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The Fischer–Tropsch Synthesis process is projected to have a significant impact in the near future due to its potential for synthesizing sustainable fuels from biomass, carbon dioxide and organic wastes. In this catalytic process, catalyst activation plays a major role in the overall performance of Fischer–Tropsch Synthesis. Catalyst activation temperatures are considerably higher than the typical operating conditions of industrial reactors. Consequently, ex situ activation is often required for industrial Fischer–Tropsch Synthesis processes. This study evaluated the influence of different activation approaches (in situ, ex situ, passivation and low-temperature activation). Catalytic experiments were conducted in a fixed-bed reactor at 230 °C and 20 bar·g using a reference supported Co/γ-Al2O3 catalyst. Experimental results demonstrate that catalysts can be effectively reduced ex situ. This work reveals that re-activation of the catalyst after ex situ reduction is unnecessary, as the reaction conditions themselves re-reduce any superficial oxides formed, owing to the reducing nature of the reactant mixture. This approach could simplify reactor design by enabling temperature requirements to match operating conditions (e.g., 230 °C), thereby reducing both investment and operational costs and eliminating additional catalyst preparation steps. [ABSTRACT FROM AUTHOR]

CO hydrogenation is a promising approach for the storage of renewable energy in the form of hydrocarbons via the Fischer–Tropsch synthesis (FTS). Since transient operation of FTS reactors might be necessary and even be beneficial, transient kinetics for a rational catalyst and reactor design are essential. In order to advance the development of such transient kinetics, the periodic transient kinetics (PTK) method was applied to the CO hydrogenation on a Co/TiO2 catalyst under FT‐like conditions. It was revealed that there are two carbon species of different reactivity, Cα and Cβ, present on the catalyst surface during the reaction. Cα forms fast, within a few seconds, and is highly reactive. Whereas Cβ forms slowly, is accumulating on the surface over a longer time, and imposes an inhibiting effect. The results indicate an important role of the Cβ species to chain growth and the formation of C2+ products. Finally, the transient experimental results were evaluated based on a material balance and the amounts of Cα and Cβ present on the catalyst surface during the reaction were determined. [ABSTRACT FROM AUTHOR]

Bio-oil is a key alternative to fossil fuels, and its commercialization requires assessing production quality and quantity. Catalysts play a crucial role in the bio-oil production process. This study evaluates the impact of cobalt-based zeolite (Co/HZSM-5) catalysts on the pyrolysis of Azolla and Ulva biomasses, focusing on bio-oil production and comparing it with direct pyrolysis. It demonstrated that catalytic pyrolysis improved the high heat value (HHV) and energy yield of the bio-oil compared with direct pyrolysis.Specifically, for Azolla, the bio-oil yield decreased from 30.64% in direct pyrolysis to 23.5% with the catalyst, while HHV increased from 28.6 MJ/kg to 33.2 MJ/kg. For Ulva, bio-oil yield fell from 34.43% to 26.1%, with HHV rising from 30.7 MJ/kg to 32.26 MJ/kg. Catalytic pyrolysis also enhanced energy recovery, achieving 48.37% for Azolla and 69.02% for Ulva. The process altered the distribution of pyrolysis products: biogas yield dropped from 37% to 27.14% for Azolla and from 30.5% to 16.57% for Ulva, while biochar yield increased from 39.5% to 42.21% for Azolla and from 43.4% to 49% for Ulva. These results suggest that catalytic pyrolysis is effective in producing higher quality bio-oil and improves overall energy efficiency. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting has been undergoing wide investigations due to their significance toward economic production of green hydrogen. Cobalt oxide catalysts are prepared via two different synthesis methods, and these bulk oxides are characterized and studied for water splitting reaction in alkaline medium. Further, similar supported catalysts are prepared using zeolites as support materials. All the samples are characterized using N2 adsorption X-ray diffraction, electron microscopic morphology, temperature programed reduction using hydrogen, etc., and the results are discussed. The performance of cobalt and cobalt-based zeolite hybrid electrocatalyst toward water splitting. Both oxygen and hydrogen evolutions were investigated. The hybrid materials were prepared chemically using co precipitation and direct calcination protocols. The prepared electrocatalyst proved to have low overpotential, high current density, high electrochemical surface area, and enhanced hydrogen/oxygen evolution performance. [ABSTRACT FROM AUTHOR]

