PDMS/PEI复合膜对FCC汽油的脱硫性能(Ⅲ)Ag_2O载体促进传递

以聚醚酰亚胺(PEI)超滤膜为支撑层,聚二甲基硅氧烷(PDMS)为复合层,制备PDMS/1)EI渗透汽化催化裂化(FCC)汽油脱硫复合膜.实验选择Ag2O作为促进添加剂,利用可逆化学作用强化物质在膜内的传递过程,使膜分离兼具高通量和高选择性的特点,突破Robeson上限的限制,解决通量和选择性两者的矛盾.通过傅立叶红外光谱仪(FTIR-ATR)对PDMS/PEI复合膜表面进行结构分析,对比Ag2O填充前后官能团的变化.通过扫描电子显微镜(SEM)分析复合膜表面的形态.考察了添加剂的填充比例及料液温度等对渗透汽化脱硫性能的影响,讨论了固定载体促进传递的机理.     

PVA/PVP/Ag+共混膜渗透汽化分离苯/环己烷混合物

PV/PVP/Ag+膜在苯、环己烷混合物中的溶胀实验发现,膜优先吸附苯,且膜中Ag+含量越大,膜在苯中的溶胀率越大,在环己烷中溶胀率越小.渗透汽化测试结果也表明,PVA/PVP/Ag+膜对苯/环己烷的分离性能明显优于PVA/PVP膜.而且,随着膜中Ag+含量的增加,膜的渗透通量J增大;分离因子先增大后减小,当膜中w(聚合物)∶w(AgNO3)＝1∶1时,分离因子α达到最大值,为47.5,通量为7.8 g/(m2*h)(进料的质量分数为10%,20 ℃).而对膜进行交联改性后,分离因子可进一步提高,但通量下降.     

SiO_2/PDMS复合膜的制备及其渗透汽化性能研究

以PVDF为支撑层,制备了疏水性二氧化硅(SiO2)填充聚二甲基硅氧烷(SiO2/PDMS)复合膜,通过扫描电镜、接触角测试和热失重分析对复合膜微观形貌、表面疏水性和热性能进行了表征。研究发现,SiO2的加入,可以有效提高PDMS膜的表面疏水性和热稳定性。疏水性SiO2与PDMS基体结合紧密,当SiO2填充低于3%(wt,质量分数,下同)时,纳米粒子在PDMS基体中分散均匀,未发现明显团聚。将复合膜用于渗透汽化乙醇/水体系的分离,发现SiO2的加入,在填充量为1.5%时,SiO2/PDMS复合膜综合分离性能优于纯PDMS膜,尤其是操作温度升高时,与纯PDMS膜相比,复合膜分离因子下降幅度较小,而渗透通量增加较快,表现出较好的综合分离性能。     

炭黑填充PDMS复合膜的渗透蒸发性能

通过炭黑填充改性的方法,制备了一种新型聚二甲基硅氧烷(PDM S)优先脱醇渗透蒸发复合分离膜,考察了炭黑含量和料液浓度与分离膜分离性能之间的关系。结果表明,利用该复合膜可以有效分离乙醇/水混合物中的乙醇,在料液浓度为13.73%时,复合膜的选择性与空白膜相当,而渗透通量可由空白膜的70.74 g/m2.h提高到127.32 g/m2.h。     

PDMS/PEI复合膜对FCC汽油的脱硫性能(Ⅲ)放大实验研究

渗透汽化是一种新型高效的膜分离技术,尤其在汽油深度脱硫技术方面具有独特优势.以PEI超滤膜为支撑层,PDMS为复合层,制备PDMS/PEI渗透汽化FCC汽油脱硫复合膜.通过傅立叶红外光谱仪(FTIR-ATR)对其进行了结构分析,考察了交联前后官能团的变化.通过扫描电子显微镜(SEM)分析了复合膜表面和断面的形态.在以前的工作基础上,将制备的PDMS/PEI复合膜应用于放大实验,在不同的料液体系中考察膜的渗透汽化性能.结果表明,对于正庚烷/噻吩体系,在80℃下连续操作28 h,料液硫含量从200 ng/μL降到10 ng/μL,其平均通量为0.78 kg/(m2.h),平均富硫因子为7.6.对于汽油加噻吩体系,平均渗透通量为0.06 kg/(m2.h),平均富硫因子为4.8.该成果为膜法汽油脱硫深入研究和工业应用奠定了基础.     

