Efficient CO2 adsorption and mechanism on nitrogen-doped porous carbons

In this work, nitrogen-doped porous carbons (NACs) were fabricated as an adsorbent by urea modification and KOH activation. The CO₂ adsorption mechanism for the NACs was then explored. The NACs are found to present a large specific surface area (1920.72– 3078.99 m²·g⁻¹) and high micropore percentage (61.60%–76.23%). Under a pressure of 1 bar, sample NAC-650-650 shows the highest CO₂ adsorption capacity up to 5.96 and 3.92 mmol·g⁻¹ at 0 and 25 °C, respectively. In addition, the CO₂/N₂ selectivity of NAC-650-650 is 79.93, much higher than the value of 49.77 obtained for the nonnitrogen-doped carbon AC-650-650. The CO₂ adsorption capacity of the NAC-650-650 sample maintains over 97% after ten cycles. Analysis of the results show that the CO₂ capacity of the NACs has a linear correlation (R² = 0.9633) with the cumulative pore volume for a pore size less than 1.02 nm. The presence of nitrogen and oxygen enhances the CO₂/N₂ selectivity, and pyrrole-N and hydroxy groups contribute more to the CO₂ adsorption. In situ Fourier transform infrared spectra analysis indicates that CO₂ is adsorbed onto the NACs as a gas. Furthermore, the physical adsorption mechanism is confirmed by adsorption kinetic models and the isosteric heat, and it is found to be controlled by CO₂ diffusion. The CO₂ adsorption kinetics for NACs at room temperature and in pure CO₂ is in accordance with the pseudo-first-order model and Avramís fractional-order kinetic model.     

N2优先渗透ZIF-8复合膜的制备及其CO2捕集

为了获得经济节能的烟道气CO₂回收方法,制备了一种新型的N₂优先渗透ZIF-8复合膜。以柔性聚砜(PSf)多孔膜为支撑层,采用Zn²⁺与壳聚糖的交联溶液对聚砜支撑层表面改性,使Zn²⁺固定在PSf膜表面;然后与2-甲基咪唑(Hmim)配位得到ZIF-8晶种层;最后通过界面聚合法二次生长制得ZIF-8复合膜。采用FTIR、XRD及SEM对ZIF-8复合膜的形貌结构进行表征,结果显示成功制备了致密的ZIF-8复合膜。在进料气为纯气条件下,探究了二次生长时间、Zn²⁺溶液的浓度、测试时间及测试压力对ZIF-8复合膜N₂/CO₂分离性能的影响,阐明其N₂优先渗透机理;并进一步考察了混合气分离性能。结果表明：在25℃和0.1 MPa下,最优ZIF-8复合膜的N₂渗透性为523 GPU,N₂/CO₂选择性为19;同条件下混合气的N₂渗透性和N₂/CO₂选择性分别为517 GPU和18。所制备的ZIF-8复合膜可以使N₂优先渗透,实现烟道气中高浓度N₂渗透,低浓度CO₂截留在膜的上游侧。原因主要是ZIF-8复合膜含有较多的CO₂强吸附位点,使CO₂被吸附在膜内不易从膜的下游侧脱附,渗透性小,而N₂优先渗透,这为N₂优先渗透膜的制备提供了一种新思路。     

Comparative study on pressure swing adsorption system for industrial hydrogen and fuel cell hydrogen

