Deactivation Routes in Zeolite Catalyzed Isobutane/2-butene Alkylation and Regeneration Procedures PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Deactivation Routes in Zeolite Catalyzed Isobutane/2-butene Alkylation and Regeneration Procedures PDF full book. Access full book title Deactivation Routes in Zeolite Catalyzed Isobutane/2-butene Alkylation and Regeneration Procedures by Iker Zuazo. Download full books in PDF and EPUB format.
Author: Iker Zuazo
Publisher:
ISBN:
Category :
Languages : en
Pages : 214
Get Book Here
Book Description
Author: Iker Zuazo
Publisher:
ISBN:
Category :
Languages : en
Pages : 214
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The aim of this thesis was to understand the routes of deactivation of iso-butane / 2-butene alkylation on faujasitic zeolites and to correlate the alkylation performance with the physicochemical properties of the zeolite used. It was also under the scope of this thesis, to propose a reaction/regeneration mechanism that ensures a successful and continuous operation. It could be shown that the avoidance of structural damage occurring during the modification procedure is the key factor for suitable alkylation catalyst. A successful catalyst for alkylation has to posses a high concentration of strong Brønsted acid sites and a low concentration of Lewis acid sites. It could be shown that during the alkylation reaction a high quality alkylate was produced that was practically free of unsaturated compounds and aromatics, even at times close to deactivation. It could be shown that the accumulated deposits in the pores of the catalyst were mainly formed by highly branched paraffinic compounds following a (CH2)3 series and with molecular weights from 128 g/mol to 548 g/mol. The deposits formed inside the pores of the catalyst were a result of propene oligomerization. Superior catalysts showed lower masses in the deposits with a maximum at C12-C15 while inferior catalysts showed a maximum at C24-C27. Low amounts of olefins and aromatics were also found in the deposits. Small amounts of C12H26 and C16H34 from multiple alkylation were also detected in the deposits. Cyclic compounds and aromatics were formed on the surface of the catalyst as observed by MALDI-TOF. These types of compounds were not detected when the zeolite was dissolved in HF and the coke molecules extracted with methylene chloride. Therefore, their concentration was low within the total concentration of deposits. These types of molecules were responsible for pore mouth plugging on the surface of the catalyst. The size of the molecules detected by MALDI- TOF increased with time-on-stream for all catalyst. They w.
Author: Andreas Feller
Publisher:
ISBN:
Category :
Languages : en
Pages : 146
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
In this thesis, the isobutane/2-butene alkylation was studied on lanthanum-exchanged zeolite X in a CSTR-type slurry reactor. Catalysts with a high concentration of strong Brønsted acid sites and a high Brønsted to Lewis acid site ratio exhibited higher active catalytic lifetimes than samples with lower ratios. Isobutane self-alkylation activity was also increasing with increasing Brønsted/Lewis ratio. The integral productivity of the catalysts was found to be independent of the butene space velocity. The catalysts deactivated by the buildup of highly unsaturated polymers, which strongly adsorbed on the acid sites and blocked them for further reactions. With increasing reaction temperature, the deposits were increasingly aromatic.
Author: Michel Guisnet
Publisher: World Scientific Publishing Company
ISBN: 1911299530
Category : Science
Languages : en
Pages : 359
Get Book Here
Book Description
In chemical processes, the progressive deactivation of solid catalysts is a major economic concern and mastering their stability has become as essential as controlling their activity and selectivity. For these reasons, there is a strong motivation to understand the mechanisms leading to any loss in activity and/or selectivity and to find out the efficient preventive measures and regenerative solutions that open the way towards cheaper and cleaner processes. This book covers the fundamental and applied aspects of solid catalyst deactivation in a comprehensive way and encompasses the state of the art in the field of reactions catalyzed by zeolites. This particular choice is justified by the widespread use of molecular sieves in refining, petrochemicals and organic chemicals synthesis processes, by the large variety in the nature of their active sites (acid, base, acid-base, redox, bifunctional) and especially by their peculiar features, in terms of crystallinity, structural order and textural properties, which make them ideal models for heterogeneous catalysis. The aim of this book is to be a critical review in the field of zeolite deactivation and regeneration by collecting contributions from experts in the field which describe the factors, explain the techniques to study the causes and suggest methods to prevent (or limit) catalyst deactivation. At the same time, a selection of commercial processes and exemplar cases provides the reader with theoretical insights and practical hints on the deactivation mechanisms and draws attention to the key role played by the loss of activity on process design and industrial practice./a
