KOH活化制备多孔碳纤维及其CO_2吸附性能研究

采用活性碳纤维(ACFs)为原料,以KOH为化学活化剂,在ACFs:KOH的质量比为4∶1时,研究了不同活化温度下制备的多孔碳纤维的结构性能。用N2吸附仪测定多孔碳纤维的比表面积、孔容及孔径分布,通过变压吸附法研究了多孔碳纤维对CO_2的吸附性能,探讨了不同活化温度下对多孔碳纤维的孔隙结构及CO_2吸附量的影响。实验结果表明,活化温度对多孔碳材料的比表面积、孔径分布及孔容有良好的调控作用。当活化温度为900℃时,获得的多孔碳纤维有最大的比表面积(1702 m2/g)、最大孔容(0.902 cm3/g)及最大的CO_2吸附量(138 mg/g)。     

淀粉基多孔碳材料的制备及其吸附CO_2/CH_4性能

以淀粉为原料,使用水热法将其碳化后用活化剂KOH对其活化,制备了淀粉基多孔碳材料,并对其进行结构表征和CO_2/CH_4的吸附性能测试,计算吸附热以及材料对CO_2/CH_4的吸附选择性,讨论了碳材料结构对其吸附性能的影响。结果表明:在制备过程中,随着活化剂KOH用量比例的增大,所制得的材料其比表面积和孔容增大,其孔径分布也就越宽。所制得的碳材料其比表面积可达2972 m2·g-1。这些淀粉基多孔碳材料对水蒸气的吸附等温线呈现出Ⅳ类等温线。所制备材料对CO_2吸附容量主要取决于其孔径小于0.8 nm的累积孔容(Vd0.8 nm)。材料的超微孔的孔容越大,其对CO_2吸附容量也越大。所制备的C-KOH-1材料在101325 Pa和298 K条件下,对CO_2的吸附量达到4.2 mmol·g-1,其对CO_2的吸附热明显高于其对CH_4吸附热,其对CO_2/CH_4吸附选择性为3.7~4.26,同时本文通过对材料的水蒸气吸附等温线进行测试,结果表明所得材料主要表现为中等憎水性,这对材料在实际工况的应用奠定了基础。     

固载离子液体聚合物的二氧化碳吸附行为研究

采用溶液聚合法,将1-烯丙基三丁基膦双三氟甲烷磺酰亚胺盐离子液体聚合物固载在空白硅胶上,并对硅胶固载离子液体聚合物进行了FTIR红外光谱和CO2吸附性能检测。研究了温度、压力和孔径分布等对CO2吸附选择性的影响,并计算了其CO2吸附热力学参数。结果表明:相比于空白硅胶,采用溶液聚合法制备的固载离子液体聚合物具有发达的孔结构,且这种差异在孔径分布为0.5~0.6nm时表现更加明显;制备的吸附剂在常温高压条件下表现出良好的吸附性能,且对CO2/N2具有较高选择性;该固载离子液体聚合物的吸附为放热反应,且为自发的物理吸附过程。     

酸浸析对多孔玻璃性能的影响

以Na2O·B2O3·SiO2为玻璃制备系统,采用原子力显微镜、扫描电镜和氮气吸附仪分析了酸处理工艺制度对多孔玻璃孔容、平均孔径和孔径分布的影响,经过热处理和酸腐蚀后多孔玻璃的孔容可达0.8845cm3·g-1、平均孔径达76.55nm;相同H+离子浓度的盐酸和硫酸酸处理得到的多孔玻璃,其比表面积、孔容和平均孔径相差不大;用浓度为0.1mol·L-1的硫酸处理后多孔玻璃的平均孔径比浓度为1mol·L-1的略大,并对酸处理参数对多孔玻璃性质的影响进行了分析和讨论,为制备较大孔径的多孔玻璃介质奠定了基础.     