In order to improve the design of PSA system for fuel cell hydrogen production, a non-isothermal model of eight-bed PSA hydrogen process with five-component (H₂/N₂/CH₄/CO/CO₂=74.59%/0.01%/4.2%/2.5%/18.7% (vol)) four-stage pressure equalization was developed in this article. The model adopts a composite adsorption bed of activated carbon and zeolite 5A. In this article, pressure variation, temperature field and separation performance are stimulated, and also effect of providing purge (PP) differential pressure and the ratio of activated carbon to zeolite 5A on separation performance in the process of producing industrial hydrogen (CO content in hydrogen is 10 μl·L^-1) and fuel cell hydrogen (CO content is 0.2 μl·L^-1) are compared. The results show that Run 3, when the CO content in hydrogen is 10 μl·L^-1, the hydrogen recovery is 89.8%, and the average flow rate of feed gas is 0.529 mol·s^-1; When the CO content in hydrogen is 0.2 μl·L^-1, the hydrogen recovery is 85.2%, and the average flow rate of feed gas is 0.43 mol·s^-1. With the increase of PP differential pressure, hydrogen recovery first increases and then decreases, reaching the maximum when PP differential pressure is 0.263 MPa; With the decrease of the ratio of activated carbon to zeolite 5A, the hydrogen recovery increases gradually. When the CO content in hydrogen is 0.2 μl·L^-1 the hydrogen recovery increases more obviously, from 83.96% to 86.37%, until the ratio of activated carbon to zeolite 5A decreases to 1. At the end of PP step, no large amount of CO₂ in gas or solid phase enters the zeolite 5A adsorption bed, while when the CO content in hydrogen is 10 μl·L^-1, and the ratio of carbon to zeolite 5A is less than 1.4, more CO₂ will enter the zeolite 5A bed.     

CO/N2/CO2在MOF-74(Ni)上吸附相平衡和选择性

主要研究了MOF-74(Ni)材料对CO/N₂/CO₂的吸附分离性能。应用水热法合成制备MOF-74(Ni),分别采用全自动表面积吸附仪、P-XRD、扫描电子显微镜对材料的孔隙结构和晶体形貌进行了表征,应用静态吸附法测定了CO、N₂和CO₂在MOF-74(Ni)上的吸附等温线,应用DSLF方程模拟了3种气体MOF-74(Ni)上的吸附等温线,依据IAST理论模型计算了MOF-74(Ni)对CO/N₂二元混合物和CO/CO₂二元混合物的吸附选择性。研究结果表明:在0.1 MPa和常温条件下,MOF-74(Ni)材料对CO吸附容量高达6.15 mmol·g^-1,而相同条件下N₂的吸附量只有0.86 mmol·g^-1。MOF-74(Ni)在低压下(0～40 kPa)对CO的吸附量明显高于其对CO₂的吸附量。应用IAST模型估算MOF-74(Ni)对二元混合物吸附选择性的结果表明:MOF-74(Ni)对CO/N₂混合物的吸附选择性在1000以上;MOF-74(Ni)对CO/CO₂的吸附选择性在4～9范围,在所研究的二元气体混合物吸附体系中,MOF-74(Ni)都能优先吸附CO。     

High-performance SSZ-13 membranes prepared using ball-milled nanosized seeds for carbon dioxide and nitrogen separations from methane

SSZ-13 membranes with high separation performances were prepared using ball-milled nanosized seeds by once hydrothermal synthesis. Separation performances of SSZ-13 membranes in CO_2/CH_4 and N_2/CH_4 mixtures were enhanced after synthesis modification. Single-gas permeances of CO_2, N_2 and CH_4 and ideal selectivities were recorded through SSZ-13 membranes. The effects of temperature, pressure, feed flow rate and humidity on separation performance of the membranes were discussed. Three membranes prepared after synthesis modifications had an average CO_2 permeance of 1.16 × 10~(-6) mol·(m~2· s·Pa)~(-1)(equal to 3554 GPU) with an average CO_2/CH_4 selectivity of 213 in a 50 vol%/50 vol% CO_2/CH_4 mixture. It suggests that membrane synthesis has a good reproducible. The membrane also displayed a N_2 permeance of 1.07 × 10~(-7) mol·(m~2·s·Pa)~(-1)(equal to 320 GPU) with a N_2/CH_4 selectivity of 13 for a 50 vol%/50 vol% N_2/CH_4 mixture. SSZ-13 membrane displayed stable and good separation performance in the wet CO_2/CH_4 mixture for a long test period over 100 h at 348 K. The current SSZ-13 membranes show great potentials for the simultaneous removals of CO_2 and N_2 in natural gas purification as a facile process suitable for industrial application.     

