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.     

胆碱类低共融溶剂在CO2捕集与分离中的应用

胆碱类低共融溶剂是一种新型的离子液体。它不仅具有传统离子液体的优点,还具有价格低廉、低毒、生物可降解等优势。对胆碱类低共融溶剂在CO₂捕集与分离中所涉及的物理性质,如气体的溶解度、CO₂的吸收-解吸、密度、稳定性、黏度和表面张力等进行考察,并分析了胆碱类低共融溶剂的结构对各物性的影响。通过与传统离子液体的对比,胆碱类低共融溶剂在CO₂捕集与分离中的应用具有一定的优势,如CO₂溶解度高,黏度低。然而,胆碱类低共融溶剂在气体的选择性分离、表面张力等的研究还不足,且热稳定性方面还存在瓶颈,因此,其在CO₂捕集和分离中的应用还有待进一步探讨。     

离子液体和低共熔溶剂催化二氧化碳合成有机碳酸酯的研究进展

离子液体和低共熔溶剂因其良好的溶解与催化能力,可催化CO₂转化为高附加值化学品。本文综述了离子液体和低共熔溶剂催化CO₂转化为有机碳酸酯的研究进展,分析了CO₂与醇生成直链碳酸酯以及与环氧化物生成环状碳酸酯的反应机理;介绍了传统型、质子型、功能化离子液体以及由氯化胆碱、季铵盐与季膦盐、有机碱等作为氢键受体组成的低共熔溶剂,及其在CO₂转化为直链和环状碳酸酯反应中的催化性能;总结了此两类反应中离子液体和低共熔溶剂设计的基本规律;指出了CO₂转化反应中离子液体与低共熔溶剂存在的催化效率低、稳定性不高、后续分离困难等问题,后续研究可结合计算机辅助设计方法,探索更合适的阴阳离子/氢键供受体组合,获得更高效的催化体系。     

新型酚基深共熔溶剂的物性表征及NH3捕集性能研究

NH₃污染问题一直是化工、环保等领域关注的重点问题，对工业尾气中的NH₃进行捕集和回收具有十分重要的意义。以氯化1-乙基-3-甲基咪唑 （［Emim］Cl） 为氢键受体，苯酚、间苯二酚和间苯三酚为氢键供体，构建了一类新型酚基深共熔溶剂。详细测定了酚基深共熔溶剂在不同温度下的密度和黏度，并采用经验方程对密度和黏度数据进行了关联。此外，系统考察了酚基深共熔溶剂对NH₃的吸收-解吸性能和吸收选择性，发现其具有较高的NH₃吸收容量，被吸收的NH₃可在加热和减压的条件下释放出来，经过多次循环NH₃吸收容量基本保持不变。而酚基深共熔溶剂的CO₂吸收容量则较低，因而具有优异的NH₃/CO₂吸收选择性。最后，借助光谱表征和量子化学计算，深入探究了NH₃在酚基深共熔溶剂中吸收的相互作用机制。     

苯甲酸型低共熔溶剂吸收一氧化氮的性能研究

低共熔溶剂（DESs）已被广泛研究并应用于酸性气体的吸收，本研究发现苯甲酸类DESs能够可逆高效地吸收一氧化氮（NO）。以苯甲酸（BA）、硫脲、尿素和咪唑为氢键供体（HBD），以离子液体为氢键受体（HBA）制备了一系列的DESs。吸收NO的实验结果表明，以氯化四丁基膦（P₄₄₄₄Cl）为HBA和以BA为HBD的DESs表现出较高的NO吸收速率和饱和吸收量。BA/P₄₄₄₄Cl (1∶2) DES在101.3 kPa、303.15 K下，NO吸收量为2.75 mol/mol。热重测试和再生实验的结果表明，BA/P₄₄₄₄Cl (1∶2) DES具有理想的热稳定性和重复使用性。通过FTIR、¹H NMR和高斯模拟计算，探讨了BA/P₄₄₄₄Cl (1∶2) DES对NO的吸收机理，发现NO与BA的含氢氧原子之间存在化学相互作用，且BA的易去质子化性质有利于NO的吸收。     

