Continuous flow ZIF-8/NaA composite membrane microreactor for efficient Knoevenagel condensation

A ZIF-8/NaA composite membrane microreactor was fabricated on multi-channel stainless steel plate. NaA zeolite membrane was first introduced into the microchannel as a modification layer via a secondary growth. Subsequently, a layer of ZIF-8 membrane was grown over the NaA zeolite layer as a catalytic layer by using ZnO-induced synthesis method. Such ZIF-8/NaA composite membrane microreactor was applied in continuous flow Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate. Nearly 100% product yield was achieved in a short residence time under mild conditions. Importantly, no obvious deactivation was observed even after 50 h, indicating its excellent stability. (C) 2015 Elsevier B.V. All rights reserved

Preparation of alkali-resistant, Sil-1 encapsulated nickel catalysts for direct internal reforming-molten carbonate fuel cell

A thin layer of silicalite-1 zeolite membrane was grown on the surface of Ni/SiO2 and Ni/Al2O3 catalyst beads after seeding and secondary regrowth to create core-shell catalysts that are resistant to alkali poisoning from direct internal reforming-mol ten carbonate fuel cell (DIR-MCFC). The zeolite shell thickness was optimized to prevent poisoning and minimize diffusion resistance. An out-of-cell test was designed to simulate the fuel cell operating conditions, which showed that the new core-shell catalysts maintained a high activity similar to the original fresh catalyst in spite of the exposure to alkali vapor at high temperature. The conventional Ni/SiO2 and Ni/Al2O3 catalysts suffered higher than 80\% decrease in activity for steam reforming of methane reaction (SRM). (c) 2009 Elsevier B.V. All rights reserved

A new alkali-resistant Ni/Al2O3-MSU-1 core-shell catalyst for methane steam reforming in a direct internal reforming molten carbonate fuel cell

An alkali-resistant catalyst for direct internal reforming molten carbonate fuel cell (DIR-MCFC) is prepared by growing a thin shell of mesoporous MSU-1 membrane on Ni/Al2O3 catalyst beads. The MSU-1 shell is obtained by first depositing a monolayer of colloidal silicalite-1 (Sil-1) on the catalyst bead as linkers and then using NaF stored in the beads to catalyze the growth of the MSU-1 layer. The resulting core-shell catalysts display excellent alkali-resistance and deliver stable methane conversion and hydrogen yield in an out-of-cell test simulating the operating conditions of an operating DIR-MCFC. Higher conversion and yield (i.e., up to over 70%) are obtained from the new core-shell catalyst with MSU-1 shell compared to the catalyst with microporous Sil-1 shell. A mathematical model of the reaction and poisoning of the core-shell catalyst is used to predict the optimum shell thickness for its reliable use in a DIR-MCFC. (C) 2013 Elsevier B.V. All rights reserved

A novel silicalite-1 zeolite shell encapsulated iron-based catalyst for controlling synthesis of light alkenes from syngas

A well-designed zeolite capsule catalyst with a Core (Fe/SiO(2))-Shell (Silicalite-1) structure was successfully prepared by zeolite seeding and then zeolite shell growing via secondary hydrothermal method. The characterization on this zeolite capsule catalyst indicated that it had a compact, defect-free zeolite shell enwrapping core catalyst tightly. The application of this zeolite capsule catalyst was the direct synthesis of light alkenes from syngas via Fischer-Tropsch synthesis (FTS) reaction. This zeolite capsule catalyst exhibited excellent abilities compared with the traditional FTS catalyst, both on the controlled synthesis of the desirable light alkenes and the suppressing formation of the undesired long-chain hydrocarbons. (C) 2011 Elsevier B.V. All rights reserved

Preparation of titanium silicalite-1 catalytic films and application as catalytic membrane reactors

Titanium silicalite-1 (TS-1) films were prepared on porous alpha-Al2O3 tubes using nanosized silicalite-1 (Sil-1) particles as seeds by hydrothermal treatment and a TS-1 catalytic membrane reactors (CMR) was reasonably designed and evaluated by phenol hydroxylation with hydrogen peroxide as oxidant. Some factors on influencing TS-1 film formation and catalytic properties were investigated and the TS-1 films were characterized by scanning electron microscope (SEM), transmission electron micrograph (TEM), X-ray diffractometer (XRD), FTIR, UV-vis and X-ray fluorescence (XRF). It was indicated that TS-1 films prepared from Sil-1 and TS-1 seeds were comparable in structure, morphology and reaction behavior. The crystallization time and times of TS-1 film had a strong effect on its morphology, thickness and orientation. However, the film thickness could be easily controlled by crystallization time and times. The Ti/Si ratio in synthesis solution intensely influenced the content of the titanium atoms incorporated as framework Ti that was correlated well with the activity. The maximum Ti (IV) incorporated corresponds to a Ti/Si ratio of approximately 0.02-0.03. A constant conversion for phenol hydroxylation was obtained with the film thickness of over 7.5 mu m. It is demonstrated that most of the reaction occurred in a shallow layer near the film due to the mass transfer effects in the TS-1 films. (C) 2009 Elsevier B.V. All rights reserved

A rapid synthesis route for Sn-Beta zeolites by steam-assisted conversion and their catalytic performance in Baeyer-Villiger oxidation

Sn-Beta zeolites were prepared by a rapid and clean steam-assisted conversion (SAC) method from dry stannosilicate gel. The amorphous gel was converted to highly crystalline Sn-Beta within 5 h at mild reaction temperature of 453 K. The properties of the as-prepared samples were characterized by XRD, SEM, UV-Vis, UV-Raman, ICP and N-2 adsorption. A high gel conversion to BEA can be obtained with Sn4+ inserted in the zeolite framework. The SAC method was successfully used to produce pure silica Beta zeolite (Si/Sn = infinity) to Sn-Beta zeolite with 3.8 wt.% SnO2 (i.e., Si/Sn = 83). The Sn-Beta prepared by SAC method is an efficient catalyst for Baeyer-Villiger (B-V) reaction of cyclohexanone to epsilon-caprolactone. (C) 2012 Elsevier B.V. All rights reserved