膜基-氨基酸盐及其复合溶液吸收CO2的性能

选择了氨基乙酸(GLY)和氨基丙酸(ALA)的盐溶液作为CO2吸收剂,将高效活化剂哌嗪(PZ)添加于GLY形成新型氨基酸基复合溶液,采用膜接触器-再生循环装置,研究了液速、吸收剂浓度等因素对总传质系数和脱除率的影响,评价和比较了GLY和ALA及其复合溶液的吸收性能。结果表明:GLY的传质推动力大于ALA,GLY的总传质系数和脱除率大于ALA;在吸收剂浓度对总传质系数的影响程度上,GLY大于ALA;复合溶液的吸收性能明显优于单一的氨基酸盐溶液,少量的PZ能显著地增强传质效率。     

以AMP为主体的混合胺溶液捕集CO_2性能研究

空间位阻胺2-氨基-2-甲基-1-丙醇(AMP)捕集CO_2技术具有吸收容量大、低能耗、腐蚀性小等优势,但因其吸收速度慢,制约了该项技术的大规模应用。将AMP分别与乙醇胺(MEA)和N-氨乙基哌嗪(AEP)混合,探讨不同配比以AMP为主体的混合胺溶液捕获CO_2性能。结果表明:常温常压下,AMP和MEA的体积比为5∶5时,该混合胺捕集CO_2效果最佳,相对纯AMP溶液,吸收容量提高了12.34%,吸收速率提高了29.21%,解析速率提高了20.00%;AMP和AEP的体积比为7∶3时,捕集效果最佳,相对纯AMP溶液,吸收容量提高了9.680%,吸收速率提高了28.10%,解析速率提高了32.50%;在最佳配比时,AMP和MEA的混合胺溶液,与AMP和AEP的混合胺溶液相比较,前者吸收容量比后者大2.558%,吸收速率比后者快1.587%,解析速率比后者慢18.52%。     

活化MDEA脱碳溶剂的研究

基于分子设计的原理,开发了一种醇胺分子结构中具有位阻效应的新型活化剂,评价了由新型活化剂和N-甲基二乙醇胺(MDEA)组成的活化脱碳溶液的吸收性能。试验结果表明,与常规烷醇活化剂相比,新型活化脱碳溶液吸收CO2的速度快、吸收容量大、处理能力高;相同条件下,位阻胺活化剂的处理能力比二乙醇胺(DEA)活化剂提高20%左右。     

基于基团贡献法的CO2复合吸收溶剂实验研究

基于基团贡献法的基本原理,对用于脱除天然气中CO₂的复合溶剂进行组成设计。通过对比不同活化剂分子结构对其碱性、空间位阻效应等物化参数的影响,筛选出最佳的CO₂活化剂HZ,与N-甲基二乙醇胺(MDEA)水溶液混合组成复合溶剂。采用常压吸收-常压再生实验装置测定复合溶剂对CO₂的脱除能力,考察了活化剂种类、活化剂添加量、吸收温度、H₂S浓度和再生温度等因素对CO₂脱除效果的影响,以及复合溶剂的抗发泡性能。实验结果表明:活化剂HZ的活化效果优于MEA、DEA和PZ;HZ最佳添加量为0.7mol/L;最佳吸收温度为40℃;原料气中H₂S浓度增加,会降低复合溶剂对CO₂的脱除效果;最佳再生温度为115℃;复合溶剂具有良好的抗发泡性能。     

空间位阻胺AMP捕集CO_2技术研究进展

空间位阻胺AMP(2-氨基-2-甲基-1-丙醇)捕集CO_2具有吸收容量大、解吸能耗低和腐蚀性小等特点,对工艺过程的设计优化以及系统节能降耗具有重要的意义。综述了应用AMP捕集CO_2的动力学和热力学特性研究进展,介绍了其低腐蚀性的优良特性。其中,AMP混合体系改善其综合性能是当前研究热点,并对今后利用AMP捕集CO_2技术的研究方向提出了展望。     

