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University of Kentucky

Center for Applied Energy Research Faculty and Staff Publications

Articles 1 - 21 of 21

Full-Text Articles in Chemical Engineering

Fischer–Tropsch Synthesis: Effect Of The Promoter’S Ionic Charge And Valence Level Energy On Activity, Mirtha Z. Leguizamón León Ribeiro, Joice C. Souza, Muthu Kumaran Gnanamani, Michela Martinelli, Gabriel F. Upton, Gary Jacobs, Mauro C. Ribeiro Oct 2021

Fischer–Tropsch Synthesis: Effect Of The Promoter’S Ionic Charge And Valence Level Energy On Activity, Mirtha Z. Leguizamón León Ribeiro, Joice C. Souza, Muthu Kumaran Gnanamani, Michela Martinelli, Gabriel F. Upton, Gary Jacobs, Mauro C. Ribeiro

Center for Applied Energy Research Faculty and Staff Publications

In this contribution, we examine the effect of the promoter´s ionic charge and valence orbital energy on the catalytic activity of Fe-based catalysts, based on in situ synchrotron X-ray powder diffraction (SXRPD), temperature-programmed-based techniques (TPR, TPD, CO-TP carburization), and Fischer–Tropsch synthesis catalytic testing studies. We compared the promoting effects of K (a known promoter for longer-chained products) with Ba, which has a similar ionic radius but has double the ionic charge. Despite being partially “buried” in a crystalline BaCO3 phase, the carburization of the Ba-promoted catalyst was more effective than that of K; this was primarily due to its …

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Hydrocracking Of Octacosane And Cobalt Fischer–Tropsch Wax Over Nonsulfided Nimo And Pt-Based Catalysts, Wenping Ma, Jungshik Kang, Gary Jacobs, Shelley D. Hopps, Burtron H. Davis Sep 2021

Hydrocracking Of Octacosane And Cobalt Fischer–Tropsch Wax Over Nonsulfided Nimo And Pt-Based Catalysts, Wenping Ma, Jungshik Kang, Gary Jacobs, Shelley D. Hopps, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

The effect of activation environment (N2, H2 and H2S/H2) on the hydrocracking performance of a NiMo/Al catalyst was studied at 380 °C and 3.5 MPa using octacosane (C28). The catalyst physical structure and acidity were characterized by BET, XRD, SEM-EDX and FTIR techniques. The N2 activation generated more active nonsulfided NiMo/Al catalyst relative to the H2 or H2S activation (XC28, 70–80% versus 6–10%). For a comparison, a NiMo/Si-Al catalyst was also tested after normal H2 activation and showed higher activity at the same process …

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Fischer–Tropsch Synthesis For Light Olefins From Syngas: A Review Of Catalyst Development, Arash Yahyazadeh, Ajay K. Dalai, Wenping Ma, Lifeng Zhang Jul 2021

Fischer–Tropsch Synthesis For Light Olefins From Syngas: A Review Of Catalyst Development, Arash Yahyazadeh, Ajay K. Dalai, Wenping Ma, Lifeng Zhang

Center for Applied Energy Research Faculty and Staff Publications

Light olefins as one the most important building blocks in chemical industry can be produced via Fischer–Tropsch synthesis (FTS) from syngas. FT synthesis conducted at high temperature would lead to light paraffins, carbon dioxide, methane, and C5+ longer chain hydrocarbons. The present work focuses on providing a critical review on the light olefin production using Fischer– Tropsch synthesis. The effects of metals, promoters and supports as the most influential parameters on the catalytic performance of catalysts are discussed meticulously. Fe and Co as the main active metals in FT catalysts are investigated in terms of pore size, crystal size, and …

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New Mechanism Insight For The Hydrogenation Of Co/Co2 Gas Mixtures To Hydrocarbons Over Iron-Based Catalyst, Sandeep Badoga, Michela Martinelli, Muthu Kumaran Gnanamani, Young Koh, Wilson D. Shafer Jan 2021

New Mechanism Insight For The Hydrogenation Of Co/Co2 Gas Mixtures To Hydrocarbons Over Iron-Based Catalyst, Sandeep Badoga, Michela Martinelli, Muthu Kumaran Gnanamani, Young Koh, Wilson D. Shafer