高通量ZSM-5填充硅橡胶复合膜渗透汽化性能研究

以硅铝比为360的ZSM-5型沸石对聚二甲基硅氧烷(PDMS)进行填充,以聚偏氟乙烯(PVSF)为支撑层,制备了ZSM-5填充PDMS/PVDF复合膜,用于渗透汽化乙醇/水混合物的分离.研究了沸石填充量、操作温度、进料液浓度对乙醇/水的渗透汽化分离性能的影响,发现该复合膜较文献报道中的沸石填充膜,其渗透通量有了明显的提高,在50℃沸石填充量为40%时,对乙醇的分离因子为11.7,其渗透通量达到749.8 g/(m2·h).随着操作温度的升高或料液中乙醇浓度升高,渗透通量增大,分离因子下降.     

交联PEG/PVDF复合膜分离环己醇/环己烷混合物的渗透汽化研究

以PVDF超滤膜为支撑层,PEG为分离层,制备了交联PEG/PVDF复合膜,用于环己醇/环己烷的渗透汽化分离,此复合膜优先脱除环己醇.通过傅立叶红外光谱仪对PEG/PVDF复合膜表面进行结构分析,证实交联后PEG复合膜在1 104.63 cm-1有典型的饱和醚键C—O—C的特征吸收峰;从扫描电镜图看出,PEG在PVDF多孔膜表面形成均匀致密的分离层.将PEG/PVDF复合膜应用于环己醇/环己烷体系,考察了料液浓度和操作温度对膜分离性能的影响以及膜的溶胀性和长时间操作下的稳定性.实验结果表明:随操作温度或料液中环己醇浓度的增加膜的分离因子逐渐减小而渗透通量增大.膜在环己醇中的溶胀度小于6%.在环己醇浓度为2.5%,操作温度80℃,72 h长时间操作下PEG/PVDF复合膜的渗透通量为0.46 kg/(m2.h),分离因子为7.30.     

HTBN/PAN复合膜分离正庚烷/乙硫醚/正丁硫醇混合物的渗透汽化研究

制备了一系列HTBN/PAN复合膜,用于渗透汽化脱除正庚烷/乙硫醚/正丁硫醇混合物体系中的乙硫醚和正丁硫醇,此复合膜优先脱除乙硫醚和正丁硫醇.通过扫描电子显微镜(SEM)对复合膜的表面和断面进行表征.考察了复合膜在正庚烷和正庚烷/乙硫醚/正丁硫醇混合物体系中的溶胀性以及复合膜在长时间操作下的稳定性,研究了膜液浓度对膜结构和膜分离性能的影响以及操作温度对膜分离性能的影响.结果表明:交联的HTBN在PAN多孔膜表面形成均匀致密的分离层;膜在正庚烷及正庚烷/乙硫醚/正丁硫醇混合物体系中的溶胀度均小于5%;操作温度对于膜的富硫因子影响不大,而渗透通量则随着温度的升高而增大;对于正庚烷/乙硫醚/正丁硫醇混合物分离体系(含硫量为160μg/g),在80℃,50 h长时间操作下,HTBN/PAN复合膜的渗透通量为0.23 kg/(m2.h),富硫因子为2.85.     

SiO2/胶原水解物-聚乙烯醇杂化复合膜的制备与性能

以正硅酸乙酯(TEOS)为前驱体,采用溶胶-凝胶法原位制备了SiO2/胶原水解物-聚乙烯醇杂化复合膜(SiO2/CH-PVA杂化膜).通过溶胀、热重(TG)、红外光谱(FTIR)、扫描电镜(SEM)和拉伸实验,考察了SiO2对杂化膜性能的影响.结果表明,SiO2的引入减小了膜的平衡溶胀度,减缓了膜的溶胀速率,有效地抑制...     

PDMS有机硅膜的制备及其渗透汽化脱硫的研究

以聚二甲基硅氧烷(PDMS)为原料,正庚烷为溶剂,正硅酸乙酯为交联剂,二月桂酸二丁基锡为催化剂,聚丙烯腈为基膜,制得聚二甲基硅氧烷／聚丙烯腈复合膜．采用红外谱图和扫描电镜对膜的物理及化学结构进行了分析和表征．所得膜用于辛烷中噻吩的脱除,研究了硫化温度、料液温度等因素对膜性能的影响．结果表明:在同一料液温度下,硫化温度越高,交联硫化越完全,膜对辛烷中噻吩的选择性越高,渗透通量下降;在相同硫化温度下,料液温度升高,渗透通量增加,膜对噻吩的选择性下降．对硫化温度50℃的膜,在料液温度为30℃时,膜的渗透通量370 g／(m2·h),膜对噻吩的选择系数为5．212．     

VLE data for CO2-CF2Cl2, N2-CO2, N2-CF2Cl2 and N2-CO2-CF2Cl

Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state.     

