Article
Chemistry, Physical
Tobias F. Kimpel, Jin-Xun Liu, Wei Chen, Robert Pestman, Emiel J. M. Hensen
Summary: Through IR spectroscopy and DFT calculations, it has been discovered that in the Fischer-Tropsch reaction, Mn promotes a silica-supported Co catalyst with a MnO layer covering the Co surface, activating adsorbed CO through reaction with an oxygen vacancy. This results in higher activity, higher CHx coverage, increased C5+ selectivity, and decreased CH4 selectivity. Increasing pressure amplifies the selectivity differences. However, above around 4 bar, the addition of Mn decreases C5+ selectivity, possibly due to its promotion of C-O bond dissociation but not chain growth. Migration of formed monomers for chain growth on the Co surface may be hindered by high CO coverage, especially at high pressure.
JOURNAL OF CATALYSIS
(2023)
Article
Chemistry, Physical
Luke M. van Koppen, A. Iulian Dugulan, G. Leendert Bezemer, Emiel J. M. Hensen
Summary: This study explored the role of manganese as a structural promoter on silica-supported cobalt nanoparticles under high CO conversion conditions. It was found that adding manganese oxide enhanced the dispersion of cobalt but resulted in cobalt silicate formation. Without manganese, the cobalt particles sintered and transformed into cobalt carbide.
JOURNAL OF CATALYSIS
(2023)
Article
Chemistry, Physical
Luke M. van Koppen, A. Iulian Dugulan, G. Leendert Bezemer, Emiel J. M. Hensen
Summary: This study investigates the role of manganese oxide as a structural promoter against sintering in a carbon nanofiber supported cobalt model catalyst. The results show that steam accelerates the sintering of non-promoted metallic cobalt particles, while in the presence of manganese oxide, sintering is significantly reduced. However, some cobalt particles in close interaction with manganese oxide carburize under these conditions, resulting in lower catalytic activity.
JOURNAL OF CATALYSIS
(2022)
Article
Chemistry, Physical
Chelsea L. Tucker, Yatheshthrao Ragoo, Silethukuthula Mathe, Lebohang Macheli, Ankur Bordoloi, Tulio C. R. Rocha, Sandeeran Govender, Patricia J. Kooyman, Eric van Steen
Summary: The addition of manganese to cobalt-based Fischer-Tropsch catalysts improves their activity and liquid fuel yield by reducing CO2 and CH4 selectivity. DFT calculations suggest that the promotion of manganese is associated with improved oxygen removal from the catalytically active surface, leading to reduced selectivity towards CO2 and increased liquid fuel yield.
JOURNAL OF CATALYSIS
(2022)
Article
Chemistry, Applied
Prasad Gonugunta, A. Iulian Dugulan, G. Leendert Bezemer, Ekkes Bruck
Summary: Operando spectroscopic techniques were used to investigate the impact of oxygenates deposition on the deactivation of cobalt on titania Fischer-Tropsch catalysts under high pressure. It was found that catalysts prepared via impregnation had more and heavier carboxylates, likely due to higher olefin content in the products, leading to increased formation of oxygenates. Gas chromatography/infrared spectroscopy data indicated that the surface carboxylate species were not involved in catalyst deactivation, serving as spectator species on the titania support.
Article
Energy & Fuels
Hong Du, Miao Jiang, Hejun Zhu, Chuande Huang, Ziang Zhao, Wenda Dong, Wei Lu, Tao Liu, Z. Conrad Zhang, Yunjie Ding
Summary: A highly efficient activated carbon supported cobalt based catalyst for Fischer-Tropsch synthesis was prepared and activated through multistep processes, exhibiting superior performance in CO conversion and CH4 selectivity compared to conventional catalysts. The catalyst's excellent performance was attributed to its increased amount of active sites and dominant hcp metallic cobalt phases. Further improvements in catalytic performance were achieved by adjusting the content of hcp metallic cobalt phase stacking through proper treatment conditions in the multistep activation method.
Article
Chemistry, Physical
C. J. (Kees-Jan) Weststrate, Daniel Garcia Rodriguez, Devyani Sharma, J. W. (Hans) Niemantsverdriet
Summary: This study investigates the interaction between hydrogen and cobalt surfaces, revealing the adsorption and desorption behavior of hydrogen on different surface structures. It also discovers the variation of hydrogen adsorption strength and equilibrium constant under different conditions.
