Iron contamination of FCC catalysts: Quantification of different crystalline phases and valence states

Two different methods of simulating iron contamination in a laboratory were studied. The catalysts were characterized using X-ray diffraction, N2 adsorption–desorption, and SEM-EDS. The catalyst performance was evaluated using an advanced cracking evaluation device. It was found that iron was evenly distributed in the catalyst prepared using the Mitchell impregnation method and no obvious iron nodules were found on the surface of the catalyst. Iron on the impregnated catalyst led to a strong dehydrogenation capacity and a slight decrease in the conversion and bottoms selectivity. The studies also showed that iron was mainly in the range of 1–5 μm from the edge of the catalyst prepared using the cycle deactivation method. Iron nodules could be easily observed on the surface of the catalyst. The retention of the surface structure in the alumina-rich areas and the collapse of the surface structure in the silica-rich areas resulted in a continuous nodule morphology, which was similar to the highly iron-contaminated equilibrium catalyst. Iron nodules on the cyclic-deactivated catalyst led to a significant decrease in conversion, an extremely high bottoms yield, and a small increase in the dehydrogenation capacity. The nodules and distribution of iron on the equilibrium catalyst could be better simulated by using the cyclic deactivation method.

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Valence state analysis of elements by EPMA and its application

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134752 ◽

1990 ◽

Vol 48 (2) ◽

pp. 230-231

Author(s):

Chen Liqing ◽

Liu Zuqin ◽

Zhang Wei

Keyword(s):

Valence State ◽

Line Intensities ◽

Valence States ◽

Valence Electrons ◽

Fe And Mn ◽

Intensity Ratios ◽

State Analysis

Valence state analyses of Fe and Mn in oxides by EPMA have been reported in literature. In this paper, the effects of valence state on intensity ratios ILα/IKα and ILα/ILβ of Cu, Ni, Co, Fe, Mn, Cr and their oxides, and on intensity ratios ILβ2/ILα1 and ILγ1/ILα1 of Mo, Nb, Zr and their oxides were studied. It was observed that intensity ratios change with valence states in accordance with some regularities, and these effects could be utilized for analyzing the valence states of catalysts.Valence state analysis of elements by EPMA is based on the fact that changes in the states of valence electrons in the outer shells of an atom cause corresponding changes in line intensities. The M electrons of Cu, Ni, Co, Fe, Mn, Cr and the N electrons of Mo, Nb, Zr are valence electrons. Line Kα1,2 and six lines of L are produced from the transitions of K-L2,3 and L-M or L-N respectively.

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Tracer diffusion in perfectly aligned liquid crystalline phases Kinetic theory and molecular dynamics simulations

Molecular Physics ◽

10.1080/00268979709482789 ◽

1997 ◽

Vol 91 (6) ◽

pp. 993-1003 ◽

Cited By ~ 1

Author(s):

ANJALI KHARE ◽

DAVID KOFKE ◽

GLENN EVANS

Keyword(s):

Molecular Dynamics ◽

Kinetic Theory ◽

Molecular Dynamics Simulations ◽

Liquid Crystalline ◽

Tracer Diffusion ◽

Crystalline Phases ◽

Liquid Crystalline Phases ◽

Dynamics Simulations

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Valence states of O2 Feynman's way

Molecular Physics ◽

10.1080/00268979609482559 ◽

1996 ◽

Vol 89 (5) ◽

pp. 1577-1602 ◽

Cited By ~ 4

Author(s):

THOMAS SORENSEN ◽

WALTER ENGLAND

Keyword(s):

Valence States

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Hydrothermal Synthesis and Solid-State Laser Refrigeration of Ytterbium-Doped Potassium Lutetium Fluoride (KLF) Microcrystals

10.26434/chemrxiv.12330737.v3 ◽

2020 ◽

Author(s):

Xiaojing Xia ◽

Anupum Pant ◽

Xuezhe Zhou ◽

Elena Dobretsova ◽

Alex Bard ◽

...

Keyword(s):

Hydrothermal Synthesis ◽

Solid State ◽

Information Science ◽

Point Group ◽

Solid State Laser ◽

Lanthanide Ions ◽

Group Symmetry ◽

Luminescence Spectra ◽

Crystalline Phases ◽

State Laser

Fluoride crystals, due to their low phonon energies, are attractive hosts of trivalent lanthanide ions for applications in upconverting phosphors, quantum information science, and solid-state laser refrigeration. In this article, we report the rapid, low-cost hydrothermal synthesis of potassium lutetium fluoride (KLF) microcrystals for applications in solid-state laser refrigeration. Four crystalline phases were synthesized, namely orthorhombic K2LuF5 (Pnma), trigonal KLuF4 (P3121), orthorhombic KLu2F7 (Pna21), and cubic KLu3F10 (Fm3m), with each phase exhibiting unique microcrystalline morphologies. Luminescence spectra and emission lifetimes of the four crystalline phases were characterized based on the point-group symmetry of trivalent cations. Laser refrigeration was measured by observing both the optomechanical eigenfrequencies of microcrystals on cantilevers in vacuum, and also the Brownian dynamics of optically trapped microcrystals in water. Among all four crystalline phases, the most significant cooling was observed for 10%Yb:KLuF4 with cooling of 8.6 $\pm$ 2.1 K below room temperature. Reduced heating was observed with 10%Yb:K2LuF5

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On definition of electronegativity within the framework of MO methods

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19821479 ◽

1982 ◽

Vol 47 (5) ◽

pp. 1479-1485 ◽

Cited By ~ 4

Author(s):

Robert Ponec

Keyword(s):

Valence States ◽

Cndo Approximation ◽

Definition Of

The possibility of generalization of the electronegativity concept to valence states of atom in molecule has been studied by semiempirical CNDO and INDO approximations. It is shown that the concept of electronegativity as the property of a given atom in molecule can be defined only on the basis of the simplest CNDO approximation.

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The model rotator phase

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19880889 ◽

1988 ◽

Vol 53 (5) ◽

pp. 889-902

Author(s):

Josef Šebek

Keyword(s):

High Temperature ◽

Partition Function ◽

Conformational Flexibility ◽

Small Probability ◽

Crystalline Phases ◽

Rotator Phase

It is shown that the formation of the so-called rotator phase of alkanes (one of the high temperature crystalline phases) might be connected with a partial increase of the conformational flexibility of chains. The conformations with higher number of kinks per chain, which have been neglected till now, are shown to contribute effectively to the conformational partition function. Small probability of these states given by the Boltzmann exponent is compensated by a large number of ways in which they can be distributed along the chain. The deduced features of the rotator phase seem to be in agreement with the experimentally observed properties.

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Valence states of atoms and their conversions

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19841247 ◽

1984 ◽

Vol 49 (5) ◽

pp. 1247-1261 ◽

Cited By ~ 9

Author(s):

Jaroslav Koča ◽

Milan Kratochvíl ◽

Milan Kunz ◽

Vladimír Kvasnička

Keyword(s):

Chemical Reactions ◽

Computer Assisted ◽

Efficient Tool ◽

Common Features ◽

Systematic Application ◽

Organic Syntheses ◽

Valence States ◽

Algebraic Formalism

The algebraic formalism for the description of valence states of atoms and their interconversions is elaborated. It offers a possibility to construct and trace mechanistic paths of chemical reactions, the problem of which is of great importance in computer-assisted organic syntheses. Its systematic application gives exhaustive lists of possible mechanistic paths, and furthermore, very efficient tool to classify chemical reactions and look for their common features.

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