共查询到20条相似文献,搜索用时 46 毫秒
1.
SAPO-34 zeolite membranes show high efficiency for CO2/CH4 separation but suffer from the reduction of separation performance when exposed to humid atmosphere. In this work, n-dodecyltrimethoxysilane (DTMS) was used to modify the hollow fibers supported SAPO-34 membranes to increase the external surface hydrophobicity and thus sustain their performance under moisture environment. The modified membranes were fully characterized. Their separation performance was extensively investigated in both dry and wet gaseous systems and compared with the un-modified ones. The un-modified SAPO-34 membrane exhibited a high separation selectivity of 160 and CO2 permeance of 1.18×10-6 mol·m-2·s-1·Pa-1 for separation of dry CO2/CH4 at 298 K. However, its separation selectivity declined to 0.9 and the CO2 permeance was only about 1.7×10-8 mol·m-2·s-1·Pa-1 for wet CO2/CH4 at same temperature. High temperature (e.g. 353 K) could reduce the effect of moisture to improve SAPO-34 separation selectivity, but further increasing temperature (e.g. 373 K) led to decrease in CO2/CH4 separation selectivity. A significant decrease of selectivity was observed at higher pressure drop. The modified SAPO-34 membrane showed decreased CO2 permeance but increased separation selectivity for dry CO2/CH4 gas mixture, and super performance for wet CO2/CH4 gas mixture due to the improved hydrophobicity of membrane surface. A separation selectivity of 65 and CO2 permeance of 4.73×10-8 mol·m-2·s-1·Pa-1 for wet CO2/CH4 mixture can be observed at 353 K with a pressure drop of 0.4 MPa. Furthermore, the modified membrane exhibited stable separation performance during the 120-hour test for wet CO2/CH4 mixture at 353 K. The hydrophobic modification paves a way for SAPO-34 membranes in real applications. 相似文献
2.
Ping Zhang Chao Gong Tao Zhou Peng Du Jieyu Song Mengyang Shi Xuerui Wang Xuehong Gu 《中国化学工程学报》2022,49(9):122-129
Helium(He) is commercially produced from natural gas by low-temperature condensation. The process is energy extensive because of the extremely low He concentration(<0.3%) and the operation at cryogenic temperature. Herein we demonstrated DD3R zeolite membrane was efficient to extract He from natural gas at atmosphere temperature. The membrane performance was evaluated in terms of temperature,pressure and molar fractions. The overall membrane performance was dominated by the diffusivity select... 相似文献
3.
The special channels and intrinsic defects within GO laminates make it a very potential candidate for gas separation in recent years. Herein, the gas separation performance of GO membranes prepared on the surface of ceramicα-Al_2O_3 hollow fibre was investigated systematically. The microstructures of ceramic hollow fibre supported GO membranes were optimized by adjusting operation conditions. And, the GO membrane fabricated at 30 min exhibited great promising H_2 recovery ability from H_2/CO_2 mixture. At room temperature, the H_2 permeance was over 1.00 × 10~(-7)mol·m~(-2)·s~(-1)·Pa~(-1)for both single gas and binary mixture. The corresponding ideal selectivity and mixture separation factor reached around 15 and 10, respectively. In addition, humility, operation temperature, H_2 concentration in the feed and the reproducibility were also studied in this work. 相似文献
4.
Membrane separation is a high-efficiency, energy-saving, and environment-friendly separation technology. Covalent organic framework (COF)-based mixed-matrix membranes (MMMs) have broad application prospects in gas separation and are expected to provide new solutions for coal-bed methane purification. Herein, a high-throughput screening method is used to calculate and evaluate COF-based MMMs for CH4/N2 separation. General design rules are proposed from thermodynamic and kinetic points of view using the computation-ready, experimental COFs. From our database containing 471,671 generated COFs, 5 COF membrane materials were screened with excellent membrane selectivities, which were then used as the filler of MMMs for separation performance evaluation. Among them, BAR-NAP-Benzene_CF3 combined with polydimethylsiloxane and styrene-b-butadiene-b-styrene show high CH4 permeability of 4.43×10-13 mol·m·s-1·Pa-1·m-2 and high CH4/N2 selectivity of 9.54, respectively. The obtained results may provide reasonable information for the design of COF-based membranes for the efficient separation of CH4/N2. 相似文献
5.