种子溶胀法制备多孔离子液体聚合物

采用种子溶胀法合成了两种多孔离子液体聚合物--1-烯丙基-3-甲基咪唑四氟硼酸盐与丙烯腈单体配比为70:3哄聚物和聚苄乙基三甲基铵四氟硼酸盐,并对离子液体聚合物样品进行了FTIB、SEM和CO2吸附表征.研究了溶胀剂种类和用量对聚合物产率的影响.测定了CO2在多孔聚合物吸附剂上的吸附平衡数据.结果表明:对于多孔咪唑类聚...     

离子液体对CO_2捕集及电转化的研究

离子液体具有蒸汽压低、稳定性高及溶解性能强等一系列优良特性,使其成为新型CO_2捕获剂的理想选择。本文采用微波合成法,制备了咪唑氨基酸、咪唑四氟硼酸盐和咪唑六氟磷酸盐功能型离子液体,考察吸附CO_2性能,并以咪唑氨基酸离子液体为电解质,在外加电压条件下将CO_2转化为甲醇。实验结果表明:咪唑甘氨酸离子液体对CO_2吸附效果较好,最大吸附量为每摩尔离子液吸收0.24mol的CO_2,电转化甲醇的转化率在64.1%~77.4%。     

硅胶固载咪唑离子液体的制备及二氧化碳吸附性能

分别采用浸渍法和溶胶-凝胶法将1-丁基-3-甲基咪唑四氟硼酸离子液体固载在A型和B型硅胶上,并对硅胶固载离子液体样品进行了FTIR、SEM、元素分析和CO2吸附表征。研究了负载方法、离子液体负载量、孔径分布等对CO2吸附性能的影响。结果表明:采用溶胶-凝胶法固载的离子液体负载量远远大于浸渍法的;制备的吸附剂均具有发达的微孔结构,且在0.4～0.8 nm有连续的分布;浸渍法制备的硅胶固载离子液体的CO2吸附性能较优,在273 K、0.1 MPa时,A型硅胶浸渍离子液体和乙醇混合液样品的CO2吸附量达1.92%。     

粉煤灰基地质聚合物制备及其对Cu~(2+)的吸附性能

为探讨地质聚合物的制备条件对其孔隙结构和吸附性能的影响,以粉煤灰为原料、水玻璃为碱激发剂,分别改变水玻璃模数、液固比、养护温度、养护时间制备地质聚合物,改变溶液的pH值、地质聚合物加入量、吸附时间、Cu~(2+)初始浓度进行Cu~(2+)吸附试验,采用N_2吸附法测量粉煤灰基地质聚合物的孔隙结构,并采用分光光度法分析粉煤灰基地质聚合物对Cu~(2+)的吸附效果。结果表明:不同条件下制备的地质聚合物,孔径主要分布在1~3 nm和70~110 nm;当液固比为0.9、养护温度80℃、养护时间3 d、水玻璃模数为1.4时,制备的地质聚合物比表面积最大,Cu~(2+)吸附量达46.3 mg/g;液固比为1.1时,地质聚合物中1.5~6.0 nm孔含量最高,Cu~(2+)吸附量为43.1 mg/g,养护温度对吸附效果的影响不大;随着养护时间的增加,地质聚合物对Cu~(2+)吸附量增加;地质聚合物对Cu~(2+)的单位吸附量与地质聚合物的比表面积有关,比表面积越大,吸附量越大。在Cu~(2+)溶液pH4的情况下,地质聚合物对铜离子的单位吸附量随p H值的降低而减少,其吸附等温线符合Freundlich吸附方程。     

搅拌对高内相比乳液法制备多孔聚合物的影响

研究了不同的搅拌速率和搅拌时间下,采用高内相比乳液法制备的多孔聚合物密度、孔径和吸附性能,用扫描电镜和N2吸附仪对多孔聚合物的形态和结构进行了表征。结果表明:搅拌速率和搅拌时间主要影响高内相比乳液的形成和稳定性,对多孔聚合物的密度影响不大,增加搅拌时间,增加了多孔聚合物的比表面积和孔容,从而增加了对水和甲苯的吸附,由于多孔聚合物的亲油性,使之对甲苯的吸附率明显高于水的吸附率。     