In this work, we described a general monometallic cobalt heterogeneous catalyst for the hydroformylation of olefins, achieving good yields and recyclability up to five times with no loss in catalytic activity. These catalysts were prepared through the pyrolysis of the well‐defined metal–organic framework ZIF‐67. The addition of steam during the pyrolysis did not affect the final phase composition of the cobalt particles; nonetheless, it resulted in an increase of the cobalt particle size and the partial removal of the carbonaceous matrix. The materials were extensively characterized by several techniques, and it was observed that the N‐doped carbon matrix played a crucial role in terms of activity and stability. Different liquid olefins, including internal, terminal, and cyclic were successfully tested in our hydroformylation protocol. Aldehydes yields of 48%–77% for different liquid olefins were achieved with the optimal catalyst. No leaching of the active sites was observed over five catalytic cycles. The high stability of the catalyst is attributed to the presence of stabilizing nitrogen atoms bearing the cobalt sites. [ABSTRACT FROM AUTHOR]

Direct CO2 conversion to liquid hydrocarbons (HCs) in a single process was achieved using cobalt (Co) catalysts supported on lanthanum ion (La3+)‐doped cerium oxide (CeO2) under a gas stream of H2/CO2/N2=3/1/1. The yield of liquid HCs was the highest for 30 mol% of La3+‐doped CeO2, which was because extrinsic oxygen vacancy formed by doping La3+ could act as an effective reaction site for reverse water gas shift reaction. However, the excess La3+ addition afforded surface covering lanthanum carbonates, resulting in depression of the catalytic performance. On the other hand, bare CeO2 lead to an increase in the selectivity of undesirable methane, which arose from reduction of CO2 to CO proceeding by intrinsic oxygen vacancy generated by only Ce3+, and weaker CO2 capture ability of intrinsic oxygen vacancy than extrinsic one, resulting in the proceeding of Sabatier reaction on Co catalyst. The rational design of reaction sites presented in this study will contribute to sustainability. [ABSTRACT FROM AUTHOR]

Structured Fischer–Tropsch synthesis catalysts were tested in tubular reactors of industry-standard diameters of 0.5 or 0.75 inches. The structured catalyst bed was manufactured by the obturation of a straight bunch of graphite-based extrudates (D = 1.5 mm, L = 30 mm). A conventional loose bed of granulated catalyst (D = 1.5 mm, L = 3 mm) was tested as a reference. In a 1000–3000 h−1 syngas space velocity range, structured and loose catalyst bed testing showed no significant differences in their main catalytic parameters. Nevertheless, their C5+ hydrocarbon group composition was quite different, i.e., the alkene fraction rose from 9 to 23%, while n-alkanes dropped from 81 to 64%. This could be a result of secondary reaction intensification in the conventional loose bed due to its zeolite acid site's higher availability. Further FTS testing of the structured catalysts in 4000–6000 h−1 manifested distinctive limits in C5+ productivity for 0.5 and 0.75 inches of 512 kg C5+/(m3 reactor·h) and 362 kg C5+/(m3 reactor·h), respectively. This may be explained by limitations in structured bed thermal conductivity. It suggests that the arrangement of extrudates in the structured catalyst can significantly affect the reaction heat and mass transfer conditions and affords new opportunities for group composition control by means of catalyst bed organization. [ABSTRACT FROM AUTHOR]

Cobalt-based catalysts are recognized as promising electrocatalysts for oxygen reduction reactions (ORRs) in fuel cells that operate within acidic electrolytes. A synthesis process involving a cobalt complex, nanocellulose, and dopamine, followed by pyrolysis at 500 °C under a nitrogen atmosphere, was used to create a cobalt and nitrogen-doped carbonaceous material. Additionally, urea was incorporated to enhance nitrogen doping in the carbonaceous material. The morphology and structure of the material were examined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), where SEM unveiled dispersed metal oxides within the carbonaceous framework. Energy Dispersive X-ray Spectroscopy (EDS) analysis showed an even distribution of elements across the cobalt-doped carbonaceous material. X-ray Photoelectron Spectroscopy (XPS) analysis further highlighted significant alterations in the elemental composition due to pyrolysis. The electrochemical behavior of the cobalt-doped carbonaceous material, with respect to the oxygen reduction reaction (ORR) in an acidic medium, was investigated via cyclic voltammetry (CV), revealing an ORR peak at 0.30 V against a reversible hydrogen reference electrode, accompanied by a notably high current density. The catalyst's performance was evaluated across different pH levels and with various layers deposited, showing enhanced effectiveness in acidic conditions and a more pronounced reduction peak with uniformly applied electrode layers. Rotating disk electrode (RDE) studies corroborated the mechanism of a four-electron reduction of oxygen to water, emphasizing the catalyst's efficiency. [ABSTRACT FROM AUTHOR]