Strategies for CO2 capture from different CO2 emission sources by vacuum swing adsorption technology☆

Different VSA(Vacuum Swing Adsorption) cycles and process schemes have been evaluated to find suitable process configurations for effectively separating CO2 from flue gases from different industrial sectors. The cycles were studied using an adsorption simulator developed in our research group, which has been successfully used to predict experimental results over several years. Commercial zeolite APGIII and granular activated carbon were used as the adsorbents. Three-bed VSA cycles with- and without-product purge and 2-stage VSA systems have been investigated. It was found that for a feed gas containing 15% CO2(representing flue gas from power plants), high CO2 purities and recoveries could be obtained using a three-bed zeolite APGIII VSA unit for one stage capture, but with more stringent conditions such as deeper vacuum pressures of 1–3 k Pa. 2-stage VSA process operated in series allowed us to use simple process steps and operate at more realistic vacuum pressures. With a vacuum pressure of 10 k Pa, final CO2 purity of 95.3% with a recovery of 98.2% were obtained at specific power consumption of 0.55 MJ·(kg CO2)-1from feed gas containing15% CO2. These numbers compare very well with those obtained from a single stage process operating at1 k Pa vacuum pressure. The feed CO2 concentration was very influential in determining the desorption pressure necessary to achieve high separation efficiency. For feed gases containing N 30% CO2, a singlestage VSA capture process operating at moderate vacuum pressure and without a product purge, can achieve very high product purities and recoveries.     

Separation and enrichment of carbon dioxide by capillary membrane module with permeation of carrier solution

A novel facilitated transport membrane for gas separation using a capillary membrane module is proposed in which a carrier solution is forced to permeate the membrane. Both a feed gas and a carrier solution are supplied to the lumen side (high pressure side, feed side) of the capillary ultrafiltration membrane and flow upward. Most of the carrier solution which contains dissolved solute gas, CO₂ in the present case, permeates the membrane to the permeate side (low pressure side, shell side), where the solution liberates dissolved gas to form a lean solution. The lean solution is circulated to the lumen side. This type of capillary membrane module was applied to the separation of CO₂ from model flue gases consisting of CO₂ and N₂. Monoethanolamine (MEA), diethanolamine (DEA) and 2-amino-2-methyl-1-propanol (AMP) were used as carriers or absorbents of CO₂. The feed side pressure was atmospheric and the permeate side was evacuated at about 10 kPa. CO₂ in the feed gas was successfully concentrated from 5–15% to more than 98%. The CO₂ permeance was as high as 2.7×10⁻⁴ mol m⁻² s⁻¹ kPa⁻¹ (8.0×10⁻⁴ cm³ cm⁻² s⁻¹ cmHg⁻¹) when the CO₂ mole fraction in the feed was 0.1 and temperature was 333 K. The selectivity of CO₂ over N₂ was in the range from 430 to 1790. The membrane was very stable over a discontinuous one-month testing period.     

Intensification of low-grade methane enrichment in nitrogen mixture by CH4/CO2 displacement

To solve the problem of CO₂ uncompleted desorption in the process of CO₂ displacement enhancing the adsorption separation of CH₄/N₂, a small amount of product gas CH₄ was used as purge gas to improve the CO₂ desorption. CH₄/CO₂ mixture gas obtained from desorption step was recycled as the displacement gas to enhance the enrichment of low-grade methane in nitrogen mixture. In this work, the research conducted the experiments for CH₄/N₂ separation using CH₄/CO₂ displacement intensification adsorption and the laboratory-made coconut shell activated carbon as sorbent. The mathematical models were built in gPROMS and the accuracy of models was verified by comparison of simulations and CH₄/N₂/CO₂ breakthrough experiments. The performance of enrichment of low-grade methane with displacement intensification using different displacer was compared. The result showed that the process with CH₄/CO₂ displacement had higher purity product than CO₂ displacement. The CH₄/ CO₂ mixed gas replacement enhanced vacuum pressure swing adsorption cycle experiment was carried out, which can jointly enrich 14% CH₄/ N₂ and 53% CH₄/CO₂ to 98.8%, and at the same time obtain a recovery rate of 77.8%.     

