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High-temperature synthesis of SAPO-34 molecular sieve using a dry gel method

Particuology 2016年第4期14卷 61-65页

作者： yazdan rezaei Rouein Halladj Sima Askari Ali Tarjomannejad Tofan rezaei Department of Chemical Engineering Amirkcibir University of Technology (Tehran Polytechnic) P.O. Box 15875-4413 TehranIran Department of Chemical Engineering Science and Research Branch Islamic Azad University P.O. Box 14515. 775 Tehran Iran Department of Chemical Engineering &Petroleum University of Tabriz P.O. Box 51664-16471 Tabriz Iran Chemistry Department Islamic Azad University llam Branch P.O. Box 69319-86447 Ilam Iran

SAPO-34 is one of the main catalysts used in the petrochemical industry. Various effective methods have been developed to synthesize SAPO-34 with optimal size and characteristics for such application, In the present study, SAPO-34 was synthesized using a dry gel method at high temperatures. Morpholine was used as an organic template. The products were characterized by X-ray diffraction, field-emission scan- ning electron microscopy, energy-dispersive X-ray spectroscopy, and gas sorption analysis, The results showed that application of the dry gel method at high temperatures successfully afforded a pure catalyst with high crystallinity, Small particles of less than 500 nm could be obtained within a short reaction time of 30 min.

关键词： SAPO-34 Rapid High temperature Dry gel method Synthesis

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Radiative Heat Transfer and Thermocapillary Effects on the Structure of the Flow during Czochralski Growth of Oxide Crystals

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Advances in Chemical Engineering and Science 2015年第3期5卷 389-407页

作者： Reza Faiez yazdan rezaei Solid State Lasers Department Laser & Optics Research School Tehran Iran

A numerical study was carried out to describe the flow field structure of an oxide melt under 1) the effect of internal radiation through the melt (and the crystal), and 2) the impact of surface tension-driven forces during Czochralski growth process. Throughout the present Finite Volume Method calculations, the melt is a Boussinnesq fluid of Prandtl number 4.69 and the flow is assumed to be in a steady, axisymmetric state. Particular attention is paid to an undulating structure of buoyancy-driven flow that appears in optically thick oxide melts and persists over against forced convection flow caused by the externally imposed rotation of the crystal. In a such wavy pattern of the flow, particularly for a relatively higher Rayleigh number , a small secondary vortex appears nearby the crucible bottom. The structure of the vortex which has been observed experimentally is studied in some details. The present model analysis discloses that, though both of the mechanisms 1) and 2) end up in smearing out the undulating structure of the flow, the effect of thermocapillary forces on the flow pattern is distinguishably different. It is shown that for a given dynamic Bond number, the behavior of the melt is largely modified. The transition corresponds to a jump discontinuity in the magnitude of the flow stream function.

关键词： Numerical Simulation Fluid Flow Radiative Heat Transfer Thermocapillary Forces Czochralski Method Oxides

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