MDEA复合溶液吸收CO2反应热实验研究

采用自主设计的中压搅拌反应釜及反应热测试装置,以CO_2和CH_4体积比为1∶1的混合气体作为模拟原料气,N-甲基二乙醇胺(MDEA)为主吸收剂,分别添加单乙醇胺(MEA)、二乙醇胺(DEA)、哌嗪(PZ)和2-氨基-2-甲基-1-丙醇(AMP)作为活化剂,通过反应热对比分析,优选了最佳的MDEA二元复合溶液。得出各体系最佳配比分别为:32%MDEA+3%MEA、30%MDEA+5%DEA、32%MDEA+3%PZ、30%MDEA+5%AMP。其中,32%MDEA+3%PZ是最佳的二元复合溶液,反应热为67.330 kJ·mol~(-1)CO_2。     

水泥窑用混合胺二氧化碳吸收剂的实验研究

本实验以2-氨基-2-甲基-1-丙醇(AMP)和二乙烯三胺(DETA)为吸收剂，探究了二者在不同配比下的吸收解吸性能，并与其他醇胺复配，开发出一种高性能混合胺二氧化碳吸收剂。实验发现AMP-DETA二元体系的吸收解吸性能均优于传统的乙醇胺(MEA)溶液，当AMP∶DETA=1∶1时，综合性能最优，物质的量负载为0.73 mol/mol，解吸率为82.99%。在此配比下进行三元复配时，加入哌嗪(PZ)可使吸收剂的初始吸收速率提升38.57%，三乙烯四胺(TETA)可使吸收剂的CO2物质的量负载提升36.99%，而N-甲基二乙醇胺(MDEA)可缩短1/3的解吸时间，从不同维度降低再生能耗。     

一种氨基酸盐基复合溶液捕集CO_2气体性能评价

将无机盐硼酸钾作为活化剂添加于甘氨酸盐溶液中,形成活化复合吸收剂;采用膜接触器装置,评价和比较了甘氨酸盐和活化复合吸收剂捕集CO2的性能。研究了活化剂浓度、液相流量和操作温度等因素对总体积传质系数、传质通量和捕集率的影响。结果表明:活化复合吸收剂对CO2的捕集产生明显的影响,活化复合吸收剂的总体积传质系数高于甘氨酸盐吸收剂;活化剂浓度对传质通量的影响表明,少量活化剂的作用远比多量的活化作用大;活化复合吸收剂的捕集率远大于甘氨酸盐吸收剂;膜接触器流体力学状态的改变,能够改善膜接触器传质性能,增大传质通量,但增大的程度有限;操作温度对膜吸收传质通量影响较大,温度越高,传质通量越高。     

复合溶液膜吸收CO2的性能及其对膜孔润湿的影响

利用自行搭建的CO₂膜吸收实验台，采用聚丙烯（PP）膜组件，以质量分数10%的N-甲基二乙醇胺（MDEA）作为主体胺溶液，添加不同配比的哌嗪（PZ）、乙醇胺（MEA）、甘氨酸钾（PG），考察CO₂脱除效率和传质速率的变化，比较不同复配比的复合溶液表面张力以及对PP膜的浸润性，并以10%MDEA+10%PG混合溶液作为吸收液进行长时间实验。结果表明：添加少量的添加剂对MDEA溶液膜吸收CO₂均有显著的促进作用，当配比小于0.2时，促进作用大小为PZ>MEA>PG；当配比大于0.2时，促进作用大小为PZ>PG>MEA；PZ和MEA均随着添加配比的增加，溶液表面张力减小，而PG相反；表面张力小的溶液对膜浸润性较强，容易造成膜润湿；添加剂质量分数均为10%时，对膜溶胀性和疏水性以及膜孔结构影响大小为PZ>MEA>PG；在20天内，PG/MDEA混合溶液作用下的CO₂脱除效率从89.56%下降为83.09%，对PP的疏水性影响较小，膜组件可以稳定运行。吸收液表面张力对膜吸收法脱除CO₂性能的影响显著。所得结果可为膜吸收CO₂吸收剂复配提供依据，并可为揭示膜吸收CO₂过程中膜润湿导致膜失效的机理以及抑制膜润湿提供实验数据。     

