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Doctoral Thesis
DOI
10.11606/T.46.2003.tde-21122015-142529
Document
Author
Full name
Guintar Luciano Baugis
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2003
Supervisor
Committee
Oliveira, Wanda de (President)
Cerqueira, Henrique Soares
Constantino, Vera Regina Leopoldo
Schuchardt, Ulf Friedrich
Silva, Denise de Oliveira
Title in Portuguese
Estudo das interações entre vanádio e terras raras conjugados ao catalisador zeolítico para craqueamento
Keywords in Portuguese
Catalisador para craqueamento
Lantanídios (Estudo)
Polímeros (Química orgânica)
Terras raras (Estudo)
Vanádio
Abstract in Portuguese
No processo de craqueamento catalítico fluidizado do petróleo (FCC) ocorre o envenenamento do catalisador pelo V presente sob a forma de complexos, que se decompõem na etapa de regeneração resultando espécies que atacam estruturalmente a zeólita - o principal componente do sistema catalítico. O emprego de terras raras (TR) como passivadores do efeito deletério provocado pelo V neste processo é estudado no presente trabalho. Sob condições similares àquelas encontradas no processo de regeneração, tris-acetilacetonatos TR foram adicionados ao catalisador para craqueamento na presença de V em proporções estabelecidas. Os resultados da interação entre os componentes deste sistema foram analisados e observou-se que as TR têm razoável capacidade de inibir o ataque do V ao catalisador desativado, preservando parcialmente a conversão catalítica do material. Análises de propriedades texturais, luminescência e DRX indicaram que a inserção de TR por meio de complexos é mais efetiva que por meio de óxidos no método empregado, além de não influenciarem as propriedades originais do catalisador na ausência de V. Os resultados dos ensaios realizados por RPE, EFX, RMN 51>/sup>V e MEV-EED revelaram que a capacidade demonstrada pelas TR em neutralizar o V está associada à formação de TRVO4 termo-quimicamente estáveis nas condições estudadas. Em virtude da reduzida capacidade de permeação das TR através das partículas do catalisador, a interação ocorre preferencialmente na superficie das micro-esferas. Todas as TR foram encontradas no catalisador desativado no estado de oxidação (III) e o V no estado de oxidação (V). As TR estudadas apresentaram desempenhos ligeiramente diferentes, no que conceme à neutralização do V no sistema e o Y apresenta o melhor desempenho. Propôs-se, para este sistema um mecanismo que relaciona a capacidade de passivação da TR às propriedades termodinâmicas da reação com V.
Title in English
Study of interactions between vanadium and rare earth combined to zeolite catalyst for cracking
Keywords in English
Catalyst for cracking
lanthanide (Study)
Polymers (Organic Chemistry)
Rare Earth (Study)
Vanadium
Abstract in English
In the fluidized catalytic cracking process (FCC process) of petroleum, vanadium complexes present in the FCC feed cause catalyst poisoning. The decomposition of these complexes in the regeneration step produces species that attack the zeolite structure - the main active component in the catalytic system. This work evaluates the employment of rare earths (RE) as passivators to mitigate the deleterious effects ofthe V in the FCC feed. Controlled amounts of tris-acethylacetonate of RE were added to cracking catalyst containing V, under similar conditions to those of the regeneration process. The results of the interaction among the components of this system were analyzed and it was observed that RE have reasonable capacity to inhibit the V attack to the disabled catalyst, partially preserving the material catalytic conversion. Analyses of textural properties, luminescence and XRD indicated that the insertion of RE as complexes is more effective than as oxides in the methods employed. Also, they do not influence the catalyst original properties in the absence of V. The results of the experiments accomplished by EPR, XPS, 51V NMR and SEM-EDS revealed that the capacity demonstrated by RE to neutralize the V is associated with the formation of thermo chemically stable REVO4 at the test conditions. Due to the reduced capacity of RE penetration into the catalyst particles, the interaction happens preferentially in the surface of the micro spheres. All RE found in the catalyst were at the oxidation state (III) and the V at the oxidation state (V). The RE studied presented approximately the same performance in terms of V immobilization on the system and Y presents the best performance. For this system, a mechanism that relates the passivation capacity of RE to the thermodynamic properties of the reaction with V is proposed.
 
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Publishing Date
2015-12-21
 
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