高效分离乙烷/乙烯的烷烃选择性吸附剂研究进展

乙烯是石油化学工业的基础原材料,聚合级乙烯工业纯化的关键挑战是去除其中的乙烷杂质,这一步骤难度大、能耗高。近年来,以乙烷选择性吸附剂为核心的吸附分离纯化技术快速发展,并得到学术界和工业界的关注。该技术可在温和工况下高选择性分离出乙烯中的乙烷杂质,显现出巨大潜力。本文总结了近年来乙烷选择性吸附剂（特别是乙烷选择性MOFs）的研究进展,并归纳阐释其选择性吸附机理。同时,在前人研究成果的基础上,总结可行的乙烷选择性吸附剂的设计策略,指出当前开发高效乙烷选择性吸附剂面临的挑战和未来的研究方向。     

乙烯-乙烷分离吸附剂的研究进展

对吸附法分离乙烯的研究作了综述 ,分析了不同的乙烯吸附剂及其吸附性能。     

乙烯/乙烷分离用树脂型吸附剂的研究

制备和研究了用于乙烯/乙烷吸附分离的经改性的吸附剂——银离子交换树脂。在25℃、1atm下,银离子交换树脂S9对乙烯的平衡吸附容量为0.992 mmol·g-1, 乙烯/乙烷平衡吸附容量之比为3.56。25℃和75℃时,其吸附容量可恢复85%以上;105℃时,其吸附容量能完全恢复。由于这一吸附包含了能量不同的物理吸附和Л络合化学吸附, 平衡数据由含两个拟合参数的平衡等温吸附方程关联而得。通过综合考虑几个主要吸附特性,讨论了这些吸附剂在工业吸附过程中的应用潜力。     

萃取精馏分离乙烷/乙烯的溶剂

引　言乙烯 /乙烷的分离是乙烯生产过程中非常重要的一步 .长期以来 ,低温精馏在烷烃 /烯烃分离中占主导地位[1] .尽管精馏是一种非常成熟的工艺 ,并且近期内不易被其他方法取代 ,但低温精馏一直存在着压缩功耗高 ,冷耗大 ,板数多的缺点 .例如 ,在一个 10 0多块塔板的精馏塔内分离乙烷 /乙烯 ,需要在 - 2 5℃的低温和 2 .30 6ＭＰａ的高压下操作[1] .所以研究人员一直致力于寻求一种高效、节能、低成本的方法 ,以取代低温精馏分离烷烃 /烯烃 .目前 ,文献报道[2～ 5] 中有关轻烃分离的方法主要有膜分离、吸附、吸收和萃取精馏等 .膜分离法具…     

乙烯/乙烷分离用π络合吸附剂的制备

采用热分散法制备了以活性炭负载CuCl,并添加稀土LaCl3的π络合吸附剂.考察了活性炭改性、CuCl分散量、稀土不同掺入量对吸附剂分离乙烯/乙烷性能的影响,并优化吸附剂配方及制备条件.结果表明采用氢氟酸对活性炭载体的改性效果优于双氧水;X射线相定量参比法测得CuCl在活性炭载体上的分散容量为0.056 g(CuCl)/100m2(活性炭);当氯化镧添加量为11.2%(质量分数),可使乙烯的选择性提高到原来的2倍以上.     

多孔炭吸附剂的乙烯-乙烷选择性反转机制

烯烃是重要的化工原料,吸附分离技术可在温和工况下实现烯烃纯化,而吸附剂的烷烃选择性是实现高效化工分离过程的关键。基于分子模拟,提出调节孔道尺寸以控制多孔炭优先吸附乙烯或乙烷的选择性反转机制;控制活化条件,实验制备出不同孔径的多孔炭材料并验证了乙烯-乙烷选择性反转规律。结果表明,多孔炭的石墨化表面优先吸附乙烷;随着孔径尺寸的增大,可出现优先吸附乙烯的孔道区间;若孔径进一步增大,多孔炭可回归到优先吸附乙烷的石墨化表面吸附特征。选择性反转机制适用于不同形状的孔道结构。因此,可利用微孔孔道的限域作用放大多孔炭表面的烷烃选择性,并得到高性能的烷烃选择性吸附剂。     

