ and H₂S increases but with a larger rate of increase for CO₂ For selective H₂S removal, it is preferable to operate at low liquid and high gas flow rates, low temperatures and low DIPA concentrations.     

醇胺法吸收二氧化碳在填料塔中的应用

采用工业流程中的填料吸收塔和解吸塔,研究了乙醇胺(MEA)、哌嗪(PZ)、二乙烯三胺(DETA)、三乙烯四胺(TETA)与N-甲基二乙醇胺(MDEA)的混合溶液作为吸收剂对模拟合成气中CO2的吸收性能. 结果表明,胺活化性能依次为TETA>DETA>PZ>MEA;含TETA的吸收液可将尾气中CO2的浓度降至0.05%(mol),CO2脱除率达98.62%;增加活化剂浓度和降低气体流量有利于提高CO2脱除率;吸收-解吸循环条件下吸收速率是随吸收时间和活化剂浓度变化的指数递减函数.     

Carbon Dioxide Absorption in Triethanolamine Aqueous Solutions: Hydrodynamics and Mass Transfer

The carbon dioxide absorption process by triethanolamine aqueous solutions was analyzed in a bubble‐column reactor taking into account the chemical reaction mechanism, gas‐liquid interfacial area, and mass transfer rate. A speciation study of this gas‐liquid system was developed by ¹H and ¹³C NMR spectroscopy in order to obtain the reaction mechanism and stoichiometry. The gas‐liquid interfacial area was evaluated considering the variations of bubble size distribution and gas holdup during the operation time. The liquid‐phase mass transfer coefficient was calculated from the carbon dioxide absorption rate data by interfacial area evolution and reaction stoichiometry.     

Absorption of Carbon Dioxide from Flue Gas using Blended Amine Solutions

Employing systematic experiments and comparing the CO₂ absorption amount, absorption rate and CO₂ loading of various amines and their mixtures, the optimal formula of blended amine solution is investigated. The results demonstrate the absorption characteristics of diethylenetriamine are the best, followed by monoethanolamine and methyldiethanolamine, while diethanolamine has no competitive advantage, neither in terms of the absorption amount and rate nor loading of CO₂. The amine concentration has a significant influence on CO₂ absorption, followed by formula and ratio, while the temperature and pressure affect little. The optimal formula of blended amine solution with the highest rate constant and activation energy of CO₂ absorption was determined.     

Copper(I)‐Catalyzed Desulfinative Carboxylation of Sodium Sulfinates using Carbon Dioxide

A copper(I)‐catalyzed desulfinative carboxylation of sodium sulfinates using carbon dioxide has been developed. This reaction showed wide functional group tolerance. A series of sodium aryl‐ and alkenylsulfinates could be converted into the corresponding carboxylic acids in good to excellent yields. Additionally, the reaction mechanism was studied by in situ NMR analysis and isotopic labeling experiments.

     

CO2 Absorption into Aqueous Solutions of Monoethanolamine,Methyldiethanolamine, Piperazine and their Blends

The removal of carbon dioxide from industrial gases, e.g. in thermal power stations to meet the discharge limits for CO₂ in flue gases, is usually achieved with a reactive absorption technique using aqueous solutions of alkanolamines. From the absorption performance point of view, primary and secondary amines are preferred. However, in case the costs of the solvent regeneration are also taken into account, tertiary amines are much more attractive. In order to combine the specific advantages of tertiary and primary/secondary alkanolamines, both types of solvents are mixed. In this paper, mixtures of monoethanolamine and methyldiethanolamine with piperazine as absorption activator are experimentally compared with respect to CO₂ removal performances at 25 °C. The absorption process in a special packed column has also been simulated with the use of published data on reaction kinetics, physicochemical properties (densities, viscosities, diffusivities, Henry coefficients) of the CO₂‐amines systems, including experimentally determined hydrodynamic and mass transfer characteristics of the CO₂ scrubber.