基于TiO2溶胶杂化的分子筛炭膜制备及其结构与性能

以聚酰亚胺为前体,TiO₂溶胶为掺杂剂,经成膜和炭化制得杂化炭膜。采用热失重、电子显微镜、X-射线衍射、红外光谱和渗透法对前体的热性能、炭膜的微观形貌、微结构、表面官能团和气体分离性进行了表征。考察了TiO₂溶胶用量、渗透温度和渗透压力对炭膜的结构与性能影响。结果显示,掺杂TiO₂溶胶显著提高了最终炭膜渗透性和选择性;采用TiO₂溶胶量为10%前体所制备的杂化炭膜对H₂、CO₂、O₂渗透性分别为1993.8、1555.6、266.9 Barrer,同时H₂/N₂、CO₂/N₂、O₂/N₂选择性分别为93.6、73.0、12.5。     

Optimization of the gas separation performance of polyurethane–zeolite 3A and ZSM-5 mixed matrix membranes using response surface methodology

In the present work, the response surface method software was used with five measurement levels with three factors.These were applied for the optimization of operating parameters that affected gas separation performance of polyurethane–zeolite 3A, ZSM-5 mixed matrix membranes.The basis of the experiments was a rotatable central composite design(CCD).The three independent variables studied were: zeolite content(0–24 wt%), operating temperature(25–45 ℃) and operating pressure(0.2–0.1 MPa).The effects of these three variables on the selectivity and permeability membranes were studied by the analysis of variance(ANOVA).Optimal conditions for the enhancement of gas separation performances of polyurethane–3A zeolite were found to be 18 wt%, 30 ℃ and 0.8 MPa respectively.Under these conditions, the permeabilities of carbon dioxide, methane, oxygen and nitrogen gases were measured at 138.4, 22.9, 15.7 and 6.4 Barrer respectively while the CO_2/CH_4, CO_2/N_2 and O_2/N_2 selectivities were 5.8, 22.5 and 2.5, respectively.Also, the optimal conditions for improvement of the gas separation performance of polyurethane–ZSM 5 were found to be 15.64 wt%, 30 ℃ and 4 bar.The permeabilities of these four gases(i.e.carbon dioxide, methane, oxygen and nitrogen) were 164.7, 21.2, 21.5 and 8.1 Barrer while the CO_2/CH_4, CO_2/N_2 and O_2/N_2 selectivities were 7.8, 20.6 and 2.7 respectively.     

Pebax/a-MoS2/MIP-202混合基质膜的制备及CO2分离性能

为了获得高性能的CO₂/N₂分离膜,把空气中氧刻蚀的二硫化钼（a-MoS₂）和金属有机框架材料MIP-202通过机械力化学反应制备的双功能填料作为分散相,聚醚嵌段酰胺（Pebax-1657）作为连续相,采用溶液浇铸法制备了Pebax/a-MoS₂/MIP-202混合基质膜。采用FT-IR表征了填料的化学结构,借助ATR-FTIR、SEM、TG和力学性能测试表征了混合基质膜的化学结构、微观形貌结构、热稳定性和物理力学性能。研究了水含量、双功能填料配比、含量、膜两侧压差和操作温度对膜气体分离性能的影响,并考察了模拟烟道气（CO₂/N₂体积比15/85）条件下混合基质膜的长时间运行稳定性。结果表明：在温度为25℃、膜两侧压差为0.1 MPa的操作条件下,a-MoS₂与MIP-202质量比为5∶5和双功能填料含量为6%（质量）时,膜的气体分离性能达到最优,CO₂渗透性和CO₂/N₂选择性分别为380 Barrer和124.7,超过了2019年McKeown等提出的上限值。连续测试360 h后,混合基质膜的性能没有明显降低,其平均CO₂渗透性和CO₂/N₂选择性分别为358 Barrer和120.1。这主要是由于a-MoS₂和MIP-202协同提高了膜的气体分离性能。     

