有机改性凹凸棒土对腐殖酸的吸附性能研究

合成了十六烷基三甲基氯化铵(CTAC)改性的凹凸棒土吸附剂,并研究了其对水中腐殖酸的吸附行为。通过FTIR、TG对改性前后凹凸棒土进行表征。结果表明,十六烷基三甲基氯化铵成功结合到凹凸棒土表面,结合到凹凸棒土表面的量为9.78%。在25℃时,腐殖酸在吸附剂上吸附行为符合Freundlich方程,吸附动力学符合拟二级动力学方程,初始浓度为54.60~200.20mg/L时,ATP-CTAC对腐殖酸的最大吸附量为253mg/g;温度对吸附行为影响不大;改性后的凹凸棒土对腐殖酸的吸附随pH的增大而降低;改性后的凹凸棒土显著地提高了对腐殖酸的吸附量。     

氨基硅烷修饰的SBA-15用于CO2的吸附

以3-丙胺基三乙氧基硅烷(APTES)为硅烷化试剂,分别采用后修饰法和一步嫁接法将其嫁接到SBA-15的孔内,形成了功能化的介孔分子筛用于CO2吸附.利用X射线衍射和氮气物理吸附等方法考察了嫁接前后SBA-15的孔结构变化,用静态吸附天平考察了不同温度和不同分压下CO2的吸附行为.实验结果表明,一步嫁接法比后修饰法更有利于实现APTES在SBA-15上的嫁接.与传统的活性炭吸附剂相比,该种介孔分子筛更有利于较低分压下CO2的吸附脱除.     

葡萄糖还原法制备CuCl/NaY吸附剂及其CO吸附和CO/H2分离性能

以NaY分子筛为载体,CuCl2为铜源,加入还原剂葡萄糖,在温和条件下制备CuCl/NaY吸附剂,通过变压吸附考察了该吸附剂对CO的吸附性能及CO/H2的分离性能。运用X射线衍射（XRD）、X射线光电子能谱（XPS）及程序升温还原（TPR）对吸附剂进行表征,结果表明采用葡萄糖还原法制备CuCl/NaY吸附剂,其制备条件温和,吸附剂表面的亚铜含量高,对CO的吸附及CO/H2的分离性能优越且稳定性好。     

CeO2纳米管负载Pd纳米颗粒催化CO低温氧化

高效负载型Pd催化剂的制备及其在CO低温氧化反应中的机理探究是近年来的研究热点.普遍认为,Pd催化剂上的CO氧化反应遵循Langmuir-Hinshelwood机理:首先,CO吸附于Pd物种表面;然后,CO与催化剂表面的晶格氧发生反应转化为CO2,反应发生在金属-载体界面.另外,高分散的Pd活性物种有利于CO氧化反应.同时载体的形貌、暴露的晶面、氧空位以及孔结构等都是影响催化剂活性的重要因素.CeO2纳米管具有独特的管状特征和较高的比表面积,是一种潜在的CO低温氧化催化剂载体.本文利用乙醇还原法,以CeO2纳米管为载体,制备不同Pd含量的Pd/CeO2-nanotube纳米催化剂,并利用N2吸附脱附、X射线衍射(XRD)、透射电子显微镜(TEM)、CO程序升温脱附(CO-TPD)、X射线光电子能谱(XPS)等表征手段,探索纳米催化剂载体形貌对CO氧化反应活性的影响.氮气吸脱附结果表明,Pd/CeO2-nanotube具有较高的比表面积(58.0 m2/g),且存在介孔结构.XRD表征发现,Pd/CeO2-nanotube的衍射峰对应立方萤石型结构的CeO2的(111),(200),(220),(311)等品面.TEM结果表明,Pd/CeO2-nanotube具有均匀的纳米管形貌,其外径为40-60 nm,Pd纳米颗粒均匀分散在其表面.CO-TPD结果表明,Pd/CeO2-nanotube在1 10℃附近具有很强的脱附峰,在370℃和600℃附近分别具有较宽和较弱的脱附峰,这表明该催化剂具有较多的吸附位,且具有很强的CO吸附能力;CO不可逆吸附量计算结果表明,该催化剂上的Pd具有很高的表面分散度(23.3％),Pd颗粒尺寸为7.3 nm.XPS表征显示,Pd以pd2+的形式分散于CeO2纳米管的表面,且与载体发生相互作用,存在Pd-O-Ce键;同时该催化剂表面存在丰富的Ce3+,为反应提供更多的氧空位.0.9Pd/CeO2-nanotube纳米催化剂在CO氧化反应中表现出优良的活性,能在100℃实现CO的完全转化;通过计算发现,该催化剂具有较高的TOF值(0.63 s-1),由Arrhenius 曲线可得到该催化剂的活化能为26.5 kJ/mol.综上可见:金属活性组分的尺寸和分散度、载体的结构特征、CO吸附能力以及金属-载体间的相互作用决定催化剂的性能.Pd/CeO2-nanotube的高比表面积有利于Pd的分散;其强CO吸附能力有利于CO吸附于Pd物种表面;催化剂表面丰富的Ce3+能为反应提供更多的氧空位,Pd-O-Ce键的形成能增强金属-载体间的相互作用,有利于CO与催化剂表面品格氧发生反应.同时催化剂介孔结构有利于反应气体和产物气体的吸附和扩散,因此,Pd/CeO2-nanotube纳米催化剂在CO氧化反应中表现出优良的活性.     

