Topic
MCM-41
About: MCM-41 is a research topic. Over the lifetime, 2355 publications have been published within this topic receiving 91416 citations.
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TL;DR: A series of alkali metal and nickel-exchanged Al-MCM-41 catalysts were prepared via aqueous ion exchange and then investigated for gas-phase oligomerization of propene at 453 K and near ambient pressures as discussed by the authors.
Abstract: A series of alkali metal- and nickel-exchanged Al-MCM-41 catalysts were prepared via aqueous ion exchange and then investigated for gas-phase oligomerization of propene at 453 K and near ambient pressures. All catalysts were active and produced oligomers with >98% selectivity. The highest activities per Ni2+ cation were observed when the cations were highly dispersed as a consequence of either lowering the Ni loading for a fixed MCM-41 Si/Al ratio or by decreasing the concentration of exchangeable sites within the material by increasing the MCM-41 Si/Al ratio at a fixed Ni loading. The identity of the alkali metal cation had no significant effect on the catalytic activity or degree of dimer branching, except for the sample containing Cs+ cations, where the decreased pore volume resulted in a lower catalyst activity and slightly more linear dimer products. Comparison of Ni-MCM-41 prepared with and without Na+ cations showed that a higher yield of oligomers could be achieved when Na+ cations are present bec...
40 citations
TL;DR: In this article, the deposition-precipitation (DP) method was used for the preparation of Ni/SiMCM-41 and Ni/AlMCM41 catalysts with different DP times (1−4 h).
Abstract: The deposition−precipitation (DP) method was used for the preparation of Ni/SiMCM-41 and Ni/AlMCM-41 catalysts with different DP times (1−4 h), and the catalysts were characterized by BET, XRD, TPR, FTIR spectroscopy, and TEM. On both types of catalysts, the Ni(II) phases formed are a mixture of 1:1 nickel phyllosilicate and Ni(OH)2. The quantity of each phase at the end of the deposition process determines the final Ni particle size; i.e., greater amounts of Ni(OH)2 lead to larger Ni particles. In addition, it was found that the presence of aluminum in the framework of MCM-41 delays the formation of the nickel hydrosilicate phase. As a result of the consumption of the siliceous pore walls during DP, the long-range order of the MCM-41 hexagonal pore structure is gradually lost. Catalytic activity in the hydrogenation of naphthalene was higher for Ni/SiMCM-41 catalysts and was a linear function of the exposed area of Ni particles.
40 citations
TL;DR: In this article, transmission electron microscopy of purely siliceous and gallosilicate mesoporous molecular sieves MCM-41 showed that the neighbouring crystal edges meet at the angle of 120°, thus suggesting the most likely mechanism of crystal growth.
40 citations
TL;DR: The MCM-41 sample prepared in this study exhibited well defined long-range order and good hydrothermal stability and it was demonstrated that reducing the time of self-assembly step to 2 h during the synthesis had no unfavorable effect on the quality of MCM.
40 citations
TL;DR: In this article, the effect of dodecylamine in the direct synthesis of MCM-41 silica bearing propylthiol groups, and using cetyltrimethylammonium bromide as surfactant, is studied.
40 citations