Pebax/a-MoS2/MIP-202混合基质膜的制备及CO2分离性能

为了获得高性能的CO₂/N₂分离膜,把空气中氧刻蚀的二硫化钼（a-MoS₂）和金属有机框架材料MIP-202通过机械力化学反应制备的双功能填料作为分散相,聚醚嵌段酰胺（Pebax-1657）作为连续相,采用溶液浇铸法制备了Pebax/a-MoS₂/MIP-202混合基质膜。采用FT-IR表征了填料的化学结构,借助ATR-FTIR、SEM、TG和力学性能测试表征了混合基质膜的化学结构、微观形貌结构、热稳定性和物理力学性能。研究了水含量、双功能填料配比、含量、膜两侧压差和操作温度对膜气体分离性能的影响,并考察了模拟烟道气（CO₂/N₂体积比15/85）条件下混合基质膜的长时间运行稳定性。结果表明：在温度为25℃、膜两侧压差为0.1 MPa的操作条件下,a-MoS₂与MIP-202质量比为5∶5和双功能填料含量为6%（质量）时,膜的气体分离性能达到最优,CO₂渗透性和CO₂/N₂选择性分别为380 Barrer和124.7,超过了2019年McKeown等提出的上限值。连续测试360 h后,混合基质膜的性能没有明显降低,其平均CO₂渗透性和CO₂/N₂选择性分别为358 Barrer和120.1。这主要是由于a-MoS₂和MIP-202协同提高了膜的气体分离性能。     

Effect of Na-addition on catalytic activity of Pt-ZSM-5 for low-temperature NO–H2–O2 reactions

The effect of additives on Pt-ZSM-5 catalysts was studied for the selective NO reduction by H₂ in the presence of excess O₂ (NO–H₂–O₂ reaction) at 100 °C. The reaction of NO in a stream of 0.08% NO, 0.28% H₂, 10% O₂, and He balance yielded N₂ with less than 10% selectivity, which could not be increased by changing Pt loading or H₂ concentration in the gas feed. Co-impregnation of NaHCO₃ and Pt onto ZSM-5 decreased the BET surface area and the Pt dispersion. Nevertheless, the Na-loaded catalyst (Na-Pt-ZSM-5) exhibited the higher NO_x conversion (>90%) and the N₂ selectivity (ca. 50%). Such a high catalytic activity even at high Na loadings (≥10 wt.%) is completely contrast to other Na-added Pt catalyst systems reported so far. Further improvement of N₂ selectivity was attained by the post-impregnation of NaHCO₃ onto Pt-ZSM-5. In situ DRIFT measurements suggested that the addition of Na promotes the adsorption of NO as NO₂⁻-type species, which would play a role of an intermediate to yield N₂. The introduction of Lewis base to the acidic supports including ZSM-5 would be applied to the catalyst design for selective NO–H₂–O₂ reaction at low temperatures.     

Cu(Qc)2强化Pebax混合基质膜分离CO2

为了提高Pebax-1657的CO₂分离性能,本文制备了对CO₂有吸附作用的金属有机骨架Cu(Qc)₂,将其加入到Pebax-1657基质中,制备混合基质膜,用于CO₂的气体分离。通过扫描电子显微镜、热重分析、红外光谱和X射线衍射对溶液浇铸法制备的膜进行表征,通过膜的气体渗透性能测试考察填料含量、操作压力和混合气对膜气体渗透性能的影响。结果表明,Cu(Qc)₂在Pebax基质中随机有效地堆叠形成了高选择性的气体传输通道,极大地提高了CO₂/N₂的选择性。随着Cu(Qc)₂填充量的增加,CO₂渗透系数和CO₂/N₂选择性均呈现先上升后下降的趋势。当Cu(Qc)₂的质量分数为3%时,呈现最佳的CO₂/N₂分离性能,CO₂ 渗透系数和CO₂/N₂选择性分别为102Barrer和84,与Pebax-1657膜相比,分别提高了45.7%和40.0%,突破了Robeson分离上限,表明该混合基质膜在CO₂的分离应用上具有潜力。     

