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Download or read book Nanoscale Attrition During Activation of Precipitated Iron Fischer-Tropsch Catalysts: Implications for Catalyst Design written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Role of Catalyst Activation on the Activity and Attrition of Precipitated Iron Fischer - Tropsch Catalysts written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Mehul D. Shroff
Publisher :
ISBN 13 :
Total Pages : 292 pages
Book Rating : 4.:/5 (344 download)
Download or read book Activation of Precipitated Iron Fischer-Tropsch Catalysts written by Mehul D. Shroff and published by . This book was released on 1995 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Joe W. Hightower
Publisher :
ISBN 13 :
Total Pages : 758 pages
Book Rating : 4.F/5 ( download)
Download or read book 11th International Congress on Catalysis, 40th Anniversary written by Joe W. Hightower and published by . This book was released on 1996 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
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ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (685 download)
Download or read book Attrition and Carbon Formation on Iron Catalysts written by and published by . This book was released on 1994 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: A serious engineering problem that needs to be addressed in the scale-up of slurry-phase, Fischer-Tropsch reactors is attrition of the precipitated iron catalyst. Attrition, which can break down the catalyst into particles too small to filter, results from both mechanical and chemical forces. This study examines the chemical causes of attrition in iron catalysts. A bench-scale, slurry-phase CSTR is used to simulate operating conditions that lead to attrition of the catalyst. The average particle size and size distribution of the catalyst samples are used to determine the effect of slurry temperature, reducing gas, gas flow rate and time upon attrition of the catalyst. Carbon deposition, a possible contributing factor to attrition, has been examined using gravimetric analysis and TEM. Conditions affecting the rate of carbon deposition have been compared to those leading to attrition of the precipitated iron catalyst.
Author : Rama Krishna Manne
Publisher :
ISBN 13 :
Total Pages : 306 pages
Book Rating : 4.:/5 (332 download)
Download or read book Activation Studies with Promoted Precipitated Iron Fischer- Tropsch Catalysts written by Rama Krishna Manne and published by . This book was released on 1991 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 11 pages
Book Rating : 4.:/5 (684 download)
Download or read book Development of Attrition Resistant Iron-based Fischer-Tropsch Catalysts written by and published by . This book was released on 2000 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H2) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. The use of iron-based catalysts is attractive not only due to their low cost and ready availability, but also due to their high water-gas shift activity which makes it possible to use these catalysts with low H2/CO ratios. However, a serious problem with use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, makes the separation of catalyst from the oil/wax product very difficult if not impossible, and results a steady loss of catalyst from the reactor. The objective of this research is to develop robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry bubble column reactor. Specifically we aim to develop to: (1) improve the performance and preparation procedure of the high activity, high attrition resistant, high alpha iron-based catalysts synthesized at Hampton University (2) seek improvements in the catalyst performance through variations in process conditions, pretreatment procedures and/or modifications in catalyst preparation steps and (3) investigate the performance in a slurry reactor. The effort during the reporting period has been devoted to effects of pretreating procedures, using H2, CO and syngas (H2/CO = 0.67) as reductants, on the performance (activity, selectivity and stability with time) of a precipitated iron catalyst (100Fe/5Cu/4.2K/10SiO2 on a mass basis) during F-T synthesis were studied in a fixed-bed reactor.
Author : Samantha Harding
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (89 download)
Download or read book The effect of CO{208} on the activation of a precipitated Iron Fischer-Tropsch catalyst written by Samantha Harding and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
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ISBN 13 :
Total Pages : 71 pages
Book Rating : 4.:/5 (871 download)
Download or read book Technology Development for Iron and Cobalt Fischer-Tropsch Catalysts written by and published by . This book was released on 1999 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
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ISBN 13 :
Total Pages : 63 pages
Book Rating : 4.:/5 (727 download)
Download or read book The Development of Precipitated Iron Catalysts with Improved Stability written by and published by . This book was released on 1988 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: This program has the objective of developing a precipitated iron Fischer-Tropsch catalyst with improved stability. During this second quarter of the program most of the work was done under Task 3 which involves the development of a baseline iron catalyst. Under this task, several Fe/Cu catalysts were prepared by precipitation at different pH levels between 3 an 10. These catalysts were characterized by STEM, XRD, DSC, TGA, TPR and N2 adsorption in order to examine precipitation pH, copper level, calcination and reduction temperature requirements for the baseline iron catalyst. Work during the next quarter will focus on the design of the slurry reactor system for testing the precipitated iron catalysts.
