نتایج جستجو برای: hierarchical zsm 5 zeolite
تعداد نتایج: 1308277 فیلتر نتایج به سال:
Non-oxidative dehydroaromatization of methane (MDA) is a promising catalytic process for direct valorization of natural gas to liquid hydrocarbons. The application of this reaction in practical technology is hindered by a lack of understanding about the mechanism and nature of the active sites in benchmark zeolite-based Mo/ZSM-5 catalysts, which precludes the solution of problems such as rapid ...
Zeolite ZSM-5 presents a great source of interest in catalysis because of its shape selective properties. The absence of a relationship between the template size and shape of the structure generated during the synthesis of zeolites is illustrated by the case of ZSM-5. In this study, we have investigated the role of ethanol, methyltriphenylphosphonium bromide (MTPBr) and cetyltrimethylammonium b...
ZnO modified ZSM-5 and Y zeolites are synthesized by performing atomic layer deposition (ALD) of ZnO to HZSM-5 and HY using diethyl zinc and water as the precursors. The surface area and pore volume of ZSM-5 and Y zeolites are progressively reduced with the increasing number of ZnO ALD cycles. XRD and SEM characterization methods show that highly dispersed ZnO species are deposited on the inter...
1. Introduction Mesoporous UL-ZSM-5 materials have zeolitic structure in the form of nano-particles inter-grown in the walls of the amorphous wormhole-like aluminosilicate mesoporous precursor, and were shown to exhibit an intermediate acidity between the parent mesoporous precursor and ZSM-5 zeolite [1,2]. These materials combine the advantages of both, i.e., microporous crystalline zeolites (...
The catalytic activity of large zeolite H-ZSM-5 crystals in methanol (MTO) and ethanol-to-olefins (ETO) conversions was investigated and, using operando UV/Vis measurements, the catalytic activity and deactivation was correlated with the formation of coke. These findings were related to in situ single crystal UV/Vis and confocal fluorescence micro-spectroscopy, allowing the observation of the s...
A detailed and systematic polarized confocal fluorescence microscopy investigation is presented on three batches of large coffin-shaped ZSM-5 crystals (i.e., parent, steamed at 500 °C, and steamed at 700 °C). In total, six laser lines of different wavelength in the visible region are employed on two crystal positions and three orientations with respect to the polarization plane of the excitatio...
Desilication of commercial MFI-type (ZSM-5) zeolites in solutions of alkali metal hydroxides is demonstrated to generate highly selective heterogeneous catalysts for the aqueous-phase isomerization of biobased dihydroxyacetone (DHA) to lactic acid (LA). The best hierarchical ZSM-5 sample attains a LA selectivity exceeding 90 %, which is comparable to that of the state-of-the-art catalyst (i.e.,...
The catalytic conversion of palm oil was carried out over four zeolite catalysts—Y, ZSM-5, Y-ZSM-5 hybrid, and Y/ZSM-5 composite—to produce jet biofuel with high amount alkanes low aromatic hydrocarbons. hybrid catalyst synthesized using crystalline Y as the seed for growth ZSM-5. Synthesized catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field-emiss...
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