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Pyrolytic Synthesis of Carbon Nanotubes on Ni, Co/MCM-41 Catalysts  [PDF]
K. V. Katok,V. A. Tertykh,A. N. Pavlenko,S. Ya. Brichka,G. P. Prikhod'ko
Physics , 2004,
Abstract: Process of vapor pyrolytic deposition of carbon on nickel and cobalt-containing ordered mesoporous MCM-41 matrices at decomposition of acetylene have been investigated. Formation of nanotubes, nanowires and amorphous carbon particles depending pyrolysis conditions is observed.
Acidic and cesium salts of polyoxometalates with and without vanadium supported on MCM-41 as catalysts for oxidation of cyclohexane with H2O2
W. Trakarnpruk,J. Jatupisarnpong
Applied Petrochemical Research , 2013, DOI: 10.1007/s13203-012-0023-5
Abstract: Acidic and cesium salts of polyoxometalate (POM) with and without vanadium supported on MCM-41 were synthesized and their catalytic activities were investigated in the oxidation of cyclohexane with H2O2 under solvent-free condition. The products are cyclohexanol and cyclohexanone. The catalytic activity order is: CsVPOM/MCM > HVPOM/MCM > CsPOM/MCM ~ HPOM/MCM > CsVPOM > CsPOM catalysts. High conversion and selectivity to cyclohexanone over the supported catalysts are due to redox property and high surface area. These heterogeneous catalysts can be reused.
Synthesis of MCM–41 mesoporous molecular sieves containing heteroatoms and their catalytic activity

ZHOU Huafeng YANG Yongjin,ZHANG Jinsong,

材料研究学报 , 2009,
Abstract: MCM–41 mesoporous molecular sieves containing heteroatoms (Zn, Ni, Fe, Al, Cu, Ce) (T–MCM–41) were synthesized by direct hydrothermal process and were applied in the synthesis of dioctyl phthalate (DOP) in this paper. The effects of different heteroatoms incorporation on structure, specific surface area and pore volume, aciditity and catalytic activity of T–MCM–41 were investigated. The results show that T–MCM–41 which still remains the well–ordered hexagonal mesostructure of MCM–41 has high surface area (550–900 m2/g), large pore diameter (~3 nm). Meanwhile, it has high catalytic activity and selectivity in DOP synthesis because heteroatoms incorporation can produce acid centers. When T–MCM– 41 (T=Zn, Fe, Al, Cu) is used as the catalyst, the conversion of phthalic anhydride (PA) reaches above 95.5% and DOP selectivity reaches above 96.5% in 5 h. Moreover, T–MCM–41 has good stability and Al–MCM–41 holds good catalytic activity after being reused five times.
Chlorination of Carbon Nanotubes Obtained on the Different Metal Catalysts  [PDF]
Iwona Pe?ech,Robert Pe?ech,Urszula Narkiewicz,Dariusz Moszyński,Anna J?drzejewska,Bart?omiej Witkowski
Journal of Nanomaterials , 2013, DOI: 10.1155/2013/836281
Abstract: In this paper, a chlorination method is proposed for simultaneous purification and functionalization of carbon nanotubes, thus increasing their ability to use. Carbon nanotubes were obtained by CVD method through ethylene decomposition on the nanocrystalline iron or cobalt or bimetallic iron-cobalt catalysts. The effects of temperature (50, 250, and 450°C) in the case of carbon nanotubes obtained on the Fe-Co catalyst and type of catalyst (Fe, Co, Fe/Co) on the effectiveness of the treatment and functionalization were tested. The phase composition of the samples was determined using the X-ray diffraction method. The quantitative analysis of metal impurity content was validated by means of the thermogravimetric analysis. Using X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive Spectroscopy (EDS) analysis, and also Mohr titration method, the presence of chlorine species on the surface of chlorinated samples was confirmed. 1. Introduction Carbon nanotubes (CNTs), since their discovery in 1991, constantly incite an immense interest owing to their special physical and chemical properties. Due to unique mechanical, thermal, and electrical properties, these materials are not only an ideal candidate for many applications but also a very interesting material from a scientific point of view. Concerning industrial applications carbon nanotubes can be used, for example, as electron emitters, filtration membranes, drug carriers, energy containers, or catalyst supports [1–6]. A particular interest is connected with the application of carbon nanotubes as fillers for polymers. The presence of carbon nanotubes as an additive to a polymer can improve such properties of the composite such as tensile strength [7], tensile modulus [8], toughness [9], glass transition temperature [10], thermal conductivity [11], resistance to solvents [12], optical properties [13], and electrical conductivity [14]. The main bottleneck in the application of carbon nanotubes as fillers for polymers is their insufficient dispersion in a polymer matrix, because CNTs have a tendency to agglomerate due to the Van der Waals forces. Recently there are several methods improving the dispersion of carbon nanotubes in a polymer matrix. One of the very promising methods preventing an aggregation of nanotubes and facilitating a good dispersion in a polymer matrix is their chemical functionalization, involving changes of the surface of nanotubes through an addition of various functional groups. The most popular method of carbon nanotubes functionalization is their oxidation using oxygen [15, 16] or
Comparative Study of Regioselective Synthesis of β-Aminoalcohols under Solventless Conditions Catalyzed by Sulfated Zirconia and SZ/MCM-41  [PDF]
Guillermo Negrón-Silva,C. Xochitl Hernández-Reyes,Deyanira Angeles-Beltrán,Leticia Lomas-Romero,Eduardo González-Zamora,Juan Méndez-Vivar
Molecules , 2007, DOI: 10.3390/12112515
Abstract: Sulfated zirconia and SZ/MCM-41 were used as catalysts for the synthesis of β-aminoalcohols via epoxide aminolysis. Sulfated zirconia was prepared by sol-gel andSZ/MCM-41 was obtained by impregnation. Solid catalysts were characterized by XRD,SEM-EDS, UV-Vis, FT-IR pyridine desorption and Nitrogen physisorption. Both acidmaterials were useful as catalysts, even when they were recycled several times. The β-aminoalcohols were characterized by FT-IR, 1H- and 13C-NMR and GC-MS.
Preparation of MCM-41-supported chiral Salen Mn (III) catalysts and their catalytic properties in the asymmetric epoxidation of olefins
DongMin Zhao,JiQuan Zhao,ShanShan Zhao,LeQin He,WeiYu Wang
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-0333-7
Abstract: A secondary amino-modified mesoporous molecular sieve MCM-41 was obtained by reaction of bis(3-(triethoxysilyl)propyl)amine with MCM-41. The chiral Salen-Mn (III) complex was anchored onto the modified MCM-41 by a multi-step grafting method and two heterogenized catalysts with different Mn contents were obtained. The catalysts were characterized by XRD, N2 adsorption, ICP, FT-IR and DR UV-Vis. Their catalysis on asymmetric epoxidation of several olefins was studied with NaClO and m-CPBA as oxidants respectively. It was found that both the activity and enantioselectivity of the catalysts decreased after the homogeneous catalyst was heterogenized. The reasons resulting in the decrease of catalytic performance were discussed.
Physicochemical Properties of CuO2 (acac)2 Supported on Functionalized MCM41 Containing Thiourea Ligand  [PDF]
Amirah Ahmad,Hamizah Md. Rasid,Karimah Kassim
International Journal of Chemical Engineering and Applications , 2013, DOI: 10.7763/ijcea.2013.v4.249
Abstract: A new material is prepared by encapsulating functionalized-MCM41 with 2-hydroxy-2-mercaptopyrimidine (2-thiouracil) and copper acetate monohydrate. The functionalized-MCM41 was first synthesized by using Ludox as silica source and cetyltrimethylammonium bromide (CTABr) as template and was modified via co-condensation method using 3-aminopropyltriethoxysilane (APTES). The surface and textural of synthesized material have been characterized by using X-ray diffraction (XRD), N2 adsorption isotherms, BET surface area measurement, FT-IR, elemental analyzer and scanning electron microscopy (SEM). The low-angle XRD results indicated that the CuO2(acac)-Thio-APS-MCM41has similar XRD pattern as the mesoporous MCM41 although the intensity decreases. For high-angle XRD, the results show the presence of monoclinic CuO at 2θ = 35.3 and 38.6° while N2 adsorption and BET results were revealed that the CuO2(acac)-Thio-APS-MCM41 possessed a good mesoporous structural ordering and uniform mesoporosity. FTIR spectra confirmed that the organosilane group still retained in the pore channel of the CuO2(acac)-Thio-APS-MCM41 even after modification and the band of C=S and Cu=O also appeared in CuO2(acac)-Thio-APS-MCM41 spectra with the presence of thiourea ligand and copper. Hence, the characterization results were revealed that the synthesized material has an ordered hexagonal structure, a narrow pore size distribution, a high surface area and thiourea complex were successfully grafted onto the pores of functionalized-MCM41.
