Mesoporous Silicoaluminum Pillared Clays with High Thermal Stability and Br?nsted /Lewis Acidity by One-pot Synthesis

The intercalation of polynuclear hydroxy metal cations in smectites affords porouspillared clays which show great potential applications involving separations,adsorptionand catalysis.Though the range of pillared agents has been considerably enlarged1since its invention,aluminum Keggion ions[Al13O4(OH)]7+24and silicon cations arestill often used as pillaring species.Pinnavaia reported that introduction of silica intointerlayers by ion exchange of swollen clays with silicon acetylacetonate cat…     

Photocatalytic degradation of dimethyl phthalate ester using novel hydrophobic TiO2 pillared montmorillonite photocatalyst

TiO₂ pillared montmorillonites were prepared by introducing Ti⁴⁺ into a layer of montmorillonite modified with or without cetyltrimethylammonium bromide. The components and texture of the prepared composites were characterized by thermogravimetric analysis, X-ray powder diffraction and scanning electron misroscopy. The adsorption and photocatalytic degradation performance of a model environmental endocrine disruptor, dimethyl phthalate ester, were investigated using this newly prepared hydrophobic TiO₂ pillared montmorillonite photocatalyst. The adsorption of dimethyl phthalate ester from water varied from 9% to 28% on the prepared hydrophobic photocatalyst. Although the experimental results showed that the photocatalytic activity of the hydrophobic photocatalyst was slightly lower than that of hydrophilic one, electron spin resonance verified that hydroxyl radicals were also generated in hydrophobic TiO₂ pillared montmorillonite photocatalyst under UV irradiation. To elucidate the decomposition mechanism of dimethyl phthalate ester, 12 main photocatalytic intermediates were identified during the photocatalytic degradation process, and a plausible degradation mechanism was also proposed.     

Preparation and characterization of hydrophobic TiO(2) pillared clay: the effect of acid hydrolysis catalyst and doped Pt amount on photocatalytic activity

Titanium hydrate sols were prepared using different acid hydrolysis catalysts, i.e., acetic acid and hydrochloric acid. The platinum-doped TiO(2) sol-gels were also synthesized by adding K(2)PtCl(6) into the titanium hydrate sols. The hydrophobic montmorillonite clay, treated with organic cationic surfactant, i.e., hexadecyltrimethylammonium bromide, was used as a template to prepare TiO(2) pillared photocatalyst with the above sols. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) were employed to characterize the resulting photocatalysts. The adsorption performance and photoactivity of prepared pillared clays were studied by using methyl orange as a model organic pollutant. The preliminary results indicated that the hydrophobic TiO(2) pillared clay prepared with acetic acid as the acid hydrolysis catalysts possessed higher photocatalytic activity than that with hydrochloric acid. Due to the excellent sedimentation property of the clay, the resulting pillared photocatalyst is easily recovered and reused in the postrun treatment. Also the doping of platinum into the hydrophobic photocatalyst can increase the photocatalytic activity significantly.     

La(OH)3负载锌铝水滑石的制备及其应用在锌镍二次电池中的性能

采用共沉淀法将氢氧化镧(La(OH)₃)负载在锌铝水滑石(Zn-Al LDHs)的表面,扫描电镜(SEM)、X射线衍射(XRD)表明La(OH)₃成功负载在锌铝水滑石表面,并且负载后的锌铝水滑石仍然为六边形片状晶体,且粒径均匀、分散性好。La(OH)₃质量其具有较好的可逆性、更大的正腐蚀电位及较小的电池内阻。5%La(OH)₃@Zn-Al LDHs在经过80次循环后,其循环保持率为94.84%。     

Vapor generation – atomic spectrometric techniques. Expanding frontiers through specific-species preconcentration. A review

We review recent progress in preconcentration strategies associated to vapor generation techniques coupled to atomic spectrometric (VGT-AS) for specific chemical species detection. This discussion focuses on the central role of different preconcentration approaches, both before and after VG process. The former was based on the classical solid phase and liquid–liquid extraction procedures which, aided by automation and miniaturization strategies, have strengthened the role of VGT-AS in several research fields including environmental, clinical, and others. We then examine some of the new vapor trapping strategies (atom-trapping, hydride trapping, cryotrapping) that entail improvements in selectivity through interference elimination, but also they allow reaching ultra-low detection limits for a large number of chemical species generated in conventional VG systems, including complete separation of several species of the same element. This review covers more than 100 bibliographic references from 2009 up to date, found in SCOPUS database and in individual searches in specific journals. We finally conclude by giving some outlook on future directions of this field.     