Samples of methane molecules grade diameter channel CHA-type molecular sieves(Chabazite-K, SAPO-34 and SSZ-13) were investigated using the adsorption separation of CH_4/N_2 mixtures. The isotherms recorded for CH_4 and N_2 follow a typical type-Ι behavior, which were fitted well with the Sips model(R~20.999) and the selectivity was calculated using IAST theory. The results reveal that Chabazite-K has the highest selectivity(SCH_4/N= 5.5).2 SSZ-13 has the largest capacity, which can adsorb up to a maximum of 30.957 cm~3·g~(-1)(STP) of CH_4, due to it having the largest pore volume and surface area, but the lowest selectivity(S_(CH_4/N_2)= 2.5). From the breakthrough test, we can conclude that SSZ-13 may be a suitable candidate for the recovery of CH_4 from low concentration methane(CH_420%) based on its larger pore volume and higher CH_4 capacity. Chabazite-K is more suited to the separation of high concentration methane(CH_450%) due to its higher selectivity. 相似文献
6.
Xionghui Liu Jianfeng Du Yu Ye Yuchuan Liu Shun Wang Xianyu Meng Xiaowei Song Zhiqiang Liang Wenfu Yan 《中国化学工程学报》2022,42(2):64-72
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. 相似文献
7.
Guoqing Guan Katsuki Kusakabe Shigeharu Morooka 《Microporous and mesoporous materials》2001,50(2-3):109-120
Zeolite membranes, which were composed of ETS-4 with Na cations, were prepared on porous -alumina tubes by hydrothermal synthesis. The membranes, which were formed under optimized conditions, sharply rejected molecules with sizes larger than 0.4 nm. For mixtures of N2–CO2, N2–O2, N2–Ar and N2–CH4 systems, N2 permeated faster than the coexisting gas. The N2/O2 separation factor for an equimolar mixture was in the range of 2.3–3.5, and the N2 permeance was in the range of (0.55–2.8)×10−8 mol m−2 s−1 Pa−1 at permeation temperatures of 283–333 K. Moisture had some effect on the permeation properties for N2–O2 mixtures. The separation factor for the N2/CH4 system was larger than that of the N2/O2 system. When the membrane was ion exchanged with either Li+ or Sr2+, the separation factors for N2/O2 and N2/CH4 systems increased, while the permeances decreased. 相似文献
8.
Haoqing Xu Wenyan Feng Menglong Sheng Ye Yuan Bo Wang Jixiao Wang Zhi Wang 《中国化学工程学报》2022,43(3):152-160
Thin film composite (TFC) membranes with nanofillers additives for CO2 separation show promising applications in energy and environment-related fields. However, the poor compatibility between nanofillers and polymers in TFC membranes is the main problem. In this work, covalent organic frameworks (COFs, TpPa-1) with rich —NH— groups were incorporated into polyamide (PA) segment via in situ interfacial polymerization to prepare defect-free TFC membranes for CO2/N2 separation. The formed covalent bonds between TpPa-1 and PA strengthen the interaction between nanofillers and polymers, thereby enhancing compatibility. Besides, the incorporated COFs disturb the rigid structure of the PA layer, and provide fast CO2 transfer channels. The incorporated COFs also increase the content of effective carriers, which enhances the CO2 facilitated transport. Consequently, in CO2/N2 mixed gas separation test, the optimal TFC (TpPa0.025-PIP-TMC/mPSf) membrane exhibits high CO2 permeance of 854 GPU and high CO2/N2 selectivity of 148 at 0.15 MPa, CO2 permeance of 456 GPU (gas permeation unit) and CO2/N2 selectivity of 92 at 0.5 MPa. In addition, the TpPa0.025-PIP-TMC/mPSf membrane also achieves high permselectivty in CO2/CH4 mixed gas separation test. Finally, the optimal TFC membrane showes good stability in the simulated flue gas test, revealing the application potential for CO2 capture from flue gas. 相似文献
9.
