SO2 absorption of the CO2- laser emission measured by the photoacoustic technique

Spectra of coincidence of SO₂ IR absorption with CO₂-laser emission at pressure of 50,100 and 450 Torr were recorded by the use of a photoacoustic detection method in the whole range of CO₂-laser emission. The spectra show that SO₂ absorbs many CO₂-laser lines in the range 1084–1071 cm⁻¹ with the strongest absorption at 1082.29cm⁻¹, laser line R(26). The intensities of all absorptions rise with increasing pressure, but some absorptions change their relative intensity with respect to one another. In addition, the fine structure of line spectra, characteristic of lower pressure samples, disappear as pressure is increased.     

Photoacoustic study of CO2-laser coincidences with absorption of some organic solvent vapours

Detection of specific molecules in the atmosphere is motivated by the need for monitoring the emission of industrial pollutants. CO₂-laser photoacoustic (PA) spectroscopy was used here to obtain coincidence spectra of the vapours of three organic solvents: trichloroethylene (TCE), benzene, and dioxan. Spectra of coincidences were obtained as a function of total pressure, adding dry air to the vapour of the solvents up to 1000 mbar.A narrow cavity photoacoustic cell with window acoustic buffers was built for improved sensitivity, and is reported here.The vapour molecules studied do have some significant absorption in the CO₂-laser region, or close to it, but that fact does not necessarily lead to usable coincidences with the narrow laser lines. The results reveal several prominent coincidences that can be used for practical purposes, especially in the case of trichloroethylene.     

Buffer gas effect on laser photoacoustic spectra of methyl chloride

Spectra of coincidence of CH₃C1 IR absorption with CO₂-laser emission were recorded by a photoacoustic detection method in the whole range of CO₂-laser emission. The samples were neat gas and mixtures with argon, at several pressures (10 to 600Torr) so that pressure effects could be observed. The results show that argon affects absorption of CO₂-laser emission quite differently from neat chloromethane, both regarding the most prominent coincidences and background absorption.     

Li2ZrO3材料吸收CO2性能的进一步研究

用不同结构的ZrO₂合成了一系列在高温下吸收CO₂的Li₂ZrO₃材料，并详细的研究了反应物质的物理和化学性质对生成物吸收CO₂性能的影响。采用SEM、XRD以及TG分析法分别进行了材料结构及其吸收CO₂性能的表征，并使用XPS法测定了材料表面的元素组成。实验结果表明，使用不同结构的ZrO₂合成的Li₂ZrO₃，其吸收CO₂的性能明显的不同。用ZrO₂(t)(四方)合成的Li₂ZrO₃吸收CO₂的速度快，在500 ℃下，20% CO₂（80%空气）的气氛中保持3h，其吸收量可达25（±0.6）%（wt），而以ZrO₂(m)(单斜)为原料制备的Li₂ZrO₃在上述吸收条件下重量仅增加9（±0.6）%（wt）。此外，实验结果还表明化学元素的掺杂对用ZrO₂(m)合成的Li₂ZrO₃的CO₂吸收速度及吸收容量影响较大。     

乙二胺改性轻金属铝-金属有机骨架材料用于CO2/CH4分离

胺类分子在CO₂的捕获中可以起到选择性提升的作用,本文选择小尺寸的乙二胺分子对具有不饱和金属位点的轻金属铝基金属有机骨架（Al-MOFs）材料MIL-100Al进行改性,利用XRD、N₂吸附和FT-IR等对改性材料的结构进行表征,测试了不同浓度的乙二胺改性的MIL-100Al对CO₂和CH₄吸附性能。结果表明,与原始的MIL-100Al材料相比,改性后的材料对CO₂吸附量有明显提高,CH₄的吸附量却降低,从而进一步提高了材料的CO₂/CH₄吸附选择性,提升了吸附分离的效果。     

乙二胺改性轻金属铝-金属有机骨架材料用于CO_2/CH_4分离

胺类分子在CO_2的捕获中可以起到选择性提升的作用,本文选择小尺寸的乙二胺分子对具有不饱和金属位点的轻金属铝基金属有机骨架(Al-MOFs)材料MIL-100Al进行改性,利用XRD、N2吸附和FT-IR等对改性材料的结构进行表征,测试了不同浓度的乙二胺改性的MIL-100Al对CO_2和CH4吸附性能。结果表明,与原始的MIL-100Al材料相比,改性后的材料对CO_2吸附量有明显提高,CH4的吸附量却降低,从而进一步提高了材料的CO_2/CH4吸附选择性,提升了吸附分离的效果。     