CeO_2纳米管负载Pd纳米颗粒催化CO低温氧化（英文）

高效负载型Pd催化剂的制备及其在CO低温氧化反应中的机理探究是近年来的研究热点.普遍认为,Pd催化剂上的CO氧化反应遵循Langmuir-Hinshelwood机理:首先,CO吸附于Pd物种表面;然后,CO与催化剂表面的晶格氧发生反应转化为CO_2,反应发生在金属-载体界面.另外,高分散的Pd活性物种有利于CO氧化反应.同时载体的形貌、暴露的晶面、氧空位以及孔结构等都是影响催化剂活性的重要因素.CeO_2纳米管具有独特的管状特征和较高的比表面积,是一种潜在的CO低温氧化催化剂载体.本文利用乙醇还原法,以CeO_2纳米管为载体,制备不同Pd含量的Pd/CeO_2-nanotube纳米催化剂,并利用N_2吸附脱附、X射线衍射(XRD)、透射电子显微镜(TEM)、CO程序升温脱附(CO-TPD)、X射线光电子能谱(XPS)等表征手段,探索纳米催化剂载体形貌对CO氧化反应活性的影响.氮气吸脱附结果表明,Pd/CeO_2-nanotube具有较高的比表面积(58.0 m~2/g),且存在介孔结构.XRD表征发现,Pd/CeO_2-nanotube的衍射峰对应立方萤石型结构的CeO_2的(111),(200),(220),(311)等晶面.TEM结果表明,Pd/CeO_2-nanotube具有均匀的纳米管形貌,其外径为40-60 nm,Pd纳米颗粒均匀分散在其表面.CO-TPD结果表明,Pd/CeO_2-nanotube在110℃附近具有很强的脱附峰,在370℃和600℃附近分别具有较宽和较弱的脱附峰,这表明该催化剂具有较多的吸附位,且具有很强的CO吸附能力;CO不可逆吸附量计算结果表明,该催化剂上的Pd具有很高的表面分散度(23.3%),Pd颗粒尺寸为7.3 nm.XPS表征显示,Pd以Pd~(2+)的形式分散于CeO_2纳米管的表面,且与载体发生相互作用,存在Pd-O-Ce键;同时该催化剂表面存在丰富的Ce~(3+),为反应提供更多的氧空位.0.9Pd/CeO_2-nanotube纳米催化剂在CO氧化反应中表现出优良的活性,能在100℃实现CO的完全转化;通过计算发现,该催化剂具有较高的TOF值(0.63s~(-1)),由Arrhenius曲线可得到该催化剂的活化能为26.5 kJ/mol.综上可见:金属活性组分的尺寸和分散度、载体的结构特征、CO吸附能力以及金属-载体间的相互作用决定催化剂的性能Pd/CeO_2-nanotube的高比表面积有利于Pd的分散;其强CO吸附能力有利于CO吸附于Pd物种表面;催化剂表面丰富的Ce~(3+)能为反应提供更多的氧空位,Pd-O-Ce键的形成能增强金属-载体间的相互作用,有利于CO与催化剂表面晶格氧发生反应.同时催化剂介孔结构有利于反应气体和产物气体的吸附和扩散,因此,Pd/CeO_2-nanotube纳米催化剂在CO氧化反应中表现出优良的活性.     