Enhancing the hydrolysis reaction of NaBH 4 for efficient hydrogen production requires the development of effective catalysts. In this study, the solution particles used for nanoparticles synthesized using the ultrasonic spray (US) method were produced for the first time in N 2 at room temperature in the gas and liquid intermediate phases. It also brings a new approach to synthesizing low-cost and efficient catalysts using ultrasonic spray technology. The proposed method involves US the CoCl 2 solution into the NaBH 4 solution to reduce cobalt, producing catalysts for hydrogenation. This innovative approach pioneers a gas-liquid interface reaction for metal reduction. The resulting catalysts were characterized using SEM, XRD, XPS, TEM, BET and FT-IR analysis. The influence of NaOH/NaBH 4 concentration, solution temperature, and catalyst amount on hydrogen production rate was investigated, and kinetic parameters were analyzed to understand the reaction kinetics better. The hydrogen production rates of US-Co and reduction method (RM) Co catalysts under the same conditions were calculated as 3995 ml H2 /min.g cat and 1245 ml H2 /min.g cat , respectively. The activation energy values calculated for the NaBH 4 hydrolysis of the US-Co catalyst using the nth-order and Langmuir-Hinshelwood kinetic models are 46.75 kJ/mol and 46.87 kJ/mol, respectively. Therefore, it can be concluded that the Langmuir-Hinshelwood kinetic model is consistent with the nth-order kinetic model. Experimental results showed that the ultrasonic spray method is very effective in producing active metal catalysts, offering promising opportunities for catalytic advances. [Display omitted] • A novel method of ultrasonic spray was improved for Co NPs pioneering a gas and liquid interface reaction. • The US-Co is highly active for NaBH 4 with an H 2 production rate of 3995 ml H2 /min.g cat at 30 °C. • The activation energy was calculated to be 46.75 kJ/mol with US-Co NPs. [ABSTRACT FROM AUTHOR]

The selective conversion of unsaturated compounds has emerged as a crucial method in chemical synthesis, enabling the synthesis of functional organic molecules. In recent decades, transition metal‐catalyzed hydrosilylation has emerged as a highly successful exemplar of industrialization within the realm of organic chemistry for the production of organosilanes, which have a pivotal role in organic chemistry and materials science. Precious metal complexes are typically employed as catalysts in most industrial hydrosilylation processes. The exploration of Earth‐abundant alternatives has emerged as a focal point of considerable research attention due to the high cost, poor selectivity, and many side reactions reported for precious metal catalysts. Ligand skeleton construction, selectivity, and mechanism research are areas where cobalt catalysts have more potential than iron and nickel. This review discusses the recent advances in cobalt‐catalyzed hydrosilylation across carbon‐carbon, carbon‐oxygen, and carbon‐nitrogen multiple bonds from 2019 to 2023. [ABSTRACT FROM AUTHOR]

Bicenter (BCn) cobalt-bis(imine) catalysts were synthesized, used to polymerize methyl methacrylate (MMA), and 1-hexene. The effect of catalyst structure, bridging ligand, and polymerization reaction conditions were investigated. Synthesis of primary ligand of (2,6-dibenzhydryl-4-ethoxyphenyl)-N=(CH3)-C(CH3)=O is prepared. Following to that, the final ligands of BC1 and BC2 bicenter catalysts were prepared via reacting the primary ligand with 2,3,5,6-tetramethylbenzene-1,4-diamine and 4,4-methylenedianiline bridges, respectively. The BC1 catalyst demonstrated higher activity than the BC2 catalyst. The highest activity for the BC1 catalyst was obtained when the co-catalyst to catalyst molar ratio was [Al]/[Co]=1500:1, and the polymerization temperature was 40 °C. In comparison the BC2 catalyst demonstrated the highest activity in [Al]/[Co]=500:1 ratio, polymerization temperature of 70 °Cand showed higher thermal stability. 1HNMR analysis revealed that the highest branching density for poly(methyl methacrylates) (PMMA) produced by BC1 and BC2 catalysts was 222 and 249 branches per 1000 carbon atoms, respectively. PMMA synthesized with BC2 catalysts had the highest syndiotacticity (59%). The polymer produced with bicenter catalyst (BC1) had a relatively broad molecular weight distribution (2.9), according to GPC analysis. The synthesized catalysts demonstrated appropriate activity for the polymerization of MMA, but only moderate activity for 1-hexene monomer