孔隙率对膜吸收过程影响的实验研究

采用纯CO2-去离子水和0.1 mol·L-1NaOH溶液为实验体系,选用8种具有不同微观结构的板式膜,研究了膜厚度、孔隙率,微孔形态等对膜吸收过程中传质性能的影响.结果表明,不同的微孔形态(拉伸孔、柱状孔)以及所用膜的厚度对膜吸收过程传质性能的影响较小,在吸收速率较快时孔隙率会影响膜吸收过程的传质性能.同时,还对溶质在液相侧表面的传质行为进行了探讨,结果表明膜孔隙率对膜吸收过程的传质性能的影响与流动状态、反应体系、微孔间距等多因素有关.     

Absorption of carbon dioxide into aqueous solutions of piperazine activated 2-amino-2-methyl-1-propanol

In this work, new experimental data on the rate of absorption of CO₂ into piperazine (PZ) activated aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) are reported. The absorption experiments using a wetted wall contactor have been carried out over the temperature range of 298-313 K and CO₂ partial pressure range of 2-14 kPa. PZ is used as a rate activator with a concentration ranging from 2 to 8 wt%, keeping the total amine concentration in the solution at 30 wt%. The CO₂ absorption into the aqueous amine solutions is described by a combined mass transfer-reaction kinetics-equilibrium model, developed according to Higbie's penetration theory. Parametric sensitivity analysis is done to determine the effects of possible errors in the model parameters on the accuracy of the calculated CO₂ absorption rates from the model. The model predictions have been found to be in good agreement with the experimental results of rates of absorption of CO₂ into aqueous (PZ+AMP). The good agreement between the model predicted rates and enhancement factors and the experimental results indicates that the combined mass transfer-reaction kinetics-equilibrium model with the appropriate use of model parameters can effectively represent CO₂ mass transfer in PZ activated aqueous AMP solutions.     

SOLUBILITY OF CO2 AND H2S IN A HINDERED AMINE SOLUTION

The solubility of H₂S and CO₂ in aqueous solutions of the sterically hindered amine, 2-amino-2-methyl-1-propanol (AMP), was determined at 40 and 100°C. Partial pressures of C)₂ ranged from approximately 2 to 6000 kPa and of H₂S from 2 to 2200 kPa. The solubility results were compared with previously reported acid gas solubilities in aqueous monoethanolamine (MEA) solutions.     

CO2 Absorption into Aqueous Solutions of a Polyamine (PZEA), a Sterically Hindered Amine (AMP), and their Blends

Among numerous techniques existing for reducing CO₂ emissions, CO₂ capture by absorption in aqueous alkanolamine solutions was specifically studied in this work. For the choice of the adequate amine solution, two major criteria must be taken into account: absorption performances (higher with primary and secondary amines) and energy costs for solvent regeneration (more interesting with tertiary and sterically hindered amines). The different types of amines can also be mixed in order to combine the specific advantages of each type of amines, an activation phenomenon being observed. Aqueous solutions of (piperazinyl‐1)‐2‐ethylamine (PZEA, a polyamine known as absorption activator) and 1‐amino‐2‐propanol (AMP, a sterically hindered amine), pure or mixed with other amines, are experimentally compared with respect to CO₂ removal performances by means of absorption test runs achieved in a special gas‐liquid contactor at 25 °C. The positive impact of addition of PZEA to monoethanolamine (MEA), N‐methyldiethanolamine (MDEA), and AMP solutions was clearly highlighted. The absorption performances have also been satisfactorily simulated with coherent physicochemical data.     