碱木质素接枝聚丙烯腈多孔材料的性能表征

在碱木质素与丙烯腈单体接枝共聚过程中分别添加无机模板剂硝酸铵、硝酸铁和氯化钠制备碱木质素接枝聚丙烯腈 (AL-g-PAN)多孔材料。利用SEM、XRD对AL-g-PAN的结构进行表征;以FT-IR对材料的官能团进行分析;以TG-DTG、DSC对AL-g-PAN的热性能进行测定。以硝酸铅为目标污染物,考察了多孔AL-g-PAN对Pb²⁺的吸附性能。结果表明:在25 ℃、Pb²⁺初始浓度为308.5 mg/L、pH值为5的条件下,以硝酸铁为模板剂制备的多孔AL-g-PAN对Pb²⁺平衡吸附量为145.83 mg/g,Pb²⁺去除率为94.5%;该多孔材料成孔均匀、平均孔径在0.913 nm、孔径主要分布在2 nm以下的微孔区域;相同条件下,无模板剂的碱木质素接枝聚丙烯腈对Pb²⁺平衡吸附量仅为28.06 mg/g,其去除率为18.2%。多孔AL-g-PAN的热稳定性较碱木质素明显增强。     

固载离子液体聚合物的制备及其二氧化碳吸附性能

分别采用溶液聚合法和表面引发反向原子转移自由基聚合法(ATRP),在硅胶表面接枝离子液体聚合物,并对其进行了FTIR、TG和SEM表征。研究了固载离子液体聚合物样品的CO2吸附性能和CO2/N2的选择性能,探讨了CO2在固载离子液体聚合物上的吸附热力学和动力学行为。结果表明:由ATRP法制备的固载离子液体聚合物,其接枝量远大于溶液聚合法;而溶液聚合法制备的样品具有较发达的孔结构,在273 K、0.1 MPa时,样品的CO2吸附量达4.54%(1.03 mmol/g);固载离子液体聚合物较空白硅胶具有更优的CO2/N2选择性,且循环使用性良好;CO2在固载离子液体聚合物上的吸附为物理吸附;与离子液体聚合物相比,CO2在固载离子液体聚合物中的扩散效率更高。     

Charakterisierung von vernetzten Polymeren, 9a. Verfolgung der Nachvernetzung von Poly(styrol-co-divinylbenzol) zu feinporigen Adsorberpolymeren

The post-crosslinking of chloromethylated poly(styrene-co-divinylbenzene) to highly crosslinked, porous adsorbent polymers has been studied over a wide range of reaction temperature (50-80°C) and reaction time (up to 24.5 h). The crosslinked materials were characterized by nitrogen adsorption/desorption, mercury porosimetry, determination of the chlorine content, swelling measurements, pyrolysis gas chromatography, and Fourier transform infrared spectroscopy. Surface area, pore size distribution, pore volume, chlorine content, swelling degree, selected peak ratios in the pyrograms and in the FTIR spectrograms are shown to be clear functions of the post-crosslinking time. Therefore the post-crosslinking process can be monitored by physical as well as by chemical characterization methods. Moreover, information on the chemical homogeneity or inhomogeneity of the chloromethylated copolymers and the porous adsorbent polymers can be derived from the swelling and pyrolysis gas chromatographic results. Application of different solvents in the swelling experiments enables the construction of swelling diagrams. Based on these swelling diagrams, the anomalous swelling behaviour of adsorbent polymers during the post-crosslinking can be explained. The surface area and pore volume strongly increase with progressing post-crosslinking, and well-defined correlations between sample texture, pyrolysis and FTIR data are found. In general, changes of physical properties can be attributed to the chemical modification of the material due to the post-crosslinking.     