The direct synthesis of cyclic carbonates through oxidative carboxylation of alkenes using CO2 and O2 offers a sustainable and carbon‐neutral method for CO2 utilization, which is, however, still a largely unexplored field. Here we develop a single‐atom catalyst (SAC) Co−N/O−C as the earth‐abundant metal catalyst for the oxidative carboxylation of styrene with CO2 and O2. Remarkably, even using the flue gas as an impure CO2 and O2 source, desired cyclic carbonate could be obtained with moderate productivity, which shows the potential for integrated CO2 capture and conversion, leveraging the high CO2 adsorption capacity of Co−N/O−C. In addition, the catalyst can be reused five times without an obvious decline in activity. Detailed characterizations and theoretical calculations elucidate the crucial role of single Co atoms in activating O2 and CO2, as well as controlling selectivity. [ABSTRACT FROM AUTHOR]

Bicenter (BCn) cobalt-bis(imine) catalysts were synthesized to be used for the polymerization of methyl methacrylate (MMA) and 1-hexene. The effect of catalyst structure, bridging ligand and polymerization reaction conditions was investigated. Synthesis of primary ligand (2,6-dibenzhydryl-4-ethoxyphenyl)-N=(CH3 )- C(CH3 )=O was also done. Following to that, the final ligands of the BC1 and BC2 bicenter catalysts were prepared via reacting the primary ligand with 2,3,5,6-tetramethylbenzene-1,4-diamine and 4,4-methylenedianiline bridges, respectively. The BC1 catalyst demonstrated higher activity than the BC2 catalyst. The highest activity for the BC1 catalyst was obtained when the co-catalyst to catalyst molar ratio was [Al]/[Co]=1500:1, and the polymerization temperature was 40°C. In comparison, the BC2 catalyst demonstrated the highest activity and higher thermal stability in the conditions of: [Al]/[Co]=500:1 ratio and 70°C polymerization temperature. The ¹H NMR analysis results revealed that the highest branching density for the poly(methyl methacrylate) (PMMA) produced by the BC1 and BC2 catalysts was 222 and 249 branches per 1000 carbon atoms, respectively. The PMMA synthesized with the BC2 catalysts had the highest syndiotacticity (59%). The polymer produced with the bicenter catalyst (BC1) showed a relatively broad molecular weight distribution (2.9), according to the GPC analysis results. The synthesized catalysts demonstrated appropriate activity for the polymerization of MMA, but only moderate activity for 1-hexene monomer. [ABSTRACT FROM AUTHOR]

A series of supports were synthesized using two methods of sol-gel and oil-drop. In this work, the simultaneous effects of P123 surfactant, promoters (cerium, zirconium, and boron), and ethanol solvent on catalytic activity for the Fischer–Tropsch Synthesis (FTS) were studied. Cobalt catalysts were prepared using the incipient wetness impregnation method on γ-alumina granules for FTS in a fixed-bed reactor. All the prepared granules Co catalysts were characterized using FTIR, BET, XRD, TPR, FESEM, EDS, and ICP techniques. The FTS operation condition was carried out at T = 503 K, P = 15 bar, H2/CO = 2, and space velocity 5.1 NL g–1 h-1. The obtained results clearly showed that the catalytic evaluation of the Co catalysts supported on γ-alumina, with respect to the activity and selectivity of C5+ products were increased by the addition of surfactant and promoters in FTS. Also, the Co catalysts supported with γ-alumina P123 surfactant were more active than the Co catalysts supported with γ-alumina. Furthermore, the morphologies of the γ-alumina supported granules were changed by surfactant and promoters and the presence of CeO2 on the surface of the supports favors the reducibility of cobalt oxide with a shift down in reduction temperature of about 50 °C. Meanwhile, the addition the simultaneous of P123 surfactant and Ce promoter with ethanol solvent remarkably influenced the improvement of activity, selectivity, and stability of the catalyst as well. Ce promoter reduced the methane selectivity by increasing the chain-growth probability (α-value).