Ceramic Supported PDMS and PEGDA Composite Membranes for CO2 Separation

Composite membranes have attracted increasing attentions owing to their potential applications for CO2 separation. In this work, ceramic supported polydimethylsiloxane （PDMS） and poly （ethylene glycol） diacrylate （PEGDA） composite membranes were prepared. The microstructure and physicochemical properties of the compos- ite membranes were characterized. Preparation conditions were systematically optimized. The gas separation performance of the as-prepared membranes was studied by pure gas and binary gas permeation measurement of CO〉 N2 and H〉 Experiments showed that PDMS, as silicone rubber, exhibited larger permeance and lower separation factors. Conversely, PEGDA composite membrane presented smaller gas permeance but higher ideal selectivity for CO2/N2. Compared to the performance of those membranes using polymeric supports or freestanding membranes, the two kinds of ceramic supported composite membranes exhibited higher gas permeance and acceptable selectivity. Therefore, the ceramic supported composite membrane can be expected as a candidate for CO2 separation from light gases.     

SPEEK/PSI半互穿网络共混膜的制备及其CO2分离研究

为了获得高性能的气体分离膜,实现烟道气中CO₂/N₂高效分离回收,以磺化聚醚醚酮（SPEEK）和聚琥珀酰亚胺（PSI）为原料,己二胺为交联剂,原位交联反应制备富含氨基的半互穿网络共混膜,在膜内构建CO₂传递通道和亲和位点,并采用红外光谱对共混膜的结构进行表征。研究水含量、PSI用量和进料气压力对膜气体分离性能的影响,在混合气条件下考察其气体分离性能和长时间运行稳定性。研究结果表明：SPEEK与PSI两相界面相容性较好,它们之间存在较强的相互作用,且呈半互穿网络微结构;PSI含量为60%（质量）时,纯气和混合气条件下CO₂渗透性分别为652和601 Barrer,对应的CO₂/N₂选择性为67.6和60.3,优于纯SPEEK膜,且超过2008年的Robeson上限;共混膜运行360 h后,CO₂渗透性和CO₂/N₂选择性仍然稳定。这主要是因为SPEEK与PSI形成富含氨基的半互穿网络微结构后,一方面提供了CO₂促进传递载体;另一方面,增强了共混膜的保水性能,形成大量CO₂传递水通道。     

Preparation of SPEEK/PSI semi-interpenetrating network blend membrane and its CO2 separation

To obtain high-performance gas separation membranes and realize high-efficiency separation and recovery of CO₂/N₂ in flue gas, the amino-rich semi-interpenetrating network blend membranes were prepared by in-situ crosslinking reaction, which provided CO₂ transport channels and affinity sites. Sulfonated poly(ether ether ketone) (SPEEK) and polysuccinimide (PSI) were used as raw materials, and hexamethylenediamine was crosslinking agent. The structure of the blend membranes was characterized by Fourier-transform infrared spectroscopy. The effects of water content, PSI dosage and feed gas pressure on the gas separation performance were studied, and its gas separation performance and the long-time stability were investigated under mixed gas conditions. The results showed that SPEEK and PSI have a good compatibility, and there is a strong interaction between them, which exhibited the semi-interpenetrating network microstructure in the membranes. When the PSI loading is 60%(mass), the CO₂ permeability of pure gas and mixed gas are 652 and 601 Barrer, respectively, and the corresponding CO₂/N₂ selectivity is 67.6 and 60.3, which is better than that in pristine SPEEK membrane, surpassing 2008 Robeson upper bound. The CO₂ permeability and CO₂/N₂ selectivity are still stable after 360 h durability test of SPEEK/PSI-60 blend membrane. This is mainly due to the formation of the amino-rich semi-interpenetrating network microstructure between SPEEK and PSI, which not only provides CO₂ facilitated transport carriers, but also enhances the water retention performance of the blend membranes and forms a large number of CO₂ transport water channels.     

