Effect of Promoter (Mn) on the Performance of SBA-15 Supported Iron Catalysts for High Temperature Fischer-Tropsch Synthesis PDF Download
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Author: Sreya Mariya Seby Publisher: ISBN: Category : Catalyst supports Languages : en Pages : 56
Book Description
Development of an effective High Temperature Fischer-Tropsch Synthesis (HTFTS) catalyst is of interest in process intensification that combines methane reforming with long chain hydrocarbon production. Literature indicates iron catalysts supported on mesoporous silica performed relatively well in high temperature applications. In this work, we investigated the effect of manganese promoter on iron catalysts for FTS at 430 °C as it was known from previous studies that manganese promotion could enhance the CO conversion with higher hydrocarbon yields. Also, the effect of temperature on FTS activity was evaluated by testing the base and promoted Fe/SBA-15 catalysts for temperature ranging from 370 to 430 °C. Incipient wetness impregnation method was used to prepare the catalysts. The catalysts used in this work were un-promoted iron (15 wt%) and Mn promoted (1.4, 2.8, 4.2, 5.6, 11.2 wt%) iron (15 wt%) catalysts supported on SBA-15. The catalysts were characterized using XRD, TPR, N2 Physisorption, and SEM. These catalysts were first activated in synthesis gas (H2: CO = 2:1) at 430 °C and then tested for their catalytic performance at the same temperature and atmospheric pressure. Prior work with SBA-15 supported iron catalysts showed that manganese promotion could improve the CO conversion when compared to copper and potassium. The main goal of this work was to study the effect of varying the manganese content on SBA-15 supported iron catalysts to determine the optimum loading of Mn along with the effect of temperature. It was found that CO conversion increases from 27% to74% with increasing the amount of manganese. The yield of CO2 increased substantially with higher Mn loadings. When different Mn promoted iron catalysts were compared, the catalysts with 2.8 wt% Mn loading showed the best performance in terms of the CO conversion and yield of C2+ hydrocarbons. Catalyst with 2.8 wt% of manganese loading yielded a CO conversion of 54%, with a methane yield of 17%, 32% (carbon) yield of C2- C4 and 9%(carbon) yields of C5+ hydrocarbon products, respectively. The effect of operating temperature on the catalytic performance of both the base catalyst 15Fe/SBA-15 and the promoted 2.8Mn/15Fe/SBA-15 catalyst was also examined. The unpromoted iron catalyst showed an improved catalytic activity at 400 °C with the total CO conversion of 38% and a higher yields of C5+ hydrocarbons. A significant decrease was also observed in the yields of CH4 and CO2. The methane and carbon dioxide yield increased from 11% and 8% to 25% and 40%, respectively, as the temperature increased from 400 to 450 °C. The catalyst with 2.8 wt% of manganese promotion gave better CO conversion and hydrocarbon product yields at 430 °C. Lower temperature showed negative effect on hydrocarbon product yield for manganese promoted catalysts. promoted catalysts.
Author: Sreya Mariya Seby Publisher: ISBN: Category : Catalyst supports Languages : en Pages : 56
Book Description
Development of an effective High Temperature Fischer-Tropsch Synthesis (HTFTS) catalyst is of interest in process intensification that combines methane reforming with long chain hydrocarbon production. Literature indicates iron catalysts supported on mesoporous silica performed relatively well in high temperature applications. In this work, we investigated the effect of manganese promoter on iron catalysts for FTS at 430 °C as it was known from previous studies that manganese promotion could enhance the CO conversion with higher hydrocarbon yields. Also, the effect of temperature on FTS activity was evaluated by testing the base and promoted Fe/SBA-15 catalysts for temperature ranging from 370 to 430 °C. Incipient wetness impregnation method was used to prepare the catalysts. The catalysts used in this work were un-promoted iron (15 wt%) and Mn promoted (1.4, 2.8, 4.2, 5.6, 11.2 wt%) iron (15 wt%) catalysts supported on SBA-15. The catalysts were characterized using XRD, TPR, N2 Physisorption, and SEM. These catalysts were first activated in synthesis gas (H2: CO = 2:1) at 430 °C and then tested for their catalytic performance at the same temperature and atmospheric pressure. Prior work with SBA-15 supported iron catalysts showed that manganese promotion could improve the CO conversion when compared to copper and potassium. The