磷钨酸插层MgAl水滑石层间距的调变及催化酯化脱酸性能

通过改变离子交换温度和时间合成了具有不同层间距的磷钨酸(H_3PW_(12)O_(40),HPW)插层MgAl水滑石(LDHs),采用XRD、FT-IR、Raman、~(31)P MAS NMR、ICP-AES和Hammett指示剂-正丁胺滴定法等表征其性质,并研究其对模型原油的催化酯化脱酸性能。高的离子交换温度有利于形成较大的层间距(d_(003)约1.46 nm),较长的交换时间有利于形成较小的层间距(d_(003)约1.05 nm)。不同的层间距源自HPW在层间不同的存在形式,P_2W_(18)O_(62)~(6-)以C_2轴倾斜于层板和PW_(11)O_(39)~(7-)以C_2轴垂直于层板的方式排列于层间时,形成d_(003)约1.46 nm的层间距;PW_(12)O_(40)~(3-)与层板发生嫁接,并以C_2轴垂直于层板的方向排列于层间时,形成d_(003)约1.05 nm的层间距。层间P_2W_(18)O_(62)~(6-)和PW_(11)O_(39)~(7-)能产生更高比例的中强酸中心,同时大的层间距有利于反应物扩散进入层间与酸中心接触,能够提高LDHs的催化酯化脱酸性能。     

水滑石负载碘催化合成α-氨基腈类衍生物

以水滑石(LDHs)负载碘(I_2/LDHs)为催化剂,芳香醛、芳香胺和三甲基硅氰(TMSCN)为原料,合成了10种α-氨基腈类衍生物,其结构经~1H NMR确认。优化反应条件为:n_(苯甲醛)∶n_(苯胺)∶n_(TMSCN)=1.0∶1.0∶1.4,水滑石负载碘10(mol)%作催化剂,甲醇为溶剂,搅拌反应10min,收率最高可达98.3%。     

规整Mn-Zn-Mg-Al-CO3四元LDHs层状材料的水热合成、结构及性能

以Mn(NO3)2.6H2O、Zn(NO3)2.6H2O、Mg(NO3)2.6H2O和Al(NO3)3.9H2O为原料,采用水热合成法,一步合成了Mn-Zn-Mg-Al-CO3四元LDHs层状材料。采用ICP、元素分析仪、XRD、FTIR、TG-DSC、SEM、低温氮吸附-脱附等对样品进行了表征。探讨了pH值、反应温度、反应时间和原料配比对Mn-Zn-Mg-Al-CO3四元LDHs层状材料合成的影响。结果表明,在pH=10、反应温度控制在140℃、反应时间为24 h的条件下,可以合成出结构规整、晶形良好、各层间排列紧密有序的含不同比例金属阳离子的Mn-Zn-Mg-Al-CO3四元LDHs层状材料。其吸附等温线符合V型吸附,H3滞后环,晶体内层间存在2 nm以上的孔,晶体内部结构的有序性高,层间碳酸根离子的排列整齐,通道内孔密度大、孔径小、比表面积大。     

MgAlZnFe-CO3 LDHs对PBS膨胀阻燃体系性能的影响

采用恒定pH值共沉淀法在自制反应器中合成了不同原料配比的碳酸根型镁铝锌铁层状双羟基金属氧化物（MgAlZnFe-CO₃ LDHs）,并通过熔融共混MgAlZnFe-CO₃ LDHs、聚磷酸铵（APP）、三聚氰胺（MA）和全降解材料聚丁二酸丁二醇酯（PBS）制备出PBS膨胀阻燃材料. 采用傅里叶红外光谱（FTIR）、热失重（TG）、X射线衍射（XRD）、扫描电子显微镜（SEM）及元素分析（ICP）对MgAlZnFe-CO₃ LDHs进行了表征,并对PBS膨胀体系进行了力学性能和阻燃性能等测试. 结果表明,当Mg²⁺,Zn²⁺,Al³⁺和Fe³⁺的摩尔比为9：3：3：1时,合成的MgAlZnFe-CO₃ LDHs热稳定性最好,晶态结构规整,呈形貌规则的六边形片状;当MgAlZnFe-CO₃ LDHs的添加质量分数为1%时（阻燃剂的总添加质量分数为20%）时,PBS膨胀阻燃体系的极限氧指数（LOI）达到35%,垂直燃烧测试达到UL-94 V-0级别,力学性能得到较大改善. 实验结果表明,低添加量的MgAlZnFe-CO₃ LDHs与膨胀阻燃剂（IFR）协效阻燃PBS,一方面能够改善膨胀阻燃剂恶化PBS力学性能的现象,另一方面协同效应能够明显提高PBS的阻燃性能.     

氧化石墨烯诱导的Ni-Co氢氧化物整体电极的制备及电储能特性

超级电容器作为一种新型储能装置,由于其能量密度、功率密度高和良好的循环稳定性,而在实际工业应用中(新能源汽车、航天航空业、电子通信系统、可穿戴设备等)显示出巨大的潜力.但目前面临的最大挑战是构造柔性、轻薄可变形的储能设备.在本项研究工作中,利用溶剂热法和真空抽滤法开发了一种碳基/层状金属氢氧化物的复合材料.设计将氧化石...