拟薄水铝石负载PEI/AMP吸附CO2性能

用富含胺基的物质对多孔材料进行修饰可以得到高CO₂吸附量的吸附剂。采用浸渍法将聚乙烯亚胺(PEI)和2-氨基-2-甲基-1-丙醇(AMP)负载在拟薄水铝石上,考察了CO₂压力、胺类物质负载量等对吸附性能的影响。采用低温N₂吸附/脱附法(BET)、扫描电镜(SEM)、傅里叶变换红外线光谱分析仪(FTIR)等手段表征了吸附剂的结构特征及其物理性质,并使用重量法微天平实验装置对吸附剂的性能进行了评价。实验结果表明,当温度恒定为50℃,压力小于1 MPa时,负载PEI的吸附剂最高的CO₂吸附量为77.53 mg CO₂·(g吸附剂)^-1,最佳负载量为85%;压力大于1 MPa时,负载PEI的吸附剂最高的CO₂吸附量为123.79 mg CO₂·(g吸附剂)^-1,最佳负载量为10%。负载AMP的吸附剂最高的CO₂吸附量为128.01 mg CO₂·(g吸附剂)^-1,最佳负载量为85%。CO₂吸附稳定性实验表明,吸附剂对CO₂的吸附性能稳定。     

2-甲基咪唑/乙二醇体系常温脱除天然气中的二氧化碳

将2-甲基咪唑溶于乙二醇中形成混合溶液体系,利用该体系常温下实现对天然气中二氧化碳的脱除。首先分别测定单组分甲烷和二氧化碳在体系中的吸收容量,在0.1 MPa下,CO₂在2-甲基咪唑/乙二醇混合溶液中溶解度约为0.87 mol·L^-1,高于同等条件下CO₂在大部分离子液体中的溶解度,二氧化碳的吸收容量远大于甲烷的;然后对混合气CH₄/CO₂进行分离,发现该体系能较好吸收分离CH₄/CO₂。最后考察了体系的再生性和重复利用性,得出2-甲基咪唑/乙二醇溶液体系能完全再生并且能重复使用。     

CO2在PET熔体中的溶解度

通过高温高压磁悬浮天平(MSB)测定表观溶解度、高温高压视窗釜进行溶胀度校正的方法研究了CO₂在PET熔体中的溶解度,考察了温度、压力对改性前后PET在CO₂环境中的溶胀度和CO₂溶解度的影响。结果表明,PET在CO₂环境中的溶胀度和CO₂溶解度均随温度的增加而减小,随压力增加而增加,但高压下溶胀度的增加趋势减缓并趋于某定值;与常规线性PET相比,改性PET具有较小的溶胀度和溶解度。在250~280℃,4~6 MPa下,CO₂在PET熔体中的溶解度具有10^-2 g CO₂·(g PET melt)^-1的量级。1~6 MPa下CO₂在PET熔体中的溶解行为符合亨利定律,利用最小二乘法拟合得到了CO₂在PET熔体中的溶解热。     

氨水吸收CO2的吸收热预测模型

基于e-NRTL模型,利用Aspen Plus软件建立了氨水吸收CO₂的吸收热预测模型,验证了NH₃-CO₂-H₂O体系的汽液平衡、液相组成形态并与前人的实验数据做了对比,进而结合负载CO₂的氨水溶液中各离子及分子的变化特征,对CO₂吸收过程的反应热随着CO₂负载量的变化规律进行了预测并与已发表的数据进行了比较。结果表明,该吸收热模型能够准确地实现氨水吸收CO₂过程中汽液平衡、液相反应以及吸收热的计算。氨水吸收CO₂的反应热主要受H₂O的电离、NH₃的电离、NH₂COO^-的生成与水解、CO₂的溶解等反应过程的影响,H₂O的电离过程受NH₃的电离过程的抑制,对于总吸收热的贡献最大, NH₂COO^-的反应则随着CO₂负载量的增加先放热再吸热。随着温度的升高,总吸收热有所降低,当温度为80℃时,在较低的CO₂负载区间[0.2～0.5 mol CO₂·(mol NH₃)^-1],总吸收热约为70.5 kJ·(mol CO₂)^-1。     