JOURNAL OF CATALYSIS
(2022)
Article
Chemistry, Physical
F. Platero, S. Todorova, L. Aoudjera, L. Michelin, B. Lebeau, J. L. Blin, J. P. Holgado, A. Caballero, G. Colon
Summary: In this study, cobalt catalyst supported on mesostructured TiO2 was prepared and subjected to calcination and reduction. The results showed that cobalt nanoparticles were uniformly distributed along the mesopore channels of TiO2, and the highly stable metal active sites contributed to the generation of C5+ products in Fischer-Tropsch synthesis reaction.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Energy & Fuels
Francisco Platero, Alfonso Caballero, Gerardo Colon
Summary: Cobalt supported TiO2 catalysts were prepared by wet-impregnation and by immobilization over APTES grafted TiO2. The impregnated system showed better catalytic performance after reduction at 260 degrees C, but significant deactivation was observed. In contrast, the functionalized catalyst showed better catalytic performance after reduction at 400 degrees C with notable stability. CO-DRIFT operando analysis revealed that the impregnated system was strongly affected by negative SMSI upon reduction at higher temperature, while immobilization on APTES hindered the loss of metal active sites. The study of spent catalysts indicated that Co was redispersed in the impregnated catalyst while functionalized catalyst tended to form agglomerates.
Article
Energy & Fuels
Dalia Liuzzi, Francisco J. Perez-Alonso, Sergio Rojas
Summary: Ru-Co/Al2O3 and Ru-Fe/Al2O3 catalysts prepared by reduction-deposition method exhibit high activity in Fischer-Tropsch Synthesis, showing different conversion rates and product selectivity. The interaction between Ru and Co in Ru-Co/Al2O3 enhances the activity, while Ru-Fe/Al2O3 displays superior initial performance but declines over time, with less enriched products compared to Ru/Al2O3.
Article
Chemistry, Physical
Yunlei An, Xinxing Wang, Hailing Yu, Xingzhen Qi, Dong Lv, Tiejun Lin, Liangshu Zhong
Summary: The promotion effect of manganese on the Ru-based Fischer-Tropsch to olefins (FTO) reaction was investigated. Methane formation and second hydrogenation of olefins were effectively suppressed, while catalytic activity and olefin formation, especially for long-chain olefins, were greatly promoted with the addition of Mn. Structure characterization suggested that the addition of Mn could promote the dispersion of Ru nanoparticles (NPs) and enhance the electron density of metallic Ru sites, thus boosting the level of CO adsorption and dissociation. The electronic effect of Mn also creates a C*-rich local chemical environment that could weaken the hydrogenation of olefins. This work provides a simple and feasible way to improve Ru atom utilization for the rational design of Ru-based FTO catalysts.
Article
Chemistry, Physical
Lebohang Macheli, Emanuela Carleschi, Bryan P. Doyle, Gerard Leteba, Eric van Steen
Summary: Metal-support interactions in inverse catalysts prepared by adsorbing TEOS on Co3O4 can be manipulated by varying the solvent mixture. Deposition of TEOS on Co3O4 nanoparticles in n-hexane results in the formation of silica oligomers interacting strongly with cobalt(II,III)oxide after calcination at 573 K. Modification of Co3O4 nanoparticles with TEOS in a hydrolysing environment results in a stronger interaction due to the formation of surface cobalt silicate through hydrolysis.
JOURNAL OF CATALYSIS
(2021)
Article
Chemistry, Physical
Madita Einemann, Simon Haida, Nico Fischer, Nattawut Osakoo, Jatuporn Wittayakun, Frank Roessner
Summary: The role of cobalt chloride hexahydrate as a precursor of cobalt bulk catalysts was investigated for the Fischer-Tropsch reaction. Different oxygen-containing cobalt compounds were detected through in situ DRIFTS, in situ XANES, in situ XRD, and inverse TPR techniques. The reaction network of cobalt chloride transformation was discussed, taking into account the back mixing in different geometries of measuring cells. The choice of catalyst activation procedure is important for the formation of cobalt oxide and subsequent activity in the Fischer-Tropsch reaction.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Applied
Ljubisa Gavrilovic, Erik A. Jorgensen, Umesh Pandey, Koteswara R. Putta, Kumar R. Rout, Erling Rytter, Magne Hillestad, Edd A. Blekkan
Summary: Fischer-Tropsch synthesis has been investigated over a commercial cobalt-based catalyst, showing a positive effect of water on catalyst activity and increased C(5+) selectivity regardless of the H2/CO ratio. Increasing conversion led to increased C(5+) selectivity, while higher conversions resulted in significantly enhanced selectivity to CO2.