CO2 fixation by hydrogenation over coprecipitated Co/Al2O3

CO₂ fixation by hydrogenation over coprecipitated 36 wt.% Co/Al₂O₃ has been studied under a range of reaction conditions to clarify the effects of reaction variables and to determine the kinetics and mechanism of the reaction. A comparison of the results with those reported for CO hydrogenation on the same catalyst indicates that, although product distributions of CO₂ and CO hydrogenation differ, the kinetics and mechanism are similar.     

锂参与合成MOF-5用于CO2/CH4混合气体分离

利用溶剂热法合成了不同锂含量的MOF-5(xLi-MOF-5, x=0, 1, 3, 5).在MOF-5结晶过程中,锂离子被合并入其骨架结构中.实验表明,合并入骨架的锂能够改变MOF-5的结构和表面化学性质.不同的xLi-MOF-5能够不同程度降低骨架相互穿插的程度从而导致其吸附分离能力的大幅改变.其中,3Li-MOF-5具有最高的二氧化碳捕获能力(5.47 mmol·g^-1),对40% CO₂/60% CH₄混合气体具有最优吸附选择性.     

锂参与合成MOF-5用于CO_2/CH_4混合气体分离

利用溶剂热法合成了不同锂含量的MOF-5(x Li-MOF-5,x=0,1,3,5)。在MOF-5结晶过程中,锂离子被合并入其骨架结构中。实验表明,合并入骨架的锂能够改变MOF-5的结构和表面化学性质。不同的x Li-MOF-5能够不同程度降低骨架相互穿插的程度从而导致其吸附分离能力的大幅改变。其中,3Li-MOF-5具有最高的二氧化碳捕获能力(5.47 mmol·g-1),对40%CO2/60%CH4混合气体具有最优吸附选择性。     

La2(CO3)3纳米线的微乳液法制备与表征

La₂(CO₃)₃ nanowires were prepared in the nonionic surfactant microemulsion(Triton X-100/cyclohexane/water)system. Transmission electron microscopy (TEM) and selected area electronic diffraction (SAED) were used to characterize the shape and size of the products. The results showed that the pH value and concentration of mother solution, temperature and aging time all could affect the morphology and size of the La₂(CO₃)₃ nanowires. The lengths of the nanowires were more than 10 μm and the diameters were in the range of 30～200 nm.     

片状纳米结构CeO2晶体的制备及其吸附CO2性能

在室温下,将CeCl₃溶液与CO₂储存材料（CO₂SM）混合、搅拌0.5 h制备了片状碳酸铈前驱体（CCPs）,并在500℃下煅烧CCPs 4 h,制得平均尺寸为4.94 μm×0.92 μm,厚度为0.04~0.08 μm纳米结构片状CeO₂晶体。在此过程中,CO₂SM不但可以提供CO₃^2-,还能起到分散剂和结构导向剂的作用。反应过程中,系统地研究了CO₂SM用量、Ce³⁺浓度和搅拌时间3个因素对CCPs形态和大小的影响,得到最优制备条件：0.1 g CO₂SM和50 mL 0.03 mol·L^-1 Ce³⁺水溶液以1 000 r·min^-1转速在室温下搅拌0.5 h。煅烧CCPs后,所制备的片状CeO₂晶体在室温下CO₂吸附量可达0.554 mmol·g^-1。     

Preparation of activated carbons and their adsorption properties for greenhouse gases: CH4 and CO2

Three kinds of activated carbons were prepared using coconut-shells as carbon precursors and characterized by XRD, FT-IR and texture property test. The results indicate that the prepared activated carbons were mainly amorphous and only a few impurity groups were adsorbed on their surfaces. The texture property test reveals that the activated carbons displayed different texture properties, especially the micropore size distribution. The adsorption capacities of the activated carbons were investigated by adsorbing CH4, CO2, N2 and O2 at 25 ?C in the pressure range of 0-200 kPa. The results reveal that all the activated carbons had high CO2 adsorption capacity, one of which had the highest CO2 adsorption value of 2.55 mmol/g at 200 kPa. And the highest adsorption capacity for CH4 of the activated carbons can reach 1.93 mmol/g at 200 kPa. In the pressure range of 0-200 kPa, the adsorption capacities for N2 and O2 were increased linearly with the change of pressure and K-AC is an excellent adsorbent towards the adsorption separation of greenhouse gases.     

