Characterization of Alumina Supported Cobalt Copper Catalysts for Fischer-Tropsch Synthesis of Light Hydrocarbons PDF Download

Author: Brent K. Bailey
Publisher:
ISBN:
Category : Aluminum compounds
Languages : en
Pages : 172

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 11

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The effect of ammonia in syngas on the performance of various supported cobalt catalysts (i.e., Al2O3, TiO2 and SiO2) was investigated during Fischer-Tropsch synthesis (FTS) using a continuously stirred tank reactor (CSTR). The addition of ammonia (10 ppmv NH3) caused a significant deactivation for all supported cobalt catalysts, but the rate of deactivation was higher for the silica-supported catalysts relative to the alumina and titania-supported catalysts used in this work. Ammonia addition had a positive effect on product selectivity (i.e., lower light gas products and higher C5+) for alumina and titania-supported catalysts compared to ammonia free conditions, whereas, the addition of ammonia increased lighter hydrocarbon (C1-C4) products and decreased higher hydrocarbon (C5+) selectivity compared to ammonia-free synthesis conditions for the silica-supported catalyst. For alumina and titania-supported catalysts, the activity almost recovered with mild in-situ hydrogen treatment of the ammonia exposed catalysts. For the silica-supported catalyst, the loss of activity is somewhat irreversible (i.e., cannot be regained after the mild hydrogen treatment). Addition of ammonia led to a significant loss in BET surface area and changes in pore diameter (consistent with pore collapse of a fraction of pores into the microporous range as described in the literature), as well as formation of catalytically inactive cobalt support compounds for the silica-supported catalyst. On the other hand, the pore characteristics of alumina and titania-supported catalysts were not significantly changed. In conclusion, XANES results of the ammonia exposed silica-supported catalysts further confirm the formation of cobalt-support compounds (cobalt silicates).

Author: Wilson D. Shafer
Publisher: MDPI
ISBN: 303928388X
Category : Science
Languages : en
Pages : 414

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Since the turn of the last century when the field of catalysis was born, iron and cobalt have been key players in numerous catalysis processes. These metals, due to their ability to activate CO and CH, haev a major economic impact worldwide. Several industrial processes and synthetic routes use these metals: biomass-to-liquids (BTL), coal-to-liquids (CTL), natural gas-to-liquids (GTL), water-gas-shift, alcohol synthesis, alcohol steam reforming, polymerization processes, cross-coupling reactions, and photocatalyst activated reactions. A vast number of materials are produced from these processes, including oil, lubricants, waxes, diesel and jet fuels, hydrogen (e.g., fuel cell applications), gasoline, rubbers, plastics, alcohols, pharmaceuticals, agrochemicals, feed-stock chemicals, and other alternative materials. However, given the true complexities of the variables involved in these processes, many key mechanistic issues are still not fully defined or understood. This Special Issue of Catalysis will be a collaborative effort to combine current catalysis research on these metals from experimental and theoretical perspectives on both heterogeneous and homogeneous catalysts. We welcome contributions from the catalysis community on catalyst characterization, kinetics, reaction mechanism, reactor development, theoretical modeling, and surface science.

Author: Adnan Khalil Oues
Publisher:
ISBN:
Category :
Languages : en
Pages : 90

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A Fischer-Tropsch catalyst composed of cobalt supported on alumina was prepared. This catalyst was cobalt/alumina (Co/AL2 O3 ). The physical characterization of the catalyst was conducted using surface area analysis through the BET method, and particle size analysis. Fischer-Tropsch experiments were conducted in a fixed bed reactor. A flow rate of 100sml/min was selected based experimentally. Two temperatures were 330, and 350°C, and three different pressures as follows 145, 217.6, and 290 psig. The results were evaluated and studied based on conversion of hydrogen and carbon monoxide, in addition to selectivity of products.

Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781719501361
Category :
Languages : en
Pages : 100