PEO/聚吡咯中空纳米微球混合基质膜的制备及其CO2渗透分离性能

采用壳层具有介孔结构的聚吡咯中空纳米微球作为填料，和聚氧化乙烯单体共混自由基聚合制备了混合基质膜。结果表明，聚吡咯微球与基质相容性较好，未见明显团聚现象和缺陷。混合基质膜的渗透系数随填料含量的增加先增大后减少，在0.5%处达到最大值，CO₂渗透系数增长31%；CO₂/N₂分离系数有所降低，CO₂/CH₄分离系数则变化不大。研究表明，由于聚合物链段对微球壳层的介孔填充，气体在膜内的扩散系数不升反降，渗透系数的提高主要是由于溶解度系数的变化，而这也导致了溶解选择性的变化，进而影响了分离系数。     

ZSM-5 zeolite films on Si substrates grown by in situ seeding and secondary crystal growth and application in an electrochemical hydrocarbon gas sensor

ZSM-5 zeolite films were grown on Si substrates by a two-step hydrothermal synthesis consisting of in situ seeding and secondary crystal growth. The films were 8–13 μm thick and partly oriented with the c-axis perpendicular to the substrate surface. After ion exchange with sodium ions, one film was applied as solid electrolyte in a potentiometric hydrocarbon gas sensor. A fast and reversible voltage response of the sensor to varying propane concentrations (100 ppm – 10%) was observed in O₂/CO₂/N₂ gas mixtures at 723 K.     

GO-TSC/聚酰亚胺混合基质膜的制备及气体分离性能研究

使用氨基硫脲（TSC）对氧化石墨烯（GO）进行改性,制备GO-TSC层状复合材料。随后,将该复合材料加入到Matrimid^®5218（PI）基质中,制备用于二氧化碳分离的混合基质膜（MMMs）。通过TGA、SEM及气体分离性能测试考察了GO-TSC对膜热稳定性、结构和气体分离性能等的影响。SEM结果显示GO-TSC可均匀分散在聚合物基质上并与基质紧密结合;TGA结果显示混合基质膜在250 ℃以上仍保持稳定。与纯PI膜相比,MMMs显著增强了二氧化碳的渗透性。GO-TSC中所含的氨基与二氧化碳具有良好的亲和力,增加的碱性位点可以有效地转运二氧化碳。GO-TSC的层状结构增加了气体的传输路径,不利于大动态直径气体（甲烷、氮气）的通过,从而提高了分离性能。GO-TSC负载量为0.75%（质量分数）时混合基质膜的分离性能最佳。相比较纯PI膜,混合基质膜的二氧化碳渗透系数和二氧化碳/甲烷、二氧化碳/氮气分离系数分别提高了42.16%、95.79%和83.72%。     

ZSM-5@t-ZrO2制备及其对甲硫醇催化合成影响机制

采用水热包覆法和物理共混法分别制备了ZSM-5@t-ZrO₂和ZSM-5/t-ZrO₂复合催化剂,并以ZSM-5和t-ZrO₂为对比参考,研究了不同结构催化剂的物化性质和催化性能。在此基础上,借助漫反射傅里叶变换红外光谱,考察了反应温度和预硫化操作对ZSM-5@t-ZrO₂复合催化剂上甲醇和硫化氢反应分子吸附转化的影响。结果表明,水热包覆环境修饰了ZSM-5@t-ZrO₂复合催化剂的物化性质,提升了甲醇硫醇化反应的催化性能和抗积碳积硫失活能力。在反应压力1 MPa、反应温度380 ℃、预硫化1 h、N₂流量100 mL/min的条件下,甲醇转化率、甲硫醇选择性及甲硫醇收率分别达到92.02%、90.56%和82.76%。硫化氢分子在ZSM-5@t-ZrO₂催化剂的碱位上吸附解离为巯基,进而攻击甲氧基,这是甲硫醇合成反应的速率控制步骤。380 ℃的反应温度和预硫化操作有助于构建形成匹配的甲氧基和巯基生成速率,在提高催化性能的同时还可有效降低积碳积硫形成速率。     

