TMCS修饰MFI分子筛膜的制备及乙醇/水分离稳定性的研究

采用三甲基氯硅烷（TMCS）作为修饰源对MFI分子筛膜进行表面改性,系统考察了TMCS浓度以及修饰时间对于MFI分子筛膜在分离乙醇/水混合物时的性能影响。SEM、XRD、²⁹Si NMR、FT-IR、接触角实验及分离实验结果表明,TMCS可以与硅羟基反应,嫁接分子筛膜表面,在消除膜表面硅缺陷的同时提高膜的疏水性及膜分离性能的稳定性。随着TMCS浓度以及反应时间的增加,修饰后MFI分子筛膜的通量及分离因子略有下降,但稳定性增强。在TMCS的浓度为0.4%（质量）,修饰时间为2 h时,所得到的膜具有最佳渗透汽化分离性能,并可在60℃下分离5%（质量）乙醇/水混合物时保持良好的稳定性。在连续90 h渗透汽化分离过程中,其渗透通量稳定在1.61 kg·m^-2·h^-1 左右,分离因子保持在20以上。     

四通道中空纤维MFI分子筛膜用于二甲苯异构体分离

采用二次生长法在高机械强度、高装填密度的四通道α-Al₂O₃中空纤维载体(7 cm)上制备MFI分子筛膜，探究了膜合成时间、操作温度、原料分压和吹扫气流量等条件对二甲苯异构体膜分离性能的影响。结果表明，160℃水热合成12 h制得的四通道中空纤维MFI分子筛膜对二甲苯异构体分离性能较优，在150℃、原料分压2 kPa、吹扫气流量20 ml/min时对二甲苯/邻二甲苯分离因子高达878,PX渗透性为2.1×10^-8 mol·m^-2·s^-1·Pa^-1。基于优化的制膜及分离操作条件，进一步将MFI分子筛膜制备于27 cm长的四通道中空纤维载体上，也获得了优异的对二甲苯/邻二甲苯膜分离性能，且所制得的膜材料对该体系的分离可稳定运行100 h以上。为推进中空纤维MFI分子筛膜的批量化制备和传统分离工艺的技术革新奠定了基础。     

二乙胺导向合成中空纤维负载型SAPO-34分子筛膜

采用价格低廉的二乙胺为模板剂，通过球磨晶种诱导二次生长法制备中空纤维负载型SAPO-34分子筛膜用于CO₂/CH₄气体分离。系统考察了诱导晶种大小、膜合成液中二乙胺含量、铝源含量与晶化时间对膜结构形貌以及分离性能的影响。结果表明：相比于原始晶种，球磨晶种诱导制备SAPO-34分子筛膜层更加致密。随着膜合成液中二乙胺含量增加，膜表面分子筛晶体逐渐由SAPO-11向SAPO-34转变，当二乙胺含量过高时，载体表面未形成SAPO-34膜。当合成液中铝源含量较低时，分子筛膜晶化不够完全，当铝源含量过高时，膜表面晶体粒径逐渐减小甚至难以成核，膜层厚度减薄，不易生成连续的膜层。随着晶化时间的增加，膜层厚度逐渐增加，膜表面趋于致密。当膜合成液摩尔组成为1.0Al₂O₃∶0.9P₂O₅∶0.6SiO₂∶2.0DEA∶100H₂O，晶化时间为36 h时，球磨晶种诱导制得的SAPO-34分子筛膜分离性能最佳，膜的CO₂渗透性为1.11×10^?6 mol·m^?2·s^?1·Pa^?1，CO₂/CH₄分离选择性达80。     

MFI型分子筛膜的制备及表征

采用无模板剂的二次生长合成方法,在-αA l2O3基膜上合成了MFI型分子筛膜,用XRD,SEM和气体渗透实验等方法进行表征,表明合成在-αA l2O3基膜的物质为MFI型分子筛。二次生长分子筛膜的正/异丁烷理想分离系数在298 K和473 K时分别为77和70,气体分离数据表明,2种分子筛膜对气体分离是由分子筛分占主导,同时分子筛膜完整无裂缺。不同温度,通过MFI分子筛膜渗透汽化分离质量分数分别为5%、50%和95%的乙醇/水的渗透通量和分离因子,结果表明渗透通量随温度的升高而升高,而分离因子随温度的升高却降低;渗透通量随乙醇质量分数的升高而降低,分离因子却随质量分数的升高而升高。     