银离子交换树脂π-络合吸附分离乙烯乙烷的研究

Ag+-exchanged resins are prepared and studied for ethylene/ethane separation by adsorption. On Ag+-exchanged S9, at 25℃ and 0.1013MPa, the equilibrium adsorbed amount for C2H4 is 0.992mmol·g-1, and the adsorption ratio for C2H4/C2H6 is 3.56. The adsorption capacity can be restored almost completely at 25℃ and 75℃, and the desorption residual amount is less than 0.01mmol·g-1. For the adsorption consisting of physical adsorption and π-complexation with energy heterogeneity, the equilibrium data are correlated with Langmuir-Freundlich isotherm equation. Furthermore, the heat of adsorption and the overall diffusion time constants are calculated from the experimental data. Considering all the adsorption characteristics, the application potential for industrial adsorption process is discussed.     

三维KIT-6分子筛对乙烯乙烷吸附分离的研究

采用水热法合成三维KIT-6分子筛,以KIT-6为载体,采用等体积浸渍法负载Ag NO3制备乙烯/乙烷分离的π络合吸附剂,通过氮气吸附脱附、X射线衍射和X射线能谱分析对吸附剂进行表征,采用自制设备测定了π络合吸附剂的乙烯乙烷吸附等温线和乙烯吸附动力学曲线,相应的乙烯乙烷吸附热用克劳修斯-克拉伯龙方程求得。结果表明,Ag NO3最佳负载量为29%,在303.15 K、0.6 MPa下,络合吸附剂的乙烯吸附量高达47 m L/g,分离系数为3.3,乙烯吸附热值显示乙烯与吸附剂的作用是介于物理吸附和化学吸附之间的π络合吸附,乙烯在络合吸附剂上传质较快,具有一定的应用前景。     

添加稀土镧对吸附分离乙烯/乙烷的影响

考察了添加稀土镧, 氧化镧、硝酸镧和氯化镧,对载铜活性炭吸附剂分离乙烯/乙烷的影响.测定了乙烯,乙烷40℃吸附等温线.乙烯选择性实验结果表明,氯化镧的添加效果最佳.合适的添加量在11.2%(wt)附近,可使乙烯的选择性提高到原来的两倍以上. 比表面及孔径分布数据表明, 添加适量稀土镧增大了吸附剂孔的比表面和孔体积, 特别是对微孔,因而更有利于提高吸附剂表面的利用率.通过SEM对稀土络合吸附剂的形貌观察可知,稀土分散于未被活性组分CuCl利用的活性炭表面.由于稀土对乙烷吸附量极小,从而极大抑制了活性炭载体对乙烷的物理吸附,这是此复合吸附剂提高乙烯乙烷分离性能的主要原因.     

乙烯-乙烷在不同吸附剂上的吸附平衡研究

以活性炭负载Cu（Ⅰ）为原料，添加适量稀土化合物，制备成NA型和NJ型配合吸附剂。实验测定了乙烯-乙烷混合气在NA型、NJ型吸附剂和活性炭上的吸附平衡等温线，并对乙烯、乙烷两种气体的等温线模型进行了拟合。结果表明，配合型吸附剂对乙烯有很好的平衡选择性，有利于乙烯-乙烷的分离，具有工业应用前景。     

Ethane‐selective carbon composites CPDA@A‐ACs with high uptake and its enhanced ethane/ethylene adsorption selectivity