Correlation between the porous structure of polystyrene and its discolouring ability

Porous polystyrene was prepared according to the following methods by variation of the production parameters: (A) Method based on the suspension polymerization using a nonsolvent of the polymer. (B) Method based on the dissolution of polystyrene in a solvent and then precipitation using a nonsolvent of the polymer. The molecular weight of the polymer, its structure using Hg-porosimetry, and the microscopic pattern of the polymer grains were determined. The ability of the produced polystyrene to discolour aqueous solutions of different dyes (mainly methylene blue) was also examined. From the correlation between porous structure and discolouring ability in comparison with corresponding discolouring examination of other adsorptive agents (activated carbon) the importance of the following parameters was found out and evaluated: (a) total value of pore volume or pore volume distribution, (b) intermediate part of pore distribution 10000 – 100 Å for the adsorption of the given dyes, (c) shape of pores, which are different in method A and B (the comparison of produced polystyrene by different production parameters should be done only by independent methods and not between A and B method). It also resulted that it is necessary to introduce appropriate groups into the molecules of the porous polystyrene in order to increase the adsorption rate of an ionic or a polar substance. In conclusion, by appropriate choice of the production parameters of porous polystyrene a product with the desired characteristics of porosity could be produced.     

功能型离子液体的合成表征及CO2吸收性能

合成了两种传统型离子液体［bmim］BF₄和［emim］BF₄及含有胺基和羟基的功能型离子液体［NH₂P-mim］Br、［NH₂-e-mim］BF₄、［OH-e-mim］Br,并对合成的离子液体进行IR和¹H NMR表征。常温常压条件下,对所合成的离子液体开展CO₂吸收性能实验,发现胺基改性离子液体［NH₂P-mim］Br、［NH₂-e-mim］BF₄和羟基改性离子液体［OH-e-mim］Br的CO₂饱和吸收量分别是常规离子液体的3～9倍和1～2倍,且含有乙基官能团的离子液体吸收平衡时间普遍较短。最终探讨了温度、CO₂分压等对功能型离子液体吸收CO₂过程的影响。     

CO2 sorption capacity of porous poly(ionic liquid)s

Porous poly(ionic liquid)s based on copolymer of 1-allyl-3-methyimidazolium tetrafluoroborate and acrylonitrile with 70:30 monomer ratio were prepared and characterized for CO₂ sorption. The well-developed pore structure are formed in all the poly(ionic liquid)s and the pore size distribution(PSD) mainly concentrates in 0.4 ~ 0.8 nm. The effects of different pore-forming agents and their amount on the porous structure and CO₂ sorption were also discussed. For example, porous poly(ionic liquid) treated with n-heptane as the pore-forming agent and the amount of n-heptane 16 mL has the highest CO₂ sorption capacity of 1.43 wt % at 273 K and 0.101 MPa.     

Bi-/multi-modal pore formation of PLGA/hydroxyapatite composite scaffolds by heterogeneous nucleation in supercritical CO2 foaming

Scaffolds with multimodal pore structure are essential to cells differentiation and proliferation in bone tissue engineering.Bi-/multi-modal porous PLGA/hydroxyapatite composite scaffolds were prepared by supercritical CO_2 foaming in which hydroxyapatite acted as heterogeneous nucleation agent.Bimodal porous scaffolds were prepared under certain conditions,i.e.hydroxyapatite addition of 5%,depressurization rate of 0.3 MPa·min~(-1),soaking temperature of 55℃,and pressure of 9 MPa.And scaffolds presented specific structure of small pores(122 μm±66 μm)in the cellular walls of large pores(552μm±127μm).Furthermore,multimodal porous PLGA scaffolds with micro-pores(37 μm±11 μm)were obtained at low soaking pressure of 7.5 MPa.The interconnected porosity of scaffolds ranged from(52.53±2.69)% to(83.08±2.42)%by adjusting depressurization rate,while compression modulus satisfied the requirement of bone tissue engineering.Solvent-free CO_2 foaming method is promising to fabricate bi-/multi-modal porous scaffolds in one step,and bioactive particles for osteogenesis could serve as nucleation agents.     