膜气体吸收过程中复合溶液化学增强因子预测

建立了一个膜吸收复合溶液化学增强因子计算模型,实验测定和模型预测了胺类复合溶液膜吸收CO2的增强因子,研究了Hatta准数Ha、气液流速、吸收剂浓度等因素对增强因子的影响,通过比较评价了模型的准确性。结果表明:当Ha>2,增强因子E值近似等于Ha,胺类膜吸收CO2的反应可作为拟一级快速反应处理;吸收剂浓度对增强因子的影响很大,随吸收剂浓度增大增强因子迅速增大;液速增大,增强因子也增大,但增大幅度有限;气速对增强因子几乎无影响。数学模型能较好地预测复合溶液膜吸收CO2的化学增强因子,预测的平均相对偏差为8.7%,最大为15.5%。     

Determination of mass transfer resistance during absorption of carbon dioxide by mixed absorbents in PVDF and PP membrane contactor

In this study, the absorption of carbon dioxide by the absorbent which was composed of 2-amino-2-methyl-l-propanol (AMP) + piperazine (PZ) or methyldiethanolamine (MDEA) + piperazine (PZ) in polyvinylidinefluoride (PVDF) and polypropylene (PP) membrane contactors werewas examined. Three resistances were considered in each hollow fiber, i.e., liquid-film diffusion, membrane diffusion, and gas-film diffusion. The mass transfer resistance of membrane k_m was influenced by the wetting ratio using an absorbent with higher reaction rate. The wetting ratio was affected by contact angle between the membrane and absorbent and the viscosity of absorbent. The calculated absorption rates considering wetting ratio of membrane and using the modified correlation equation of gas-phase mass transfer coefficient were reasonably agreeable to those of measured ones (standard deviation, 4%). The fractional resistance of each transport step during the experiments was then determined. The rate-controlling step was dominated by the resistance of gas-film diffusion with mixed absorbents. The absorption rates of CO₂ increase with the increasing of gas flow rates in the most experimental cases. The resistance of liquid-film diffusion was only important using an absorbent with lower reaction rate. The rate-controlling step was the membrane diffusion only at higher gas flow rate with the absorbent composed of AMP and PZ in PVDF hollow fiber membrane contactor.     

Absorption of carbon dioxide in piperazine activated concentrated aqueous 2-amino-2-methyl-1-propanol solvent

In this work new experimental data on the rate of absorption of CO₂ into piperazine (PZ) activated concentrated aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) over the temperature range 303–323 K are presented. The absorption experiments have been carried out in a wetted wall contactor over CO₂ partial pressure range of 5–15 kPa. PZ is used as a rate activator with a concentration ranging from 2 to 8 wt% keeping the total amine concentration in the solution at 40 wt%. The physical properties such as density and viscosity of concentrated aqueous AMP+PZ, as well as physical solubility of CO₂ in concentrated aqueous AMP+PZ, are also measured. New experimental data on vapor liquid equilibrium (VLE) of CO₂ in these concentrated aqueous solutions of AMP+PZ in the temperature range of 303–323 K have also been presented. The VLE measurements are carried out in an equilibrium cell in CO₂ pressure range of 0.1–140 kPa. A thermodynamic model based on electrolyte non-random two-liquid (eNRTL) theory is used to represent the VLE of CO₂ in aqueous AMP+PZ. Liquid phase speciations are estimated considering the nonideality of concentrated solutions of the amines and the calculated activity coefficients by eNRTL model. The CO₂ absorption in the aqueous amine solutions is described by a combined mass transfer-reaction kinetics model developed according to Higbie's penetration theory. The model predictions have been found to be in good agreement with the experimental results of the rates of absorptions of CO₂ into aqueous AMP+PZ.     

Kinetics of the absorption of carbon dioxide into mixed aqueous solutions of 2-amino-2-methyl-l-propanol and piperazine

The reaction kinetics of the absorption of CO₂ into aqueous solutions of piperazine (PZ) and into mixed aqueous solutions of 2-amino-2-methyl-l-propanol (AMP) and PZ were investigated by wetted wall column at 30-40 °C. The physical properties such as density, viscosity, solubility, and diffusivity of the aqueous alkanolamine solutions were also measured. The N₂O analogy was applied to estimate the solubilities and diffusivities of CO₂ in aqueous amine systems. Based on the pseudo-first-order for the CO₂ absorption, the overall pseudo first-order reaction rate constants were determined from the kinetic measurements. For CO₂ absorption into aqueous PZ solutions, the obtained second-order reaction rate constants for the reaction of CO₂ with PZ are in a good agreement with the results of Bishnoi and Rochelle (Chem. Eng. Sci. 55 (2000) 5531). For CO₂ absorption into mixed aqueous solutions of AMP and PZ, it was found that the addition of small amounts of PZ to aqueous AMP solutions has significant effect on the enhancement of the CO₂ absorption rate. For the CO₂ absorption reaction rate model, a hybrid reaction rate model, a second-order reaction for the reaction of CO₂ with PZ and a zwitterion mechanism for the reaction of CO₂ with AMP was used to model the kinetic data. The overall absolute percentage deviation for the calculation of the apparent rate constant k_app is 7.7% for the kinetics data measured. The model is satisfactory to represent the CO₂ absorption into mixed aqueous solutions of AMP and PZ.     