Novel composites (CPDA@A‐ACs) of carbonized polydopamine (CPDA) and asphalt‐based activated carbons (A‐ACs) were successfully synthesized, and characterized for adsorption separation of ethane/ethylene. The resulting CPDA@A‐ACs exhibited high Brunauer–Emmett–Teller surface area of 1971 m²/g. The O and N contents on CPDA@A‐ACs are higher than those on A‐ACs due to the introduction of CPDA. Interestingly, CPDA@A‐ACs exhibited great preferential adsorption of ethane over ethylene. Its ethane capacity reached as high as 7.12 mmol/g at 100 kPa and 25°C, and its ethane/ethylene adsorption selectivity became higher compared to A‐ACs, reaching as high as 3.0～20.6 below 100 kPa, significantly superior to the reported ethane‐selective adsorbents. Simulation results revealed the mechanism of enhanced selectivity toward C₂H₆/C₂H₄, and suggested that the surface oxygen functionalities of the composites play predominant role in enhancing ethane/ethylene adsorption selectivity. Fixed‐bed experiments showed that C₂H₆/C₂H₄ mixtures can be well separated at room temperature, suggesting great potential for industrial C₂H₆/C₂H₄ separation. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3390–3399, 2018     

高稳定双金属MOF材料用于低浓度乙烷的高效分离

针对乙烷/乙烯分离过程中,缺乏高效稳定的乙烷选择吸附剂,采用溶剂热法合成了一种具有高稳定性的双金属微孔MOF材料MUV-10 (Mn),通过吸附分离的方式,实现了乙烯中低浓度乙烷的高效分离。采用XRD、SEM、TGA、比表面分析等表征手段对所制备材料的结构及形貌进行了确认和分析,详细测试了MUV-10 (Mn)对乙烷和乙烯单组分气体的吸附性能,并进行了选择性和吸附热的计算。结果表明,MUV-10 (Mn)在室温下的乙烷吸附量高于乙烯对于乙烷/乙烯混合气的选择性为1.42,且具有高的酸、碱和水蒸气稳定性。混合气体穿透实验表明,MUV-10 (Mn)能够高效去除乙烯中的低浓度乙烷,得到高纯乙烯气体,在乙烯提纯方面显示出良好的应用前景。     

Stable mixed metal-organic framework for efficient C2H6/C2H4 separation

In view of lacking efficient ethane-selective adsorbent for ethane/ethylene separation, a highly stable microporous mixed metal-organic framework, termed as MUV-10(Mn), was synthesized by the solvothermal method and it could efficiently separate C₂H₆/C₂H₄ mixture. The structure and morphology of synthesized material was confirmed by XRD, SEM, TGA and BET, etc. Selectivity and corresponding adsorption heat of C₂H₆ and C₂H₄ were calculated based on single component adsorption results measured in details. The results show that MUV-10(Mn) features C₂H₆/C₂H₄ selectivity about 1.42 and can absorb more C₂H₆ than C₂H₄ at room temperature. And it has high acid, alkali and water vapor stability. Addtionally, dynamic breakthrough experiment showed MUV-10(Mn) could extracted low concentration of C₂H₆ from C₂H₆/C₂H₄ mixture (V_{{\mathrm{C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{6}}}\text{?}/\text{?}{V}_{{\mathrm{C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{4}}}=1∶9 and 1∶15) to collect C₂H₄ gas with high purity, which indicates the promising future of MUV-10(Mn) in C₂H₄ purification.     

回收FCC干气中乙烯的工艺技术与吸附剂

概述了回收干气中乙烯的几种工艺技术和高效吸附剂。在我国现有ＦＣＣ规模和分布的情况下，利用变压吸附法回收ＦＣＣ干气中的乙烯是行之有效的工艺技术路线，且有较好的经济效益。     

乙二醇生产和精制技术研究进展

乙二醇是一种重要的大宗化工原料,广泛应用于聚酯等行业,具有消耗量大、产品纯度要求高的特点。本文综述了石油基、煤基和生物质基乙二醇生产和精制技术的最新研究进展,介绍了不同路线乙二醇的生产工艺、催化剂体系和精制技术,分析了不同工艺路线的优缺点,总结了乙二醇精制到聚酯级乙二醇生产中存在的问题。提出未来乙二醇生产的研究重点应该放在高稳定催化剂的设计、大规模工艺的集成和原料的绿色化上。     

High purity ethane/ethylene separation by gas phase simulated moving bed using ZIF-8 adsorbent