凹凸棒土应用于重金属离子吸附剂的研究

以新型无机矿物材料凹凸棒土作为吸附剂处理废水中的重金属离子。通过扫描电镜、红外光谱及等温吸附-脱附曲线对凹凸棒土进行了表征,并阐述了凹凸棒土对重金属离子的可能吸附机理。在室温下,分别将0.05 g凹凸棒土投入初始质量浓度为500 mg.L-1的Cu(Ⅱ)、Cd(Ⅱ)、Ni(Ⅱ)和Cr(Ⅵ)的溶液中,凹凸棒土对上述离子的平衡吸附量分别高达99、56、117、198 mg.g-1。结果表明,用凹凸棒土吸附废水中的重金属离子切实可行、经济有效。     

胍改性凹凸棒土对甲基橙的吸附

采用十六烷基胍改性凹凸棒土对甲基橙废水进行脱色处理,考察了吸附时间、吸附剂用量和染料浓度等因素对脱色效果的影响。 结果表明,十六烷基胍改性凹凸棒土对甲基橙废水具有很好的脱色性能,其对甲基橙废水脱色率达98%以上,与原凹凸棒土相比有显著提高。 平衡吸附量qe与平衡浓度ρe之间关系符合Langmuir等温吸附方程。 吸附热值小于40 kJ/mol,表观表现为物理吸附。     

介孔吸附剂表面分形分析

用自溶液中吸附的方法测定了介孔硅胶和活性炭的分形维数D.结果表明:(1)硅胶自四氯化碳或环已烷中吸附脂肪醇、酮、酯和含氧芳香化合物,活性炭自水中吸附芳香化合物的等温线均服从Langmuir方程.用极限吸附量n_m^s和表观分子面积σ_a,根据方程log n_m^s=-(D)/(2)log σ_a+常数,可计算出分维D. n_m^s和σ_a是根据Langmuir方程和吸附剂比表面数据求出的.(2)用液相吸附法求出的介孔硅胶的分维值与由气体吸附法求出的值相同,并均近于2.当表面曲率半径大于吸附分子大小时,吸附剂表面可是低分维的.(3)由液相吸附法得到的介孔活性炭的分维也近似为2.可能的解释是,活化作用改变了原始炭的微孔结构,使其成为介孔和大孔.介孔活性炭也可是低分维表面.     

新型空气取水复合吸附剂在沙漠气候下的吸附性能实验研究

提出了一种由粗孔球形硅胶和氯化钙组成的新型复合吸附剂SiO2穢H2O穣CaCl2。介绍了这种吸附剂的配制方法,分析了它吸附湿空气中水蒸气的原理。模拟我国塔克拉玛干沙漠地区高温干燥的气候特点:在空气温度恒为35℃、相对湿度为30%的条件下,对不同CaCl2含量的复合吸附剂和粗孔球形硅胶、细孔球形硅胶、分子筛13X进行了吸附解吸对比实验。实验表明,这种复合吸附剂的平衡吸附量we最大可达0.263kg H2O/kg干吸附剂,是粗孔球形硅胶的5.6倍、细孔球形硅胶的3.4倍、分子筛13X的1.17倍。通过对比分析它们的吸附解吸速度曲线表明,这种复合吸附剂的吸附量大、吸附速度快、解吸速度快。这种复合吸附剂在解吸温度80℃,可解吸97%以上的吸附量。因此,可用太阳能加热解吸,是一种理想的取水用吸附剂。     

Cu-Zn-Zr/SBA-15介孔催化剂的制备及CO2加氢合成甲醇的催化性能

以具有骨架结构的SBA-15介孔分子筛为载体,采用浸渍法合成了具有高比表面积、不同金属氧化物含量的Cu-Zn-Zr介孔催化剂CZZx/SBA-15(x=0.3,0.4,0.5,0.6).采用N2吸附-脱附(BET)、X射线衍射(XRD)、H2程序升温还原(H2-TPR)、CO2吸附(CO2-TPD)和透射电子显微镜(TEM)等手段对样品进行了表征.在固定床反应器上评价了其CO2加氢合成甲醇的催化性能.实验结果表明,CZZx/SBA-15催化剂具有介孔结构,负载的Cu O,Zn O和Zr O2能够很好地分散在表面,并且负载氧化物晶粒尺寸不同.催化剂的铜比表面积SCu与甲醇催化活性呈近似线性关系,其中CZZ0.4/SBA-15催化剂表现出最大甲醇选择性(54.32%),与CZZ相比,甲醇选择性增加24.85%.随着金属氧化物负载量的增大,催化剂比表面积和SCu明显减小,甲醇选择性与收率也相应减小,负载型CZZx/SBA-15催化剂表面结构对CO2加氢合成甲醇反应活性起关键作用.     