A family of pyridine–oxazoline-ligated cobalt complexes L2CoCl2 3a–h were synthesized and characterized. Determined via single-crystal X-ray diffraction, complexes 3a and 3d, ligated by two ligands, displayed a distorted tetrahedral coordination of a cobalt center. The X-ray structure indicated the pyridine–oxazoline ligands acted as unusual mono-dentate ligands by coordinating only to Noxazoline. Upon activation with AlEt2Cl (diethylaluminum chloride), these cobalt complexes all exhibited high catalytic activity (up to 2.5 × 106 g·molCo−1·h−1), affording cis-1,4-co-3,4-polyisoprene with molecular weights of 4.4–176 kg mol−1 and a narrow Ð of 1.79–3.42, suggesting a single-site nature of the active sites. The structure of cobalt catalysts and reaction parameters, especially co-catalysts and the reaction temperature, all have significant influence on the polymerization activity but not on the microstructure of polyisoprene. [ABSTRACT FROM AUTHOR]

Tuning the metal-support interaction is a general strategy of regulating the chemical state of catalytic active site for high-efficiency hydrogen production from ethanol steam reforming (ESR) reaction. In this work, a Co catalyst supported on the Si 4 Al 2 O 2 N 6 solid solution of Si 3 N 4 and Al 2 O 3 (Co/Si 4 Al 2 O 2 N 6) has been developed to effectively catalyze ESR reaction. Our results demonstrate that the Co/Si 4 Al 2 O 2 N 6 catalyst exhibits remarkably improved performances as compared with the Co/Si 3 N 4 and Co/Al 2 O 3 catalysts. In the Co/Si 4 Al 2 O 2 N 6 -catalyzed ESR reaction, ethanol conversion of 97 % has been achieved with hydrogen yield reaching 73 %. Long-time catalytic experiment manifests the Co/Si 4 Al 2 O 2 N 6 catalyst possesses excellent durability. X-ray photoelectron spectroscopy (XPS) studies reveal that the enhanced metal-support interaction (MSI) and charge transfer from Si 4 Al 2 O 2 N 6 support to Co species in the Co/Si 4 Al 2 O 2 N 6 catalyst confer lower valence state on the Co catalyst supported on Si 4 Al 2 O 2 N 6 , thus promoting the C–C bond cleavage capability, leading to high C1 product yield and boosting the hydrogen-production efficiency. The catalytic mechanism studies explored by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveal that the Co/Si 4 Al 2 O 2 N 6 exhibits a remarkable preference for C1 products over the Co/Si 3 N 4 and Co/Al 2 O 3 catalysts at low reaction temperature, thus resulting in high hydrogen-production efficiency with excellent catalytic durability. • Co/Si 4 Al 2 O 2 N 6 boosting hydrogen production from ethanol steam reforming. • Si 4 Al 2 O 2 N 6 solid solution of Al 2 O 3 and Si 3 N 4 conferring stronger metal-support interaction (MSI) on Co/Si 4 Al 2 O 2 N 6. • Regulating chemical state of Co catalysts via enhanced electron donation from Si 4 Al 2 O 2 N 6 support to Co species. • Mechanism investigation of catalytic ESR reaction by in situ DRIFTS studies. [ABSTRACT FROM AUTHOR]