管式支撑体内表面NaA分子筛膜的合成与表征

采用转动合成方式通过二次生长法在管式α-Al₂O₃支撑体内表面合成了NaA分子筛膜,采用X射线衍射仪（XRD）、场发射扫描式电子显微镜（FE-SEM）和渗透汽化分离技术对所合成的膜进行了系统表征。考察了合成釜转速对分子筛膜合成的影响,结果表明合成釜转速的提高有利于分子筛膜合成。在转速为4 r·min^-1时所合成NaA分子筛膜分离因子高达2370,渗透通量1.86 kg·h^-1·m^-2左右（乙醇/相似文献   

T型分子筛膜的制备及其对含酸乙腈-水的分离性能

石化医药行业会产生大量乙腈废液,通过无机分子筛膜分离技术进行回收可以创造可观的经济价值。然而,乙腈废液水含量较高,并且具有一定的酸性,目前应用比较广泛的NaA型分子筛膜不能在该体系下长期使用。使用自制的平均粒径为600 nm的T型分子筛作为晶种,采用真空涂敷法将晶种负载在α-Al₂O₃载体管表面,在150 ℃下水热晶化16 h制备出T型分子筛膜,并对其做膜性能评价实验。结果表明,自制的T型分子筛膜在进料流量为3.5 L/h、温度为100 ℃条件下对含有1%（质量分数）乙酸和10%水（质量分数）的乙腈混合溶液进行膜分离脱水实验,渗透通量为2.51 kg/（m ²·h）;在120 h长时间运行过程中,分离系数保持在2 250以上,T型分子筛膜性能基本保持不变。     

PEA-NaA /α-Al2OPEA-NaA /α-Al2O3复合支撑分子筛膜的微波水热合成

采用微波水热合成法在聚醚酰亚胺(PEI)-NaA分子筛/α-Al2O3复合载体表面合成了具有高选择性的致密NaA型分子筛膜,重点考察了微波辐射时间对成膜的影响。采用X射线衍射图谱(XRD)和扫描电子显微镜(SEM)对NaA型分子筛膜进行了表征。XRD结果表明,复合载体表面生成的膜中只有NaA分子筛的晶相;SEM结果表明,复合载体基膜表面覆盖了一层致密连续的NaA型分子筛膜。合成的NaA型分子筛膜在不同质量分数乙醇中的渗透汽化性能结果表明,渗透通量随乙醇质量分数增大而减小,分离因子则反之,当乙醇质量分数为95%时,渗透通量仅0.05 kg/(m2.h),而分离因子高达13 000。     

PEI-NaA/α-Al_2O_3复合支撑分子筛膜的微波水热合成

采用微波水热合成法在聚醚酰亚胺(PEI)-NaA分子筛/α-Al2O3复合载体表面合成了具有高选择性的致密NaA型分子筛膜,重点考察了微波辐射时间对成膜的影响。采用X射线衍射图谱(XRD)和扫描电子显微镜(SEM)对NaA型分子筛膜进行了表征。XRD结果表明,复合载体表面生成的膜中只有NaA分子筛的晶相;SEM结果表明,复合载体基膜表面覆盖了一层致密连续的NaA型分子筛膜。合成的NaA型分子筛膜在不同质量分数乙醇中的渗透汽化性能结果表明,渗透通量随乙醇质量分数增大而减小,分离因子则反之,当乙醇质量分数为95%时,渗透通量仅0.05 kg/(m2.h),而分离因子高达13 000。     

ZSM-5/NaY型复合分子筛膜的制备及其渗透汽化性能研究

采用水热合成法在n(SiO₂)∶n(Al₂O₃)∶n(Na₂O)∶n(H₂O)为25∶1∶22∶600的合成液体系中合成高性能的ZSM-5/NaY型复合分子筛膜,考察了陈化时间、合成液中水的摩尔分数、合成时间以及合成温度对膜的渗透汽化分离性能的影响,同时,考察了ZSM-5/NaY型复合分子筛膜的稳定性。利用SEM和XRD对膜的形态结构进行表征。结果表明,在合成液陈化18 h后,在105℃下晶化6 h,可成功制备出连续致密的ZSM-5/NaY型复合分子筛膜;在75℃下分离90%的异丙醇/水体系,渗透侧水质量分数可以达到99.15%以上,渗透通量保持在2.12 kg/(m²·h)以上,并且具有良好的重复性。     

