scholarly journals Zeolite Y: Synthesis, Modification, and Properties—A Case Revisited

2014 ◽  
Vol 2014 ◽  
pp. 1-20 ◽  
Author(s):  
Wolfgang Lutz
Keyword(s):  
Catalytic Properties ◽  
Zeolite Y ◽  
Pore System ◽  
Y Zeolites ◽  
Zeolite Structure ◽  
Open Questions ◽  
Catalytic Behaviour ◽  
Aluminium Species ◽  
Secondary Pore ◽  
Cracking Catalysts

Y zeolites dealuminated by steaming were introduced as fluid-cracking catalysts in the year 1970. Extensive research has been done to develop suitable dealumination techniques, to investigate crystal structure, and to characterize catalytic behaviour. However, the origin of the secondary pore system formed in the zeolite structure during dealumination process remained completely obscure over a period of four decades. Open questions concerned also the existence of extraframework siliceous admixture in addition to extraframework aluminium species which can dramatically change the catalytic properties of these zeolites. This paper gives a review on the synthesis of DAY materials and provides some answers to several open questions.

Changes in Physico-Chemical and Catalytic Properties of Synthetic Erionite after Various Treatment

1992 ◽  
Vol 57 (4) ◽  
pp. 845-852 ◽  
Author(s):  
Pavol Hudec ◽  
Jozef Novanský ◽  
Anna Bučinská ◽  
Štefan Morávek ◽  
Zdenek Židek
Keyword(s):  
Alkali Metals ◽  
Catalytic Properties ◽  
X Ray Diffraction ◽  
Ammonium Ions ◽  
Pore System ◽  
X Ray ◽  
Physico Chemical ◽  
Metals Extraction ◽  
Hcl Solution ◽  
Secondary Pore

Influence of decationization by ammonium ions and dealumination by HCl as well as calcination under self-steaming conditions at 1053 K with following treatment by ammonium ions or by HCl solution on the extent of alkali metals extraction was studied together with surface, sorption, acidic and catalytic properties of synthetic erionite. Samples were also characterized by X-ray diffraction spectra and IR skeletal vibration spectra. Results showed increasing catalytic activity and acidity after thermal treatment, followed by ion exchange with HCl or ammonium ions, which can be connected with deeper substitution of potassium cations of erionite. At the same time by the treatment under self-steaming conditions, as a result of framework dealumination, the zeolite obtained a secondary pore system, which resulted in increasing sorption capacity for aromatics, suppression of coking during o-xylene conversion and also increased diffusion of Hammet indicators into the zeolite.

Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

1996 ◽  
Vol 54 ◽  
pp. 866-867
Author(s):  
H. Kinney ◽  
M.L. Occelli ◽  
S.A.C. Gould
Keyword(s):  
Surface Roughness ◽  
Zeolite Y ◽  
Atomic Level ◽  
Microporous Structure ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Roughness Measurements ◽  
Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

Insight into tri-coordinated aluminum dependent catalytic properties of dealuminated Y zeolites in oxidative desulfurization

2021 ◽  
Vol 288 ◽  
pp. 120022
Author(s):  
Zhiguo Zhu ◽  
Haikuo Ma ◽  
Weiping Liao ◽  
Pengpeng Tang ◽  
Kaixuan Yang ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Oxidative Desulfurization ◽  
Y Zeolites ◽  
Insight Into

Structural and Catalytic Properties of the Alkali Metal Ion-Exchanged Y-Zeolites by 29Si and 27Al Solid-State NMR and FT-IR Spectroscopy

2005 ◽  
Vol 277-279 ◽  
pp. 708-719
Author(s):  
Chang Seop Lee ◽  
Hee Jung Lee ◽  
Sung Woo Choi ◽  
Jahun Kwak ◽  
Charles H.F. Peden
Keyword(s):  
Solid State ◽  
Alkali Metal ◽  
Photoelectron Spectroscopy ◽  
Metal Ion ◽  
Nmr Spectra ◽  
Catalytic Properties ◽  
Nox Reduction ◽  
29Si Nmr ◽  
Y Zeolites ◽  
X Ray

A series of cation exchanged Y-zeolites were prepared by exchanging cations with various alkali (M+, M= Li, Na, K, Cs) metals. The structural and catalytic properties of the alkali metal exchanged Y-zeolites have been investigated by a number of analytical techniques. Comparative elemental analyses were determined by an Energy Dispersive Spectroscopy X-ray (EDS), X-ray Photoelectron Spectroscopy (XPS), Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and X-ray Fluorescence (XRF) before and after cation substitution. The framework and non-framework Al coordination and the Si/Al ratios of the Y-zeolites were investigated by MAS Solid-State Nuclear Magnetic Resonance (NMR) spectroscopy. The Al NMR spectra were characterized by two 27Al resonance signals at 12 and 59 ppm, indicating the presence of the non-framework and framework Al respectively. The intensities of these resonances were used to monitor the amount of the framework and non-framework Al species in the series of exchanged zeolites. The 29Si NMR spectra were characterized by four resonance signals at -79, -84, -90, and -95 ppm. Changing the alkali metal cations in the exchanged Y-zeolites significantly altered the extent of the octahedral/tetrahedral coordination and the Si/Al ratio. The Fourier Transform Infrared spectra of the CO2 adsorbed on to the exchanged Y-zeolites showed a low frequency shift, as the atomic number of the exchanged alkali metal increased. In addition, the catalytic activity of these samples for NOx reduction were tested in combination with a non-thermal plasma technique and interpreted based on the above structural and spectroscopic information.