机械化学法合成小尺寸MOF填料助力高性能CO2分离

利用金属-有机骨架UTSA-280具有特定刚性尺寸的一维孔道可以筛分CO₂、CH₄、N₂的特性,采用机械化学研磨法减小其颗粒尺寸,将UTSA-280掺入聚砜（PSf）中制备MOF基混合基质膜,用于天然气提纯和烟道气CO₂捕获。结果表明,在PSf中掺入UTSA-280不仅可以增加聚合物的CO₂渗透通量而且提高了气体分离选择性。当UTSA-280掺杂量为30%（质量）时,混合基质膜对CO₂/CH₄、CO₂/N₂的分离因子分别为56.39和53.17,CO₂的渗透通量为18.61 Barrer,相对于PSf纯膜,选择性分别提高了47.3%和63.5%,CO₂渗透通量提高了128.9%,打破了“trade-off”效应。该工作通过引进具有分子筛分效应的MOF填料,能够增加气体通量的同时提高混合基质膜对含CO₂气体的分离性能,对天然气的提纯以及烟道气的CO₂的捕获有重要意义。     

碳纳米管/环糊精金属有机骨架协同强化混合基质膜的CO2分离

为了实现混合基质膜中CO₂的高效分离,设计了羧基化多壁碳纳米管(CNT)和氨基化β-环糊精金属有机骨架(β-CD MOF)双填料(CM),并将其引入磺化聚醚醚酮(SPEEK)基质中,在膜内同时构建CO₂扩散通道和亲和位点,增强了混合基质膜的分离性能。采用FTIR和BET表征了CM的化学结构和孔结构,借助膜的SEM、FTIR和力学性能表征了填料-聚合物界面相互作用。研究了CM的合成比例、含量、压力、温度和混合气等因素对混合基质膜分离性能的影响。结果表明：CM与SPEEK之间具有良好的相容性并为气体分子提供了快速的传递通道。在改性CNT与MOF的质量比为5∶5、添加量为7%(质量)以及0.1 MPa和25℃的条件下,混合基质膜的分离性能最优,CO₂渗透性为844 Barrer,CO₂/N₂选择性为84,与纯SPEEK膜相比,分别提升了178%和163%,超过2019年上限。羧基化CNT的直孔通道缩短了CO₂的扩散路径,同时改性β-CD MOF表面的氨基载体提升了CO₂的溶解性,两者协同提高了混合基质膜的分离性能。此外,负载双填料的膜比单独负载相同含量的羧基化CNT或氨基化MOF的膜具有更好的分离性能。在360 h的测试过程中,混合基质膜保持较好的分离稳定性。     

The effect of ZIF-90 particle in Pebax/Psf composite membrane on the transport properties of CO2, CH4 and N2 gases by Molecular Dynamics Simulation method

Nowadays, mixed matrix membranes (MMMs) have considered by many researchers to overcome the problems of polymeric membranes. In addition, molecular dynamics (MD) and Monte Carlo (MC) simulation Methods are suitable tools for studying transport properties and morphology in MMMs. For this purpose, in this study using material studio 2017 (MS) software, the transport properties of CO₂, CH₄ and N₂ in Pebax, Psf neat Pebax/Psf composite and Pebax/Psf composite filled with ZIF-90 particles have been investigated. By adding Psf to Pebax matrix, the selectivity of CO₂/CH₄ and CO₂/N₂ gases has significantly increased. In addition, adding ZIF-90 particles to the Pebax/Psf composite increased the permeability of CO₂, CH₄ and N₂ compared to neat and composite membranes. The morphological properties of the membranes, such as the fractional free volume (FFV), radial distribution function (RDF), glass transition temperature (T_G), X-ray diffraction (XRD) and equilibrium density have calculated and acceptable results have obtained.     