Zeolites modified by CuCl for separating CO from gas mixtures containing CO2

Although zeolites such as NaY and 13X adsorb CO₂ much more than CO, the adsorption amount of CO₂ and CO can be reversed if the zeolites are modified with CuCl. When zeolite NaY or 13X is mixed with CuCl and heated, high CO adsorption selectivity and capacity can be obtained. Isotherms show the adsorbents have CO capacity much higher than CO₂. This is because CuCl has dispersed onto the surface of the zeolites to form a monolayer after the heat treatment and the monolayer dispersed CuCl can provide tremendous Cu(I) to selective adsorb CO and inhibit the CO₂ adsorption. The monolayer dispersion of CuCl is confirmed by XRD and EXAFS studies. The loading of CuCl on the zeolites has a threshold below which the CuCl forms monolayer after heating and crystalline phase of CuCl can not be detected by XRD. An adsorbent of CuCl/NaY with CuCl content closed to the monolayer capacity shows very high CO selective adsorbability for CO₂, N₂, H₂ and CH₄. At temperature higher than room temperature, the adsorbent has even better CO selectivity for CO₂. Using the adsorbent, a single-stage 4 beds PSA process, working at 70°C and 0.4 MPa to 0.013 MPa, can obtain CO product with purity >99.5% and yield >85%.     

CuCl改性Y型分子筛的CO吸附性能研究

利用自发单层分散原理,讨论了在NaY,NH4Y,CuY分子筛上CuCl分散改性情况,并对所得到的改性分子筛进行了CO吸附性能研究。实验结果表明,在低CuCl担载量时,CuCl可在这三种载体表面达到原子水平分散,其分散容量分别为0.58g/gNaY,0.68g/gNH4Y和0.41g/gCuY。由于CO与Cu^+可生配位化合物,经CuCl改性的Y型分子筛对CO显示出较高吸附性能。其中,0.6gCuCl/gNH4Y分子筛表现出最高的CO吸附容量,在室温、常压下可达123mL/gNH4Y.     

The synthesis of mesoporous aluminosilicate using microcline for adsorption of mercury(II)

An economical mesoporous aluminosilicate was synthesized with microcline as starting material and the precursor 13X zeolite as seed for crystal structure on mesoporous walls. In this method, a mixture of microcline and Na2CO3 with a molar ratio of 1:1.05 was first calcined at 1093 K for 2.5 h. The calcined materials were mixed with 35 ml C16TMABr aqueous solution (containing 8.2 g C16TMABr) and the precursors of 13X zeolite, resulting in mesoporous aluminosilicate after crystallization of the solution at 378 K for 48 h and calcination of the powder at 823 K for 5 h. The as-synthesized sample has a uniform pore diameter distribution centered at 3.7 nm. The as-synthesized sample had BET surface area of 725 m2/g and BJH mean pore diameter of 3.7 nm. The FT-IR results revealed that the building units of 13X zeolite were inserted into the pore walls of the as-synthesized sample. The adsorption ratio of mercury(II) onto the as-synthesized adsorbent was about 95%. The adsorption process was found to be spontaneous and can be explained by particle diffusion and chemical ion-exchange mechanisms. The equilibrium concentration of mercury(II) using the as-synthesized sample as the adsorbent was under 1 microg/L, making the concentration of mercury meet the limit for drinking water in China as recommended by the World Health Organization.     

Hydrothermal stability of pelletized zeolite 13X for energy storage applications

Three samples of pelletized zeolite Na-13X from different industrial suppliers were hydrothermally treated in an open system for up to 3500 adsorption/desorption cycles. Before and after this aging procedure, the samples have been characterized by water uptake measurements, X-ray powder diffraction (XRD), Hg-porosimetry, N₂- and CO₂-adsorption and small-angle X-ray scattering (SAXS). Large differences in the degree of degradation were found between the different materials: The adsorbent with the best performance maintains 79% of its original water uptake capacity after 3500 cycles, whereas this value is reduced to 65% after only 1600 cycles in case of the most unstable sample. For all materials, the residual water adsorption capacity was found to be higher than it was to expect from XRD data. In addition to structural changes of the zeolite cages, Hg-porosimetry and SAXS reveal a modification of the sample morphology in the meso- and macropore range. CO₂ adsorption experiments evidence that as a result of the aging process mass transfer kinetics are slowed down significantly. These findings indicate that the influence of hydrothermal treatment on the water adsorption performance not only depends on the crystal structure of the actual adsorbent, but is indeed a result of a complex interplay with the system of larger pores. The crucial role of the binder material is underlined by the fact that the most stable sample was produced by a so-called binder-free method.     