氨基修饰复合型钠基吸收剂的脱碳特性

为弥补常规钠基吸收剂活性差、脱碳量低的不足,制备了多种表面氨基修饰的新型复合型钠基吸收剂并研究其脱碳特性。通过比较氨基流失率和实际脱碳量,选定二氧化硅的前驱物正硅酸乙酯为载体前驱物,以碳酸钠为活性成分,分别以3-氨基丙基三甲氧基硅烷(APS)、3-氨基丙基三乙氧基硅烷(APTES)、二乙烯三胺(DETA)、三乙烯四胺(TETA)为氨基前驱物,制备得到多种表面氨基修饰的复合型钠基吸收剂。探究各种吸收剂的孔隙结构与脱碳特性,结果表明,APS、APTES修饰后吸收剂孔隙特性较差,脱碳量较低,DETA、TETA修饰后吸收剂孔隙结构得到改善,脱碳量较高。     

咪唑类三元低共熔溶剂捕集低压SO2的实验研究

近几年来，以氢键受体（HBA）和氢键供体（HBD）组成的低共熔溶剂（DESs）以其类似于离子液体的性质被认为是一种有潜力的SO₂吸附剂。为制备用于低压SO₂吸收的容量大、价格合理、循环性能好的低共熔溶剂，选用咪唑(Im)作为功能化组分，以价格低廉的甘油(Gly)、PEG200和乙二醇(EG)作为第二HBD，与作为HBA的氯化胆碱(CC)构建CC-GIy-Im、CC-PEG200-Im、CC-EG-Im三元功能化低共熔溶剂，并用于低压SO₂的捕集实验研究。着重考察了第二HBD种类、咪唑含量、温度等因素对DESs吸收SO₂的性能影响。结果表明：在所选的第二HBD中，PEG200的性能最佳，其构建的低共熔溶剂密度、黏度适中，热稳定性好，吸收性好；CC-PEG200-Im（1∶2∶7）在40℃下，对1% SO₂的吸收量达到0.236 g SO₂/g DES；经5次吸收-解吸循环后，低共熔溶剂吸收性能仍然稳定；¹H NMR谱图分析结果表明，CC-PEG200-Im对SO₂的吸收机理为化学吸收。     

多孔胺基化氧化石墨烯基材料对CO2的吸附性能研究

以乙二胺(EDA)、二乙烯三胺(DETA)、四乙烯五胺(TEPA)、聚乙烯亚胺(PEI)等多胺基化合物为表面改性剂,氧化石墨烯(GO)材料为载体,采用嫁接法辅以超声处理制备了表面胺基功能化多孔吸附材料,用于CO₂气体的吸附捕集。所制备的多孔吸附材料孔径约为1.35~4.34 nm,比表面积约为98.032~210.465 m²/g。制备的四种吸附材料中,以PEI功能化吸附材料对CO₂的吸附容量最大,70℃下达到了1.5 mmol/g,且经过20次循环吸附/脱附实验后,其CO₂吸附量基本不变。吸附过程的吸附等温线线型为Ⅰ型优惠型,另外吸附实验数据与Avrami模型模拟结果符合性较好。     

CO2在醚酯溶剂中的溶解度测定及热力学计算

采用恒定容积法,在温度353.15、363.15、373.15 K下,测定了CO₂在丙二醇甲醚醋酸酯(PMA)、二丙二醇甲醚醋酸酯(DPMA)、乙二醇丁醚醋酸酯(BAC)以及乙二醇苯醚醋酸酯(EPA)中的溶解度数据,压力最高可达11.73 MPa。结果表明CO₂在醚酯体系中溶解度受温度、压强的影响较大,压强一定时,CO₂在醚酯中溶解度随温度升高而减小;温度一定时,随着压强增大而增大;相同条件下,CO₂在四种醚酯中溶解度大小为PMA＜ EPA＜BAC＜DPMA。通过变形Clausius - Clapeyron方程,计算得到CO₂在醚酯溶剂中的Gibbs自由能Δ_sol G,溶解焓变Δ_sol H和熵变 Δ_sol S等热力学性质,从宏观热运动角度进一步解释了CO₂的溶解机理,为开发新型CO₂物理吸收剂提供理论支撑。     