Influence of Acid Wash on the Structural and Catalytic Properties of the Hierarchical Zeolite Y

2016 ◽  
Vol 1 (5) ◽  
pp. 934-939 ◽  
Author(s):  
Wenlin Li ◽  
Chunyan Tu ◽  
Jinyu Zheng ◽  
Yibin Luo ◽  
Zhijian Da
Keyword(s):  
Catalytic Properties ◽  
Zeolite Y ◽  
Hierarchical Zeolite ◽  
Acid Wash

Effect of Li, Na, K and Cs on Vacuum Decomposition of Tetraammineplatinum(II) in Zeolites. Catalytic Activity in CO + NO Reaction

1995 ◽  
Vol 60 (3) ◽  
pp. 428-442 ◽  
Author(s):  
Jana Nováková ◽  
Libor Brabec ◽  
Ludmila Kubelková
Keyword(s):  
Catalytic Activity ◽  
Decomposition Rate ◽  
Reaction Rate ◽  
Hydrogen Reduction ◽  
Pt Catalyst ◽  
Y Zeolites ◽  
Oxygen Layer ◽  
Zeolite Structure ◽  
X Zeolites ◽  
Vacuum Decomposition

[Pt(NH3)4]2+ ions were exchanged for alkali (Li, Na, K and Cs) in -X and -Y zeolites and decomposed in vacuum. TPR after this decomposition showed that autoreduction accompanying this process reduced roughly 2/3 of all Pt2+ to Pt0. The extent of the autoreduction rose with the ammonia pressure over the zeolite. The decomposition rate increased with increasing electropositivity of the alkali ion and this effect completely overlapped that of the zeolite structure. The CO + NO reaction rate also increased from Li to Cs, but -X zeolites were substantially more active than the -Y ones. Oxygen layer on the resulting Pt catalyst affected positively the reaction rate. The dispersion of Pt particles was relatively low, when compared to that obtained by decomposition of the Pt tetraammine complex in oxygen followed by hydrogen reduction. However, the reaction rate was higher.

Adsorption and catalytic properties of MCM-22: The influence of zeolite structure

Zeolites ◽  
1996 ◽  
Vol 16 (1) ◽  
pp. 7-14 ◽  
Author(s):  
A. Corma ◽  
C. Corell ◽  
J. Pérez-Pariente ◽  
J.M. Guil ◽  
R. Guil-López ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Zeolite Structure

Mesohaem substitution reveals how haem electronic properties can influence the kinetic and catalytic parameters of neuronal NO synthase

2010 ◽  
Vol 433 (1) ◽  
pp. 163-174 ◽  
Author(s):  
Jesús Tejero ◽  
Ashis Biswas ◽  
Mohammad Mahfuzul Haque ◽  
Zhi-Qiang Wang ◽  
Craig Hemann ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Kinetic Parameters ◽  
Catalytic Properties ◽  
No Synthase ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Midpoint Potential ◽  
Transporter Protein ◽  
Catalytic Behaviour ◽  
Synthesis Activity

NOSs (NO synthases, EC 1.14.13.39) are haem-thiolate enzymes that catalyse a two-step oxidation of L-arginine to generate NO. The structural and electronic features that regulate their NO synthesis activity are incompletely understood. To investigate how haem electronics govern the catalytic properties of NOS, we utilized a bacterial haem transporter protein to overexpress a mesohaem-containing nNOS (neuronal NOS) and characterized the enzyme using a variety of techniques. Mesohaem-nNOS catalysed NO synthesis and retained a coupled NADPH consumption much like the wild-type enzyme. However, mesohaem-nNOS had a decreased rate of Fe(III) haem reduction and had increased rates for haem–dioxy transformation, Fe(III) haem–NO dissociation and Fe(II) haem–NO reaction with O2. These changes are largely related to the 48 mV decrease in haem midpoint potential that we measured for the bound mesohaem cofactor. Mesohaem nNOS displayed a significantly lower Vmax and KmO2 value for its NO synthesis activity compared with wild-type nNOS. Computer simulation showed that these altered catalytic behaviours of mesohaem-nNOS are consistent with the changes in the kinetic parameters. Taken together, the results of the present study reveal that several key kinetic parameters are sensitive to changes in haem electronics in nNOS, and show how these changes combine to alter its catalytic behaviour.

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