main goal of this work was to study the effect of varying the manganese content on SBA-15 supported iron catalysts to determine the optimum loading of Mn along with the effect of temperature. It was found that CO conversion increases from 27% to74% with increasing the amount of manganese. The yield of CO2 increased substantially with higher Mn loadings. When different Mn promoted iron catalysts were compared, the catalysts with 2.8 wt% Mn loading showed the best performance in terms of the CO conversion and yield of C2+ hydrocarbons. Catalyst with 2.8 wt% of manganese loading yielded a CO conversion of 54%, with a methane yield of 17%, 32% (carbon) yield of C2- C4 and 9%(carbon) yields of C5+ hydrocarbon products, respectively. The effect of operating temperature on the catalytic performance of both the base catalyst 15Fe/SBA-15 and the promoted 2.8Mn/15Fe/SBA-15 catalyst was also examined. The unpromoted iron catalyst showed an improved catalytic activity at 400 °C with the total CO conversion of 38% and a higher yields of C5+ hydrocarbons. A significant decrease was also observed in the yields of CH4 and CO2. The methane and carbon dioxide yield increased from 11% and 8% to 25% and 40%, respectively, as the temperature increased from 400 to 450 °C. The catalyst with 2.8 wt% of manganese promotion gave better CO conversion and hydrocarbon product yields at 430 °C. Lower temperature showed negative effect on hydrocarbon product yield for manganese promoted catalysts. promoted catalysts.
Author: David Patrick Weber Publisher: ISBN: Category : Catalyst supports Languages : en Pages : 53
Book Description
Promoter effects on SBA-15 supported iron Fischer-Tropsch catalysts were investigated for their potential to improve high temperature catalyst performance. FTS catalysts promoted by manganese (0.15%-1.4%), copper (0.15%-1%), and potassium (0.5%-3%), with all percentages stated on the basis of mass percentage of final catalysts, were prepared and tested at 430°C and ambient pressure in a fixed bed reactor. Manganese showed the ability to promote the FT reaction, increasing both the CO conversion and the average chain length of hydrocarbon products. Compared to the unpromoted catalyst composed only of iron supported on SBA-15, 1.4%Mn (mass) promotion of 15% (mass) iron on SBA-15 improved CO conversion from 29% to 32%, increased alpha from 0.21 to 0.34, decreased carbon dioxide selectivity from 76% to 50%, increased C2-C4 selectivity from 9.6% to 30% and increased C5+ selectivity from 0.21% to 2.2%. Copper promotion gave increased conversion, but did not significantly affect alpha or carbon dioxide selectivity. Potassium promotion in the range of 0.5% to 3% by mass, on the other hand, had a negative effect on CO conversion at all concentrations tested.
Author: Muhammad Suhaimi Man Publisher: ISBN: Category : Catalysis Languages : en Pages : 48
Book Description
Fischer-Tropsch synthesis (FTS) is a part of gas-to-liquids (GTL) technology, which produces synthetic liquid hydrocarbons from natural gas. Recently the production of clean fuels and particularly of synthetic diesel by means of the FTS process has aroused renewed interest in both industrial and academic field. This process was shown to be catalyzed by certain transition metals, such as Co which present the highest activity. This research work is about the synthesis of SBA-15 and preparation of catalyst with different promoter Zr, Zn, Mn - Co based supported by SBA-15 by wet impregnation catalysts and characterizes all sampling. All materials were characterized by several physico-chemical techniques such as TGA, SEM and FTIR. The catalytic and characterization results show a great influence of mesoporous support porosity on the structure, reducibility and FTS catalytic behavior of cobalt oxide species supported over these ordered materials. After modification of SBA-15 by Co with different loading, the particles found to be attached closely with each other. The SEM picture shows a large number of SBA-15 particles attaching closely with one another. So this will make catalyst more efficient and effective during FT process. Then, using FTIR, the functional groups will be observed with certain wavelength in the samples such as cobalt oxides, Si-O-Si, Si-CH3, zinc oxide, OH band, Si-C, and others. Besides that, the identification of metal inside SBA-15 was determined by comparing the pure SBA-15 with the incorporated metal on SBA-15. For this research, the characterization of the catalyst by selecting Zn as promoter have quiet similar characterization with noble metal that already investigate.