Center for Applied Energy Research Faculty and Staff Publications

Iron-based catalysts are the most suitable candidates for converting CO2 or CO2-rich syngas to hydrocarbons. However, several issues about the mechanism of CO2 hydrogenation are still unclear. In this work, we investigated the performance of an iron-based catalyst with H2/CO2, H2/CO/N2 and H2/CO/13CO2/N2 gas mixtures at the same process conditions (T = 270°C, P = 175 psi and SV = 3 NL/h/gcat). The CO2 hydrogenation rate was much lower than that observed for CO hydrogenation. 13CO2 …

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Review On Carbon Dioxide Utilization For Cycloaddition Of Epoxides By Ionic Liquid-Modified Hybrid Catalysts: Effect Of Influential Parameters And Mechanisms Insight, Jimmy Nelson Appaturi, Rajabathar. Jothi Ramalingam, Muthu Kumaran Gnanamani, Govindasami Periyasami, Prabhakarn Arunachalam, Rohana Adnan, Farook Adam, Mohammed D. Wasmiah, Hamad A. Al‐Lohedan Jan 2021

Review On Carbon Dioxide Utilization For Cycloaddition Of Epoxides By Ionic Liquid-Modified Hybrid Catalysts: Effect Of Influential Parameters And Mechanisms Insight, Jimmy Nelson Appaturi, Rajabathar. Jothi Ramalingam, Muthu Kumaran Gnanamani, Govindasami Periyasami, Prabhakarn Arunachalam, Rohana Adnan, Farook Adam, Mohammed D. Wasmiah, Hamad A. Al‐Lohedan

Center for Applied Energy Research Faculty and Staff Publications

The storage, utilization, and control of the greenhouse (CO2) gas is a topic of interest for researchers in academia and society. The present review article is dedicating to cover the overall role of ionic liquid-modified hybrid materials in cycloaddition reactions. Special emphasis is on the synthesis of various cyclic carbonate using ionic liquid-based modified catalysts. Catalytic activity studies have discussed with respect to process conditions and their effects on conversion and product selectivity for the reaction of cycloaddition of CO2 with styrene oxide. The reaction temperature and the partial pressure of CO2 have found to play …

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Beneficial Reuse Of Industrial Co2 Emissions Using A Microalgae Photobioreactor: Waste Heat Utilization Assessment, Daniel T. Mohler, Michael H. Wilson, Zhen Fan, John G. Groppo, Mark Crocker Jul 2019

Beneficial Reuse Of Industrial Co2 Emissions Using A Microalgae Photobioreactor: Waste Heat Utilization Assessment, Daniel T. Mohler, Michael H. Wilson, Zhen Fan, John G. Groppo, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

Microalgae are a potential means of recycling CO2 from industrial point sources. With this in mind, a novel photobioreactor (PBR) was designed and deployed at a coal-fired power plant. To ascertain the feasibility of using waste heat from the power plant to heat algae cultures during cold periods, two heat transfer models were constructed to quantify PBR cooling times. The first, which was based on tabulated data, material properties and the physical orientation of the PBR tubes, yielded a range of heat transfer coefficients of 19–64 W m−2 K−1 for the PBR at wind speeds of 1–10 …

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Fischer–Tropsch: Product Selectivity–The Fingerprint Of Synthetic Fuels, Wilson D. Shafer, Muthu Kumaran Gnanamani, Uschi M. Graham, Jia Yang, Cornelius M. Masuku, Gary Jacobs, Burtron H. Davis Mar 2019

Fischer–Tropsch: Product Selectivity–The Fingerprint Of Synthetic Fuels, Wilson D. Shafer, Muthu Kumaran Gnanamani, Uschi M. Graham, Jia Yang, Cornelius M. Masuku, Gary Jacobs, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

The bulk of the products that were synthesized from Fischer–Tropsch synthesis (FTS) is a wide range (C1–C70+) of hydrocarbons, primarily straight-chained paraffins. Additional hydrocarbon products, which can also be a majority, are linear olefins, specifically: 1-olefin, trans-2-olefin, and cis-2-olefin. Minor hydrocarbon products can include isomerized hydrocarbons, predominantly methyl-branched paraffin, cyclic hydrocarbons mainly derived from high-temperature FTS and internal olefins. Combined, these products provide 80–95% of the total products (excluding CO2) generated from syngas. A vast number of different oxygenated species, such as aldehydes, ketones, acids, and alcohols, are also embedded in this product range. …