Shiguang Li John L. Falconer Richard D. Noble 《Microporous and mesoporous materials》2008,110(2-3):310-317
Silicoaluminophosphate (SAPO) membranes with Si/Al gel ratios from 0.05 to 0.3 were synthesized by in situ crystallization onto porous, tubular stainless steel support. Pure SAPO-34 membranes were obtained when the Si/Al ratio was 0.15 or higher. The adsorbate polarizability correlated with the adsorption capacity on SAPO-34, and the amounts of gases adsorbed were in the order: CO2 > CH4 > N2 > H2. The Si/Al ratio did not affect the pore volume significantly, but it changed the CO2 and CH4 adsorption equilibrium constants. The SAPO-34 membranes effectively separated CO2 from CH4 for feed pressures up to 7 MPa. At 295 K, for a pressure drop of 138 kPa and a 50/50 feed, the CO2/CH4 selectivity was 170 for a membrane with a Si/Al gel ratio of 0.15. At 7 MPa, the CO2/CH4 selectivity was 100 and the CO2 permeance was 4 × 10−8 mol/(m2 · s · Pa) at 295 K. This membrane was also separated CO2/N2 (selectivity = 21) and H2/CH4 (selectivity = 32) mixtures at 295 K and a pressure drop of 138 kPa. Competitive adsorption and difference in diffusivities are responsible for CO2/CH4 and CO2/N2 separations, whereas the H2/CH4 separation was due to diffusivity differences. For a membrane with Si/Al gel ratio of 0.1, a mixture of SAPO-34 and SAPO-5 formed, and the CO2/CH4 selectivity was lower. 相似文献
10.
采用微波辅助二次生长法在α-Al2O3载体上合成了SAPO-34分子筛膜,并将其应用于CO2/CH4分离。通过扫描电镜、X射线衍射和傅里叶变换红外光谱等表征方法,系统考察了加热方式、晶种粒径、老化时间和晶化时间对SAPO-34分子筛膜表面形貌和结构的影响。实验结果表明,以0.4 μm分子筛作为晶种,在老化24 h,然后微波加热晶化4 h后可制备出厚度约为1.5 μm的致密、无缺陷SAPO-34分子筛膜,其平均CO2/CH4分离因子和CO2渗透率分别达到81和6.6×10-7 mol·m-2·s-1·Pa-1,制备方法可靠,重复性高。 相似文献
11.
Yiyi Fan Jinyong Li Saidi Wang Xiuxia Meng Yun Jin Naitao Yang Bo Meng Jiaquan Li Shaomin Liu 《Frontiers of Chemical Science and Engineering》2021,15(4):882
Hydrogen fuel has been embraced as a potential long-term solution to the growing demand for clean energy. A membrane-assisted separation is promising in producing high-purity H2. Molecular sieving membranes (MSMs) are endowed with high gas selectivity and permeability because their well-defined micropores can facilitate molecular exclusion, diffusion, and adsorption. In this work, MXene nanosheets intercalated with Ni2+ were assembled to form an MSM supported on Al2O3 hollow fiber via a vacuum-assisted filtration and drying process. The prepared membranes showed excellent H2/CO2 mixture separation performance at room temperature. Separation factor reached 615 with a hydrogen permeance of 8.35 × 10−8 mol·m−2·s−1·Pa−1. Compared with the original Ti3C2Tx/Al2O3 hollow fiber membranes, the permeation of hydrogen through the Ni2+-Ti3C2Tx/Al2O3 membrane was considerably increased, stemming from the strong interaction between the negatively charged MXene nanosheets and Ni2+. The interlayer spacing of MSMs was tuned by Ni2+. During 200-hour testing, the resultant membrane maintained an excellent gas separation without any substantial performance decline. Our results indicate that the Ni2+ tailored Ti3C2Tx/Al2O3 hollow fiber membranes can inspire promising industrial applications. 相似文献
12.
作为一种高效的分离方法,膜法分离非常规天然气具有较理想的应用前景。相较CH4优先渗透膜,N2优先渗透膜优势在于分离N2/CH4混合气后CH4处于高压侧,利于后续处理。以均苯三甲酰氯为油相单体,间苯二胺为水相单体,采用界面聚合法在聚砜基膜上制备致密超薄聚酰胺分离层,并通过向其中引入孔径可允许N2分子通过而不允许CH4分子通过的纳米颗粒ZIF-90,在膜内形成固定的N2传递通道,成功制备了用于脱氮提纯CH4的N2优先渗透混合基质膜。膜渗透选择性能测试结果显示当混合基质膜中纳米颗粒掺杂量为0.30 g·L-1时,2 bar(1 bar=0.1 MPa)进料压力下,N2渗透速率达1.16×10-9 mol·m-2·s-1·Pa-1,N2/CH4分离因子达16.6,分离因子比未掺杂ZIF-90的聚酰胺膜提高46.5%,具有一定的处理非常规天然气脱氮提纯甲烷的应用潜力。 相似文献
13.