TEPA负载复合氧化活性炭吸附烟气中的CO2性能

以商业煤基活性炭为原料，经低浓度氧气焙烧、H₂O₂氧化改性，并以四乙烯五胺（TEPA）浸渍，得到胺负载复合氧化活性炭，用于模拟烟道气[(15%(体积)CO₂+85%(体积)N₂）+10%(体积)H₂O]中CO₂吸附。低浓度氧气焙烧后，活性炭的最大比表面积和孔体积分别为1421.82 m²/g、0.83 cm³/g。经复合氧化改性后，活性炭的介孔体积增大，表面含氧官能团增加，使得TEPA负载复合氧化活性炭的CO₂吸附性能提高。焙烧时间为4 h，H₂O₂氧化、负载40%TEPA的样品COAC-4-40TEPA，在60℃时CO₂饱和吸附量最高为2.45 mmol/g，是TEPA负载未改性活性炭AC-40TEPA的2.02倍。经过十次吸附循环后，COAC-4-40TEPA的 CO₂饱和吸附量可维持在92.24%，而TEPA的浸出量仅有0.67%。失活模型研究表明，COAC-4-40TEPA的初始吸附速率常数是AC-40TEPA的1.64倍，且失活速率常数低于AC-40TEPA。     

超临界二氧化碳-共溶剂体系与聚醋酸乙烯酯相互作用

采用多尺度模拟和实验结合研究了乙醇、丙酮、正庚烷等共溶剂的加入对超临界二氧化碳（CO₂）溶剂体系的影响,通过改善溶剂-溶剂和溶剂-溶质相互作用增强聚醋酸乙烯酯（PVAc）与CO₂的相容性。量子力学从头算结果表明,3种共溶剂中乙醇与CO₂的相互作用最强,丙酮次之,正庚烷最弱。分子动力学模拟也表明在相同共溶剂含量下,乙醇对溶剂体系溶解度参数的改善最为明显,超临界CO₂-乙醇体系与PVAc链的相互作用更强,有助于提高PVAc与溶剂的相容性。这是由于乙醇本身的溶解度参数较大,且与CO₂形成氢键作用,从而大幅增强了其与CO₂的相互作用。浊点压力实验证实了共溶剂的加入增强了超临界CO₂体系与PVAc的相容性,乙醇的加入对PVAc浊点压力的降低最为有效,且随着共溶剂含量的增加,PVAc在溶剂中的溶解能力增强。     

EMIES/nC9H10O2基低共熔溶剂的制备及其氧化脱硫活性的研究

通过简单加热1-乙基-3-甲基咪唑硫酸乙酯（EMIES）离子液体和3-苯丙酸（C₉H₁₀O₂）的混合物，制备了一系列酸性低共熔溶剂EMIES/nC₉H₁₀O₂（n=0.25,0.5,1,2,4）。通过FTIR，¹H NMR和TGA的表征，确定EMIES/nC₉H₁₀O₂的结构。以该低共熔溶剂为催化剂和萃取剂，H₂O₂为氧化剂，组成氧化-萃取脱硫体系，用于脱除模拟油中的硫化物。考察了原料配比、反应温度、氧硫比（O/S）、低共熔溶剂加入量和不同硫化物对脱硫性能的影响。结果表明，在EMIES和C₉H₁₀O₂摩尔比为1∶1，反应温度为50℃，O/S比为8，低共熔溶剂加入量为1.5 g和模拟油5 ml的反应条件下，二苯并噻吩、4,6-二甲基二苯并噻吩和苯并噻吩的脱除率分别为94.8%、91.6%和46.4%。低共熔溶剂可循环使用6次，活性无明显下降。此外，对该氧化-萃取脱硫体系的脱硫机理进行了探讨。     

SOLUBILITY OF CARBON DIOXIDE IN AQUEOUS AND ANHYDROUS MIXTURES OF METHYLDIETHANOLAMINE AND TRIETHYLENE GLYCOL MONOMETHYL ETHER

Mixed solvents are a combination of chemical and physical solvents and are used for the removal of acid gases from gas streams. The solubility of CO₂ in a mixed nonaqueous solution of methyldiethanolamine (MDEA) (50 wt.%) and triethylene glycol monomethj'l ether (TEGMME) (50 wt.%) has been measured at 40°C. The data are compared with solubility data of CO₂ in pure TEGMME. The solubility of CO₂ has been measured at 40°C and 100°C in an aqueous mixed solvent consisting of MDEA (40 wt.%) and TEGMME (40 wt. %) and water (20 wt.%) at partial pressures of CO₂ up to 12 MPa. The solubility results were compared with the solubility in the nonaqueous mixed solvent and previously reported data of aqueous MDEA. The solubility model of Deshmukh and Mather was used to correlate the data.     

