共查询到7条相似文献,搜索用时 0 毫秒
1.
Heesoo Kim Dong Ryul Park Sunyoung Park Ji Chul Jung Sang-Bong Lee In Kyu Song 《Korean Journal of Chemical Engineering》2009,26(3):660-665
Nitrogen-containing mesoporous carbon (N-MC) was synthesized by a templating method using SBA-15 and polypyrrole as a templating
agent and a carbon precursor, respectively. The N-MC was then modified to have a positive charge, and thus, to provide a site
for the immobilization of [PMo10V2O40]5−. By taking advantage of the overall negative charge of [PMo10V2O40]5−, H5PMo10V2O40 (PMo10V2) catalyst was chemically immobilized on the N-MC support as a charge-matching component. Characterization results showed
that nitrogen in the N-MC played an important role in forming a nitrogen-derived functional group (amine group), and PMo10V2 catalyst was finely and chemically immobilized on the nitrogen-derived functional group of N-MC support. In the vapor-phase
selective conversion of methanol, the PMo10V2/N-MC catalyst showed a higher conversion of methanol than the bulk PMo10V2 catalyst. Furthermore, the PMo10V2/N-MC catalyst showed a higher selectivity for dimethoxymethane (a product formed by bifunctional oxidation-acid-acid catalysis)
and a higher selectivity for methylformate (a product formed by bifunctional oxidation-acid-oxidation catalysis) than the
PMo10V2 catalyst. Reaction pathway for selective conversion of methanol to dimethoxymethane over PMo10V2/N-MC catalyst could be controlled by changing the methanol feed rate. 相似文献
2.
在SiO2载体上,以乙酰丙酮钼与次磷酸铵为原料,未经煅烧直接还原制备负载型磷化钼(MoP/SiO2)催化剂,通过XRD、N2-物理吸附、TEM和XPS等手段对催化剂进行表征。研究了浸渍液中P/Mo摩尔比(n(P):n(Mo)=1:1,2:1,3:1)、还原温度(500、550、600 ℃)对MoP相的影响,并考察其在苯甲醇选择性氧化生成苯甲醛反应中的催化性能。结果表明,浸渍液中P/Mo摩尔比为2、还原温度为550 ℃时,所获得的MoP/SiO2催化剂(MoP/SiO2-550-2)在苯甲醇选择性氧化生成苯甲醛反应中具有最好的转化率(99.7%)和优异的产物选择性(99.8%),这是由于MoP/SiO2-550-2催化剂上形成了更多小颗粒的MoP相。 相似文献
3.
Kyung Won La Heesoo Kim Ji Chul Jung Joohyung Lee Dong Ryul Park Sang Hee Lee In Kyu Song 《Korean Journal of Chemical Engineering》2008,25(4):710-713
Spherical carbon (SC) with a diameter of ca. 9 μm was synthesized by a hydrothermal method using sucrose as a carbon precursor.
The spherical carbon was then modified to have a positive charge, and thus, to provide a site for the immobilization of H5PMo10V2O40 (PMo10V2) catalyst. The PMo10V2 catalyst was immobilized on the surface-modified spherical carbon by taking advantage of the overall negative charge of [PMo10V2O40]5−. The PMo10V2 catalyst immobilized on the spherical carbon (PMo10V2/SC) was applied to the vapor-phase 2-propanol conversion reaction. In the catalytic reaction, the PMo10V2/SC catalyst showed a higher 2-propanol conversion than the unsupported PMo10V2 catalyst. Furthermore, the PMo10V2/SC catalyst showed enhanced oxidation catalytic activity (formation of acetone) and the suppressed acid catalytic activity
(formation of propylene and isopropyl ether) compared to the unsupported PMo10V2 catalyst. The enhanced oxidation activity of PMo10V2/SC catalyst was due to the fine dispersion of [PMo10V2O40]5− on the spherical carbon formed via chemical immobilization. 相似文献
4.