Article
Chemistry, Multidisciplinary
Sania Saheli, Ali Reza Rezvani, Ahmad Moghaddami, Michal Dusek, Erika Samolova
Summary: The role of the synthetic route in Fischer-Tropsch synthesis over Ba-Co-Mn catalysts was investigated. Catalysts synthesized with an inorganic precursor showed increased surface area and decreased particle sizes, leading to improved catalytic activity and selectivity to olefins and C-5(+) products.
Review
Chemistry, Multidisciplinary
Justin C. Bui, Chanyeon Kim, Alex J. King, Oyinkansola Romiluyi, Ahmet Kusoglu, Adam Z. Weber, Alexis T. Bell
Summary: The electrochemical reduction of carbon dioxide (CO2R) driven by renewable electricity offers a promising route for reusing CO2 and producing carbon-containing chemicals and fuels sustainably. Optimizing the catalyst microenvironment and selectivity, as well as controlling the electrolyte and operating conditions, are crucial for achieving economic viability and high product yields.
ACCOUNTS OF CHEMICAL RESEARCH
(2022)
Article
Chemistry, Physical
Justin C. Bui, Kaitlin Rae M. Corpus, Alexis T. Bell, Adam Z. Weber
Summary: This study developed a continuum model to understand and enhance the performance of water dissociation (WD) catalysts in bipolar membranes (BPM) by considering multiple kinetic pathways for WD in the junction catalyst layer. The research revealed that catalysts with a more alkaline or acidic pH at the point of zero charge exhibit accelerated WD kinetics due to greater surface charge, enhancing the local electric field and rate of WD.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Correction
Energy & Fuels
Chanyeon Kim, Justin C. Bui, Xiaoyan Luo, Jason K. Cooper, Ahmet Kusoglu, Adam Z. Weber, Alexis T. Bell
Review
Chemistry, Multidisciplinary
Justin C. Bui, Eric W. Lees, Lalit M. Pant, Iryna V. Zenyuk, Alexis T. Bell, Adam Z. Weber
Summary: Electrochemical synthesis using renewable energy to convert feedstocks into chemicals and fuels is promising, but understanding phenomena in porous electrode systems is challenging. Continuum modeling aids in understanding observed behaviors and guiding next-generation device design. Simulating multiscale phenomena in porous electrodes helps understand and improve the performance of electrochemical synthesis devices.
Article
Multidisciplinary Sciences
Hassan A. Aljama, Martin Head-Gordon, Alexis T. Bell
Summary: In this study, a high-throughput screening process using density functional theory was implemented to identify the energetically most favorable active sites in cation exchanged-zeolites, which is important for understanding catalysis and adsorption behaviors in zeolites.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Joseph A. Gauthier, Zhou Lin, Martin Head-Gordon, Alexis T. Bell
Summary: This study investigates the mechanism of CO2RR under experimental conditions and reveals the differences in activation barriers between alkaline and acidic pathways, as well as the kinetic favorability of COH formation under high overpotential.
ACS ENERGY LETTERS
(2022)
Article
Chemistry, Physical
Tianyu Zhang, Justin C. Bui, Zhengyuan Li, Alexis T. Bell, Adam Z. Weber, Jingjie Wu
Summary: In this study, we developed segmented gas-diffusion electrodes (s-GDEs) to improve the management of CO intermediates in tandem catalysts, thereby enhancing C2+ Faradaic efficiency and current density.