The regeneration of Fischer-Tropsch (FT) catalysts plays a crucial role in sustaining their catalytic activity and longevity in sustainable production processes. This research investigates the effectiveness of various solvents, including n-hexane, n-heptane, toluene, xylene, and the liquid fraction of FT products (LF-FT), for catalyst regeneration and extracting wax from the 15 wt%Co/Al 2 O 3 catalyst. Toluene, with a unique combination of key parameters such as polarity, solubility, boiling point, aromatic structure, and chemical interactions, exhibited the highest wax removal efficiency of 90.6%. However, due to its 41 °C lower boiling point compared to toluene and very similar wax removal efficiency, n-hexane appears as a more energy-efficient and cost-effective option for this process. The regenerated catalysts showed comparable characteristics, including the textural properties (surface area, pore size, and pore volume), crystallinity, and reducibility, to fresh catalysts. The slightly lower reduction temperature in the regenerated catalyst indicates a higher possibility for the formation of cobalt active sites during the catalyst reduction process with hydrogen, leading to an increased potential for higher catalytic activity. The LF-FT, comprising paraffins, iso-paraffins, olefins, napthenes, and aromatics, provided a unique combination of aliphatic and aromatic moieties, enhancing the solubility of both polar and nonpolar components in FT wax and improving the wax removal efficiency to 91.5%. The higher boiling point and operating temperature of the LF-FT also contributed to its better performance. Efficient separation of hydrocarbons from solvents allowed for solvent reusability in subsequent FT wax removal cycles, making it advantageous for large-scale applications. [Display omitted] • Different solvents (n-hexane, toluene, n-heptane, xylene, LF-FT) assessed for FT catalyst regeneration. • Toluene displayed the highest wax removal efficiency, followed by n-hexane, n-heptane, and xylene. • N-hexane emerges as optimal solvent with low boiling point, cost-effective, and energy-efficient for wax extraction.. • Regenerated catalysts matched fresh ones, indicating restored surface properties and accessible cobalt active sites. • LF-FT solvent, with aliphatic and aromatic components, shows promise for FT catalyst regeneration with enhanced solubility. [ABSTRACT FROM AUTHOR]

Carbon aerogel (CA) as a novel catalyst support in Fischer‐Tropsch synthesis (FTS) was synthesized by polymerization of a resorcinol‐formaldehyde (RF) precursor through an ambient pressure drying route. The cobalt‐doped CA was synthesized by three main strategies: (a) impregnation of the metal precursor on the CA (Co‐CA‐I), (b) carbonization of cobalt‐doped organic RF aerogel (Co‐CA‐II), and (c) addition of the cobalt precursor to the RF mixture (Co‐CA‐III). The pores and cobalt particle size increased in the order of Co‐CA‐I > Co‐CA‐II > Co‐CA‐III and cobalt particles wrapped between the graphite layers when cobalt was added to the RF mixture. The CA as the catalyst support presented high CO conversion and high stability under FTS conditions. The CH4 selectivity increased by reducing the size of the cobalt particles. Hydrogen spillover from the support to metallic particles was observed in the case of Co‐CA‐I and Co‐CA‐III catalysts. This phenomenon improved the reducibility and also resulted in higher hydrogenated products being produced. [ABSTRACT FROM AUTHOR]

The incorporation of cis‐1,4 and 3,4(+1,2) units is important to the overall properties of polyisoprene. Nevertheless, polymerization to prepare such polymer via coordinative‐insertion method has less reported. In the present study, 2,6‐bis(1H'‐allyl‐benzimidazolyl)pyridine has been installed onto the iron and cobalt prior to heterogeneous supporting. They are shown to be amenable to homogeneous polymerization of isoprene, affording 3,4(+1,2) units enriched polymer. The addition of disulfide carbon into cobalt catalyst is decisive for boosting productivity and elevating 3,4 (+1,2) insertion. Whereas, diethylphosphite external donor merely behaves as a chain transfer agent in iron catalyzed polymerization. The produced polymer with a controlled 3,4(+1,2) ratio and molar mass may find application as a single rubber, in polymer blends, composites, adhesives, and as a versatile platform for transforming to a wide range of functional polymer. Highlights: Novel iron and cobalt complexes are made.High activities toward isoprene polymerization are achieved.3,4(+1,2) incorporated polyisoprene is obtained. [ABSTRACT FROM AUTHOR]

