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1.
以微斜长石制备的硅铝酸盐前驱物为主要原料,以13X沸石晶核剂为孔壁结构导向剂,水热合成了含有13X沸石基本结构单元的硅铝酸盐介孔分子筛SAN-01.在该方法中,首先微斜长石与Na2CO3按物质的量比为1:1.05的比例混合后,在820℃下焙烧2h.焙烧物料室温下在0.01mol/L的NaOH水溶液陈化24h后,与50mL的十六烷基三甲基溴化铵(C16TMABr)水溶液(含7.4g C16TMABr)混合、再经105℃下晶化48h、过滤、水洗和焙烧等工艺,合成了硅铝酸盐介孔分子筛.当假定孔结构为球形散射体时,小角散射(small-angle X-ray scattering,SAXS)给出的样品平均壁间距的统计平均值为5.42nm,比XRD给出的结果偏大8.8%.SAXS给出的SAN-01的壁间距分布介于0.2~11.3 nm之间,N2吸附与XRD联合给出的壁间距分布介于3.8~4.9 nm之间,即SAXS给出的壁间距分布范围较N2吸附与XRD联合给出的壁间距分布范围宽.该差别可能源于样品中存在的部分闭孔结构,或N2分子与分子筛表面的不饱和羟基之间的分子间力. 相似文献
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13X微孔沸石和MCM-41介孔材料的合成及用于处理含Cd2+废水 总被引:4,自引:0,他引:4
以天津蓟县钾长石矿粉为主要原料,经选矿、煅烧、水热处理等工艺成功合成了13X微孔沸石. 以气相氧化硅、氢氧化钠、十六烷基三甲基溴化铵等为主要原料,在水热条件下合成了MCM-41有序介孔材料. 采用XRD和N2吸附-脱附等手段对合成的13X沸石和MCM-41介孔材料的物相、比表面积、孔径、孔体积等进行了分析对比. 在此基础上,对13X沸石和MCM-41介孔材料处理含Cd2+废水的效果和机理进行了对比研究,确定了不同分子筛用量、不同初始pH值、不同混合时间下13X沸石和MCM-41介孔分子筛对水中Cd2+的吸附率和吸附量. 研究发现,尽管MCM-41的比表面积和孔径远大于13X沸石,但其对水中Cd2+的处理效果却低于13X沸石,这与13X沸石和MCM-41的孔道结构类型、化学组成、表面荷电性质等有关. 相似文献
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以十六烷基三甲基溴化铵为模板剂,通过微波辐射方法合成钴掺杂MCM-41介孔分子筛。采用X射线粉末衍射、红外光谱、透射电子显微镜、等离子发射光谱和N2吸附-脱附等技术对样品进行表征。结果表明:样品经550℃焙烧后,模板剂被有效去除。微波辐射条件下,成功合成出钴掺杂介孔分子筛样品。与纯硅的分子筛样品相比,钴掺杂的介孔分子筛比表面积增大,孔径分布均匀。 相似文献
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在采用传统的催化剂为载体的加氢精制工艺中,柴油馏分的深度加氢脱芳、脱硫依然是当今催化领域比较难以解决的问题之一.基于柴油中典型芳烃化合物和含硫化合物的分子尺寸,在第二段加氢工艺中,设计了具有介微复合孔分布的耐硫性催化剂载体.在微孔分子筛Y表面进行了MCM-41的附晶生长,合成出了一种复合分子筛并利用各种表征手段对合成的样品进行了表征.结果表明,复合分子筛不同于同样条件下合成的纯MCM-41和Y型分子筛的机械混合物.它具有介孔和微孔双重孔结构,而且复合分子筛中介孔相MCM-41的孔壁中引入了Y型分子筛的次级结构单元,使孔壁厚度增大,改善了水热稳定性. 相似文献
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以正硅酸乙酯为硅源、十六烷基三甲基溴化铵为模板,在氟化物存在的条件下,通过水热法在不同晶化温度和时间下进行复合分子筛Y/MCM-48的合成。利用X射线粉末衍射、Fourier变换红外光谱、N2吸附–脱附、扫描电子显微镜和透射电子显微镜对合成的样品进行表征,同时考察了样品的稳定性及不同晶化时间和温度下样品的晶相。结果表明:在120℃水热晶化36h合成的Y/MCM-48具有良好有序的MCM-48介孔相以及NaY微孔相的双重孔结构,其比表面积高达864 m2/g,平均孔径为2.4 nm。样品经800℃焙烧4 h、100℃水热处理48 h后,复合分子筛的双重孔结构仍然存在。 相似文献
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采用水热法合成出不含镍和含镍的硅基介孔分子筛.利用XRD、FT-IR、TPR、TEM和比表面孔径测定等手段对样品进行了表征.结果表明:合成出有序性好的介孔分子筛(MCM-41),550 ℃焙烧可以将模板剂有效去除,所合成介孔分子筛负载Pt后介孔有序性降低,但是介孔结构仍然存在.苯催化加氢反应研究表明:不含Ni的介孔分子筛不具有加氢活性,当将其负载Pt后具有苯加氢催化活性;含Ni介孔分子筛本身具有苯加氢活性,含Ni介孔分子筛负载Pt后苯加氢催化活性有较大的提高,所有样品的环己烷选择性都接近100 %,说明含Ni介孔分子筛可以直接作为苯加氢反应的催化剂或作为苯加氢催化剂良好的载体. 相似文献
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含锆介孔分子筛的微波合成与表征(英文) 总被引:1,自引:0,他引:1
在微波辐射条件下,以硅酸钠和硫酸锆为原料、十六烷基三甲基溴化铵为模板剂合成含锆介孔分子筛(zirconium-containing mesoporous molecular sieves,Zr-MCM-41).用X射线粉末衍射、红外光谱,透射电子显微镜、等离子发射光谱和比表面积孔径测定等测试手段表征经550℃焙烧后样品,同时研究锆添加量与分子筛比表面积及孔体积之间的关系.结果表明:利用微波技术合成Zr-MCM-41介孔分子筛,操作便利,节能省时,所得产物具有典型的MCM-41介孔分子筛结构,其比表面积为598.1~971.4m2/g,平均孔径大约为2.46~3A3nm.随着介孔分子筛中锆含量的增加,介孔分子筛的比表面积、孔体积变小,介孔有序性变差. 相似文献
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Mesoporous silica SBA-15 samples were subjected to microwave heating for 10–40 min at 393 and 443 K after dry-impregnation
with TPAOH (tetrapropylammonium hydroxide) to prepare a mesoporous material with zeolytically ordered pore walls. Physicochemical
properties of the materials prepared were characterized by XRD, N2 adsorption at 77 K, SEM, TEM, UV–vis and FT-IR spectroscopies. These investigations revealed that selective transformation
of amorphous pore walls of SBA-15 to crystalline zeolytic phase is difficult to be achieved and a mixed phase of mesoporous
