炭分子筛膜研究的新进展

炭分子筛膜是一种用于气体分离的高效，节能的新型材料，具有好的气体分离选择性，高的热和化学稳定性，近年来得到国内外广泛的重视和发展，本文从制备炭分子筛膜的原料，制备工艺及其在气体分离应用等方面综合了国内外近年来炭分子筛膜的研究进展，并指出了目前存在的问题。     

热缩聚煤沥青压型制备分子筛炭膜（Ⅱ）──液相碳沉积法制备分子筛炭膜

以一定浓度的酚醛树脂溶液对炭膜基板进行碳沉积处理，考察碳沉积条件对所制备的分子筛炭膜气体分离性能的影响。实验结果表明，较好的碳沉积条件为：碳沉积液浓度为６０％，浸渍时间为１２０ｍｉｎ，碳沉积次数为三次，热处理温度为７００℃。此膜对ＣＯ_２和Ｈ_２有很好的分离作用，两者的透过速率分别为１０~（－６）和１０~（－５）ｃｍ~３（ＳＴＰ）／ｃｍ~２·ｓ·ｃｍＨｇ数量级，分离系数可达１７．８。初步研究结果表明，此膜对ＣＯ_２／Ｏ２、ＣＯ_２／Ｎ_２和ＣＯ_２／ＣＨ_４也有一定的分离能力，分离系数在６．０左右。     

热缩聚煤沥青压型制备分子筛炭膜(Ⅲ)─—表面涂层法制备分子筛炭膜

表面涂层法是制备分子筛炭膜的有效方法、以酚醛树脂的乙醇溶液作为涂层液对炭膜基板进行处理，制得适合H2/CO2分离的分子筛炭膜。结果表明，适宜的涂层液浓度为30％（Vol），涂层处理四次制得分子筛炭膜。H2与CO2的渗透速率分别为2．66×10－5和2．22×10－6cm3（STP）／cm2·s．cmHg，二者的分离系数可达到11．7。     

热缩聚煤沥青压型制备分子筛炭膜：炭膜基板的制备（Ⅰ）

以一种热缩聚煤沥青为原料制务炭膜基板，考察了预氧化、炭化条件对炭膜基板的气体透过性和选择性的影响。结果表明：炭膜基板对ＣＯ_２／Ｈ_２及Ｎ_２／Ｈ_２有一定的分离能力，分离系数在３．０左右，气体的透过速率在１０~（－３）ｃｍ~３（ＳＴＰ）／（ｃｍ~２·ｓ·ｃｍＨｇ）数量级，同时，还考察了炭化温度对炭膜基板的机械强度、失重和收缩程度的影响。     

热缩聚煤沥青压型制备分子筛炭膜 (IV)活化法在炭膜制备上的应用

在破沉积法和表面涂层法制备分子筛炭膜的基础上，在氧化气氛下对所制得的分子筛炭膜进行适当活化，可以大大提高分子筛炭膜对H_2／CO_2的分离性能．实验结果表明，在750℃通入CO_2／N_2的混合气（体积比为1：4），对前述两种方法制得的分子筛炭膜活化30min，H_2／CO_2的分离系数由活化前的11．5上升到27．8，H_2的渗透速率略有提高，CO_2稍有下降．与其它几种膜材料H_2／CO_2的分离性能相比，活化制得分子筛炭膜有很大的优越性．     

气体分离用管状炭分子筛膜

以无机陶瓷管为支撑体、热塑性酚醛树脂为原料,经高温炭化制备了炭分子筛膜。用低温N2吸附的方法测定了炭分子筛膜的比表面积,用扫描电子显微镜对膜的形貌和厚度进行了表征。考察了膜的气体透过率以及气体的理想选择性随温度的变化关系:H2、CO2、O2、N2和CH4的透过率随温度的升高而增大;理想选择性α(H2/N2)、α(CO2/N2)、α(CO2/CH4)随温度的升高而减小,而α(O2/N2)随温度的升高先增大后减小,在90℃左右气体选择性达到最大。最后由阿累尼乌斯公式计算了气体透过炭分子筛膜的活化能,进一步说明气体透过机理为活化扩散。     

聚糠醇基炭膜对氢气/低碳烃分离的研究

本实验考察了聚糠醇基炭膜对H2与低碳烃类如CH4、C2H4和C3H6分离过程中的分离性能.结果表明随着气体分子的动力学直径的增大(H2为2.89A,CH4为3.8A,C2H4为3.9A,C3H6为4.5A,1A=10-10),气体的渗透速率逐渐降低,而H2/CH4、H2/C2H4和H2/C3H6的分离系数却逐渐增大,且都远大于Knudsen扩散的理论值.这说明在分离过程中,分子筛分机理在起主要作用,利用此机理可以将H2从低碳烃中分离出来.     