CO2在ZIF-8/乙二醇-2-甲基咪唑浆液中溶解能力理论分析

有效降低CO₂排量实现碳中和是当前研究热点之一。ZIF-8/乙二醇-2-甲基咪唑浆液被发现不仅能高效地捕集CO₂,同时能利用浆液良好的流动性实现一个碳捕集-浆液流动再生-浆液再利用的连续碳捕集过程。为了有效地掌握纯CO₂气体在ZIF-8/乙二醇-2-甲基咪唑浆液中的溶解能力,本文首先测定了293.15K、303.15K和313.15K下CO₂在干ZIF-8上的吸附量和在2-甲基咪唑-乙二醇溶液中的溶解性;然后基于Langmuir方程和CO₂溶解机理进一步建立了相应吸附量和溶解度计算数学模型;最后综合考虑ZIF-8/乙二醇-2-甲基咪唑浆液中乙二醇和ZIF-8之间的共存特征和相互影响,建立了CO₂在目标浆液中溶解吸收量计算数学关联式。所得研究结果对浆液法CO₂技术的推广和后续流程模拟具有良好的指导作用和理论意义。     

用于CO_2吸收的离子液体的合成、表征及吸收性能

以N-甲基咪唑和3-溴丙胺氢溴酸盐为起始原料,合成了一种含氨基的离子液体(ionic liquid,IL)——1-(1-氨基丙基)-3-甲基咪唑溴盐(简写为[NH2p-mim]Br),总产率为90.1%,溴含量为0.980 mol Br/mol IL,胺含量为0.948 mol NH2/mol IL。探讨了合成工艺,并通过1HNMR、13CNMR、IR和MS对产物结构进行了表征。吸收实验结果表明,该离子液体能够有效地吸收CO2,在40℃和106 kPa下,质量分数为45%的离子液体水溶液吸收CO2至饱和时,溶液中CO2的摩尔分数可达0.444 mol CO2/mol IL,接近理论吸收量0.5 mol CO2/mol IL;在90℃的真空状态下,吸收的CO2能够完全解吸,重复吸收实验表明,该离子液体吸收CO2的能力无明显下降。     

负载[APMIm][Br]离子液体吸收CO2的性能

1-氨丙基-3-甲基咪唑溴盐（[APMIm][Br]）离子液体通过化学反应捕集CO₂。采用浸渍-蒸发将[APMIm][Br]离子液体负载在硅胶表面,通过比表面孔隙吸附测定仪、热重分析仪（TGA）对吸收剂的结构与性能进行研究,负载量为10%～50%,温度为303.15～323.15 K,CO₂浓度分别为10%、30%、50%。结果表明：硅胶表面的离子液体薄膜厚度达到86 nm（负载40%）时,具有最快的吸收速率,且受CO₂浓度和温度变化的影响较小,平衡吸收量在50% CO₂体系中达到理论吸收量的80%,随着温度的升高而降低,当负载量为50%时,膜厚增加到230 nm,导致吸收速率和平衡吸收量大幅度下降。值得注意的是：负载离子液体吸收剂在循环使用3次之后,结构与性能均保持不变,表现出一定的工业运用前景。     

燃煤烟气中SO2对氨法脱碳的影响

利用湿壁塔实验台对燃煤烟气中SO₂对氨水溶液［1%～7%(质量）］吸收CO₂的影响进行了实验研究,具体分析了不同反应温度（20～80℃）和CO₂体积分数（5%～20%）条件下,CO₂传质通量及传质系数随SO₂浓度和SO₂负载量的变化规律。结果表明, SO₂浓度由0增至11428 mg·m^-3,CO₂传质通量及传质系数均有一半左右降幅,而SO₂负载量［0.1～0.4 mol SO₂·（mol NH₃）^-1］的增加,同样导致CO₂传质通量及传质系数明显减小。氨水浓度及反应温度增加可有效提高CO₂传质通量和传质系数,相对降低SO₂对CO₂传质的影响。CO₂浓度的增加可明显提高其传质通量,但是CO₂的传质系数有所降低。     

杂质离子对MgCl2和CO2反应-萃取-醇析耦合过程的影响

通过反应-萃取-醇析耦合过程，将MgCl₂和CO₂制备成碳酸镁和氯化氢气体是盐湖老卤资源化利用的有效途径。系统地研究了老卤中Na⁺、K⁺、Ca²⁺对MgCl₂和CO₂反应-萃取-醇析耦合过程得到的固体产物晶型晶貌的影响。结果表明，Na⁺和K⁺对耦合过程的影响相似，固体产物均为高纯棒状三水碳酸镁（MgCO₃·3H₂O），且Na⁺和K⁺均能选择性吸附在MgCO₃·3H₂O晶体的轴面（101），阻碍该晶面的生长，使得棒状MgCO₃·3H₂O直径变小；Ca²⁺对反应-萃取-醇析耦合过程有不利的影响，由于CaCl2能参与反应，生成球状无定形纳米钙镁碳酸盐，使得三水碳酸镁纯度降低。     