Author :
Publisher :
ISBN 13 :
Total Pages : 1030 pages
Book Rating : 4.:/5 (683 download)
Download or read book Technology Development for Iron Fischer-Tropsch Catalysts. Final Technical Report, December 18, 1990--December 17, 1993 written by and published by . This book was released on 1996 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report contains the results of a three year study on the preparation of high surface area iron catalysts using a continuous precipitation technique, of a detailed program designed to define the impact of three pretreatment procedures (CO only, syngas only, or hydrogen followed by syngas) on the physical and chemical changes that the catalyst undergoes during activation, and the impact of catalyst composition and pretreatment on the ultimate activity and selectivity of the catalyst during the synthesis. Overall the results of this three year study attained, or came very close to attaining, the activity, aging and selectivity targets in the Statement of Work. This report also contains a critical review of the literature on the preparation of iron catalysts and their pretreatment for use in Fischer-Tropsch synthesis. Also included is a brief review of the action of promoters in Fischer-Tropsch iron catalysts, the models for chemisorption of CO and H2, emphasizing that which is appropriate for Fischer-Tropsch synthesis, and an over-view of the results of testing of iron catalysts for Fischer-Tropsch synthesis activity and product selectivity.
Download or read book Development of Precipitated Iron Fischer-Tropsch Catalysts written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : William James Cannella
Publisher :
ISBN 13 :
Total Pages : 356 pages
Book Rating : 4.:/5 (29 download)
Download or read book Factors Influencing Kinetics and Product Distribution in Fischer- Tropsch Synthesis Over Iron Catalysts written by William James Cannella and published by . This book was released on 1984 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 36 pages
Book Rating : 4.:/5 (684 download)
Download or read book Development of Precipitated Iron Fischer-Tropsch Catalysts. Quarterly Technical Progress Report for the Period July 1, 1996--September 30, 1996 written by and published by . This book was released on 1996 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two slurry reactor tests were completed in continuation of our studies on the effect of pretreatment conditions on catalyst reactivity and selectivity. Exceptionally good performance was obtained in run SA-2186, using the new pretreatment developed at Texas A & M University. The work on catalyst characterization by temperature programmed and isothermal reduction on a variety of iron catalysts, with different amounts of promoters, has been continued. These studies are complementing our work on pretreatment effect research, and provide additional insights into the effect of pretreatment procedures on the reduction behavior of iron catalysts. The overall objectives are to: (1) demonstrate repeatability of performance and preparation procedure of two high activity, high alpha iron Fischer-Tropsch catalysts synthesized at Texas A & M University; (2) seek potential improvements in the catalysts performance through variation in process condition, pretreatment procedures and/or modifications in catalyst synthesis; (3) investigate performance of catalysts in a small bubble column slurry reactor; and (4) investigate feasibility of producing catalysts on a large scale in collaboration with a catalyst manufacturer.
Author :
Publisher :
ISBN 13 :
Total Pages : 16 pages
Book Rating : 4.:/5 (683 download)
Download or read book Technology Development for Iron Fischer-Tropsch Catalysis. Quarterly Technical Progress Report, October--December, 1994 written by and published by . This book was released on 1994 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fischer-Tropsch catalysts must undergo a pretreatment in order to be active. As part of the authors comprehensive study to maximize the activity of iron based precipitated Fischer-Tropsch catalysts, they are currently attempting to optimize the activation procedure. Although they are able to achieve high activity using CO pretreatment, the catalysts tend to deactivate suddenly and rapidly after 500 hr of synthesis. Kolbel reports high CO conversion comparable to these results at a lower gas flow (2.4 vs. 3.4 nL/hr-g(Fe)); however, he achieved greater stability with conversions reported to be 90% after 1,400 hrs. One possibility for Kolbel's higher stability could be due to the activation procedure. Herein are reported the initial results of a study to optimize the catalyst composition and the operating conditions for the iron based slurry phase Fischer-Tropsch synthesis when synthesis gas activation is utilized.