Boosting selective C2H2/CH4, C2H4/CH4 and CO2/CH4 adsorption performance via 1,2,3-triazole functionalized triazine-based porous organic polymers

Nitrogen-rich porous organic polymers have shown great potentials in gas adsorption/separation, photocatalysis, electrochemistry, sensing and so on. Herein, 1,2,3-triazole functionalized triazine-based porous organic polymers (TT-POPs) have been synthesized by the copper-catalyzed azide-alkyne cycloaddition (Cu-AAC) polymerization reactions of 1,3,5-tris(4-azidophenyl)-triazine with 1,4-diacetylene benzene and 1,3,5-triacetylenebenzene, respectively. The characterizations of N₂ adsorption at 77 K show TT-POPs possess permanent porosity with BET surface areas of 666 m²·g^-1 (TT-POP-1) and 406 m²·g^-1 (TT-POP-2). The adsorption capacities of TT-POPs for CO₂, CH₄, C₂H₂ and C₂H₄, as well as the selective separation abilities of CO₂/N₂, CO₂/CH₄, C₂H₂/CH₄ and C₂H₄/CH₄ were evaluated. The gas selective separation ratio of TT-POPs was calculated by the ideal adsorbed solution theory (IAST) method, wherein the selective separation ratios of C₂H₂/CH₄ and C₂H₄/CH₄ of TT-POP-2 was 48.4 and 13.6 (298 K, 0.1 MPa), which is comparable to other adsorbents (5.6-120.6 for C₂H₂/CH₄, 10-26 for C₂H₄/CH₄). This work shows that the 1,2,3-triazole functionalized triazine-based porous organic polymer has a good application prospect in natural gas purification.     

CH4/CO2混合气置换强化含氮低品质甲烷的浓缩

针对CO₂置换吸附分离CH₄/N₂过程中CO₂再生困难的问题，采用少量产品气CH₄真空吹扫以提高CO₂的解吸效果，并以解吸得到的CH₄/CO₂混合气为置换步骤的置换气，通过置换来强化含氮低品质甲烷的浓缩过程。以自制椰壳活性炭为吸附剂，对CH₄/CO₂混合气置换强化吸附回收含氮低品质甲烷工艺过程进行了实验与模拟研究。在gPROMS软件中建立并求解固定床吸附分离模型方程，预测了CH₄、N₂ 和CO₂在自制椰壳活性炭上的竞争吸附穿透曲线，通过预测结果和实验的对比，验证了数学模型方程的准确性。对比了不同置换气强化吸附分离低品质甲烷的效果，结果表明CH₄/CO₂混合气置换强化相对于CO₂置换强化可获得更高纯度产品。进行了CH₄/CO₂混合气置换强化真空变压吸附循环实验，可以将14%的CH₄/N₂和53%的CH₄/CO₂联合富集到98.8%，同时获得77.8%的回收率。     

一维直孔道MOFs对CH4/N2和CO2/CH4的分离

非常规天然气未来可以作为常规天然气的有效补充,其中低浓度煤层气和生物质燃气分别需要脱除大量的N₂ 和CO₂以达到富集和纯化CH₄的目的。本研究针对CH₄/N₂这一对较难分离的气体组合,选取了具有一维菱形孔道的MOFs材料Cu(INA)₂作为吸附剂,将合成的样品做了XRD和TG表征,测试了纯气体CO₂、CH₄和N₂的吸附曲线,利用巨正则系综蒙特卡罗(GCMC)分子模拟和理想吸附溶液理论(IAST)计算了气体的吸附热和该材料对于CH₄/N₂和CO₂/CH₄的吸附选择性系数;3 MPa压力下制备的颗粒样品填装吸附分离装置,进行了混合气体CH₄/N₂ (50%/50%)和CO₂/CH₄ (50%/50%)的穿透试验,分离的结果显示,Cu(INA)₂不仅高选择性地吸附CH₄/N₂混合物中的CH₄(S_CH4/N2=10),而且对CH₄/N₂的分离效果优于CO₂/CH₄。     