The catalytic properties of granular activated carbon (GAC) in GAC/iron oxide/hydrogen peroxide (H2O2) system was investigated in this research. Batch experiments were carried out in de-ionized water at the desired concentrations of ethylene glycol and phenol. Rate constants for the degradation of hydrogen peroxide and the formation rate of iron species were determined and correlated with mineralization of ethylene glycol at various GAC concentrations. The observed first order degradation rate of hydrogen peroxide in the absence of iron oxide and organic matter increases linearity with the increasing of the GAC concentration. The decomposition rate of hydrogen peroxide was suppressed significantly as the solution pH became acidic or by reducing the surface area of the GAC. The reduction of the surface area was obtained by loading an organic compound (such as phenol) on the GAC or by using the oxidizing agent (H2O2). The addition of both chemicals, phenol and H2O2, affects mainly the surface area of the small pores, resulting in reducing the catalytic activity inside the micropores.The catalytic properties of the GAC were used to accelerate the formation rate of the ferrous ions, which is known in the literature to be the limiting rate reaction in the classic Fenton like reagent. It was shown that the ethylene glycol mineralization rate was increased by more than 50%.Finally, optimization of the GAC consumption leading to the fastest mineralization of the ethylene glycol, resulting in decreasing of the decomposition rate of H2O2 while enhancing the generation rate of ferrous ions. 相似文献
5.
Yi-Fan Han Fengxi Chen Kanaparthi Ramesh Ziyi Zhong Effendi Widjaja Luwei Chen 《Applied catalysis. B, Environmental》2007,76(3-4):227-234
A new heterogeneous Fenton-like system consisting of nano-composite Mn3O4/SBA-15 catalyst has been developed for the complete oxidation of low concentration ethanol (100 ppm) by H2O2 in aqueous solution. A novel preparation method has been developed to synthesize nanoparticles of Mn3O4 by thermolysis of manganese (II) acetylacetonate on SBA-15. Mn3O4/SBA-15 was characterized by various techniques like TEM, XRD, Raman spectroscopy and N2 adsorption isotherms. TEM images demonstrate that Mn3O4 nanocrystals located mainly inside the SBA-15 pores. The reaction rate for ethanol oxidation can be strongly affected by several factors, including reaction temperature, pH value, catalyst/solution ratio and concentration of ethanol. A plausible reaction mechanism has been proposed in order to explain the kinetic data. The rate for the reaction is supposed to associate with the concentration of intermediates (radicals: OH, O2− and HO2) that are derived from the decomposition of H2O2 during reaction. The complete oxidation of ethanol can be remarkably improved only under the circumstances: (i) the intermediates are stabilized, such as stronger acidic conditions and high temperature or (ii) scavenging those radicals is reduced, such as less amount of catalyst and high concentration of reactant. Nevertheless, the reactivity of the presented catalytic system is still lower comparing to the conventional homogenous Fenton process, Fe2+/H2O2. A possible reason is that the concentration of intermediates in the latter is relatively high. 相似文献
6.
MgO/Al2O3 and NiO/MgO/Al2O3 solid bases were prepared by mixing method. The samples were characterized by X-ray diffraction (XRD), CO2 temperature-programmed desorption (CO2-TPD) and surface area measurements. After supported sulfonated cobalt phthalocyanine (CoPcS) the catalytic performance of these catalysts was evaluated in the mercaptan oxidation reaction. The effect of Mg/Al mole ratios on activity, crystal structure, basicity and stability in air was discussed. And the mechanism of the effect of NiO was identified. Results show that the base amount of MgO/Al2O3 increases with increasing Mg/Al mole ratio and catalyst with high Mg/Al mole ratio has a higher initial activity. NiO/MgO/Al2O3–CoPcS shows a higher initial activity and a much longer lifetime than MgO/Al2O3–CoPcS. When nickel oxide is doped into the MgO/Al2O3 support more crystal defects are generated, which increases the amount and types of basic sites. 相似文献
7.
The behavior of V=O band over V2O5 crystallite during NH3 adsorption and SCR reaction was characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and the results are correlated with the reactivity in NH3 oxidation and SCR reaction. It is found that the decrease of V=O band intensity is due either to the reduction of V2O5 surface and/or to the adsorption of ammonia. The 70% intensity of original V=O band is preserved up to 573 K under the conditions of SCR reaction. The vanadium oxidation state is about +4.4. When the temperature reached 673 K, almost all the V=O band was recovered. From these results, it can be suggested that the decrease of the apparent SCR activity due to the increase of NO amount through NH3 oxidation above 673 K be attributed to the increase of two neighboring V=O sites, which favor the NO formation in ammonia oxidation. 相似文献