The CO2 absorption and desorption performance of the triethylenetetramine + N,N-diethylethanolamine + H2O system

Post-combustion CO₂ capture (PCC) process faces significant challenge of high regeneration energy consumption. Biphasic absorbent is a promising alternative candidate which could significantly reduce the regeneration energy consumption because only the CO₂-concentrated phase should be regenerated. In this work, aqueous solutions of triethylenetetramine (TETA) and N,N-diethylethanolamine (DEEA) are found to be efficient biphasic absorbents of CO₂. The effects of the solvent composition, total amine concentration, and temperature on the absorption behavior, as well as the effect of temperature on the desorption behavior of TETA-DEEA-H₂O system were investigated. An aqueous solution of 1 mol·L^-1 TETA and 4 mol·L^-1 DEEA spontaneously separates into two liquid phases after a certain amount of CO₂ is absorbed and it shows high CO₂ absorption/desorption performance. About 99.4% of the absorbed CO₂ is found in the lower phase, which corresponds to a CO₂ absorption capacity of 3.44 mol·kg^-1. The appropriate absorption and desorption temperatures are found to be 30℃ and 90℃, respectively. The thermal analysis indicates that the heat of absorption of the 1 mol·L^-1 TETA and 4 mol·L^-1 DEEA solution is -84.38 kJ·(mol CO₂)^-1 which is 6.92 kJ·(mol CO₂)^-1 less than that of aqueous MEA. The reaction heat, sensible heat, and the vaporization heat of the TETA-DEEA-H₂O system are lower than that of the aqueous MEA, while its CO₂ capacity is higher. Thus the TETA-DEEA-H₂O system is potentially a better absorbent for the post-combustion CO₂ capture process.     

苯酚型低共熔溶剂中硫酸钛作为催化剂高效氧化脱硫

低共熔溶剂广泛应用于氧化脱硫过程,开发新型的低共熔溶剂并进一步提升脱硫效果具有重要的意义。 以氯化胆碱为氢键受体,苯酚为氢键供体合成了ChCl/2Ph型低共熔溶剂。通过FT-IR和¹H NMR证实了苯酚和氯化胆碱之间存在氢键作用。以苯酚型低共熔溶剂为萃取剂,双氧水为氧化剂,硫酸钛为催化剂氧化脱除模拟油中的二苯并噻吩。考察了反应温度、V(ChCl/2Ph)/V(Oil)、n(H₂O₂)/n(S)、催化剂用量以及硫化物类型对脱硫率影响。实验表明最佳反应条件如下：模拟油量为5 ml,V(ChCl/2Ph)/V(Oil)=2∶10, n(H₂O₂)/n(S)=6,催化剂用量为0.01 g,反应温度为40℃,反应时间180 min。在此条件下脱硫率可以达到98.2%。求得体系的表观活化能为41.9 kJ/mol。含有催化剂的低共熔溶剂相可以重复使用5次且活性没有明显降低。机理研究表明形成钛的过氧化物和Br?nsted酸性是具有较高脱硫活性的关键。     

Solubility of CO2 in Methanol, 1-Octyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide, and Their Mixtures

Solubility data of carbon dioxide (CO₂) (1) in methanol (2), 1-octyl-3-methylimidazolium bis(trifluoro- methylsulfonyl)imide ([omim]⁺[Tf₂N]^-) (3), and their mixtures (w₃ 0.2, 0.5, and 0.8) at temperatures 313.2 and 333.2 K and pressures up to 7.0 MPa were measured by a high-pressure view-cell technique. The solubility of CO₂ in methanol (w₃=0), [omim]⁺[Tf₂N]^- (w₃=1.0) and their mixtures follows the order of (w₃=0)<(w₃=0.2)< (w₃=0.5)<(w₃=0.8)<(w₃=1.0) at the same temperature and pressure, while the magnitude of Henry's constants follows the reverse order at a given temperature, which is consistent with the COSMO-RS (conductor-like screening for real solvents) calculation. The solubility data of CO₂ in methanol and [omim]⁺[Tf₂N]^- are correlated with the Peng-Robinson equation of state, and the solubility of CO₂ in the mixtures of methanol and [omim]⁺[Tf₂N]^- can be well predicted based on the mole fraction average of methanol and [omim]⁺[Tf₂N]^- over the solubility of CO₂ in pure methanol and [omim]⁺[Tf₂N]^-. The mixtures of methanol and [omim]⁺[Tf2N]^- may be used as physical solvents for capturing CO₂ with high partial pressures since they combine the advantages of organic solvents and ionic liquids.     