H2, CO, N2, O2和CH4在碳膜中的扩散

Diffusion of pure H2, CO, N2,O2 and CH4 gases through nanoporous carbon membrane is investigated by carrying out non-equilibrium molecular dynamics （NEMD） simulations. The flux, transport diffusivity and activation energy for the pure gases diffusing through carbon membranes with various pore widths were investigated. The simulation results reveal that transport diffusivity increases with temperature and pore width, and its values have a magnitude of 10^-7 m^2·s^-1 for pore widths of about 0.80 to 1.21 nm at 273 to 300 K. The activation energies for the gases diffusion through the membrane with various pore widths are about 1-5 kJ·mol^-1, The results of transport diffusivities are comparable with that of Rao and Sircar （J. Membr. Sci., 1996）, indicating the NEMD simulation method is a good tool for predicting the transport diffusivities for gases in porous materials, which is always difficult to be accurately measured by experiments.     

磷酸活化法制备半纤维素基颗粒活性炭

以半纤维素的主要模型物木聚糖为原料,在不添加其他粘结剂的条件下,采用磷酸活化法制备半纤维素基颗粒活性炭。讨论了浸渍比和炭活化工艺对活性炭吸附性能和孔隙结构的影响。研究结果表明:浸渍比的增加,有利于颗粒活性炭的比表面积、亚甲基蓝吸附值、强度、总孔容积和中孔容积的提高。随着炭活化温度的升高,颗粒活性炭的碘吸附值、亚甲基蓝吸附值、比表面积、总孔容积和微孔容积呈下降的趋势,强度呈上升趋势。N₂吸附-脱附等温线和孔径分析表明,颗粒活性炭具有发达的微孔结构,炭活化温度的升高不利于孔隙结构的发达。     

离子液体自模板合成多孔碳氮材料及其对二氧化碳的吸附

以多种氰基离子液体为前驱体，采用高温碳化法直接制备多孔碳氮材料，系统考察了离子液体前驱体阳离子结构、阴离子种类及合成条件等因素对碳化材料比表面积、氮元素含量及氮种类的影响，并研究其对CO2的吸附性能。结果表明，阴离子在聚合过程中起模板剂的作用。合成材料主要呈介孔结构，比表面积最高达732.6 m2/g，氮含量最高为9.9wt%，在温度25℃、压力1.8 MPa条件下，CO2的吸附量最高达20.9wt%。多孔碳氮材料经180℃真空加热后可完全脱附再生，再生稳定性良好。     

B2O3改性Na2CO3催化剂用于甲醇脱氢制无水甲醛

以B₂O₃为助催化剂,采用研磨混合法改性Na₂CO₃催化剂,在固定床反应器中催化甲醇脱氢制备无水甲醛,考察催化剂的组成和反应条件等对催化反应的影响,采用XRD、TG-DTG、N₂吸附-脱附、SEM和CO₂-TPD等对催化剂进行表征。结果表明,以B₂O₃为助催化剂采用机械研磨混合法改性的Na₂CO₃催化剂,增加了催化剂的比表面积,在(10～30) nm增加了大量的孔道,平均孔径达18.44 nm,比表面积为1.65 m²·g^-1,且B₂O₃分布均匀,改性后的催化剂碱性降低,在催化甲醇脱氢制备无水甲醛的反应中,催化活性明显高于Na₂CO₃催化剂,表明B₂O₃改性Na₂CO₃催化剂能提高甲醇转化率和甲醛选择性。在B₂O₃/Na₂CO₃催化剂中B₂O₃质量分数为30%、甲醇进料质量分数为26%、反应温度为650 ℃和甲醇重时空速为2.94 h^-1条件下,甲醇转化率达59.97%,甲醛选择性达83.28%。