膜基复合溶液吸收CO2过程模拟

建立了膜基复合溶液吸收CO₂传质微分方程模型,模型中考虑了MDEA-AMP复合溶剂吸收反应交互作用和溶剂对膜孔的湿润性两种因素,模拟了这两种因素、不同气液速及不同组件对传质过程的影响,通过SEM摄片考察了溶剂对膜结构形态的影响.结果表明：交互作用和湿润性是影响传质过程不可忽略的重要因素;MDEA和AMP的增强因子对总增强因子不具有加和性;湿润使膜相阻力迅速上升,成为传质阻力的主导项;高液速时膜孔易被湿润;SEM摄片发现溶剂使膜孔增大,长时间运行疏水性膜有亲水化趋势.考虑交互因子β和湿润率η的模型,模型值与实验值符合更好.     

Absorption of carbon dioxide by the absorbent composed of piperazine and 2-amino-2-methyl-1-propanol in PVDF membrane contactor

This paper tests the performance of microporous polyvinylidinefluoride (PVDF) hollow fiber in a gas absorption membrane process (GAM) using the aqueous solutions of piperazine (PZ) and 2-amino-2-methyl-1-propanol (AMP). Experiments were conducted at various gas flow rates, liquid flow rates and absorbent concentrations. Experimental results showed that wetting ratio was about 0.036% when used with the aqueous alkanolamine solutions, while that was 0.39% with aqueous piperazine solutions. The CO₂ absorption rates increased with increasing both liquid and gas flow rates at N_Re < 20. The increase of the PZ concentration showed an increase of absorption rate of CO₂. The CO₂ absorption rate was much enhanced by the addition of PZ promoter. The resistance of membrane was predominated as using a low reactivity absorbent and can be neglected as using absorbent of AMP aqueous solution. The resistance of gas-film diffusion was dominated as using the mixed absorbents of AMP and PZ. An increase of PZ concentration, the resistance of liquid-film diffusion decreased but resistance of gas-film increased. Overall, GAM systems were shown to be an effective technology for absorbing CO₂ from simulated flue gas streams, but the viscosity and solvent-membrane relationship were critical factors that can significantly affect system performance.     

Experimental investigation of the effects of different chemical absorbents on wetting and morphology of poly(vinylidene fluoride) membrane

Membrane wetting is of one the most important factor that affects the CO₂ absorption efficiency in membrane contactors due to the increase of mass transfer resistance. In this study, the effects of different absorbents on the wettability of poly(vinylidene fluoride) membranes were investigated. Four absorbents including monoethanolamine, potassium carbonate–piperazine (PZ), potassium carbonate–monoethanolamine, and methyldiethanolamine–PZ were applied to investigate the effects of different absorbents on membrane wetting. Membrane properties before and after contact with absorbents were investigated using methods of thermogravimetric analysis, Fourier transform infrared spectroscopy, electron scanning microscope, and contact angle measurements. The results revealed that methyldiethanolamine and mixed absorbents containing methyldiethanolamine caused the most morphological changes in membrane. The results showed that reduction percentages of contact angle for water, K2CO3/PZ, K2CO3/MEA, MEA, and MDEA/PZ solutions were 14.52, 16.9, 21.19, 23.7, and 28.33, respectively, after 30 days immersion. The results also showed that potassium carbonate–PZ solution caused the least change in membrane wettability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45543.