Hydrogen is considered the cleanest, most environmentally friendly fuel and energy carrier required for the gradual decarbonisation of many industrial sectors. Using ammonia as a Cox-free source of hydrogen is the most reasonable and most applicable method. This paper studies the properties and activity of cobalt catalysts in the ammonia decomposition reaction using a plasma-catalytic system. The effect of catalyst type (supported versus bulk) was evaluated. The catalysts were examined using XRD, STEM-EDX, and sorption techniques (N2 physisorption, TGA-TPR, H2-TPD, CO2-TPD) to reveal the influence of physicochemical properties of these two types of catalysts on the efficiency of NH3 decomposition in the plasma-catalytic process using a gliding discharge plasma. The results disclose that the supported-type catalyst (Ba-Co/CeO2) decomposed NH3 more effectively than the bulk-type catalyst (Co/Ce/Ba). At discharge power of 300 W and flow rate of 180 dm3 h–1 of NH3:N2 mixture (50/50 vol%), the ammonia conversion over the Ba-Co/CeO2 catalyst was 70%, whereas over the Co/Ce/Ba catalyst it was only 21%. The favourable performance of the supported-type catalyst was attributed to a more thermally stable surface area compared with the bulk-type catalyst. Smaller and more stable cobalt nanoparticles (NPs) with numerous weak hydrogen adsorption sites were also seen. Meanwhile, the strong basic sites were generated, improving the electron-donating ability of the surface active sites. High ammonia conversion and relatively low-energy consumption of the plasma-catalytic ammonia decomposition over Ba-Co/CeO2 make it suitable for practical hydrogen production applications, such as fuel cells and hydrogen storage.

A Pt–Co/Al 2 O 3 bimetallic catalyst for catalytic hydrogen combustion (CHC) is prepared and its performance is evaluated. A colloidal dispersion of a Pt-sulphite complex is used as the Pt precursor instead of the conventional H 2 PtCl 6 solution. The prepared catalyst maintains its catalytic activity at a temperature of up to 337 °C for 500 h of continuous CHC. To assess the catalytic activity and thermal conductivity of the catalyst, a catalytic cartridge for a recombiner section is designed. The thermal distribution over the catalytic surface during CHC is measured, using an infrared camera, as a function of inlet hydrogen concentration (0–10 vol%) and gas flow velocity (4–12 m/s). Hydrogen conversion is also determined, to evaluate the catalytic activity of the prepared catalysts. Results of this study indicate that the Pt reactive metal can be partially replaced with Co—thus reducing the cost of the catalyst, without diminishing the catalyst performance towards CHC. [Display omitted] • Reactive Pt–Co bimetallic catalyst was prepared for catalytic hydrogen combustion. • Pt colloidal dispersion resulted in deposition of Pt particles of 1.2 nm in size. • The maximum conversion of 86% was obtained for Pt–Co catalyst. • No decrease in catalytic activity after 500 h of hydrogen combustion at >270 °C. • Co metal demonstrated low performance even at temperatures as low as 80 °C. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Reductive deoxygenation of ketones using H2 is a highly desirable but also challenging transformation in both chemical synthesis, industrial‐scale petroleum and biomass feedstock reforming processes. Herein, we report a cooperative cobalt/Lewis acid (LA)‐catalyzed hydrodeoxygenation of ketones using H2 as the reductant. In particular, the newly developed pincer cobalt catalyst possesses dual hydrogenation activities for both ketones and alkenes under the same reaction conditions. This reaction features a broad substrate scope, excellent functional‐group compatibility, and potential applicability. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Reductive deoxygenation of ketones using H2 is a highly desirable but also challenging transformation in both chemical synthesis, industrial‐scale petroleum and biomass feedstock reforming processes. Herein, we report a cooperative cobalt/Lewis acid (LA)‐catalyzed hydrodeoxygenation of ketones using H2 as the reductant. In particular, the newly developed pincer cobalt catalyst possesses dual hydrogenation activities for both ketones and alkenes under the same reaction conditions. This reaction features a broad substrate scope, excellent functional‐group compatibility, and potential applicability. [ABSTRACT FROM AUTHOR]

In order to diminish environmental issues such as global warming due to increased carbo dioxide (CO2) emissions, considerable efforts have been made in the research community. Photocatalytic hydrogen (H2) production is a very important way towards this goal, since sunlight is an abundant source of energy and H2 is a clean fuel, producing no greenhouse gases. Inexpensive, stable and non‐toxic carbon dots were easily synthesized and used as photosensitizers in water in the presence of a series of molecular cobalt catalysts (CoTSC). The catalysts were thiosemicarbazone‐based complexes able to transfer electrons for hydrogen evolution reaction. Under visible light irradiation, the nitrogen‐doped carbon dots (NCdots) transfer the photoexcited electrons to the catalyst, producing an activity of 358 μmol gNCdot−1 h−1 (TONCo=570) for CoTSC−N(CH3)2CN after 24 h of irradiation. These types of molecular catalysts display great activity and stability in combination with the easily synthesized and modified carbon dot materials. [ABSTRACT FROM AUTHOR]