有机硅烷改性ZSM-5/BPPO非对称膜制备及其渗透汽化性能

以硅烷改性ZSM-5分子筛为填充剂,采用沉浸凝胶相转化法制备了ZSM-5/BPPO非对称膜. 结果表明,分子筛在BPPO膜中分散均匀,填充分子筛后膜表面粗糙度增大、疏水性增强. 以低浓度乙醇-水体系为研究对象,考察了分子筛填充量、进料液浓度及进料液温度对ZSM-5/BPPO膜渗透汽化分离性能的影响. 结果表明,随乙醇浓度增大,ZSM-5/BPPO膜的分离因子减小,渗透通量增大;随进料液温度升高,ZSM-5/BPPO膜的分离因子及渗透通量均增大;在60℃、分子筛填充量为0.3%(w)时,ZSM-5/BPPO膜对5%(w)乙醇-水体系的分离因子高达18.49,渗透通量为529.69 g/(m2×h). ZSM-5/BPPO膜对不同醇-水体系的分离结果表明,醇类分子量越大,膜分离性能越好.     

Scale-up of NaA zeolite membranes onα-Al2O3 hollow fibers by a secondary growth method with vacuum seeding

NaA zeolite membranes were prepared by secondary growth method on the outer surface ofα-Al2O3 hollow fiber supports. Vacuum seeding method was used for planting zeolite seeds on the support surfaces. Hydrother-mal crystallization was then carried out in a synthesis solution with molar ratio of Al2O3:SiO2:Na2O:H2O=1:2:2:120 at 100 °C for 4 h. Effects of seeding conditions on preparation of hollow fiber NaA zeolite membranes were extensively investigated. Moreover, hollow fiber membrane modules with packing membrane areas of ca. 0.1 and 0.2 m2 were fabricated to separate ethanol/water mixture. It is found that the thickness of seed layer is obviously affected by seed suspension concentration, coating time and vacuum degree. Close-packing seed layer is required to obtain high-quality membranes. The optimized seeding conditions (seed suspension mass concentration of 0.5%–0.7%, coating time of 5 s and vacuum degree of 10 kPa) lead to dense NaA zeolite layer with a thickness of 6–8μm. Typically, an as-synthesized hollow fiber NaA zeolite membrane exhibits good pervaporation performance with a permeation flux of 7.02 kg·m?2·h?1 and separation factor N 10000 for sepa-ration of 90%(by mass) ethanol/water mixture at 75 °C. High reproducibility has been achieved for batch-scale production of hollow fiber NaA zeolite membranes by the hydrothermal synthesis approach.     

合成次数及硅铝比调控SAPO-34分子筛膜的乙醇脱水性能

SAPO-34分子筛膜因其独特的孔道结构和优异的稳定性被广大学者所青睐,目前的研究大多集中在催化、吸附和气体分离等方面,而关于其在液体分离中的研究鲜少报道。本文在Al₂O₃中空纤维支撑体表面分别一次和二次合成制备了SAPO-34分子筛膜,考察了四种不同硅铝比对SAPO-34分子筛膜结构形貌和性能的影响,并用于乙醇溶液的渗透汽化脱水,考察了操作温度、原料液中乙醇浓度以及分子筛合成次数对分离效果的影响。研究结果表明,硅铝比为0.5的二次合成的SAPO-34分子筛膜具有连续而致密的分离层和良好的渗透汽化分离性能,60℃下对乙醇（90%）-水（10%）的分离因子可以达到1170,渗透通量为0.9 kg/(m²·h)。     

Enhancement of NaA zeolite membrane properties through organic cation addition

Thin NaA zeolite membranes, with uniform and small crystals, were prepared on the tubular -Al₂O₃ support by adding a small amount of tetramethylammonium hydroxide (TMAOH) in the clear synthesis solution. The as-synthesized NaA zeolite membranes were characterized by XRD and SEM. The permeation properties of the membranes were evaluated by pervaporation and gas permeation. The effects of TMAOH amount on membrane formation and permeation properties were investigated. By addition of suitable amount of TMAOH in the clear synthesis solution, the crystals size of NaA zeolite could be remarkably reduced from about 10 μm to 3–4 μm, and the membrane thickness correspondingly reduced from about 16 μm to 5 μm. The thinner membrane prepared by adding TMAOH in the clear synthesis solution, with uniform and small crystal, displayed higher perm-selective properties than that without adding TMAOH. For the as-synthesized NaA zeolite membrane prepared with adding suitable amount of TMAOH (x = 1), the separation factor (water/isopropanol) was 4700 and the flux was 1.67 kg/(m² h), which were higher than that without adding TMAOH of 339 and 1.08 kg/(m² h), respectively. The ideal separation factor of H₂/N₂ was 6.60, higher than that without adding TMAOH of 3.41.     