聚乙烯胺/埃洛石纳米管混合基质膜的制备及其CO2/N2分离

制备高性能的气体分离膜,是实现CO₂高效回收的关键。为了提高CO₂分离膜的性能,将中空管状结构的埃洛石纳米管（HNTs）添加到聚乙烯胺（PVAm）中配制涂膜液,并将PVAm-HNTs涂膜液涂覆到聚砜（PSf）超滤膜上制备PVAm-HNTs/PSf混合基质膜。其中PSf超滤膜作为支撑层,PVAm-HNTs致密涂层作为功能层,功能层结构与形态对CO₂分离具有关键作用。采用XRD、SEM对HNTs的结构与形态进行表征,并借助FTIR和SEM对膜的形态与结构进行分析。在进料气为纯气条件下,系统地研究了HNTs添加量、进料压力、PVAm-HNTs涂层厚度对PVAm-HNTs/PSf膜的CO₂分离性能影响,并考察了混合基质膜的CO₂/N₂混合气分离性能。结果显示：在水溶液中显示正电性的PVAm与负电性的HNTs具有较好的界面相容性。HNTs添加量为1%（质量）、PVAm-HNTs湿涂层厚度为50 μm的混合基质膜,表现出最优的CO₂分离性能。在进料气压力为0.1 MPa、测试温度为25℃、CO₂/N₂（15/85,体积比）混合气进料的条件下,膜的CO₂渗透速率为178 GPU,CO₂/N₂选择性为83;该膜具有较好的稳定性,经过120 h运行后,渗透性和选择性仍能保持稳定。     

PEBA/氮硫共掺杂多孔碳球混合基质膜的制备及CO2分离性能研究

为了获得高性能的混合基质膜,有效捕集烟道气中的CO₂,设计了对CO₂有优异的扩散选择性和吸附选择性的氮硫共掺杂多孔碳球添加剂,实现了烟道气中CO₂/N₂的高效分离。选用表面含氧基团丰富的葡萄糖作为碳源,硫脲作为氮源和硫源,通过水热法制备了氮硫共掺杂碳球（NSC）,并用KOH活化,获得了具有多孔结构的氮硫共掺杂碳球（NSPC）,再加入聚醚嵌段酰胺（PEBA）中制备出PEBA/NSPC混合基质膜。采用FTIR、XRD和BET表征了材料的化学结构和孔结构,借助力学性能表征了膜的两相界面相容性。系统研究了PEBA/NSPC混合基质膜中葡萄糖与硫脲的质量比、NSC和KOH的质量比、NSPC的添加量、操作压力、操作温度,以及模拟烟道气条件对膜CO₂渗透性、CO₂/N₂选择性的影响。结果表明：NSPC材料成功实现了氮、硫元素的共掺杂,而且具有较好的孔结构。在操作温度25℃、操作压力0.2 MPa的条件下,混合基质膜中NSPC添加量为3%（质量）时气体分离性能最优,CO₂渗透系数和CO₂/N₂选择性分别为589 Barrer和64,相比纯PEBA膜分别提高了244%和139%。这是因为多孔碳球的微孔结构显著提高了CO₂的扩散选择性,同时氮、硫元素的掺杂因为酸碱相互作用和良好亲和性有效提高了CO₂的吸附选择性。稳定性实验表明,PEBA/NSPC混合基质膜在360 h连续运行过程中气体分离性能稳定,具有较好的工业应用前景。     

五乙烯六胺改性制备CO2吸附剂及其对模拟烟气中CO2捕集性能的研究（英文）

A novel solid support adsorbent for CO2 capture was developed by loading pentaethylenehexamine (PEHA) on commercial y available mesoporous molecular sieve MCM-41 using wet impregnation method. MCM-41 sam-ples before and after PEHA loading were characterized by X-ray powder diffraction, N2 adsorption/desorption, thermal gravimetric analysis and scanning electron microscope to investigate the textural and thermo-physical properties. CO2 adsorption performance was evaluated in a fixed bed adsorption system. Results indicated that the structure of MCM-41 was preserved after loading PEHA. Surface area and total pore volume of PEHA loaded MCM-41 decreased with the increase of loading. The working adsorption capacity of CO2 could be significantly improved at 60%of PEHA loading and 75 °C. The effect of the height of adsorbent bed was investigated and the best working adsorption capacity for MCM-41-PEHA-60 reached 165 mg·(g adsorbent)?1 at 75 °C. Adsorption/desorption circle showed that the CO2 working adsorption capacity of MCM-41-PEHA kept stable. ? 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. Al rights reserved.     