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Effect Of Pt Promotion On The Ni-Catalyzed Deoxygenation Of Tristearin To Fuel-Like Hydrocarbons, Ryan Loe, Kelsey Huff, Morgan Walli, Tonya Morgan, Dali Qian, Robert Pace, Yang Song, Mark Isaacs, Eduardo Santillan-Jimenez, Mark Crocker Feb 2019

Effect Of Pt Promotion On The Ni-Catalyzed Deoxygenation Of Tristearin To Fuel-Like Hydrocarbons, Ryan Loe, Kelsey Huff, Morgan Walli, Tonya Morgan, Dali Qian, Robert Pace, Yang Song, Mark Isaacs, Eduardo Santillan-Jimenez, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

Pt represents an effective promoter of supported Ni catalysts in the transformation of tristearin to green diesel via decarbonylation/decarboxylation (deCOx), conversion increasing from 2% over 20% Ni/Al2O3 to 100% over 20% Ni-0.5% Pt/Al2O3 at 260 °C. Catalyst characterization reveals that the superior activity of Ni-Pt relative to Ni-only catalysts is not a result of Ni particle size effects or surface area differences, but rather stems from several other phenomena, including the improved reducibility of NiO when Pt is present. Indeed, the addition of a small amount of Pt to the supported Ni …

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Continuous Catalytic Deoxygenation Of Waste Free Fatty Acid-Based Feeds To Fuel-Like Hydrocarbons Over A Supported Ni-Cu Catalyst, Ryan Loe, Yasmeen Lavoignat, Miranda Maier, Mohanad Abdallah, Tonya Morgan, Dali Qian, Robert Pace, Eduardo Santillan-Jimenez, Mark Crocker Jan 2019

Continuous Catalytic Deoxygenation Of Waste Free Fatty Acid-Based Feeds To Fuel-Like Hydrocarbons Over A Supported Ni-Cu Catalyst, Ryan Loe, Yasmeen Lavoignat, Miranda Maier, Mohanad Abdallah, Tonya Morgan, Dali Qian, Robert Pace, Eduardo Santillan-Jimenez, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

While commercial hydrodeoxygenation (HDO) processes convert fats, oils, and grease (FOG) to fuel-like hydrocarbons, alternative processes based on decarboxylation/decarbonylation (deCOx) continue to attract interest. In this contribution, the activity of 20% Ni-5% Cu/Al2O3 in the deCOx of waste free fatty acid (FFA)-based feeds—including brown grease (BG) and an FFA feed obtained by steam stripping a biodiesel feedstock—was investigated, along with the structure-activity relationships responsible for Ni promotion by Cu and the structural evolution of catalysts during use and regeneration. In eight-hour experiments, near quantitative conversion of the aforementioned feeds to diesel-like hydrocarbons was achieved. …

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Effect Of Crystallization Modes In Tips-Pentacene/Insulating Polymer Blends On The Gas Sensing Properties Of Organic Field-Effect Transistors, Jung Hun Lee, Yena Seo, Yeong Don Park, John E. Anthony, Do Hun Kwak, Jung Ah Lim, Sunglim Ko, Ho Won Jang, Kilwon Cho, Wi Hyoung Lee Jan 2019

Effect Of Crystallization Modes In Tips-Pentacene/Insulating Polymer Blends On The Gas Sensing Properties Of Organic Field-Effect Transistors, Jung Hun Lee, Yena Seo, Yeong Don Park, John E. Anthony, Do Hun Kwak, Jung Ah Lim, Sunglim Ko, Ho Won Jang, Kilwon Cho, Wi Hyoung Lee

Center for Applied Energy Research Faculty and Staff Publications

Blending organic semiconductors with insulating polymers has been known to be an effective way to overcome the disadvantages of single-component organic semiconductors for high-performance organic field-effect transistors (OFETs). We show that when a solution processable organic semiconductor (6,13-bis(triisopropylsilylethynyl)pentacene, TIPS-pentacene) is blended with an insulating polymer (PS), morphological and structural characteristics of the blend films could be significantly influenced by the processing conditions like the spin coating time. Although vertical phase-separated structures (TIPS-pentacene-top/PS-bottom) were formed on the substrate regardless of the spin coating time, the spin time governed the growth mode of the TIPS-pentacene molecules that phase-separated and crystallized on the …

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Determination Of Chemical Speciation Of Arsenic And Selenium In High-As Coal Combustion Ash By X-Ray Photoelectron Spectroscopy: Examples From A Kentucky Stoker Ash, Biao Fu, James C. Hower, Shifeng Dai, Sarah M. Mardon, Guijian Liu Dec 2018