Determination of deep eutectic solvents as eco-friendly catalysts for biodiesel esterification from an alcohol-palmitic acid mixture

Deep eutectic solvents (DESs) were prepared by mixing a quaternary salt as a hydrogen bond acceptor with a hydrogen bond donor. In this study, DESs had an excellent effect as a solvent-catalyst for the esterification of palmitic acid and methanol. This method was found to be safe, mild, simple, and eco-friendly. A range of DESs with different mixing ratios were used to optimize the preparation of methyl palmitate. Other factors, such as temperature, time and DESs/methanol ratio, were also examined. The optimal DES was prepared from tetrabutyl ammonium chloride and acetic acid (1 : 2); the methanol and palmitic acid sample to DES ratio was 1 : 0.5 (v/v). The reaction was optimized at a methanol/palmitic acid ratio of 10 : 1 (mol/mol) at 60 °C for 60 min. The yield was 94.3% under the optimized conditions. Therefore, DESs can be developed as a catalyst for the esterification of palmitic acid for obtaining methyl palmitate as biodiesel, and have potential applicability in other biodiesel pretreatments.     

四乙烯五胺改性多孔二氧化硅制备及CO2吸附性能

以十六烷基三甲基溴化铵（CTAB）为模板剂，原硅酸乙酯（TEOS）为硅源，1,3,5-三异丙基苯（TPB）为扩孔剂，制备不同孔道结构的多孔二氧化硅纳米微球（PSNs），将四乙烯五胺（TEPA）通过物理浸渍法负载到PSNs上，合成TEPA-PSNs吸附剂。利用扫描电镜、透射电镜、红外光谱、N₂吸附-脱附循环实验和热重分析对材料的结构性能和热稳定性能进行表征，成功制备了具有不同孔道结构的胺基化多孔二氧化硅。对吸附剂材料进行CO₂吸脱附实验和动力学研究，结果表明：当TPB含量增多时，吸附剂材料吸附的CO₂量也随之增大，并且TEPA-PSNs-0.5在75℃时吸附量最大，达4.70mmol/g；一阶动力学模型能较好地预测该吸附剂的CO₂吸附过程；经过5次循环，其再生性能仍然高达94.34%。因此，合成的胺基化多孔二氧化硅具有高吸附量和良好稳定性，是用于二氧化碳捕集的潜在材料。     

离子液体[Bmim][NTf2]对CO2在碳酸二乙酯中溶解性能的强化

采用恒定容积法在温度范围308.15~328.15 K、压力范围0~3 MPa条件下测定了CO₂在碳酸二乙酯（DEC）、离子液体[Bmim][NTf₂]以及二者不同质量分数配比混合溶剂中的溶解度,并用COSMO-RS模型研究了离子液体的加入对DEC蒸气分压的影响。实验表明,在相同实验条件下CO₂在[Bmim][NTf₂]中的溶解度大于在DEC中的溶解度。[Bmim][NTf₂]的加入可强化CO₂在DEC中的溶解性能,在相同温度下CO₂在混合溶剂中的溶解度随[Bmim][NTf₂]质量分数增加而增大,在相同浓度的混合溶剂中CO₂的溶解度随温度升高而降低。COSMO-RS模型计算表明,DEC的蒸气分压下降的分数随混合溶剂中离子液体质量分数增加而增大,而对于相同质量分数配比的混合溶剂温度对DEC的蒸气分压影响较小。     

面向二氧化碳捕集的过程强化技术进展

化石能源的大量燃烧在推进人类工业化进程的同时也使当今世界面临愈发严峻的气候变化和环境问题。为降低大气中日益增长的CO₂浓度并实现《巴黎协定》所设定的2℃目标，CO₂捕集技术得到了越来越广泛的关注和研究，其中部分技术已实现了小规模工业化。在持续推进节能减排的背景下，通过CO₂捕集对现有工业过程进行强化是CO₂捕集技术发展的一个新兴方向，如此不但可提高原有过程的效率和产品品质，还可大幅减少其碳排放，是具有应用前景的技术路线。本文从CO₂捕集的主流技术出发，介绍了面向CO₂捕集的过程强化技术，重点介绍CO₂捕集强化的蒸汽重整制氢过程、水气变换过程和生物质气化过程，以及耦合CO₂捕集的CO₂加氢过程、CH₄干重整过程和化学链燃烧过程，最后还对捕集后CO₂的利用与转化技术进行了简介。