Thermal diffusion in binary mixtures H2-CCl2F2 and H2-CHClF2

Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·10⁴ N/m² and at a freon concentration of 0.25–0.8.     

Preparation of ZrO2-CeO2 and HfO2-CeO2 nanopowders

We prepared weakly agglomerated powders of ZrO₂-CeO₂ and HfO₂-CeO₂ solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO₂.     

Comparison of the Electronic Structures of La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2

First-principles cluster calculations are reported of the local electronic structure of the three compounds: La₂CuO₄, Sr₂CuO₂Cl₂, and Sr₂CuO₂F₂. The copper ${\text{3d}}_{x^2 - y^2 } $ and the planar oxygen 2p _σ atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the ${\text{3}}d_{3z^2 - r^2 } $ atomic orbital lowered significantly in energy for chlorine and fluorine apical positions.     

Radial GRIN glasses in Li2O-Na2O-Al2O3-TiO2-SiO2 systems

A series of GRIN glass rods have been developed in Li2O-Na2O-Al2O3-TiO2-SiO2 systems. Negative radial refractive index profiles were generated by exchanging Na+ for Li+ ions in these glass rods. It has been observed that TiO2 plays a vital role in increase in the profile depth and maximum change in the refractive index because of its ambivalent nature. Change in the refractive index can be further increased by increasing the concentration of exchanging cation in the base glass.     

Elastic and Electronic Properties of Superconducting CaPd 2 As 2 and SrPd 2 As 2 vs. Non-superconducting BaPd 2 As 2

The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr₂Si₂-type phases CaPd₂As₂ and SrPd₂As₂ in comparison with the non-superconducting CeMg₂Si₂-type phase BaPd₂As₂. Besides, the same properties were compared for CeMg₂Si₂- and ThCr₂Si₂-type polymorphs of BaPd₂As₂. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd₂As₂] with decisive contributions of Pd 4d states. The values of N(E _F) increase in the sequence: CaPd₂As₂ < SrPd₂As₂ < BaPd₂As₂, i.e. in the reverse sequence relative to the transition temperatures T _C. Thus, the change in T _C cannot be explained by the electronic factor, i.e. by the simple correlation T _C～N(E _F). Most likely the decrease in T _C in the sequence CaPd₂As₂ → SrPd₂As₂ and the absence of a superconducting transition in BaPd₂As₂ are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism.     

Si_2N_2O-Al_2O_3-La_2O_3和Si_2N_2O-Al_2O_3-CaO系统的亚固相关系

本文给出了 Si_2N_2O-Al_2O_3-La_2O_3和 Si_2N_2O-Al_2O_3-CaO 系统的亚固相图。实验结果表明:在 Si_2N_2O-Al_2O_3-CaO 系统中有一个未知结构的新化合物 CaO·Si_2N_2O,在3CaO·Si_2N_2O 和3CaO·Al_2O_3两化合物之间形成连续立方固溶体。而 Si_2N_2O-Al_2O_3-La_2O_3系统中则没有发现新化合物。在两个系统的富 Si_2N_2O区,过量的 Si_2N_2O 与 La_2O_3和 CaO 分别反应形成 Si_3N_4与 La_(10)[SiO_4]_(?)N_2(H-相)(和 CaSiO_3。所研究的这两个三元系统中,分别形成了如下几个四元相容性区。在 Si_2N_2O-Al_2O_3-La_2O_3系统内有:H-Si_3N_4-La_2O_3·Si_2N_2O-La_2O_3·Al_2O_3;H-Si_3N_4-La_2O_3·Al_2O_3-La_2O_3·11 Al_2O_3;H-Si_3N_4-La_2O_3·11 Al_2O_3-Al_2O_3;H-Si_3N_4-Al_2O_3-O′s.s;H-Si_3N_4-O′s.s-Si_2N_2O在 Si_2N_2O-Al_2O_3-CaO 系统内有:Si_3N_4-CaSiO_3-CaO·Si_2N_2O-3CaO·Al_2O_3;Si_3N_3-CaSiO_3-3CaO·Al_2O_3-2CaO·Al_2O_3·SiO_(?);Si_(?)N_(?)-CaSiO_3-2CaO·Al_2O_3·SiO_2-Al_2O_3;Si_3N_4-CaSiO_3-Al_2O_(?)-O′s.s;Si_3N_4-CaSiO_3-O′s.s-Si_(?)N_(?)O