Article
Chemistry, Physical
Paul Kim, Jeroen Van der Mynsbrugge, Martin Head-Gordon, Alexis T. Bell
Summary: Passive NOx adsorbers (PNAs) are proposed for trapping NOx in automotive exhaust during cold start. In this study, it is found that Pd+ cations can be formed through water adsorbed on zeolite acid sites and can be fully desorbed by adsorbing NO. These reactions are thermodynamically feasible and Pd+ is not formed in the absence of adsorbed water and can be readily reoxidized to Pd2+ by trace amounts of O2.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Multidisciplinary
Liang Qi, Sonali Das, Yanfei Zhang, Danna Nozik, Bruce C. Gates, Alexis T. Bell
Summary: Catalysts for ethene hydroformylation were prepared by grafting Rh into nests of -SiOZn-OH or -SiOCo-OH species in BEA zeolite. The Rh dispersion increased with increasing M/Rh ratio and had a positive effect on the turnover frequency for ethene hydroformylation. The Co-containing catalyst exhibited higher activity and selectivity than the Zn-containing catalyst.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Danna Nozik, Alexis T. Bell
Summary: Ethane and propane derived from shale gas are preferred feedstocks for the production of aromatics. Ga/H-MFI zeolite exhibits high activity and selectivity for light alkane dehydroaromatization, with Ga3+ sites playing a crucial role. The enhanced activity of Ga/H-MFI is attributed to cooperative effects between Ga3+ sites and Bronsted acid protons.
Article
Chemistry, Multidisciplinary
Brooke Soobrian, Alex J. King, Justin C. Bui, Adam Z. Weber, Alexis T. Bell, Frances A. Houle
Summary: Artificial photosynthesis is a promising method to produce commodity chemicals using abundant chemical feedstocks and renewable energy sources. However, affordable and effective hands-on activities for primary school students to demonstrate and teach artificial photosynthesis are lacking. Educating young students on this topic is crucial for developing a diverse next-generation energy workforce. This study confirms that an active learning-based lesson plan using cheap and accessible materials can effectively educate a broad range of young students on artificial photosynthesis, as demonstrated by the improved understanding of fifth grade students before and after the lesson plan.
JOURNAL OF CHEMICAL EDUCATION
(2023)
Article
Nanoscience & Nanotechnology
Alex J. King, Adam Z. Weber, Alexis T. Bell
Summary: A metal-insulator-semiconductor (MIS) structure is an attractive photoelectrode-catalyst architecture for promoting photoelectrochemical reactions, such as the formation of H2 by proton reduction. Understanding how the insulator layer determines the photovoltage and what properties lead to high photovoltages is critical to the development of MIS structures for solar-to-chemical energy conversion.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Physical
John Safipour, Adam Z. Weber, Alexis T. Bell
Summary: Reactive carbon capture (RCC) is a promising solution for carbon capture and utilization. A systematic study found that RCC in aqueous environments is less effective and does not directly reduce into carbamate. Instead, the presence of amine solution suppresses the rate of CO formation while increasing that of H2.
ACS ENERGY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Chanyeon Kim, Alex J. King, Shaul Aloni, Francesca M. Toma, Adam Z. Weber, Alexis T. Bell
Summary: Photoelectrochemical carbon-dioxide reduction (PEC CO2R) is a promising method for producing chemicals and fuels using sunlight, water, and carbon dioxide. However, the focus has been mostly on producing C-1 products, while the production of C2+ products has been rarely demonstrated. In this study, a Cu/TiO2/p-Si photocathode/catalyst structure was investigated to understand the effects of semiconductor-insulator interactions and illumination direction on the performance and product distribution. Coating the Cu surface with a thin bilayer of Sustainion/Nafion significantly enhanced the current density and faradaic efficiency to ethylene.
ENERGY & ENVIRONMENTAL SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Annette Bohme, Justin C. Bui, Aidan Q. Fenwick, Rohit Bhide, Cassidy N. Feltenberger, Alexandra J. Welch, Alex J. King, Alexis T. Bell, Adam Z. Weber, Shane Ardo, Harry A. Atwater
Summary: We investigated how the micrometer-scale morphology of a CO2R gas diffusion electrode (GDE) affects the mass transport properties and local CO2R performance. Using fluorescence confocal laser scanning microscopy (CLSM), we created local pOH maps around a copper GDE and observed that pOH decreases in microtrenches compared to the electrode surface. Multiphysics simulations correlated well with experimental measurements and suggested that the decreased pOH inside microcavities leads to enhanced selectivity towards multicarbon products. This study highlights the importance of a GDE's micromorphology on CO2R performance.
ENERGY & ENVIRONMENTAL SCIENCE
(2023)