1-氨丙基-3-甲基咪唑溴盐水溶液的汽液相平衡

1-氨丙基-3-甲基咪唑溴盐([APMIm][Br])是一种对CO₂有良好吸收性能的功能型离子液体,在工业中可采用水溶液来实现高效能的吸收和解吸循环过程,因此对其水溶液特性的研究至关重要。对[APMIm][Br]水溶液在中低温度下的汽液相平衡进行了测量,获得可靠的实验数据,从而揭示其水溶液特性。实验温度范围为278.15～348.15 K,[APMIm][Br]在水溶液中质量分数分别为10.0%、20.3%、29.5%、40.0%、57.5%、75.3%、84.0%、88.9%、90.9%。考虑了低温下离子液体分子在水溶液中的强缔合特性,采用带缔合惰化因子的离子液体水溶液活度模型对实验数据进行了拟合,实验值与计算结果符合很好,平均相对误差为2.15%。     

Solubility and absorption rate enhancement of CO2 in K2CO3

The influence of addition of 2-(1-piperazinyl)-ethylamine (as a promoter) on the solubility and absorption rate of carbon dioxide (CO₂) in aqueous potassium carbonate solution (as a main solvent) was investigated experimentally, using a vapor liquid equilibrium (VLE) equipment in temperatures from 303.15 to 323.15 K and CO₂ initial partial pressures between 25 and 75 kPa. The experimental data showed that the addition of 2-(1-piperazinyl)-ethylamine to potassium carbonate solution results in a significant enhancement in the solubility and absorption rate of CO₂. The response surface methodology was applied to explore the relationship between independent parameters on the CO₂ loading capacity of blended solution.     

Investigation of CO2 solubility in monoethanolamine hydrochloride based deep eutectic solvents and physical properties measurements

Deep eutectic solvents (DESs) have drawn a growing research interest for applications in a wide range of scientific and industrial arenas. However, a limited effort has been reported in the area of gas separation processes and particularly the carbon dioxide capture. This study introduces a novel set of DESs that were prepared by complexing ethylenediamine (EDA), monoethanolamine (MEA), tetraethylenepentamine (TEPA), triethylenetetramine (TETA) and diethylenetriamine (DETA) as hydrogen bond donors to monoethanolamide hydrochloride (EAHC) salt as a hydrogen bond acceptor. The absorption capacity of CO₂ was evaluated by exploiting a method based on measuring the pressure drop during the absorption process. The solubility of different DESs was studied at a temperature of 313.15 K and initial pressure of 0.8 MPa. The DES systems 1EAHC:9DETA, 1EAHC:9TETA and 1EAHC:9TEPA achieved the highest CO₂ solubility of 0.6611, 0.6572 and 0.7017 mol CO₂·(mole DES)⁻¹ respectively. The results showed that CO₂ solubility in the DESs increased with increasing the molar ratio of hydrogen bond donor. In addition, the CO₂ solubility increased as the number of amine groups in the solvent increases, therefore, increasing the alkyl chain length in the DESs, resulted in increasing the CO₂ solubility. FTIR analysis confirms the DES synthesis since no new functional group was identified. The FTIR spectra also revealed the carbamate formation in DES-CO₂ mixtures. In addition, the densities and viscosities of the synthesized DESs were also measured. The CO₂ initial investigation of reported DESs shows that these can be potential alternative for conventional solvents in CO₂ capture processes.     

Experimental studies and modeling of CO2 solubility in high temperature aqueous CaCl2, MgCl2, Na2SO4, and KCl solutions

The phase equilibria of CO₂ and aqueous electrolyte solutions are important to various chemical‐, petroleum‐, and environmental‐related technical applications. CO₂ solubility in aqueous CaCl₂, MgCl₂, Na₂SO₄, and KCl solutions at a pressure of 15 MPa, the temperatures from 323 to 423 K, and the ionic strength from 1 to 6 mol kg^?1 were measured. Based on the measured experimental CO₂ solubility, the previous developed fugacity‐activity thermodynamic model for the CO₂‐NaCl‐H₂O system was extended to account for the effects of different salt species on CO₂ solubility in aqueous solutions at temperatures up to 523 K, pressures up to 150 MPa, and salt concentrations up to saturation. Comparisons of different models against literature data reveal a clear improvement of the proposed PSUCO2 model in predicting CO₂ solubility in aqueous salt solutions. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2286–2297, 2015     