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The objective of this study was to evaluate the effect of titanium oxide, lanthanum oxide, and zirconium oxide on alumina supported cobalt catalysts. The hypothesis was that the presence of lanthanum oxide, titanium oxide, and zirconium oxide would reduce the interaction between cobalt and the alumina support. This was of interest because an optimized weakened interaction could lead to the most advantageous cobalt dispersion, particle size, and reducibility. The presence of these oxides on the support were investigated using a wide range of characterization techniques such as SEM, nitrogen adsorption, x-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed reduction after reduction (TPR-AR), and hydrogen chemisorptions/pulse reoxidation. Results indicated that both La2O3 and TiO2 doped supports facilitated the reduction of cobalt oxide species in reference to pure alumina supported cobalt catalysts, however further investigation is needed to determine the effect of ZrO2 on the reduction profile. Results showed an increased corrected cluster size for all three doped supported catalysts in comparison to their reference catalysts. The increase in reduction and an increase in the cluster size led to the conclusion that the support-metal interaction weakened by the addition of TiO2 and La2O3. It is also likely that the interaction decreased upon presence of ZrO2 on the alumina, but further research is necessary. Preliminary results have indicated that the alumina-supported catalysts with titanium oxide and lanthanum oxide present are of interest because of the weakened cobalt support interaction. These catalysts showed an increased extent of reduction, therefore more metallic cobalt is present on the support. However, whether or not there is more cobalt available to participate in the Fischer-Tropsch synthesis reaction (cobalt surface atoms) depends also on the cluster size. On one hand, increasing cluster size alone tends to decrease the

Author: B. H. Davis
Publisher: CRC Press
ISBN: 1420062573
Category : Science
Languages : en
Pages : 430

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Rising oil costs have stimulated significant interest in the Fischer-Tropsch synthesis (FTS) as a method for producing a synthetic petroleum substitute. Drawn from the proceedings at a symposium held during the 236th meeting of the American Chemical Society in Philadelphia in August 2008, Advances in Fischer-Tropsch Synthesis, Catalysts, and Cataly

Author: Wade H. Shafer
Publisher: Springer Science & Business Media
ISBN: 1468436201
Category : Science
Languages : en
Pages : 306

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Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis seminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 23 (thesis year 1978) a total of 10,148 theses titles from 27 Canadian and 220 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work. While Volume 23 reports these submitted in 1978, on occasion, certain universities do report theses submitted in previous years but not reported at the time.

Author:
Publisher:
ISBN:
Category : Aluminum oxide
Languages : en
Pages : 252

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Effect of alumina support modification for applications as cobalt and iron catalyst supports in Fischer-Tropsch reaction were studied. Alumina supports consisting of various gamma to chi ratios were prepared using solvothermal method and employed as supports for cobalt catalysts. In order to identify the characteristics, all the catalysts were characterized using surface area analysis, X-ray diffraction (XRD), Scanning electron microscopy2Energy dispersive X-ray (SEM/EDX), Transmission electron microscopy (TEM), Fourier transform Infrared Spectroscopy (FT-IR), Temperature programmed reduction (TPR), and hydrogen and carbon monoxide chemisorption. CO hydrogenation (H 2CO = 10/1) was also performed to determine the overall activity and selectivity of the Co/AL O catalysts containing various gamma to chi ratios. It was found that both activity and selectivity were increased with increasing the chi to gamma ratios of the alumina supports. It is suggested that the spherical;-shape like morphology of the -phase AL O provide better stability and dispersion of the Co particles. In addition, the effect of Cu-modification of alumina support for applications as iron catalyst supports in Fischer-Tropsch reaction (H 2CO - 2/1) was also investigated. It was found that the use of copper-modified alumina supports enhanced both reducibilities and the overall activities of Fe/AL O catalysts. However, Cu-modification of alumina support appeared to have no effect on selectivity of the F-T products.

Author: Robert Merrill Stanfield
Publisher:
ISBN:
Category :
Languages : en
Pages : 363

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Author: Alexandre Antônio Bento Carvalho
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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The work exposed in this manuscript concerns the study of the intrinsic activity and localization of active sites in cobalt and iron based catalysts using a combination of transient kinetic methods such as SSITKA, extended physicochemical characterization and catalytic tests under quasi steady state conditions. Promotion of iron catalysts with metals used for soldering (Bi and Pb) results a remarkable increase in the light olefin production rate with the possibility to conduct Fischer-Tropsch synthesis at very mild reaction conditions (low pressure) and even at atmospheric pressure. Transient kinetic experiments showed facilitation of CO dissociation in the presence of promoters by scavenging O atoms from iron carbide. Cobalt catalyst supported by mordenite zeolite presented higher value of SSITKA rate constant. Localization of cobalt active sites in bifunctional cobalt-zeolite catalysts has a major impact on the reaction rate and in particular on the hydrocarbon selectivity. A proximity between the cobalt active site and Bronsted active sites was found to be a key parameter to obtain higher selectivity and yield of isomerized hydrocarbons. SSITKA combined with catalyst characterization revealed that carbon deposition and cobalt nanoparticle agglomeration were responsible for the deactivation of silica supported cobalt catalysts. Catalyst rejuvenation in hydrogen lessened the amounts of deposited carbon species and partially released the most active sites of carbon monoxide dissociative adsorption and stronger sites of carbon monoxide reversible adsorption.