Author: Muhammad Zakwan A. Razak Publisher: ISBN: Category : Catalyst Languages : en Pages : 35
Book Description
The influence of promoter (Zn) on the physiochemical and catalytic properties of mesaporous silica Co/SBA-15 catalysts for the Fischer-Tropsch (FT) synthesis was investigated. SBA-15 was synthesized as support. The mesoporous silica Co-Zn/SBA-15 catalysts were prepared by incipient wetness impregnation method. Cobalt nitrate and zinc nitrate were used as sources of metal that are introduced onto catalysts with same cobalt loading (15 wt %) and different zinc loading (5 wt %, 10 wt%, 15 wt %) The characterization of catalysts was performed by using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results for FTIR were identification of Si-O-Si functional group indicating the absortion of silica inside SBA-15 support. Beside that, the identification of metal inside SBA-15 was determined by comparing the pure SBA-15 with the incorporated metal on SBA-15. For SEM analysis the image shows that the rope like domain aggregated to wheat-like microstructure. For this research, the characterization of the catalyst by selecting Zn as promoter have quiet similar characterization with noble metal that have been already investigate.
Author: B. H. Davis Publisher: CRC Press ISBN: 1420062573 Category : Science Languages : en Pages : 430
Book Description
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: Shuo Chen Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The production of fuel additives, having high octane numbers, from biosourced molecules such as 5-hydroxymethylfurfural (HMF), is the subject of many studies. The Pt, Pd and Ru-based catalysts are described as particularly active in the conversion reaction of HMF to 2,5-dimethylfuran (DMF) and to 2,5-dimethyltetrahydrofuran (DMTHF). However, their substitutions in the catalytic formulations are desirable in view of their high cost and low availability. The substitution elements can be transition metals (for example Cu or Ni), which are more abundant, but generally less active. My research has focused on the preparation of catalysts, based on transition metals, active and selective for the hydrogenation of HMF into molecules that can be incorporated into fuels. The active phases studied during my Ph. D. are based on Ni and Cu transition metals. These active phases were supported on mesoporous silica of SBA-15 type. The study is divided into two distinct parts, depending on the metal studied. The first part of the Ph. D. presents the results obtained with Ni supported monometallic catalysts. In a first step, the optimization of the reaction parameters for the selective hydroconversion of HMF to DMF and DMTHF was carried out using a catalyst prepared by the incipient wetness impregnation (IWI) of the nitrate precursor solution (Chapter 3). Optimized reaction parameters include reaction temperature, dihydrogen pressure, HMF/Ni molar ratio, and reaction time. A preliminary kinetic study was also performed. The effect of the dispersion and size of Ni metal particles on the catalytic performance of Ni/SBA-15 catalysts was studied on materials prepared by the melt infiltration (MI) method of nitrate precursors (Chapter 4). The level of dispersion of the nickel was modified using SBA-15 supports containing different interconnection porosities, obtained at different synthesis temperatures. The results show that the Ni/SBA-15 catalyst, prepared by the simple IWI method, achieves high yields of DMF and DMTHF under optimal reaction conditions. The level of Ni dispersion, as observed from the materials obtained by infiltration of molten salts, has a significant effect on the catalytic activity of the catalyst. The second part of my research focuses on the catalytic properties of Cu/SBA-15 monometallic catalysts prepared by different methods, and having different Cu phase division degree (Chapter 5). The methods of preparation applied include the IWI method, the in situ autocombustion method (ISAC) and the deposition-precipitation method (DP). The first part of the study therefore focused on the optimization of the reaction conditions for the selective hydroconversion of HMF to DMF (over the Cu/SBA-15 catalyst prepared by the ISAC method). Optimized reaction parameters, as for Ni/SBA-15, were reaction temperature, hydrogen pressure, HMF/Cu molar ratio, and reaction time. The reuse of the catalyst was also studied, and a kinetic study of the transformation of HMF on Cu/SBA-15 conducted. This part demonstrates that the activity of Cu for the selective conversion of HMF to DMF depends mainly on the state of dispersion of Cu. The use of the DP method led to a highly divided Cu/SBA-15 catalyst, which made it possible to achieve high yields of DMF.