نتایج جستجو برای: pentasil zeolites
تعداد نتایج: 4917 فیلتر نتایج به سال:
Hydrophobically modified Y-zeolites were prepared by simple modification with triethoxyfluorosilane (TEFS). These zeolites, used as supports, enhanced the efficiency of deposited TiO(2) for the photocatalytic degradation of organics diluted in water.
Zeolites have potential application as ion-exchangers, catalysts and molecular sieves. Zeolites are once again drawing attention in Japan as stable adsorbents and solidification materials of fission products, such as (137)Cs(+) from damaged nuclear-power plants. Although there is a long history of scientific studies on the crystal structures and ion-exchange properties of zeolites for practical...
Incorporation of germanium in zeolites is well known to confer static flexibility to their framework, by stabilizing the formation of small rings. In this work, we show that the flexibility associated to Ge atoms in zeolites goes beyond this static effect, manifesting also a clear dynamic nature, in the sense that it leads to enhanced molecular diffusion. Our study combines experimental and the...
Frameworks of precisely defined pores with diameters matching the size of small molecules endow crystalline zeolites with valuable size- and shape-selectivity. Being important selective adsorbers and separators, zeolites are also indispensable as solid acids in size-selective catalysis. However, despite being extremely beneficial, micropores impose restrictions on the mass transport of reactant...
the purpose of this study was to find a relatively inexpensive method for removal of arsenate and arsenite from drinking water. the capability of iranian natural clinoptilolites, relevant synthetic zeolites a and p and iron(п) modified of them was investigated for the uptake of arsenic anions from drinking water. data obtained from ion-exchange using batch (static) technique showed that among t...
amygdaloidal, cavity- and fracture-filling zeolites in eocene volcanic rocks from the kuh-e-aradeh of southern kahrizak, in the northernmost part of central iran have been studied in some detail by optical, chemical analysis, sem, and xrd techniques. the zeolites identified, in order of their relative time of formation from early to late, are tetranatrolite, analcime, natrolite, mesolite, stilb...
Lewis acidic zeolites are used to synthesize unsaturated dicarboxylic acid esters via aldol condensation of keto esters. Hafnium-containing BEA (Hf-BEA) zeolites catalyze the condensation of ethyl pyruvate into diethyl 2methyl-4-oxopent-2-enedioate and diethyl 2-methylene-4oxopentanedioate (an itaconic acid ester analogue) with a selectivity of ca. 80% at ca. 60% conversion in a packed-bed reac...
Application of high resolution electron microscopy (HREM) to the study of Pt-Sn/y-Al20 3 supported catalyst, zeolites, iron catalyst for ammonia synthesis, rare-earth oxide catalysts, etc., is described. Micro-twins, dislocations and other crystallographic imperfections are observed. Moreover, the structure images of channels representing columns of cages in several kinds of zeolites as well as...
—A machine learning approach is applied to classify zeolite crystals according to their framework type. The Zeolite-Structure-Predictor is introduced based on the Random Forest algorithm. Zeolites structural data from the Inorganic Crystal Structure Database (ICSD) are used to train the model. The ZSP uses sixteen attributes including topological descriptors obtained with statistical geometry a...
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