排序方式: 共有121条查询结果,搜索用时 31 毫秒
21.
双金属复合氧化物的结构与紫外阻隔性能 总被引:8,自引:1,他引:7
双金属复合氧化物(CLDH)是一类发展迅速的无机层状材料的煅烧产物,在催化、吸附等领域已获长足进展[1],但作为紫外阻隔材料的性能研究尚鲜见报道.本文研究了不同双金属复合氧化物的紫外阻隔性能,结果发现二价金属离子为锌离子的CLDH具有良好的紫外阻隔性能.实验所用试剂均为分析纯.CLDH由NaOH,Na2CO3,MgSO4·7H2O,ZnSO4·7H2O,Al2(SO4)3·18H2O为原料,按文献[2]方法制备.ZnO+Al2O3复配物是按一定比例机械混合后,研磨,并在与CLDH相同的条件下煅烧… 相似文献
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采用自行创制的成核晶化隔离法将Ni^2 引入层状双金属复合氢氧化物(LDHs)的层板,首次合成得到了层板含Ni^2 的三元金属铜镍铬的碳酸根型LDHs(CuNiCr—LDHs),通过X射线衍射(XRD)、红外光谱(FT-IR)、透射电镜(TEM)、热重及微商热重分析(TODTG)、等离子电感偶合元素分析(ICP)和激光粒度分析等手段对产物的晶体结构特征进行了研究,结果表明:当反应Cu^2 /Ni^2 /Cr^3 投料摩尔比介于1:2:1~1:3:1之间,晶化温度为180℃和晶化时间大于4h时,利用成核晶化隔离法可以合成得到晶型规整的CuNiCr—LDHs;研究同时发现,层板引入Ni^2 后可以削弱Cu^2 的Jahn-Tellex效应对层板对称性的影响,提高了LDHs的晶型完整性和结构稳定性。 相似文献
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硼酸根插层水滑石层间组成及取向结构的控制 总被引:1,自引:0,他引:1
以Mg0 .67Al0 .3 3 (OH) 2 (CO3 ) 0 .165·0 .62H2 OLDHs为前体 ,以水为分散介质 ,由离子交换法组装了硼酸根插层LDHs ,并用XRD ,FT IR ,TG DTA ,ICP ,11BMASNMR等手段对样品进行了分析和表征 .结果表明 ,通过控制离子交换时的pH ,可使硼酸根取代Mg Al CO3 LDHs前体层间的CO2 -3 ,且可控制离子交换程度及客体的取向 ,从而控制插层结构 .对硼酸根插层LDHs的结构进行研究发现 ,控制pH =4.5 ,层间阴离子主要是一硼酸根和离子平面与LDHs层板平行的三硼酸根 ,出于结构稳定的需要 ,CO2 -3 不能完全被置换 ;控制pH =3 .5 ,层间阴离子是一硼酸根和离子平面与LDHs层板垂直的三硼酸根 相似文献
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目前研究较多的锂离子电池正极材料主要有LiCoO2、LiNiO2和LiMn2O4犤1犦,虽然LiCoO2的成本相对较高,但LiCoO2具有最为优良的电化学性能,如高且平稳的充放电平台、高比容量以及良好的循环性能犤2犦,是目前应用最广泛的商品化电极材料。LiCoO2材料主要采用高温固相法犤3~5犦制备,该方法工艺简单,容易实现大规模生产,但缺点是需要较高的焙烧温度和较长的焙烧时间,且反应原料混合均匀程度有限,易导致非化学计量、非均相以及不规则的颗粒形貌等,因此材料的比容量、循环寿命等电化学性能以及反应的可控性还不甚理想。研究表明犤6犦电极材… 相似文献
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γ-Al2O3表面原位合成Ni-Al-CO3LDHs研究 总被引:1,自引:0,他引:1
Ni-Al-CO3LDHs/γ-Al2O3have been prepared using an in-situ synthesis technique. NH3·H2O was chosen as activation agent of Al on the γ-Al2O3surface as well as precipitant. Ni-Al-CO3LDHs/γ-Al2O3was synthesized by controlling the reaction conditions such as temperature, concentration of Ni2+ and initial pH. The crystalline structure, chemical composition and porous structure were characterized by means of XRD, FT-IR, TG-DTA, 27Al MAS-NMR and N2 adsorption-desorption. The resulting sample of Ni-Al-CO3LDHs/γ-Al2O3possesses higher specific area and narrower pore distribution, in which Ni-Al-CO3LDHs are located on the surface of γ-Al2O3and share the same Al-O bonds with the γ-Al2O3lattice. Finally a possible structural model was proposed to account for the porous characters of Ni-Al-CO3LDHs/γ-Al2O3. 相似文献
26.
镁铁和镁铝双羟基复合金属氧化物的结构和性能差异 总被引:6,自引:2,他引:6
Layered Double Hydroxides MgFe-LDH and MgAl-LDH have been prepared by the method involving separate nucleation and ageing steps. The structure analyses for these two materials show that the values of the parameters both a and c of MgAl-LDH are smaller than that of MgFe-LDH though their structures are similar, and MgAl-LDH with higher crystallinity is more easily formed than MgFe-LDH in the same preparing conditions. The IR analyses manifest that the structures of layer sheets and the orderings of the anions in the interlayer regions of MgAl-LDH are more regular than that of MgFe-LDH. The temperature programmed XRD analyses reveal that the diffraction peak of 003 reflections for MgAl-LDH could be seen after calcining at 300℃, while this peak for MgFe-LDH disappears after calcining at 200℃. Together with the TG-DTA analysis it can be concluded that the thermal stability of MgAl-LDH is obviously higher than that of MgFe-LDH. 相似文献
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Mg-AI layered double hydroxides (LDH) with different particle sizes were prepared using different aging times at high supersaturation by a new method developed in our laboratory. The key features of this method are a very rapid mixing and nucleation process followed by a separate aging process. By calcination of LDH at 500癈, mesoporous Mg-AI composite oxides with an extremely narrow pore size distribution were produced. The crystal structure of the Mg-AI composite oxides was a multiphasic one consisting of MgO-like crystals and a layered material. 相似文献
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本文以H_2在Cu/ZnO/Al_2O_2型低变催化剂上的程序升温脱附为例,解析了其TPD谱图。提出了T_f法及曲线拟合法。与其它几种方法计算结果的对比表明,该方法具有一定的可靠性及可行性。由分析计算得到的动力学参数可知,同一催化剂,不同的活泼部位具有相同形式的脱附动力学方程,而只是动力学参数不同。计算结果还表明,Cu/ZnO/Al_2O_3型低变催化剂对H_2的有效表面为非理想表面,并求出脱附过程中的频率因子γ_d、活化能E_d与表面复盖度θ的函数关系分别为指数函数和对数函数。从脱附级数推测出,H_2在Cu/ZnO/Al_2O_3型低变催化剂上的吸附为分解二位吸附。 相似文献
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硅甲基接枝改性MCM-48的结构特征及表面性质 总被引:3,自引:0,他引:3
本文利用三甲基氯硅烷与未焙烧MCM-48反应,实现对MCM-48的表面硅甲基接枝改性。结果表明:原未焙烧MCM-48孔道内的CTAB模板剂被脱除,三甲基氯硅烷与表面羟基反应,将硅甲基官能团接枝到MCM-48的内外表面。改性后MCM-48具有良好的长程有序结构,较窄的孔径分布,较大的孔体积和较高的比表面积,相对于未焙烧MCM-48,硅甲基接枝改性MCM-48的表面亲水性降低,亲油性得到提高。 相似文献
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