Effects of Cetyltrimethylammonium Bromide and Heptane on the Surface Properties and CO2 Adsorption of Zeolite NaX

Zeolite X was synthesized by the gelation method for use as a CO₂ adsorbent. The zeolite was prepared from a sodium silicate solution and Al(OH )₃ as silicon and aluminum source, respectively. The effects of cetyltrimethylammonium bromide (CTAB ) and heptane addition on surface properties, morphology, and CO₂ adsorption capacities were investigated. The CO₂ adsorption capacity of the synthesized zeolite with the addition of CTAB and heptane increased as demonstrated by the higher CO₂ uptake (3.00 mmol/g), which was due to the higher surface area and pore volume. Interaction between CTAB micelles and sodium cations with aluminosilicate anions led to an increase in the nucleation rate and smaller crystalline sizes. The addition of heptane resulted in higher positively charged CTAB micelles and improved the affinity between the micelles and aluminosilicate anions.     

CO2 capture by polyethylenimine-modified fibrous adsorbent

This work focuses on developing a novel adsorbent for CO2 capture, by coating polyethylenimine (PEI) on glass fiber matrix and using epichlorohydrin (ECH) as cross-linking agent. The physicochemical properties of the fibrous adsorbent were characterized. The CO2 adsorption capacity was evaluated. Factors that affect the adsorption capacity of the fibrous adsorbent were studied. The experimental results show that this fibrous PEI adsorbent exhibits a much higher adsorption capacity for CO2 compared with another PEI fiber prepared in our previous work, which employed epoxy resin as the cross-linking agent. A CO2 adsorption capacity as high as 4.12 mmol CO2/g of adsorbent was obtained for this fibrous PEI adsorbent at 30 degrees C, equal to 13.56 mmol CO2/g of PEI, with a PEI/ECH ratio of 20:1. The adsorbent can be completely regenerated at 120 degrees C.     

13X分子筛去除水中重金属离子的研究

以人工合成的13X型分子筛为吸附剂,研究了水中Pb2 、Cd2 和Cu2 在分子筛上的吸附行为,讨论了Pb2 、Cd2 和Cu2 共存条件下的竞争吸附,并考察了水中存在的Na 、Mg2 、Ca2 等离子对分子筛吸附去除重金属的影响.实验结果表明,13X分子筛对Pb2 、Cd2 和Cu2 3种离子的吸附符合Langmuir模型,最大吸附量分别为2.47mmol/L、2.0mmol/L和1.78mmol/L.在竞争吸附条件下,13X分子筛对3种重金属离子的选择性依次为pb2 ＞Cd2 ＞Cu2 .水中存在的Na 、Mg2 、Ca2 等对分子筛吸附重金属效率有一定的影响,其中Ca2 对Cu2 在分子筛上的去除影响最为显著.     

Anomalous adsorption of nitrogen and argon in silver exchanged zeolite A

A new adsorbent based on zeolite AgA having N2 adsorption capacity of 22.3 cc g(-1) at 101.3 kPa and N2/O2 selectivity in the range of 5 to 14.6 at 303 K, the highest known so far for any zeolite A type of adsorbent, is reported; furthermore, this adsorbent also shows argon selectivity over oxygen.     

Effect of chemical modification on carbon dioxide adsorption property of mesoporous silica

Three adsorbents were prepared by different modification methods, which were grafting silica gel with (3-aminopropyl) trimethoxysilane, grafting silica gel with acrylamide polymer, and impregnating silica gel with acrylamide polymer, respectively. The characterization of materials was carried out by N(2) adsorption experiments, Fourier transform infrared spectroscopy, scanning electron microscopy, thermo-gravimetric analysis, and elemental analyses. The results showed that the amine group was successfully loaded on all three modified adsorbents; among that, the polymer-modified silica adsorbents had higher amine content and larger surface area than the aminopropyl-grafted silica adsorbent and displayed higher thermal stability than the other polymer-modified silica materials previously reported. The CO(2) adsorption/desorption experiments performed at 25°C by TGA-DSC method showed that the highest CO(2) adsorption capacity (0.98 mmol/g) was observed for the polymer-impregnated silica adsorbent. CO(2) adsorbed on all samples was completely desorbed by purging with inert gas at 60°C except for the aminopropyl-grafted silica material, which showed the highest enthalpy of CO(2) adsorption.