沥青基炭膜的制备研究

以煤沥青为原料经热处理、预氧化和炭化等工艺制备了炭膜,研究了制备条件对炭膜性能的影响及其气体分离的机理。结果表明,制备炭膜的最佳条件是热处理温度３７０℃,时间１２０ｍｉｎ;预氧化温度２２０℃,时间１２０ｍｉｎ,炭化温度９００℃。炭膜的气体分离机理是努森扩散,在高压差时伴有粘性流。     

炭膜气体分离性能研究

以酚醛树脂为原料制备了炭支撑膜和炭－炭复合膜，研究了其气体分离性能。结果表明：炭支撑膜分离气体和机理包括努森扩散和粘性流；采用浸涂－干燥－炭化的工艺制备的炭－炭复合膜对Ｈ２／ＣＯ２具有较好的分离性能，Ｈ２／ＣＯ２分离系数达５．６，大于理想努森扩散的分离系数３．７。但在高压差时复合膜上ＣＯ２的表面扩散增强，使Ｈ２／ＣＯ２分离系数下降。     

Synthesis of silicalite-poly(furfuryl alcohol) composite membranes for oxygen enrichment from air

ABSTRACT: Silicalite-poly(furfuryl alcohol) [PFA] composite membranes were prepared by solution casting of silicalite-furfuryl alcohol [FA] suspension on a porous polysulfone substrate and subsequent in situ polymerization of FA. X-ray diffraction, nitrogen sorption, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to characterize silicalite nanocrystals and silicalite-PFA composite membranes. The silicalite-PFA composite membrane with 20 wt.% silicalite loading exhibits good oxygen/nitrogen selectivity (4.15) and high oxygen permeability (1,132.6 Barrers) at 50°C. Silicalite-PFA composite membranes are promising for the production of oxygen-enriched air for various applications.     

Preparation of C/CMS composite membranes derived from Poly(furfuryl alcohol) polymerized by iodine catalyst

C/CMS composite membranes derived from poly(furfuryl alcohol) (PFA) polymerized by iodine catalyst were prepared. Gas separation performance was investigated by molecular probe study with pure gases (H₂, CO₂, O₂, N₂, and CH₄) at 25 °C. The pyrolysis behaviour of PFA was studied by TG and DTG. The surface morphology of C/CMS composite membranes was observed by SEM and HRTEM. The results show a C/CMS composite membrane with uniform and defect-free thin top layer can be prepared by the PFA liquid in only one coating step. The C/CMS composite membranes have excellent gas separation properties for the gas pairs such as H₂/N₂, CO₂/N₂, O₂/N₂ and CO₂/CH₄, the permselectivities for above gas pairs in same sequence were 124.72, 12.74, 9.12 and 15.91 respectively. Compared to carbon membranes derived from PFA polymerized by acid catalyst, the carbon membranes obtained from PFA polymerized by iodine catalyst have slightly lower permselectivity, but higher permeance.     

Effects of polymerization conditions on the properties of poly(furfuryl alcohol) composite membranes

Poly(furfuryl alcohol) (PFA) composite membranes were prepared by polymerization of furfuryl alcohol (FA) using sulfuric acid (H₂SO₄) as the catalyst and polysulfone ultrafiltration membrane as the substrate. The membrane samples were characterized by ATR‐IR, TGA, SEM, and gas permeation technique. The effects of synthesis conditions including the FA/H₂SO₄ molar ratio, polymerization temperature, and the type of solvent on the chemical structure, surface morphology, and gas permeation properties of PFA composite membranes were studied. Our results showed that the suitable synthesis conditions for the preparation of PFA composite membranes with smooth surfaces and uniform structure include (1) FA/H₂SO₄ molar ratios: 74‐300, (2) polymerization temperatures: 80–100°C, and (3) solvents: ethanol and acetone. The PFA composite membrane prepared with a FA/H₂SO₄ molar ratio of 250, a polymerization temperature of 80°C and ethanol as the solvent exhibited the highest H₂/N₂ ideal selectivity ( $ {\rm{\alpha }}_{{\rm{H}}_{\rm{2}} {\rm{/N}}_{\rm{2}} } = 24.9 $ ), and a H₂ permeability of 206 Barrers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of furfuryl alcohol addition on the cure of furfuryl alcohol resin used in the glassy carbon manufacture