On-stream modification of MFI zeolite membranes for enhancing hydrogen separation at high temperature

-Alumina-supported MFI zeolite membranes were modified by on-stream catalytic thermal cracking of methyldiethoxysilane (MDES) molecules inside the zeolitic channels during the separation of H₂/CO₂ gas mixture at 450 °C and atmospheric pressure. The MDES vapor was carried by the H₂/CO₂ feed gas and the effect of modification was monitored continuously through online analysis of the permeate stream. The modified membrane exhibited a significant increase in H₂ selectivity over CO₂ with a moderate decrease in H₂ permeance. At 450 °C, the modified MFI membrane obtained a H₂/CO₂ permselectivity of 17.5 with H₂ single gas permeance of 1.86 × 10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹ as compared to a permselectivity of 2.78 and permeance of 2.75 × 10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹ for the membrane before modification. The modified membrane also showed good performance and stability in separation of H₂/CO₂ gas mixture containing up to 28.4% water vapor at 450 °C and atmospheric pressure.     

二次水热合成法制备ZSM-5分子筛膜及其渗透汽化性能

采用二次水热合成法在管状多孔莫来石支撑体上制备高耐酸性ZSM-5分子筛膜,系统地研究分子筛晶种和合成溶胶中H₂O/SiO₂摩尔比率对ZSM-5分子筛膜生长与渗透汽化性能的影响,采用X射线衍射、冷场扫描电子显微镜和电子能谱等表征技术分别对制备的ZSM-5分子筛及其ZSM-5分子筛膜的结构、形貌和Si/Al比进行表征。针对分离75℃、90% HAc/H₂O的水溶液,最优化条件下制备的ZSM-5分子筛膜表现出优良的渗透汽化性能,渗透通量和分离因子分别为0.98kg/(m²·h)和890。此外,本研究所采用制备耐酸性ZSM-5分子筛膜的方法表现出良好的重现性,重复制备的12根ZSM-5分子筛膜在75℃下分离90% HAc/H₂O的水溶液时,平均通量和分离系数分别为（0.85±0.15）kg/(m²·h)和650±290。再者,ZSM-5分子筛膜在45～75℃的温度范围内分离50%～95% HAc/H₂O水溶液时都表现出优良的渗透汽化性能。     

Separation of gas and organic/water mixtures by MFI type zeolite membranes synthesized in a flow system

MFI type zeolite membranes were synthesized in a recirculating flow system at 95 °C where the synthesis solution was flown over the tubular α-alumina supports. The performance of the membranes for the separation of binary gas mixtures and alcohol/water liquid mixtures was investigated. A membrane synthesized by two consecutive synthesis steps had a separation selectivity of 15 and 11 for equimolar mixtures of n-C₄H₁₀/CH₄ and n-C₄H₁₀/N₂ at 200 °C, respectively. The membrane selectively permeated large n-C₄H₁₀ over small CH₄ and N₂, suggesting that the separation is essentially adsorption-based and the membrane has few nonselective intercrystalline pores. The selectivities in the pervaporation separation of 5% ethanol/95% water mixture were 43 and 23 with permeate fluxes of 0.2 and 1.9 kg/m² h at 25 and 85 °C, respectively. The separation performance of membranes showed that MFI type membranes prepared in a recirculating flow system can be used both in the separation of gas and liquid mixtures.     

Growth process and short chain alcohol separation performance of fluoride-containing NaY zeolite membrane

Growth process of the NaY zeolite membranes was investigated by fluoride-containing precursor synthesis gel.Compared with the fluoride-free precursor synthesis gel,the irregular NaY zeolite crystals were dissolved into amorphous by the fluoride-containing precursor synthesis gel initially,the amorphous contained the Y-type zeolite characteristic bands by the IR characterization.The fine square NaY zeolite crystals arose from the amorphous,which were accumulated and gradually grew into a dense NaY zeolite layer on the support surface after 6.5 h.Because the excessive NaY zeolites were dissolved by the strong alkaline and fluoride-containing precursor synthesis gel,there was plenty of amorphous on NaY zeolites layer for prolonging the crystallization time.The assynthesized NaY zeolite membranes had a good separation performance and repeatability for separation of 10 wt%methanol(MeOH)/methyl methacrylate(MMA) mixture by pervaporation,the flux and separation factor were(1.27 ± 0.07) kg·M~(-2)·h~(-1) and(4900 ± 1500) at 323 K,respectively.Besides,the NaY zeolite membranes were applied to separate the other short chain alcohol from the various alcohol/organic ester and alcohol/organic ether mixtures,the NaY zeolite membranes showed high short chain alcohol perm-selectivity.