Contribution to the hydrothermal synthesis of zeolite beta and its modifications with gallium

Zarama, Mery Carolina Pazos; Ríos, Jesús Sigifredo Valencia; Alba, María D.; Castro, Miguel

doi:10.1007/s10934-006-9029-7

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…They found the presence of Ga atoms in the tetrahedral positions in the zeolite framework by powder X-ray diffraction, 71 Ga MAS NMR, and IR spectroscopy . Zarama et al studied the hydrothermal synthesis of gallium-modified Beta zeolite and found that almost all the gallium atoms had been incorporated into the framework …”

Section: Introductionmentioning

confidence: 99%

“…8 Zarama et al studied the hydrothermal synthesis of gallium-modified Beta zeolite and found that almost all the gallium atoms had been incorporated into the framework. 9 The Ga-modified zeolites have many applications in the methanol conversion industry due to their excellent catalytic ability. 10−12 Jin et al investigated the catalytic performance of the MFI-type metallosilicates (M = Al, Fe, and Ga) for the methanol-to-olefin (MTO) reaction.…”

Section: Introductionmentioning

confidence: 99%

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Methanol to Propene over Gallium-Modified FAU Zeolite: Theoretical Study on the Polymethylbenzene and Alkene Cycles

Miao,

Sun,

Han

et al. 2024

J. Phys. Chem. C

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The catalytic performance of gallium-modified acidic FAU (Ga-FAU) zeolite in the methanol to propene (MTP) process was theoretically investigated by a two-layer ONIOM (our own N-layered integrated molecular orbital and molecular Mechanics) method. The whole MTP mechanism includes two cycles: the polymethylbenzene (polyMB) cycle and the alkene cycle. The polyMB cycle consists of the direct internal H-shift pathway, spiro pathway, methyl-transfer pathway, and paring pathway. Compared with the previous theoretical results on the MTP process on the pure acidic Si/Al FAU, the addition of Ga atoms into the Si/Al H-FAU could reduce the contribution of the polyMB cycle and increase the reactivity of the alkene cycle on the MTP process. A careful analysis of activation free energy barriers on the transition states (TSs) shows that the internal H-shift step is the ratedetermining step for the direct internal H-shift pathway and the paring pathway. The ratedetermining step for the spiro and methyl-transfer pathways is the methylation of the PMB molecule. The methylation of the propene molecule is the rate-determining step for the alkene cycle. The polyMB and alkene cycles have almost the same reactivity on the Ga-FAU zeolite. For the polyMB cycle, the different elementary steps are in the following order of reactivity: internal methyl transfer > deprotonation > C−C bond cracking > ring contraction > methylation > internal H-shift. The order in the alkene cycle is different: deprotonation > proton transfer > beta-scission > methylation. The differential charge density (DCD), local orbital locator (LOL), and reduced density gradient (RDG) revealed the direction of electron flow in different fragments in the TS structures and the nature of interactions between the fragments in the TSs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Methanol to Propene over Gallium-Modified FAU Zeolite: Theoretical Study on the Polymethylbenzene and Alkene Cycles

Miao,

Sun,

Han

et al. 2024

J. Phys. Chem. C

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“…For the synthesis of heteroatomic b zeolite, assistant agents, pretreatment procedures, and even special devices are indispensable. In Carolina's study [8], Ga-b zeolite was prepared by an unseeded hydrothermal synthesis using both sodium and potassium chlorides as assistant agents; Oumi et al [9] employed a post-synthesis route to incorporate Al and Ga into the framework of b zeolite via the treatment of the dealuminated zeolite by the bimetallic aqueous solutions with various Al/(Al ? Ga) ratios.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Catalytic Performance of the Framework-Substituted Manganese β Zeolite

Zhang

Liu

et al. 2010

Catal Lett

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The framework-substituted manganese b zeolite was synthesized by an unseeded hydrothermal method, using manganese nitrate, colloidal silica, sodium aluminate, and tetraethylammonium hydroxide as raw materials. The optimized synthetic conditions were obtained by adjusting the key synthesis parameters, such as SiO 2 /Al 2 O 3 ratio, TEAOH/SiO 2 ratio, pH value, crystallization temperature, and SiO 2 /MnO ratio. The resulting samples were characterized by powder XRD, UV-vis spectroscopy, nitrogen physical adsorption, and ICP, which complementarily demonstrate the incorporation of manganese into the zeolite framework. Tested in hydroisomerization of n-heptane as a carrier for Pt catalyst, the Mn-incorporated sample showed a very high selectivity for isomerized products 94.7% with a high conversion of n-heptane 71.1% at 230°C.

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Zeolite-β based molecular sieves: A potential catalyst for esterification of biomass derived model compound levulinic acid

Sahu

Sakthivel

2021

Materials Science for Energy Technologies

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Contribution to the hydrothermal synthesis of zeolite beta and its modifications with gallium

Cited by 3 publications

References 7 publications

Methanol to Propene over Gallium-Modified FAU Zeolite: Theoretical Study on the Polymethylbenzene and Alkene Cycles

Methanol to Propene over Gallium-Modified FAU Zeolite: Theoretical Study on the Polymethylbenzene and Alkene Cycles

Synthesis and Catalytic Performance of the Framework-Substituted Manganese β Zeolite

Zeolite-β based molecular sieves: A potential catalyst for esterification of biomass derived model compound levulinic acid

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