silica/zeolite composite material was obtained, instead. Microwave heating time, temperature, TPAOH concentration, and hydrothermal
stability of the mesoporous host materials tested (MCM-41, HMS, and SBA-15) were important factors to maintain the mesopore
structure of the host materials during the post-synthetic microwave heating treatment. 相似文献
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Yuping Li Wei Zhang Xiaoli Wang Ying Zhang Tao Dou Kechang Xie 《Journal of Porous Materials》2008,15(2):133-138
A Beta/MCM-41 composite has been synthesized with a new method by using well-crystallized zeolite Beta as silica and aluminum
source. The prepared composite was characterized by XRD, FTIR, N2 adsorption/desorption at 77 K, FE-SEM, DTG, 29Si MAS NMR spectral techniques. It was shown that the composite consisted of a highly ordered mesoporous MCM-41 phase and
a zeolite Beta phase. Its hexagonal mesoporous structure was still retained after statically treated for 120 h in boiling
water. In contrast, the structure of generally synthesized Al-MCM-41 nearly completely collapsed. This might be attributed
to the assembly of the dissolved fragments such as the first and/or secondary structural units of zeolite Beta into the mesoporous
structure around surfactant micelles. This is supported by the catalytic result that the prepared composite showed higher
activity and selectivity for medium fraction in hydrocracking of Daqing vacuum residue than the parent zeolite Beta, the Al-MCM-41
as well as the mechanical mixture of these two materials. 相似文献
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《Applied Catalysis A: General》2001,205(1-2):85-92
In this study, MCM-41 material was synthesised and the mesoporous structure was confirmed by powder XRD patterns. Organic group 3-chloropropyl was anchored on the surface of MCM-41(∞) by reaction of 3-chloropropyltrimethoxysilane with terminal silanol groups on the surface of MCM-41(∞) material. The modified material MCM-41(∞)-Cl still kept its mesoporous structure even after the material was calcined again at 550°C for 4 h and the organic groups were removed. Prepared by solid state ion-exchange under flowing nitrogen, CuCl/MCM-41 catalyst had 100% selectivity of dimethyl carbonate based on methanol and 5–10 wt.% conversion of methanol at 130°C. With the decreasing mole ratio of Si/Al of MCM-41 material, e.g. increasing the aluminium content in the material, the catalytic activity increased because more CuI was loaded on the material. When the reaction temperature increased, the dimethyl carbonate selectivity decreased and three by-products: dimethyl ether, methyl formate, dimethoxymethane were formed at high temperature. Finally increasing the oxygen partial pressure in the feed gases resulted in more dimethyl carbonate formed. 相似文献
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N. KumarP. Mäki-Arvela T. YläsalmiJ. Villegas T. HeikkiläA.-R. Leino K. KordásT. Salmi D. Yu Murzin 《Microporous and mesoporous materials》2012,147(1):127-134
