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21.
Light cycle oil (LCO), a by-product of the fluid catalytic cracking (FCC) process in a petroleum refinery, can be used as a blendstock for the production of diesel and jet fuels. Regulatory and operational issues result in need for new and more active catalysts for the deep hydrodesulfurization (HDS) of diesel feedstocks, such as LCO. This paper reports the activity of a mesoporous molecular sieve MCM-41-supported Co-Mo catalyst in comparison to a commercial γ-alumina (Al2O3)-supported Co-Mo catalyst for the desulfurization of a LCO with a sulfur content of 2.19 wt.%. The HDS of dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene—polyaromatic sulfur compounds present in LCO—and their relative reactivities in terms of conversion were examined as a function of time on stream in a fixed-bed flow reactor. The MCM-41-supported catalyst demonstrates consistently higher activity for the HDS of the refractory dibenzothiophenic sulfur compounds, particularly 4,6-dimethyldibenzothiophene. The presence of a large concentration of aromatics in LCO appears to inhibit the HDS of the substituted dibenzothiophenes. 相似文献
22.
Mesoporous MCM-41 type silica spheres having a sub-micrometer size were synthesized following an adaptation of Stöber's method. This parent material was then functionalized with 3-aminopropyl triethoxysilane and with 3-propanonitrile triethoxysilane, followed by oxidation of the cyano-group to the corresponding carboxy-group. After proper characterization, the samples were loaded with cisplatin and subjected to in vitro tests in order to obtain the corresponding drug release profile. The carboxy-functionalized MCM-41 sample was found to show a release kinetics that should facilitate controlled drug delivery over a significantly larger time period (about 140 h) than both, unmodified MCM-41 and amino-functionalized MCM-41 samples. 相似文献
23.
Siting of Al atoms in the framework T sites, in zeolite rings and channel/cavity system, and the distribution of Al atoms between single Al atoms and close Al atoms in various Al-O-(Si-O)n-Al sequences in Si-rich zeolites represent key parameters controlling properties of counter ion species. Framework Al siting and distribution is not random or controlled by simple rules and depends on the conditions of the zeolite synthesis. Al in Al-O-(Si-O)2-Al in one 6-MR and single Al atoms predominate in Si-rich zeolites and their population can be varied to a large extent. The siting and distribution of framework Al atoms dramatically affect catalytic activity/selectivity both of protonic and transition metal ion-containing zeolite catalysts. 相似文献
24.
表面活性剂采用十六烷基三甲基溴化铵为活性成分,硅源采用正硅酸乙酯,利用低温水热法合成了MCM-4l介孔分子筛,采用动态吸附法将阿司匹林药物吸附到分子筛MCM-41的孔道中,吸附前后的介孔分子筛分别利用傅里叶红外光谱(IR)、紫外光谱(UV)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)等对吸附前后的分子筛进行了表征;借助紫外-可见吸收光谱(UV)研究了分子筛的最大吸附量、吸附时间、体外释放等。结果显示,所合成的分子筛MCM-41有序的介孔材料;MCM-4l用于药物阿司匹林的载体最大载药量为:45mg·g-1(m(药物)/m(载体))和良好的缓释效果。 相似文献
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MCM-41 materials were synthesized using alkyl(decosane, dodecyl)trimethyl ammonium bromide as structure directing surfactants. X-ray diffraction (XRD) analysis and nitrogen adsorption measurements reveal that the pores are hexagonal with tunable textural properties through the choice of surfactant and experimental condition. Poly(diphenylamine), PDPA was entrapped into the pores of MCM-41 by initial sorption of diphenylamine (DPA, monomer) in a medium (napthalein sulfonic acid) that provides self-assembling of DPA inside the pores and subsequent oxidative of polymerization with peroxydisulphate. Clear presence of an additional peak (around 9-10°) in XRD pattern for the DPA loaded MCM-41 provides evidence for self-assembled structure. Upon polymerization the self-assembly of DPA molecules resulted tubular PDPA inside the pores of MCM-41. PDPA thus formed shows different electronic property than the PDPA prepared by conventional method. XRD and FTIR spectroscopic analysis of PDPA loaded MCM-41 clearly informs that PDPA are entrapped in channels of MCM-41. 相似文献
29.
The CuO–MCM-48 catalysts prepared by wet impregnation technique were originally used as the catalysts, with high phenol conversion and diphenol selectivity, for phenol hydroxylation with hydrogen peroxide. Furthermore, the optimized reaction conditions over these catalysts for phenol hydroxylation were acquired. 相似文献
30.
Valeri?NaydenovEmail author Lubomira?Tosheva Johan?Sterte 《Journal of Porous Materials》2005,12(3):193-199
Self-bonded zeolite Beta/MCM-41 composite spheres were prepared using a two-step synthesis procedure. In the first step, mesoporous zeolite Beta spheres were obtained using anion exchange resin as macrotemplate. In the second step, the MCM-41 or Al-MCM-41 was grown both on sphere surfaces and in the pore structure of the pre-formed zeolite Beta spheres. Finally, the templating agents used in the synthesis of mesophase were removed by calcination leaving behind self-bonded Beta/MCM-41 composite spheres. Beta/MCM-41 composites were characterized by XRD, SEM and nitrogen adsorption measurements. Materials with controlled macroshape, composition and complex porosity were prepared by the approach. 相似文献