Author: Eric C. Burckle
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The acid catalyzed alkylation of isobutane with 2-butene is an effective method of obtaining highly branched C8 paraffins whose octane numbers are quite high. Zeolite-based catalysts have shown excellent initial selectivity, but their activity decreases quickly with time on stream. This deactivation is a result of two factors: acid site blockage and pore blockage. Product molecules are unable to desorb from the acid site because of a diminished hydride transfer capability, thus preventing further alkylation at the active site. The formation of coke (large carbonaceous compounds) within the zeolite cavities prevents the diffusion of reactant molecules to the active sites. This study compares the catalytic activity of three-, two-, and one-dimensional zeolites with varying acid properties. The zeolites used include USY, Beta, Mordenite, LTL, and ZSM-12. These zeolites were chosen because of their distinct pore architectures. Furthermore, the zeolites were dealuminated using various treatments to obtain samples with varying acid properties. It was found that their performance in the alkylation of isobutane with 2-butene is dependent on both the structure (pore size and dimensionality) and acidity of the catalyst, both of which play a major role in the two types of deactivation mechanisms. In particular, it was observed that the one-dimensional zeolites - traditionally believed to be poor catalyst for this reaction - are capable of possessing high activity for long times on stream. This is because of their specific pore structure; the one-dimensional zeolites do not possess the large channel intersections found in two- or three-dimensional structures that allow the formation of bulky oligomers, thus leading to deactivation. It was also concluded that the specific dealumination procedure used plays a dominant role in the catalyst activity; some procedures result in the formation of extraframework aluminum sites that disrupt the alkylation mechanism. Also, the activity of each family of zeolites was greatest at low Si/Al ratios, thus indicating the importance of the hydrogen transfer capability of the zeolite. Of the numerous samples used in this study, the non-dealuminated beta sample showed superior activity.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Lanthanum exchanged faujasite type zeolites have a great potential as heterogeneous catalysts for isobutane/2-butene alkylation. These porous solids polarize adsorbed alkanes so strongly that a hydride can be abstracted from some octane isomers under near ambient conditions. The resulting formation of carbenium ions and the subsequent cleavage of C-C bonds are catalyzed by Brønsted acidic hydroxyl groups, which are abundant in lanthanum exchanged faujasites. The high concentration of aluminum in the zeolite lattice is also of fundamental importance for efficient incorporation of La3+ cations. The catalytic lifetime of lanthanum exchanged faujasites in isobutane/2-butene alkylation increases with increasing concentration of strongly acidic hydroxyl groups. A time resolved picture of the deactivation of these highly defined materials as catalysts in isobutane/2-buten alkylation was obtained, which will provide drastically improved process and regeneration conditions.
Author: Alexander Guzmán Monsalve
Publisher:
ISBN:
Category :
Languages : en
Pages : 194
Get Book Here
Book Description
Author: Masakazu Anpo
Publisher: Gulf Professional Publishing
ISBN: 9780444513496
Category : Science
Languages : en
Pages : 612
Get Book Here
Book Description
(Selected) -- Plenary Lecures: New Catalysts for Controlled/Living Atom Transfer Radical Polymerization (ATRP; Catalysis and Applications of Gold Nanoparticles -- Oral Presentations: Ionic Liquids as New Solvents and Catalysis for Petrochemical and Refining Processes; High Throughput Experiment on the Investigation of Oxidation Catalysts with Gas Sensor System -- Poster Presentations: Development of a Low-Temperature Dioxin Decomposition Catalyst; Studies on Unique Properties of Polyolefins Prepared with Metallocene Catalyst Systems -- Index.
Author: G. Öhlmann
Publisher: Elsevier
ISBN: 0080887503
Category : Science
Languages : en
Pages : 733
Get Book Here
Book Description
The proceedings of ZEOCAT 90 reflect the wide-ranging aspects of the rapidly expanding field of zeolite science and technology. The invited plenary lectures given by eminent zeolite scientists summarize current knowledge and address topical areas of zeolite research, including a contribution on the use of zeolites as membranes. The field of investigations described in the submitted articles in this volume covers a wide area of problems ranging from the influence of the synthesis process on the properties to questions of acidity, adsorption, diffusion, and catalysis. Of special interest are the newly developed applications of zeolites in the synthesis of fine chemicals, the use of zeolites for sensors and solid electrolytes, and the sophisticated zeolite-based separation processes.