Growing population and demand for plastics and synthetic fluids in climate friendly environment sets the unprecedented industrial challenge to increase production of clean chemical precursors (e.g., ethylene) with reduced energy consumption and CO₂ foot print. The production of polymer-grade ethylene (>99.9%) from steam cracked gas or oil relies on a cascade of energy intensive distillations of gases. Therefore, in this work two simulated moving bed (SMB) cycles were employed to separate mixtures containing of about 40% of ethane and 60% of ethylene on zeolitic imidazole framework-8 granulates. The separation cycles were performed with two desorbents with different relative adsorption strength. In the experiment, with carbon dioxide as desorbent, ethylene was obtained with 99.6% purity and 94.2% recovery, while in the experiment using propane as desorbent only 77.1% of ethylene is recovered with a purity of 82.7%. Indeed, it can be concluded that when CO₂ is used as desorbent, the obtained productivity is higher. The mathematical SMB model and regions of separation were determined for each desorbent based on experimental data.     

Enhanced one-step purification of C2H4 from C2H2/C2H4/C2H6 mixtures by fluorinated Zr-MOF

The extraction of C₂H₄ from C₂H₆/C₂H₄/C₂H₂ mixtures is of great significance in the chemical industry for C₂H₄ production but the process remains challenging due to the similarity of these C₂ hydrocarbon species in their molecular size and physical properties. Here, we report the fluorination of a stable Zr-MOF, UiO-66, to fine-tune the pore dimensions and pore functionality. In particular, UiO-66-CF₃ shows notably preferential adsorption of C₂H₆ and C₂H₂ over C₂H₄, with C₂H₂/C₂H₄ and C₂H₆/C₂H₄ selectivities of 1.4 and 1.9, respectively. Theoretical calculations provide insight into the binding sites of UiO-66-CF₃ for C₂ hydrocarbon adsorption. Breakthrough experiments further confirmed the capability of the material for purification of C₂H₄ from C₂H₂/C₂H₄/C₂H₆ ternary mixtures, evidenced by the high purity C₂H₄ (99.9%+) obtained directly from outlet gas.     

Reversed ethane/ethylene adsorption in a metal-organic framework via introduction of oxygen

Separation of ethane from ethylene is a very important but challenging process in the petrochemical industry. Finding an alternative method would reduce the energy needed to make 170 million tons of ethylene manufactured worldwide each year. Adsorptive separation using C₂H₆-selective porous materials to directly produce high-purity C₂H₄ is more energy-efficient. We herein report the “reversed C₂H₆/C₂H₄ adsorption” in a metal-organic framework Cr-BTC via the introduction of oxygen on its open metal sites. The oxidized Cr-BTC(O₂) can bind C₂H₆ over C₂H₄ through the active Cr-superoxo sites, which was elucidated by the gas sorption isotherms and density functional theory calculations. This material thus exhibits a good performance for the separation of 50/50 C₂H₆/C₂H₄ mixtures to produce 99.99% pure C₂H₄ in a single separation operation.     

分离乙稀-乙烷的Cu-MCM-48介阵络合吸附剂的合成、表征及吸附平衡研究

Copper incorporated MCM-48 molecular sieve adsorbents with different Cu content have been hydrothermally synthesized.The samples have been characterized by vmous physicochemical methods,including X-ray difrraction(XRD),nitrogen adsorption(N2)and X-ray photoelectron spectroscopy(XPS).The results reveal that Cu-MCM.48 with mass fraction of copper up to 10?n still retain the uniform mesoporous framework of MCM-48.The copper in the framework of MCM-48 was easily auto-reduced to Cu(Ⅰ)in N2 at high temperature,which did not alter the mesoporous structure of MCM-48.The adsorption equilibrium isotherlnS of ethylene and ethane on these molecular sieve adsorbents have been measured at 30℃.At 100 kPa,the adsorption capacities of ethylene on 5Cu-MCM一48 and 10Cu-MCM-48 are higher than those on MCM-48.The 10Cu-MCM-48 molecular sieve adsorbent has a higher selective adsorption ratio of ethylene to ethane,the separation factor is 3.8,and the amount ofethylene adsorbed is 11.1 ml·g-1.