作为一种高效的分离方法,膜法分离非常规天然气具有较理想的应用前景。相较CH4优先渗透膜,N2优先渗透膜优势在于分离N2/CH4混合气后CH4处于高压侧,利于后续处理。以均苯三甲酰氯为油相单体,间苯二胺为水相单体,采用界面聚合法在聚砜基膜上制备致密超薄聚酰胺分离层,并通过向其中引入孔径可允许N2分子通过而不允许CH4分子通过的纳米颗粒ZIF-90,在膜内形成固定的N2传递通道,成功制备了用于脱氮提纯CH4的N2优先渗透混合基质膜。膜渗透选择性能测试结果显示当混合基质膜中纳米颗粒掺杂量为0.30 g·L-1时,2 bar(1 bar=0.1 MPa)进料压力下,N2渗透速率达1.16×10-9 mol·m-2·s-1·Pa-1,N2/CH4分离因子达16.6,分离因子比未掺杂ZIF-90的聚酰胺膜提高46.5%,具有一定的处理非常规天然气脱氮提纯甲烷的应用潜力。 相似文献
14.
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。 相似文献
15.
Tensile strain of porous membrane materials can broaden their capacity in gas separation. In this work, using van der Waals corrected density functional theory(DFT) and molecular dynamics(MD) simulations, the performance and mechanism of CO_2/CH_4 separation through strain-oriented graphdiyne(GDY) monolayer were studied by applying lateral strain. It is demonstrated that the CO_2 permeance peaks at 1.29 × 10~6 gas permeation units(GPU) accompanied with CO_2/CH_4 selectivity of 5.27 × 10~3 under ultimate strain, both of which are far beyond the Robeson's limit. Furthermore, the GDY membrane exhibited a decreasing gas diffusion energy barrier and increasing permeance with the increase of applied tensile strain. CO_2 molecule tends to reoriented itself vertically to permeate the membrane. Finally, the CO_2 permeability decreases with the increase of the temperature from300 K to 500 K due to conserving of rotational freedom, suggesting an abnormal permeance of CO_2 in relation to temperature. Our theoretical results suggest that the stretchable GDY monolayer holds great promise to be an excellent candidate for CO_2/CH_4 separation, owing to its extremely high selectivity and permeability of CO_2. 相似文献
16.
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(SCH4/N2=10),而且对CH4/N2的分离效果优于CO2/CH4。 相似文献
17.
Ye Yuan Yurui Pan Menglong Sheng Guangyu Xing Ming Wang Jixiao Wang Zhi Wang 《中国化学工程学报》2022,50(10):168-176
Membrane technology features inspiring excellence from numerous separation technologies for CO2 capture from post-combustion gas. Polyvinylamine (PVAm)-based facilitated transport membranes show significantly high separation performance, which has been proven promising for industrial scale-up. However, commercialized PVAm with low molecular weight and excessive crystallinity is not available to prepare high-performance membranes. Herein, the synthesis process of PVAm was optimized by regulating polymerization and acidic hydrolytic conditions. The membranes based on PVAm with a molecular weight of 154 kDa and crystallinity of 11.37% display high CO2 permeance of 726 GPU and CO2/N2 selectivity of 55 at a feed gas pressure of 0.50 MPa. Furthermore, we established a PVAm synthesis reactor with an annual PVAm solution (1%(mass)) capacity of over 7000 kg and realized the scaled-up manufacture of both PVAm and composite membranes. 相似文献
18.
Intensification of low-grade methane enrichment in nitrogen mixture by CH4/CO2 displacement
下载免费PDF全文
![点击此处可从《化工学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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%. 相似文献
19.
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。 相似文献
20.
主要围绕从低品位煤层气中回收分离低浓度的CH4这一重要需求,探索以生物质为碳源研制具有优良CH4/N2分离性能的颗粒炭吸附剂。选择大米碎粒作为碳源,通过碳化制备颗粒状炭前体,然后应用CO2进行活化,制备出大米基颗粒炭材料(GRCM),研究其吸附分离CH4/N2的性能。所制得的颗粒炭材料具有较窄微孔分布,其中样品GRCM-900的BET比表面积为938.529 m2/g。FT-IR分析结果显示大米基颗粒炭表面含有羟基及羰基等含氧官能团。其CH4吸附容量和CH4/N2吸附选择性分别高达1.32 mmol / g和5.68(在298 K和100 kPa条件下),优于大多数已报道的粉末状炭材料和MOF材料。分子模拟揭示了甲烷和氮气在GRCM炭材料狭缝孔道中的吸附构型和差异。固定床实验证实,应用GRCM炭材料可以在常温条件下有效地分离CH4/N2混合物,所制得的颗粒GRCM在从低品位煤层气中回收CH4方面有很好的应用前景。 相似文献