Author : Victor Hugo Carreto Vazquez
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (574 download)
Download or read book Spray Drying and Attrition Behavior of Iron Catalysts for Slurry Phase Fischer-Tropsch Synthesis written by Victor Hugo Carreto Vazquez and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes results of a study aimed at developing and evaluating attrition resistant iron catalysts prepared by spray drying technique. These catalysts are intended for Fischer-Tropsch (F-T) synthesis in a slurry bubble column reactor (SBCR). One of the major challenges associated with the use of SBCR for this purpose is the problem of catalyst/wax separation. If the catalyst particles break up into smaller ones during the F-T synthesis, these small particles (>5-10 [mu]m in diameter) will cause problems with the catalyst/wax separation. Several research groups have worked on development of attrition resistant spray-dried iron catalysts, and methodology to measure and predict their attrition behavior. However, these attrition tests were not conducted under conditions representative of those encountered in a SBCR. In this work, the attrition behavior of six spray-dried catalysts and two precipitated catalysts was evaluated under slurry reaction conditions in a stirred tank slurry reactor (STSR). Spray-dried catalysts used in this study were prepared at Texas A & M University (TAMU) and at Hampton University (HU), employing different preparation procedures and silica sources (potassium silicate, tetraethyl orthosilicate or colloidal silica). The attrition properties of F-T catalysts were determined by measuring particle size distribution (PSD) of catalysts before and after F-T synthesis in the STSR. This provides a direct measure of changes in particle size distribution in the STSR, and accounts for both physical and chemical attrition effects. Also, scanning electron microscopy (SEM) was used to investigate the mechanism of attrition - erosion vs. fracture, and to obtain morphological characteristics of catalysts. Spray dried 100Fe/3Cu/5K/16SiO2 catalyst (WCS3516-1), prepared from wet precursors using colloidal silica as the silica source, was the best in terms of its attrition strength. After 337 hours of F-T synthesis in the STSR, the reduction in the average particle size and generation of particles less than 10 [mu]m in diameter were found to be very small. This indicates that both particle fracture and erosion were insignificant during testing in the STSR. All other catalysts, except one of the spray dried catalysts synthesized at Hampton University, also had a good attrition resistance and would be suitable for use in slurry reactors for F-T synthesis.
Download or read book Atomic-Scale Design of Iron Fischer-Tropsch Catalysts; A Combined Computational Chemistry, Experimental, and Microkinetic Modeling Approach written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work focuses on (1) searching/summarizing published Fischer-Tropsch synthesis (FTS) mechanistic and kinetic studies of FTS reactions on iron catalysts; (2) preparation and characterization of unsupported iron catalysts with/without potassium/platinum promoters; (3) measurement of H2 and CO adsorption/dissociation kinetics on iron catalysts using transient methods; (3) analysis of the transient rate data to calculate kinetic parameters of early elementary steps in FTS; (4) construction of a microkinetic model of FTS on iron, and (5) validation of the model from collection of steady-state rate data for FTS on iron catalysts. Three unsupported iron catalysts and three alumina-supported iron catalysts were prepared by non-aqueous-evaporative deposition (NED) or aqueous impregnation (AI) and characterized by chemisorption, BET, temperature-programmed reduction (TPR), extent-of-reduction, XRD, and TEM methods. These catalysts, covering a wide range of dispersions and metal loadings, are well-reduced and relatively thermally stable up to 500-600 C in H2 and thus ideal for kinetic and mechanistic studies. Kinetic parameters for CO adsorption, CO dissociation, and surface carbon hydrogenation on these catalysts were determined from temperature-programmed desorption (TPD) of CO and temperature programmed surface hydrogenation (TPSR), temperature-programmed hydrogenation (TPH), and isothermal, transient hydrogenation (ITH). A microkinetic model was constructed for the early steps in FTS on polycrystalline iron from the kinetic parameters of elementary steps determined experimentally in this work and from literature values. Steady-state rate data were collected in a Berty reactor and used for validation of the microkinetic model. These rate data were fitted to 'smart' Langmuir-Hinshelwood rate expressions derived from a sequence of elementary steps and using a combination of fitted steady-state parameters and parameters specified from the transient measurements. The results provide a platform for further development of microkinetic models of FTS on Fe and a basis for more precise modeling of FTS activity of Fe catalysts. Calculations using periodic, self-consistent Density Functional Theory (DFT) methods were performed on various realistic models of industrial, Fe-based FTS catalysts. Close-packed, most stable Fe(110) facet was analyzed and subsequently carbide formation was found to be facile leading to the choice of the FeC(110) model representing a Fe facet with a sub-surface C atom. The Pt adatom (Fe{sup Pt}(110)) was found to be the most stable model for our studies into Pt promotion and finally the role of steps was elucidated by recourse to the defected Fe(211) facet. Binding Energies(BEs), preferred adsorption sites and geometries for all FTS relevant stable species and intermediates were evaluated on each model catalyst facet. A mechanistic model (comprising of 32 elementary steps involving 19 species) was constructed and each elementary step therein was fully characterized with respect to its thermochemistry and kinetics. Kinetic calculations involved evaluation of the Minimum Energy Pathways (MEPs) and activation energies (barriers) for each step. Vibrational frequencies were evaluated for the preferred adsorption configuration of each species with the aim of evaluating entropy-changes, pre exponential factors and serving as a useful connection with experimental surface science techniques. Comparative analysis among these four facets revealed important trends in their relative behavior and roles in FTS catalysis. Overall the First Principles Calculations afforded us a new insight into FTS catalysis on Fe and modified-Fe catalysts.