Liquid‐liquid phase split in ionic liquid + toluene mixtures induced by CO2

High pressure carbon dioxide was dissolved in ionic liquid + toluene mixtures to obtain the conditions of pressure and composition where a liquid‐liquid phase split occurs at constant temperature. Ionic liquids (ILs) with four different cations paired with the bis(trifluoromethylsulfonyl)imide ([Tf₂N]^?) anion were selected: 1‐hexyl‐3‐methylimidazolium ([hmim]⁺), 1‐hexyl‐3‐methylpyridinium ([hmpy]⁺), triethyloctylphosphonium ([P₂₂₂₈]⁺), and tetradecyltrihexylphosphonium ([P₆₆₆₁₄]⁺). The solubility of CO₂ was measured in the liquid mixtures at temperatures between 298 and 333 K and at pressures up to 8 MPa, or until the second liquid phase appeared, for initial liquid phase compositions of 0.30, 0.50, and 0.70 mole fraction of IL. Ternary isotherms were compared with the binary solubility of CO₂ in each IL and pure toluene. The lowest pressure for separating toluene in a second liquid phase was achieved by decreasing the temperature of the system, increasing the amount of toluene in the initial liquid mixture and using [hmim][Tf₂N]. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2968–2976, 2015     

The solubility of carbon dioxide and hydrogen sulfide in a 35 wt% aqueous solution of methyldiethanolamine

The solubility of hydrogen sulfide and carbon dioxide in an aqueous solution containing 35 wt% methyldiethanolamine (MDEA) (3.04 kmol/m³, 4.52 mol/kg) has been measured at 40° and 100°C at partial pressures of the acid gas up to 530 kPa. Some data for hydrogen sulfide in a 50 wt% solution of MDEA (4.38 kmol/m³, 8.39 mol/kg) were also obtained. Also, densities of CO₂-aqueous MDEA solutions were measured at 40°C.     

CO2 absorption into a phase change absorbent: Water-lean potassium prolinate/ethanol solution

Phase change solvents are attractive energy-efficient absorbents for carbon dioxide (CO₂) capture due to CO₂-rich phase formation. Potassium prolinate + water + ethanol (ProK/W/Eth) solution has shown good capture characteristics as a promising one in our previous work. In this work, absorption rate of CO₂, solubility of N₂O, and heat of absorption for ProK/W/Eth solution were investigated using a stirred cell reactor and a CPA201 reaction calorimeter and these results were also compared with the aqueous ProK and 30 mass% MEA solutions. Using ethanol as a solvent can substantially increase the CO₂ physical solubility and the absorption rate of CO₂ in ProK/W/Eth solutions is far higher than that in aqueous 30 mass% MEA solutions especially at a low CO₂ loading range. Solid precipitation, obtained from the liquid-to-solid phase change absorption, was analyzed by ¹³C NMR and DSC-TGA. The enthalpy change for ProK/W/Eth solutions at various CO₂ loading was also discussed.     

High pressure density and solubility for the CO2 + 1-ethyl-3-methylimidazolium ethylsulfate system

The solubility and density of the CO₂ + 1-ethyl-3-methylimidazolium ethylsulfate system were investigated. The carbon dioxide solubility in the IL was measured in the temperature range 273–413 K, for pressure up to 5 MPa and CO₂ mole fractions ranging from 0.02 to 0.5 using the isochoric method, while the system density was carried out at temperatures ranging from 278.15 K to 398.15 K, pressures from 10 MPa to 120 MPa and 0.2, 0.4, 0.7 and 0.8 CO₂ mole fractions. Similar to what was previously observed for phosphonate-based ILs, the ionic liquid high polarity leads to positive deviations from ideality resulting from unfavorable interactions with the CO₂.The results from the density and solubility derived properties show that the system presents important negative excess molar volumes, over the whole range of compositions and temperatures, and a negative entropy of solvation that suggests an increase in ordering of the solvent molecules surrounding the solute. The observed negative excess molar volumes result from the large difference between the molecular volumes of the species involved, with the small carbon dioxide molecules occupying the empty spaces between the larger IL ions, supporting the notion that the carbon dioxide, upon dissolution, occupies essentially the bulk free volume since the IL does not significantly expand upon gas absorption. These results portray ionic liquids as a porous media, like a soft sponge, with a huge free volume in which large amounts of carbon dioxide are able to accommodate during the dissolution process.     

High-pressure solubility of carbon dioxide in imidazolium-based ionic liquids with anions [PF6] and [BF4]

The solubility of carbon dioxide in three ionic liquids (ILs) under supercritical fluid condition was measured at pressures up to 32 MPa and at temperatures of 313.15, 323.15, and 333.15 K in a high-pressure view cell. The imidazolium-derivative ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), and 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF₄]) were employed in this research. The effects of pressure, temperature, nature of anion and cation as well as the water content on the solubility of CO₂ in the ILs were investigated experimentally. The solubility of CO₂ in the IL was higher for the ILs with longer cationic alkyl group and for the ILs with lower anion polarity. The lower the water content or the lower the temperature as well as the higher the pressure, the higher was the solubility of CO₂.