Dimerization of 1-butene in liquid phase was studied over H-Beta zeolite catalyst and MCM-41 mesoporous material in an autoclave at temperature of 473 K and at pressure of 20 bar using n-heptane as a solvent. Liquid phase product analysis was carried out using GC-MS and a pattern recognition technique, Soft Independent Modeling of Class Analogy (SIMCA). Acidity of the catalysts was determined by FTIR, phase purity using X-ray powder diffraction, surface area by nitrogen adsorption and morphology of zeolite and mesoporous material crystals using scanning electron microscope. Influence of acidity, pore size and structure of H-Beta zeolite and H-MCM-41 mesoporous material on the conversion of n-butene and selectivity to C8 hydrocarbon such as 2,2,4-trimethylpentene, dimethylpentene and 2-methylpentene was investigated. H-MCM-41 mesoporous material exhibited higher selectivities to C8 hydrocarbons than H-Beta zeolite catalyst. However, conversion of n-butene was higher over H-Beta zeolite catalyst than H-MCM-41 mesoporous material. 相似文献
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The objective of this work is to give a comparative characterization of aluminosilicate MCM-41 and zeolite Y, in particular with respect to acidity and catalytic properties in hydrocarbon cracking. These studies are compared to a well investigated amorphous aluminosilicate, based on the fact that the new mesoporous MCM-41 materials are a mixture of ordered material with amorphous pore walls. Characterization of differently treated MCM-41 materials and zeolite Y for comparison by N2 sorption, XRD, TPAD (Temperature Programmed Ammonia Desorption) with in situ FT-IR in combination with catalytic testing by MAT (Micro Activity Test) is discussed. Combination of the characterization data and the catalytic testing gives an interesting explanation of the surface properties especially in comparison with zeolite Y. 相似文献
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The synthesis of mesoporous MCM-41 silica materials was investigated at various conditions. A series of ordered mesopores
MCM-41 silica materials was synthesized in concentrated reaction mixtures. The influence of water concentration at the constant
ratio of the remaining reagents on the morphology and structural parameters of MCM-41 was studied. Hexadecyltrimethylammonium
bromide CTAB was used as a structure-directing agent. The pore size, the wall thickness and cylindrical pores array were characterized
by powder X-ray diffraction and nitrogen adsorption. The presented results show that in concentrated reaction mixtures, the
pore size and the thickness of the pore walls remain practically constant. However, the dimensions of silica particles depend
strongly on the water concentration. A high regularity of pore structure for large MCM-41 particles synthesized in concentrated
solution was supported by independent AFM technique. 相似文献
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A Beta/MCM-41 composite zeolite with a stepwise-distributed pore structure was prepared with a silica-alumina source originated from alkaline treatment of zeolite Beta. The material was characterized by various techniques. The results indicated that this composite possesses a mesopore system of MCM-41 and the microporous structure of Beta zeolite. Hydrothermal stability and acidity was improved over MCM-41 due to the introduction of Beta building units into the mesopore walls. The composite was used as the support of a Pd-Pt catalyst for the hydrogenation of naphthalene in the presence and absence of 4, 6-dimethyldibenzothiophene. It was demonstrated that the catalyst has an enhanced activity and sulfur tolerance during naphthalene hydrogenation. 相似文献