TiO_2纳米带光催化二氧化碳甲烷化

研究了在常温常压下TiO2纳米带光催化CO2催化加氢气反应。在紫外光照射下,二氧化碳的加氢还原产物为甲烷。利用高分辨TEM,XRD,UV-Vis DRS,低温氮吸附-脱附,TG等考察了催化剂与甲烷产率的构效关系。结果表明,在600℃焙烧时得到的双晶材料具有最佳的光催化活性。优异的光催化活性主要得益于TiO2双晶脱水纳米带(DNR Bicrystalline dehydratednanoribbon)。上面形成的纳米晶界能够提高催化剂在紫外区的光吸收能力,TiO2(B)和锐钛矿独特的双晶间隔结构也提高了界面电荷分离的效率。担载贵金属Pt显著地提高了反应速率。     

Influence of surfactants on the morphologies of CaCO3 by carbonation route with compressed CO2

Three surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and polyoxyethylene-80-sorbitan monooleate (Tween 80), were used to control the growth of CaCO₃ crystals by carbonation route using Ca(OH)₂ and compressed CO₂. The obtained CaCO₃ particles were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The effects of surfactants on the morphology of the particles were studied. It was demonstrated that Tween 80 and SDS have obvious effect on the morphology of CaCO₃ particles, while CTAB does not affect morphology considerably. The possible mechanism has been discussed on the basis of the binding of the surfactants to the certain face of the crystals.     

活性炭的孔径分布对CH4和CO2的吸附性能的影响

采用不同炭化温度和活化温度,以椰壳作为前驱体制备了系列结构性能相同,表面吸附基团相似,不同孔结构的活性炭。分别采用密度函数理论(DFT)吸附法和BJH估算了系列活性炭的孔径分布。结果表明,随炭化温度和活化温度的升高系列活性炭中微孔量先增加后减少。当炭化温度为700 ℃,活化温度为800 ℃时,制备的活性炭微孔量达到最大。随炭化温度和活化温度的升高,系列活性炭的中孔依次增加。考查了CH₄,CO₂在系列活性炭上的吸附性能。结果表明该系列活性炭对CO₂有很强的吸附能力,在常温常压下对CO₂的吸附量均高于1.0 mmol·g^-1;系列活性炭对CH₄的吸附能力有较大的差异,在对CO₂具有最大吸附量的活性炭上对CH₄具有最小的吸附量。采用变压吸附法测试了该系列活性炭在25 ℃时对n_CH4∶n_CO2=9∶1的混合气体的分离性能。结果表明炭化温度为700 ℃,活化温度为800 ℃时制备的活性炭对CH₄-CO₂混合气具有最好的分离效果,是变压吸附分离CH₄,CO₂混合气的优异吸附剂。     

镧石型碳酸镨钕向碱式碳酸镨钕的相转变反应特征及其应用

镧石型碳酸镨钕[(PrNd)2(CO3)3·8H2O,LPN]在95℃的不同起始pH值的溶液中陈化不同时间所得样品的XRD衍射图证明了LPN向碱式碳酸镨钕[(PrNd)(OH)(CO3),BPN]的相态转变。为此,详细研究了这一相态转变的反应条件以及粒子特征变化。结果表明:LPN是由片状或条状结晶连生而成的聚集体,具有大的粒度和小的堆密度。当在热的水溶液中陈化时,由于水解反应而发生由LPN向BPN的相转变。这一相转变可以在95℃下pH=7以上的溶液中发生,其转化率随起始溶液pH值的升高和陈化时间的延长而增大。随着相转变的进行,溶液的pH值开始下降明显,而后趋于平缓。相应地,大的团聚体颗粒解散成小的单个粒子,导致粒度减小,分布变窄,氯根含量降低和堆密度的增大。而且,这些变化直接与溶液pH值和陈化时间相关。据此,发展了一种新的制备具有高堆密度、低氯根含量、细粒度和窄分布的新方法,而且通过改变相转变条件可以方便地调谐颗粒特征。     