Characterization of platinum–iron catalysts supported on MCM-41 synthesized with rice husk silica and their performance for phenol hydroxylation
Jitlada Chumee, Nurak Grisdanurak, Arthit Neramittagapong and Jatuporn Wittayakun
Science and Technology of Advanced Materials , 2009,
Abstract: Mesoporous material RH-MCM-41 was synthesized with rice husk silica by a hydrothermal method. It was used as a support for bimetallic platinum iron catalysts Pt–Fe/RH-MCM-41 for phenol hydroxylation. The catalysts were prepared by co-impregnation with Pt and Fe at amounts of 0.5 and 5.0 wt.%, respectively. The RH-MCM-41 structure in the catalysts was studied with x-ray diffraction, and their surface areas were determined by nitrogen adsorption. The oxidation number of Fe supported on RH-MCM-41 was + 3, as determined by x-ray absorption near edge structure (XANES) analysis. Transmission electron microscopy (TEM) images of all the catalysts displayed well-ordered structures, and metal nanoparticles were observed in some catalysts. All the catalysts were active for phenol hydroxylation using H2O2 as the oxidant at phenol : H2O2 mole ratios of 2 : 1, 2 : 2, 2 : 3 and 2 : 4. The first three ratios produced only catechol and hydroquinone, whereas the 2 : 4 ratio also produced benzoquinone. The 2 : 3 ratio gave the highest phenol conversion of 47% at 70 °C. The catalyst prepared by co-impregnation with Pt and Fe was more active than that prepared using a physical mixture of Pt/RH-MCM-41 and Fe/RH-MCM-41.
Immobilization of Lipase from Candida rugosa on Mesoporous MCM 41  [PDF]
Roberto Rodrigues de Souza, Renata D. M. Ferreira
Journal of Biosciences and Medicines (JBM) , 2014, DOI: 10.4236/jbm.2014.24011
Abstract:

The use of enzymatic route for production of biofuels is growing up due the mild reaction conditions that this method provides, as well as reducing SOx emission. To reduce costs, it’s necessary to immobilize the enzyme, making possible to use it continuously as biocatalyst. The aim of this work was to measure the influence of the mass of support and pH used for immobilization of commercial lipase from Candida rugosa acquired by Sigma laboratory. The immobilization method chosen was adsorption on mesoporous and hydrophobic support MCM 41, this has been treated with nitric acid 10% v/v to remove any organic residue. Then, 20 ml of enzymatic solution in phosphate buffer (pH 6.0, 7.0 and 8.0; 50 mM) and 1 g/L was placed under constant stirring with 0.30 and 0.45 g of support. Aliquots were taken from the reaction medium and analyzed by spectrophotometry at 10 minutes intervals. A volume of 0.2 ml of supernatant was put with 1.8 ml of substrate p-NFL at 0.18 g/L, and the absorbance at 410 nm was analyzed. In four cases there was a sharp reduction of supernatant’s activity at first 10 minutes, that ratifies the big affinity of the enzyme for the support and the negative influence of pH about the activity. Using the calibration curve, it was possible to calculate the final activity of each immobilization batch. This work suggests the occurrence of diffusional effects, which means that the enzyme mobility was restricted due the excessive amount of support, and then, it lost a part of accessibility to substrate, reflecting in not expressive activity values, and changing the state of ionization of the components of the system.

Altervalent cation-doped MCM-41 supported palladium catalysts and their catalytic properties  [PDF]
HAIHUI JIANG,LIGANG GAI,YAN TIAN
Journal of the Serbian Chemical Society , 2011,
Abstract: Metal cation-doped MCM-41 (M-MCM-41, M = Al, Ce, Co, V or Zr) supported Pd catalysts (Pd/M-MCM-41) were prepared by a solution-based reduction method. The catalysts were characterized by X-ray diffraction (XRD) analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and further evaluated by selective hydrogenation of para-chloronitrobenzene (p-CNB) in anhydrous ethanol. The metal cation-containing Pd catalysts can efficiently enhance the selectivity for para-chloroaniline (p-CAN). The highest selectivity of 96.5 % in the molar distribution for p-CNB to p-CAN was acquired over Pd (1.8 wt. %)/V-MCM-41 (Si/V = 30, molar ratio) catalyst, and the corresponding turnover frequency (TOF) was 1.24×10-2 mol p-CNB mol-1 Pd s-1. Water molecules adsorbed by the support have important effects on both the catalytic activity of the sample and the selectivity for p-CAN. A water molecule-mediated catalytic hydrogenation is discussed.
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