二次生长法制备ZIF-8膜及其对CO2/N2的分离性能

采用二次生长法在α-Al₂O₃载体上制备超薄型ZIF-8膜,研究了多种轻分子气体以及混合气体CO₂/N₂的渗透分离性能。通过SEM和XRD表征了ZIF-8晶种层的晶种涂布状态,以及ZIF-8晶体膜的生长覆盖度和晶膜厚度。研究结果表明：采用低浓度的晶种悬浮液通过浸润式连续多次涂布法,有利于获得晶种层厚度均匀且覆盖度高的超薄均匀ZIF-8晶种层,经过二次生长后所得ZIF-8膜的覆盖度高、厚度均匀且较薄,仅约为8.8 μm;在所测试范围内的CO₂/N₂混合气体中,此ZIF-8膜对CO₂具有优先选择透过性,其对CO₂/N₂的渗透分离因子随温度的升高而降低,随渗透压力的增加而增加,在298 K、406 kPa和CO₂组分含量为50%时,该分离因子能达到6,显著超过Knudsen扩散的分离系数。     

一步法制备含氨基化合物的非对称CO2分离膜

采用一步相分离法,制备以聚醚砜（PES）为主体材料,二乙醇胺（DEA）为添加剂和氨基载体的膜,用于CO₂分离。考察了PES浓度、DEA浓度、膜厚度对CO₂/N₂分离性能的影响,同时考察了膜性能的长时间稳定性。当涂膜液中DEA/PES的质量比为12/26、刮刀与无纺布的距离为300 μm、进料气压力为0.11 MPa（表压）时,膜的CO₂渗透速率可达274 GPU,CO₂/N₂分离因子可达50。测试温度低于40℃时,DEA/PES膜的CO₂渗透速率和CO₂/N₂分离因子保持稳定。另外,对CO₂/N₂分离性能较好的DEA/PES膜（质量比为12/27）进行CO₂/CH₄分离性能测试,在1 MPa（表压）下性能优于商品膜。上述结果表明,本文研制的DEA/PES膜制备步骤简单,易于规模化制备,性能较优,在CO₂分离领域具有良好的应用前景。     

Optimization of electrochemically synthesized Cu3(BTC)2 by Taguchi method for CO2/N2 separation and data validation through artificial neural network modeling

Cu₃(BTC)₂, a common type of metal organic framework (MOF), was synthesized through electrochemical route for CO₂ capture and its separation from N₂. Taguchi method was employed for optimization of key parameters affecting the synthesis of Cu₃(BTC)₂. The results indicated that the optimum synthesis conditions with the highest CO₂ selectivity can be obtained using 1 g of ligand, applied voltage of 25 V, synthesis time of 2 h, and electrode length of 3 cm. The single gas sorption capacity of the synthetized microstructure Cu₃(BTC)₂ for CO₂ (at 298 K and 1 bar) was a considerable value of 4.40 mmol·g⁻¹. The isosteric heat of adsorption of both gases was calculated by inserting temperature-dependent form of Langmuir isotherm model in the Clausius-Clapeyron equation. The adsorption of CO₂/N₂ binary mixture with a concentration ratio of 15/85 vol-% was also studied experimentally and the result was in a good agreement with the predicted value of IAST method. Moreover, Cu₃(BTC)₂ showed no considerable loss in CO₂ adsorption after six sequential cycles. In addition, artificial neural networks (ANNs) were also applied to predict the separation behavior of CO₂/N₂ mixture by MOFs and the results revealed that ANNs could serve as an appropriate tool to predict the adsorptive selectivity of the binary gas mixture in the absence of experimental data.     