镧石型碳酸镨钕向碱式碳酸镨钕的相转变反应特征及其应用

本文研究了镧石型碳酸镨钕[（PrNd）₂（CO₃）₃·8H₂O,LPN]在95℃的不同起始pH值的溶液中陈化不同时间所得样品的XRD衍射图,证明所得样品为碱式碳酸镨钕[（PrNd）（OH）（CO₃）,BPN]。为此,详细研究了这一相态转变的反应条件以及粒子特征变化。结果表明：LPN是由片状或条状结晶连生而成的聚集体,具有大的粒度和小的堆密度。当在热的水溶液中陈化时,由于水解反应而发生由LPN向BPN的相转变。这一相转变可以在95℃下pH=7以上的溶液中发生,其转化率随起始溶液pH值的升高和陈化时间的延长而增大。随着相转变的进行,溶液的pH值开始下降明显,而后趋于平缓。相应地,大的团聚体颗粒解散成小的单个粒子,导致粒度减小,分布变窄,氯根含量降低和堆密度的增大。而且,这些变化直接与溶液pH值和陈化时间相关。据此,发展了一种新的制备具有高堆密度、低氯根含量、细粒度和窄分布的新方法,而且通过改变相转变条件可以方便地调谐颗粒特征。     

S型异质结光催化剂ZnFe2O4/WO3的构筑及光催化还原CO2性能

通过在WO₃纳米片表面负载ZnFe₂O₄纳米颗粒,构建了一系列S型异质结光催化剂ZnFe₂O₄/WO₃,并研究了其光催化CO₂还原性能。在没有助催化剂和牺牲剂的条件下,所制备的ZnFe₂O₄/WO₃复合材料可对CO₂与水蒸汽进行光催化反应。优化后的材料光照5 h后CO₂还原产物CO和CH₄的产量分别为7.87和4.88 μmol·g^-1。相对于单相组分,CO和CH₄的产量明显提高。光催化活性的提高,归因于ZnFe₂O₄和WO₃异质结的形成以及光生载流子的S型电荷传输模式。     

g-C3N4/Bi2O2CO32D纳米片复合材料的制备及可见光催化性能研究

采用自组装和化学沉淀法分别制得两种可见光驱动复合材料石墨相氮化碳/碳酸氧铋(g-C_3N_4/Bi_2O_2CO_3).采用X射线衍射光谱(XRD),紫外可见光谱、扫描电镜(SEM)、N_2吸附、电化学阻抗谱(EIS)和X射线光电子能谱(XPS)等分析手段对制备的催化剂进行了表征.结果表明,制备方法对纳米复合材料的晶相、形态及光学性能没有影响,但是影响g-C_3N_4和Bi_2O_2CO_3之间的相互作用力,导致光生电子-空穴对的分离速率存在显著差异.以可见光驱动苯酚和罗丹明B的降解实验为探针反应检测催化剂的光催化性能.实验结果表明自组装法得到的异质结催化剂中相互作用力更强,催化效果最高.O_2-是罗丹明B降解反应的主要活性物种,染料的光敏化、Bi_2O_2CO_3与g-C_3N_4综合效应,导致光生载流子电荷分离效率更高.     

S型异质结光催化剂ZnFe2O4/WO3的构筑及光催化还原CO2性能

通过在WO₃纳米片表面负载ZnFe₂O₄纳米颗粒,构建了一系列S型异质结光催化剂ZnFe₂O₄/WO₃,并研究了其光催化CO₂还原性能。在没有助催化剂和牺牲剂的条件下,所制备的ZnFe₂O₄/WO₃复合材料可对CO₂与水蒸汽进行光催化反应。优化后的材料光照5 h后CO₂还原产物CO和CH₄的产量分别为7.87和4.88 μmol·g^-1。相对于单相组分,CO和CH₄的产量明显提高。光催化活性的提高,归因于ZnFe₂O₄和WO₃异质结的形成以及光生载流子的S型电荷传输模式。