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Efforts during this second year focused on four areas: (1) continued searching and summarizing of published Fischer-Tropsch synthesis (FTS) mechanistic and kinetic studies of FTS reactions on iron catalysts; (2) investigation of CO adsorption/desorption and temperature programmed hydrogenation (TPH) of carbonaceous species after FTS on unsupported iron and alumina-supported iron catalysts; (3) activity tests of alumina-supported iron catalysts in a fixed bed reactor; (4) sequential design of experiments, for the collection of rate data in a Berty CSTR reactor, and nonlinear-regression analysis to obtain kinetic parameters. Literature sources describing mechanistic and kinetic studies of Fischer-Tropsch synthesis on iron catalysts were compiled in a review. Temperature-programmed desorption/reaction methods (the latter using mass-spectrometry detection and also thermogravimetric analyzer (TGA)) were utilized to study CO adsorption/-desorption on supported and unsupported iron catalysts. Molecular and dissociative adsorptions of CO occur on iron catalysts at 25-150 C. The amounts adsorbed and bond strengths of adsorption are influenced by supports and promoters. That CO adsorbs dissociatively on polycrystalline Fe at temperatures well below those of FT reaction indicates that CO dissociation is facile and unlikely to be the rate-limiting step during FTS. Carbonaceous species formed after FT reaction for only 5 minutes at 200 C were initially hydrogenated under mild, isothermal condition (200 C and 1 atm), followed by TPH to 800 C. During the mild, isothermal hydrogenation, only about 0.1-0.2 mL of atomic carbon is apparently removed, while during TPH to 800 C multilayer equivalents of atomic, polymeric, carbidic, and graphitic carbons are removed. Rates of CO conversion on alumina-supported iron catalysts at 220-260 C and 20 atm are correlated well by a Langmuir-Hinshelwood expression, derived assuming carbon hydrogenation to CH and OH recombination to water to be rate-determining steps. In the coming year, studies will focus on quantitative determination of the rates of kinetically-relevant elementary steps on Fe catalysts with/without K and Pt promoters and at various levels of Al2O3 support, providing a database for understanding (1) effects of promoter and support on elementary kinetic parameters and (2) for validation of computational models that incorporate effects of surface structure and promoters. Kinetic parameters will be incorporated into a microkinetics model, enabling prediction of rate without invoking assumptions, e.g. of a rate-determining step or a most-abundant surface intermediate. Calculations using periodic, self-consistent Density Functional Theory (DFT) methods were performed on two model surfaces: (1) Fe(110) with 1/4 ML subsurface carbon, and (2) Fe(110) with 1/4 ML Pt adatoms. Reaction networks for FTS on these systems were characterized in full detail by evaluating the thermodynamics and kinetics of each elementary step. We discovered that subsurface C stabilizes all the reactive intermediates, in contrast to Pt, which destabilizes most of them. A comparative study of the reactivities of the modified-Fe surfaces against pure Fe is expected to yield a more comprehensive understanding of promotion mechanisms for FTS on Fe.
Author: Peter M. Maitlis Publisher: John Wiley & Sons ISBN: 3527656855 Category : Science Languages : en Pages : 404
Book Description
Greener Fischer-Tropsch Processes How can we use our carbon-based resources in the most responsible manner? How can we most efficiently transform natural gas, coal, or biomass into diesel, jet fuel or gasoline to drive our machines? The Big Questions today are energy-related, and the Fischer-Tropsch process provides industrially tested solutions. This book offers a comprehensive and up-to-date overview of the Fischer-Tropsch process, from the basic science and engineering to commercial issues. It covers industrial, economic, environmental, and fundamental aspects, with a specific focus on “green” concepts such as sustainability, process improvement, waste-reduction, and environmental care. The result is a practical reference for researchers, engineers, and financial analysts working in the energy sector, who are interested in carbon conversion, fuel processing or synthetic fuel technologies. It is also an ideal introductory book on the Fischer-Tropsch process for graduate courses in chemistry and chemical engineering.
Author: Sreya Mariya Seby
Author: Sreya Mariya Seby
Author: David Patrick Weber
Author: Muhammad Suhaimi Man
Author: Eshan Ben Yeh
Author: Muhammad Zakwan A. Razak
Author: B. H. Davis
Author: Shuo Chen
Author: Shiro Watanabe
Author: 
Author: Peter M. Maitlis