快速变压吸附制氢工艺的模拟与分析

目前工业上主要通过变压吸附技术从蒸汽甲烷重整气中制取氢产品气。然而,能源需求量的快速增加使得传统变压吸附技术在产量方面的不足越发明显。为此,进行了快速变压吸附从蒸汽甲烷重整气中制取氢气的模拟研究。采用活性炭和5A分子筛作为吸附剂,并以测得的原料气中各组分在两种吸附剂上的吸附数据为基础,进行了六塔快速变压吸附工艺的数值模拟与分析。在分析了塔内温度、压力和固相的浓度分布后,探究了进料流量、双层吸附剂高度比以及冲洗进料比三个操作参数对于快速变压吸附工艺性能的影响,结果表明：原料气组成为H₂/CH₄/CO/CO₂=76%/3.5%/0.5%/20%,吸附压力为22 bar（1 bar=10⁵ Pa）,解吸吹扫压力为1.0 bar,处理量为0.8875 mol·s^-1,吸附剂床层高度比为0.5∶0.5,冲洗进料比为22.37%时,可获得H₂纯度99.90%,回收率69.88%,此时H₂产量为0.4713 mol·s^-1。相比之下,氢气纯度为99.90%时,尽管PSA工艺回收率为83.40%,但处理量只有0.39 mol·s^-1,因此H₂产量仅为0.2472 mol·s^-1。     

基于沸石ZSM-5的CH4/N2/CO2二元体系吸附平衡

采用Rubotherm磁悬浮天平测量CH₄、N₂和CO₂在沸石ZSM-5上的单组分吸附平衡等温线,温度273～353 K,压力0～500 kPa。采用Sips模型、Toth模型和MSL模型对单组分吸附平衡实验数据进行拟合,拟合结果良好,非线性回归得到相应的模型参数。测量双组分CO₂/N₂、CO₂/CH₄和CH₄/N₂在沸石ZSM-5上的竞争吸附平衡等温线,实验温度为293 K,实验压力为0～500 kPa。采用基于Sips模型的理想吸附溶液理论和双组分MSL模型预测双组分气体在沸石ZSM-5上的竞争吸附平衡等温线,并与实验结果进行比较,预测结果良好。比较CO₂/N₂、CO₂/CH₄以及CH₄/N₂体系在沸石ZSM-5上的竞争吸附选择性系数,探究沸石ZSM-5吸附分离烟道气（CO₂/N₂体系）、垃圾填埋气（CO₂/CH₄体系）或煤层气（CH₄/N₂体系）的可行性,为将来进行工艺设计提供基础数据。     

水合物法平衡级分离CO2/N2流程模拟分析

化石燃料燃烧排放烟气中CO₂的量占CO₂总排放量的75%，为了缓解CO₂导致的全球温室效应，需将CO₂/N₂中的CO₂分离出来。水合物法分离是一种高效、低能耗的CO₂/N₂分离技术。本文研究了水合物法平衡级分离CO₂/N₂过程中，进料CO₂体积分数、反应条件与反应特性三者间的关系，利用CPA-SRK方程+Chen-Guo模型对其进行平衡级分离流程模拟分析。经计算发现，进料干基CO₂体积分数对水合物法分离CO₂/N₂工艺的反应压力、平衡级级数均有较大影响。随着体积分数的增加，反应压力呈减小趋势，减小幅度随体积分数增加而减小，当进料CO₂体积分数小于20%时，压力下降较快，当体积分数大于50%时，压力降低幅度变小。温度为277K时，CO₂体积分数小于10%时，需四个水合物平衡级分离才能得到满足要求的气样；当体积分数为10%~20%时，需三个水合物平衡级分离；体积分数大于30%时为两个水合物平衡级分离。温度对水合分离的反应压力有较大影响，但对所需平衡级分离级数的影响并不大。随着温度的升高，水合反应压力呈增加趋势，增加幅度随进料干基CO₂体积分数的增加而降低。针对所研究气样，在不同温度下，均需三个水合物平衡级分离才能达到工艺要求。