Glassy carbon can be manufactured practically without pores, named Monolithic Vitreous Carbon (MVC) or presenting up to 98% in transport pore volume, foam form, denominated Reticulated Vitreous Carbon (RVC). The glassy carbon processing is affected by some processing parameters, among them it can be cited the resin viscosity. The present work involves the optimization of RVC manufacture by monitoring the polyurethane (PU) foam impregnation with furfuryl alcohol resin with different viscosity values, which were obtained by dilution of the resin with different amounts of furfuryl alcohol. The resin samples used in the PU impregnation were characterized by thermal and rheological analyses. These results were correlated with scanning electron microscopy observations and compression test results of the impregnated polyurethane foam. The results show that the rheological behavior of the resin has significant influence on the polymerization step, affecting the homogeneity of impregnated foam and, consequently, its final properties, mainly the mechanical one. The impregnated foam prepared with the furfuryl alcohol resin diluted with 10% of furfuryl alcohol (η = 11.4 Pa s) showed higher compression values (0.26 MPa). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

糠醛在Pd-Cu膜反应器中催化加氢合成糠醇

以糠醛催化加氢合成糠醇作为模型反应,采用共沉淀法制备的Cu/MgO-K₂O作为催化剂,考察了Pd-Cu膜反应器的加氢性能.膜反应器由双套管组成,采用分别进料的方式操作.即糠醛气化后由载气带入中心膜管的催化床层,而氢气则进入管壳层通过Pd-Cu合金膜渗透到反应区.在不同条件下分别进行糠醛催化加氢反应,考察了糠醛转化率、产品糠醇选择性和收率,并与传统的共进料填充床反应器进行比较.研究结果显示,膜反应器比传统的填充床反应器具有产品收率高、选择性好和副产物少的特点.此外,本文结合催化剂的组成、结构和表面形貌的表征对催化剂的催化活性和失活行为进行了讨论.     

Preparation of colloidal microporous carbon spheres from furfuryl alcohol

Colloidal microporous carbon (MC) spheres with an average size of 260 nm-1.5 μm were prepared by carbonization of “nonstick” poly(furfuryl alcohol) (PFA) spheres, which were synthesized by a two-step polymerization of furfuryl alcohol (FA) involving slow polymerization (1st step) and sphere formation (2nd step). The high dispersibility of the MC spheres was simultaneously realized by removing surface functional groups of the PFA spheres with the evaporation-induced concentrated sulfuric acid (2nd step). By varying the temperature of slow polymerization, the spheres with different sizes could be simply synthesized. The studies also showed that surfactant and sulfuric acid treatment played an important role in the synthesis of colloidal PFA (MC) spheres.     

糠醇生产中废弃物的循环回用新工艺

将糠醛液相加氢生产糠醇产生的废渣置于真空干燥箱中 ,在较低的负压状态下保持 1 30℃的温度 ,蒸馏回收废渣中的有机物 ,返回糠醇精制车间获得合格的糠醇与糠醛产品 ;剩余的固体废弃物与纯碱混合 ,在反射炉中焙烧 ,浸取获得铬酸钠水溶液 ;最后剩下的粗氧化铜溶于硝酸得到硝酸铜溶液 ;将铬酸钠溶液、硝酸铜溶液按一定比例混合 ,加入氨水搅拌 ,分离出的沉淀经传统方法焙烧活化、造粒制得新催化剂 ,回用于糠醛液相加氢生产糠醇。铬组分和铜组分的回收率均在 90 %以上     

Structures, physicochemical properties and oxygen reduction activities of carbons derived from ferrocene-poly(furfuryl alcohol) mixtures

The structure, physicochemical properties and oxygen reduction abilities of carbons prepared by the carbonization of mixtures of ferrocene and poly(furfuryl alcohol) were studied. X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) studies revealed that the carbons thus prepared consisted of two components; amorphous and turbostratic shell-like components. The fraction, f _sharp, obtained by the analysis of the (002) peak in XRD was found to be a parameter that represented the degree of formation of the shell-like components. The formation of the shell-like components induced an increase in the mesopore volumes. Electrical conductivity increased exponentially with f _sharp, which indicated that the conduction process was governed by a percolation process of the conductive shell-like components. The amount of CO-desorption by O₂-TPD technique showed a maximum desorption at f _sharp=0.3, and the further development in the sharp component led to a decrease in the CO-desorption. Mössbauer spectroscopy technique revealed the presence of α-Fe, γ-Fe, Fe_1-x O and Fe₃C in the prepared carbons, which were soluble species to acids. The oxygen reduction activity was studied in a oxygen saturated sulfuric acid solution by rotating disk electrode voltammetry. The oxygen reduction potential varied with f _sharp; initially it increased by f _sharp=0.3 and then it decreased at higher f _sharp values. This behavior was similar to that of CO-desorption, which meant the presence of an adequate degree of the development of the shell-like structure for maximizing oxygen adsorption. Removal of the surface metal component from the carbons by acid-washing resulted in no decrease in the oxygen reduction activities of the carbons. The nature of the active sites on the carbon materials is discussed.     

近期糠醛催化加氢制糠醇催化剂研究热点

综述了近10年来催化剂在糠醛加氢制糠醇反应中应用的研究成果及催化剂的研究热点,展望了催化剂的发展方向。