碳纳米管/环糊精金属有机骨架协同强化混合基质膜的CO2分离

为了实现混合基质膜中CO₂的高效分离,设计了羧基化多壁碳纳米管(CNT)和氨基化β-环糊精金属有机骨架(β-CD MOF)双填料(CM),并将其引入磺化聚醚醚酮(SPEEK)基质中,在膜内同时构建CO₂扩散通道和亲和位点,增强了混合基质膜的分离性能。采用FTIR和BET表征了CM的化学结构和孔结构,借助膜的SEM、FTIR和力学性能表征了填料-聚合物界面相互作用。研究了CM的合成比例、含量、压力、温度和混合气等因素对混合基质膜分离性能的影响。结果表明：CM与SPEEK之间具有良好的相容性并为气体分子提供了快速的传递通道。在改性CNT与MOF的质量比为5∶5、添加量为7%(质量)以及0.1 MPa和25℃的条件下,混合基质膜的分离性能最优,CO₂渗透性为844 Barrer,CO₂/N₂选择性为84,与纯SPEEK膜相比,分别提升了178%和163%,超过2019年上限。羧基化CNT的直孔通道缩短了CO₂的扩散路径,同时改性β-CD MOF表面的氨基载体提升了CO₂的溶解性,两者协同提高了混合基质膜的分离性能。此外,负载双填料的膜比单独负载相同含量的羧基化CNT或氨基化MOF的膜具有更好的分离性能。在360 h的测试过程中,混合基质膜保持较好的分离稳定性。     

Characterization and performance of Pt-USY in the SCR of NOx with hydrocarbons under lean-burn conditions

Pt-USY was used for the selective catalytic reduction of NO_x with hydrocarbons in the presence of excess oxygen. The catalyst was prepared by an ion-exchange method and characterized by XRD, TEM, CO chemisorption, and Ar adsorption at 87 K. The platinum particle size distribution was found to be broad (2–20 nm), with no apparent sintering of the active phase during the HC-SCR process after 25 h time-on-stream. Generally, large metal clusters (>15 nm) are situated at the external surface of the zeolite, while the smaller ones are located in the pores of the support. Pt-USY shows an excellent activity in the deNO_x reaction (molar NO_x conversion 90% at 475 K) with propene as the reductant in 5 kPa O₂, as well as stable operation during time-on-stream. Propane only yields a low NO_x conversion compared to propene. The presence of high oxygen contents (5–10 kPa O₂) slightly inhibits the reaction. No significant decrease in deNO_x activity was observed at high space velocities (up to 100,000 h⁻¹). The presence of SO₂ and H₂O in the feed stream did not significantly affect the deNO_x activity. Pt-USY performs better under lean-burn conditions than other Pt-catalysts supported on e.g. ZSM-5, Al₂O₃, or SiO₂. The selectivity to N₂ was similar to the other Pt-based catalysts (30%), the other major product being N₂O.     

功能化Zr-MOF强化混合基质膜CO2分离

混合基质膜（MMMs）在气体分离领域具有良好的应用前景,金属有机框架（MOFs）由于具有高孔隙率和有机连接基团,常被用作填料制备MMMs。但由于MOFs与聚合物的界面相容性问题,MMMs的气体分离性能提升受到限制。本文合成了功能化的Zr-MOF（UiO-66-AC）,并利用其与聚醚共聚酰胺（Pebax）共同制备了混合基质膜。填料中引入的羰基和羧基等基团提供了MOFs与聚合物基质之间较强的界面相互作用。与纯Pebax膜相比,UiO-66-AC/Pebax MMMs的气体渗透性能得到了显著提高。当填料质量分数为6%时,膜的CO₂渗透系数为102.4 Barrer,CO₂/N₂和CO₂/CH₄选择性分别为90.6和26.0,CO₂/N₂分离性能突破了Robeson上限(2008),表明该混合基质膜在CO₂的分离应用上具有潜力。     

ZSM-5 zeolite membranes prepared from a clear template-free solution

Template-free nanosized ZSM-5 seeds were prepared from commercially available ZSM-5 powder. By use of these seeds, thin and hydrophilic ZSM-5 zeolite membranes were prepared on the outer surface of a porous -alumina tube in a clear solution free from organic template. The membranes showed high thermal stability to withstand pretreatment at 400 °C. At 270 °C, the ideal selectivities for H₂/i-butane and N₂/SF₆ were 61 and 20, respectively. The membrane was effective to separate butane isomers at high temperatures. The maximum of the n/i-butane ideal selectivity was 36 at 300 °C. The separation factors for a 50/50 n/i-butane mixture were as high as 13 in the temperature range from 300 to 400 °C.