Determination Of Chemical Speciation Of Arsenic And Selenium In High-As Coal Combustion Ash By X-Ray Photoelectron Spectroscopy: Examples From A Kentucky Stoker Ash, Biao Fu, James C. Hower, Shifeng Dai, Sarah M. Mardon, Guijian Liu

Center for Applied Energy Research Faculty and Staff Publications

Knowledge of the chemical speciation of arsenic and selenium in coal fly ash is essential in the evaluation of the environmental behavior of fly ash disposed in a landfill in a natural environment. In this study, a series of high-As coal fly ash from stoker boilers were collected to determine the chemical forms of arsenic and selenium. The ash surface chemical characteristics and the speciation of arsenic and selenium were characterized by X-ray photoelectron spectroscopy and X-ray-induced Auger electron spectroscopy. The results indicate that the surface enrichment ratio for selenium (63.3–309.5) is higher than that of arsenic (1.2–21.2). The Wagner …

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Reducing Biomass Recalcitrance By Heterologous Expression Of A Bacterial Peroxidase In Tobacco (Nicotiana Benthamiana), Ayalew Ligaba-Osena, Bertrand Hankoua, Kay Dimarco, Robert Pace, Mark Crocker, Jesse Mcatee, Nivedita Nagachar, Ming Tien, Tom L. Richard Dec 2017

Reducing Biomass Recalcitrance By Heterologous Expression Of A Bacterial Peroxidase In Tobacco (Nicotiana Benthamiana), Ayalew Ligaba-Osena, Bertrand Hankoua, Kay Dimarco, Robert Pace, Mark Crocker, Jesse Mcatee, Nivedita Nagachar, Ming Tien, Tom L. Richard

Center for Applied Energy Research Faculty and Staff Publications

Commercial scale production of biofuels from lignocellulosic feed stocks has been hampered by the resistance of plant cell walls to enzymatic conversion, primarily owing to lignin. This study investigated whether DypB, the lignin-degrading peroxidase from Rodococcus jostii, depolymerizes lignin and reduces recalcitrance in transgenic tobacco (Nicotiana benthamiana). The protein was targeted to the cytosol or the ER using ER-targeting and retention signal peptides. For each construct, five independent transgenic lines were characterized phenotypically and genotypically. Our findings reveal that expression of DypB in the cytosol and ER does not affect plant development. ER-targeting increased protein accumulation, and …

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Ga And In Modified Ceria As A Support For Cobalt Fischer-Tropsch Synthesis, Muthu Kumaran Gnanamani, Gary Jacobs, Wilson D. Shafer, Michela Martinelli, Donald C. Cronauer, A. Jeremy Kropf, Christopher L. Marshall, Burtron H. Davis Oct 2017

Ga And In Modified Ceria As A Support For Cobalt Fischer-Tropsch Synthesis, Muthu Kumaran Gnanamani, Gary Jacobs, Wilson D. Shafer, Michela Martinelli, Donald C. Cronauer, A. Jeremy Kropf, Christopher L. Marshall, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

Ceria modified by the addition of gallium or indium (20 mol%) was used as a support for cobalt Fischer-Tropsch synthesis. The addition of gallium to ceria improved the CO conversion for cobalt, whereas indium tended to decrease it. A similar trend was observed with the Ag-promoted cobalt/ceria catalysts that were doped with Ga or In. For Ag promoted catalysts, doping with Ga or In decreased methane and increased the product selectivities of olefins and alcohols. The sum of olefins and alcohols in terms of product selectivity for the Ag-promoted catalysts decreased in the following order: Ag-Co/Ce-Ga > Ag-Co/Ce-In > Ag-Co/Ce. The H2-TPR-XANES …

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Enhancements In Mass Transfer For Carbon Capture Solvents Part I: Homogeneous Catalyst, Leland R. Widger, Moushumi Sarma, Jonathan J. Bryant, David S. Mannel, Jesse G. Thompson, Cameron A. Lippert, Kunlei Liu Aug 2017

Enhancements In Mass Transfer For Carbon Capture Solvents Part I: Homogeneous Catalyst, Leland R. Widger, Moushumi Sarma, Jonathan J. Bryant, David S. Mannel, Jesse G. Thompson, Cameron A. Lippert, Kunlei Liu

Center for Applied Energy Research Faculty and Staff Publications

The novel small molecule carbonic anhydrase (CA) mimic [CoIII(Salphen-COO−)Cl]HNEt3 (1), was synthesized as an additive for increasing CO2 absorption rates in amine-based post-combustion carbon capture processes (CCS), and its efficacy was verified. 1 was designed for use in a kinetically slow but thermally stable blended solvent, containing the primary amines 1-amino-2-propanol (A2P) and 2-amino-2-methyl-1-propanol (AMP). Together, the A2P/AMP solvent and 1 reduce the overall energy penalty associated with CO2 capture from coal-derived flue gas, relative to the baseline solvent MEA. 1 is also effective at increasing absorption kinetics of kinetically fast solvents, such …

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Anion Exchange Membrane Capacitive Deionization Cells, Ayokunle Omosebi, Xin Gao, Nicolas Holubowitch, Zhiao Li, James Landon, Kunlei Liu Jul 2017

Anion Exchange Membrane Capacitive Deionization Cells, Ayokunle Omosebi, Xin Gao, Nicolas Holubowitch, Zhiao Li, James Landon, Kunlei Liu

Center for Applied Energy Research Faculty and Staff Publications

The electrochemical response of capacitive deionization (CDI) employing a single anion exchange membrane (AEM-CDI) is contrasted to conventional two-membrane CDI (MCDI) formed with complementary anion and cation exchange membranes. Pristine activated carbon cloth electrodes that possess native positive surface charge in solution were used as both anode (positive electrode) and cathode (negative electrode) in these cells. In a separate set of tests to investigate the impact of surface charge modification on deionization responses, the single and dual membrane cells were formed with asymmetric electrodes (AEM-aCDI and aMCDI) consisting of nitric acid oxidized electrodes that possess negative surface charge as the …

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Methanol Steam Reforming: Na Doping Of Pt/Ysz Provides Fine Tuning Of Selectivity, Michela Martinelli, Gary Jacobs, Uschi M. Graham, Burtron H. Davis May 2017

Methanol Steam Reforming: Na Doping Of Pt/Ysz Provides Fine Tuning Of Selectivity, Michela Martinelli, Gary Jacobs, Uschi M. Graham, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

In this work, we found that sodium doping can be used to improve CO2 selectivity for supported Pt catalyst during methanol steam reforming. These materials are usually very active in the low temperature range; however, they are characterized by high selectivity of CO, which is a poison in downstream polymer electrolyte membrane fuel cells (PEM-FC) application. With Na doping, we found that CO2 selectivity was higher than 90% when 2.5 wt.% of sodium was added to Pt/YSZ. We have speculated that the different product distribution is due to a different reaction pathway being opened for CH3OH …

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Capture And Recycle Of Industrial Co2 Emissions Using Mircoalgae, Michael H. Wilson, Daniel T. Mohler, John G. Groppo, Thomas E. Grubbs, Stephanie Kesner, E. Molly Frazar, Aubrey Shea, Czarena L. Crofcheck, Mark Crocker Sep 2016

Capture And Recycle Of Industrial Co2 Emissions Using Mircoalgae, Michael H. Wilson, Daniel T. Mohler, John G. Groppo, Thomas E. Grubbs, Stephanie Kesner, E. Molly Frazar, Aubrey Shea, Czarena L. Crofcheck, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

A novel cyclic flow photobioreactor (PBR) for the capture and recycle of CO2 using microalgae was designed and deployed at a coal-fired power plant (Duke Energy’s East Bend Station). The PBR was operated continuously during the period May–September 2015, during which algae productivity of typically 0.1–0.2 g/(L day) was obtained. Maximum CO2 capture efficiency was achieved during peak sunlight hours, the largest recorded CO2 emission reduction corresponding to a value of 81 % (using a sparge time of 5 s/min). On average, CO2 capture efficiency during daylight hours was 44 %. The PBR at East Bend …

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Electrode Kinetics Of Vanadium Flow Batteries: Contrasting Responses Of VIi-VIii And VIv-VV To Electrochemical Pretreatment Of Carbon, A. Bourke, M. A. Miller, R. P. Lynch, Xin Gao, James Landon, J. S. Wainright, R. F. Savinell, D. N. Buckley Oct 2015

Electrode Kinetics Of Vanadium Flow Batteries: Contrasting Responses Of VIi-VIii And VIv-VV To Electrochemical Pretreatment Of Carbon, A. Bourke, M. A. Miller, R. P. Lynch, Xin Gao, James Landon, J. S. Wainright, R. F. Savinell, D. N. Buckley

Center for Applied Energy Research Faculty and Staff Publications

Electrochemical impedance spectroscopy and cyclic voltammetry were used to investigate the electrode kinetics of VII-VIII and VIV-VV in H2SO4 on glassy carbon, carbon paper, carbon xerogel, and carbon fibers. It was shown that, for all carbon materials investigated, the kinetics of VII-VIII is enhanced by anodic, and inhibited by cathodic, treatment of the electrode; in contrast, the kinetics of VIV-VV is inhibited by anodic, and enhanced by cathodic, treatment. The potential region for each of these effects varied only slightly with carbon material. Rate constants …

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Lipid Extraction From Scenedesmus Sp. Microalgae For Biodiesel Production Using Hot Compressed Hexane, Hee-Yong Shin, Jae-Hun Ryu, Seong-Youl Bae, Czarena L. Crofcheck, Mark Crocker Aug 2014

Lipid Extraction From Scenedesmus Sp. Microalgae For Biodiesel Production Using Hot Compressed Hexane, Hee-Yong Shin, Jae-Hun Ryu, Seong-Youl Bae, Czarena L. Crofcheck, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

Lipid extraction from Scenedesmus sp. microalgae using hot compressed hexane (HCH) was investigated. Extraction performance was evaluated near the critical point of hexane and was compared with that of hexane extraction performed at room temperature and pressure, and the Bligh and Dyer extraction method. Experimental data showed that HCH significantly improves the lipid yield and rate of lipid extraction compared to the use of hexane at ambient conditions. High yields of biodiesel-convertible lipid fractions were rapidly achieved at the critical point of hexane, at a level comparable to that of the Bligh and Dyer method.

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Co2 Recycling Using Microalgae For The Production Of Fuels, Michael H. Wilson, John Groppo, Andrew Placido, S. Graham, S. A. Morton Iii, Eduardo Santillan-Jimenez, Aubrey Shea, Mark Crocker, Czarena Crofcheck, Rodney Andrews Mar 2014

Co2 Recycling Using Microalgae For The Production Of Fuels, Michael H. Wilson, John Groppo, Andrew Placido, S. Graham, S. A. Morton Iii, Eduardo Santillan-Jimenez, Aubrey Shea, Mark Crocker, Czarena Crofcheck, Rodney Andrews

Center for Applied Energy Research Faculty and Staff Publications

CO2 capture and recycle using microalgae was demonstrated at a coal-fired power plant (Duke Energy’s East Bend Station, Kentucky). Using an in-house designed closed loop, vertical tube photobioreactor, Scenedesmus acutus was cultured using flue gas as the CO2 source. Algae productivity of 39 g/(m2 day) in June–July was achieved at significant scale (18,000 L), while average daily productivity slightly in excess of 10 g/(m2 day) was demonstrated in the month of December. A protocol for low-cost algae harvesting and dewatering was developed, and the conversion of algal lipids—extracted from the harvested biomass—to diesel-range hydrocarbons via catalytic …

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Influence Of Reduction Promoters On Stability Of Cobalt/Γ-Alumina Fischer-Tropsch Synthesis Catalysts, Gary Jacobs, Wenping Ma, Burtron H. Davis Mar 2014

Influence Of Reduction Promoters On Stability Of Cobalt/Γ-Alumina Fischer-Tropsch Synthesis Catalysts, Gary Jacobs, Wenping Ma, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

This focused review article underscores how metal reduction promoters can impact deactivation phenomena associated with cobalt Fischer-Tropsch synthesis catalysts. Promoters can exacerbate sintering if the additional cobalt metal clusters, formed as a result of the promoting effect, are in close proximity at the nanoscale to other cobalt particles on the surface. Recent efforts have shown that when promoters are used to facilitate the reduction of small crystallites with the aim of increasing surface Co0 site densities (e.g., in research catalysts), ultra-small crystallites (e.g., < 2–4.4 nm) formed are more susceptible to oxidation at high conversion relative to larger ones. The choice of promoter is important, as certain metals (e.g., Au) that promote cobalt oxide reduction can separate from cobalt during oxidation-reduction (regeneration) cycles. Finally, some elements have been identified to promote reduction but either poison the surface of Co0 (e.g., Cu), or produce excessive light gas selectivity (e.g., Cu and Pd, or Au at …

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