Cyclopropanes are important structural motifs found in many natural products and are essential to the pharmaceutical and agrochemical industries. Here, we report a bioinspired cobalt catalyst that catalyzes the intermolecular cyclopropanation of various terminal olefins using ethyl diazoacetate (EDA) in high efficiency. This cobalt catalytic system is operationally simple under very mild conditions, enabling the synthesis of cyclopropane products with remarkable yields in short reaction time. Preliminary mechanistic studies suggest the presence of cobalt carbene radical species during the reaction. [ABSTRACT FROM AUTHOR]

Ammonia is currently considered a promising compound for the chemical storage of hydrogen and as an energy carrier. However, large-scale ammonia production is not possible without an active and stable catalyst enabling efficient, long-term work without the need for its replacement. In this paper, the extended stability studies of the highly active promoted cobalt catalyst for ammonia synthesis were carried out. The long-term activity measurements in NH3 synthesis reaction under conditions close to the industrial ones (400–470 °C, 6.3 MPa, H2/N2 = 3) were compiled with the characterization of catalyst properties on different stages of its work using N2 physisorption, XRPD, STEM-EDX, and H2-TPD. The accelerated aging method was used to simulate the deterioration of catalyst performance during industrial operation. Textural and structural characteristics revealed that the tested catalyst is highly resistant to high temperatures. The lack of significant changes in the specific surface area, morphology of the catalyst particles, surface distribution of elements, and chemisorption properties of cobalt surface during long-term heating (436 h) at 600 °C suggests that stable operation of the catalyst is possible in an ammonia synthesis reactor in the temperature range of 400–470 °C without the risk of losing its beneficial catalytic properties over time. The decline in catalyst activity during the long-term stability test was less than 10%. [ABSTRACT FROM AUTHOR]

The production of ammonia through the Haber–Bosch process is a large-scale catalytic industrial endeavour with substantial energy consumption. A key area of energy optimisation for this process involves efforts to ease the synthesis reaction conditions, particularly by reducing the operating pressure. To achieve this goal, new catalysts are designed to function effectively at lower pressures and temperatures. In recent years, reports in the literature concerning including lanthanide oxides in the catalysts' composition have started appearing more frequently. This review article offers a concise overview of the pivotal role that lanthanide oxides play in the field of ammonia synthesis catalysts. The paper delves into the diverse utilisation of lanthanide oxides, emphasising their role in catalytic systems. The review explores recent advances in the design of catalysts incorporating lanthanide oxides as promoters or support materials, highlighting their impact on enhancing catalyst stability, activity, and operation. Three main groups of catalysts are discussed, where iron, ruthenium, and cobalt constitute the active phase. Insights from recent research efforts are synthesised to provide a comprehensive perspective on the application prospects of lanthanide oxides in ammonia synthesis catalysts. [ABSTRACT FROM AUTHOR]

Hydrogenation of carbon monoxide (Fischer–Tropsch synthesis) is a promising route to ultraclean motor fuels, base oils and petrochemicals on the basis of non-petroleum feed such as natural gas, coal and biomass. Although cobalt-based industrial catalysts for this process are in operation for many years, they still need to be improved in terms of specific activity and selectivity to target hydrocarbons. This paper describes the effect of catalyst support coating with carbon on the formation of cobalt active phase and catalytic performance in CO hydrogenation. Carbonization of Mg–Al spinel was performed by impregnating with aqueous glucose solution followed by thermal treatment in inert atmosphere. Thus prepared carbonized material was used for cobalt deposition by incipient wetness impregnation method. The catalysts were characterized by N2 adsorption–desorption, scanning electron microscopy, thermoanalytical measurements combined with mass spectrometry of released gases, X-ray diffraction and in situ magnetic measurements during activation in H2 flow. Catalytic performance in Fischer–Tropsch synthesis was assessed at T = 210 °C, P = 20 bar. The size of Co3O4 crystallites in calcined catalysts and metallic cobalt in activated catalysts decreases with carbon content in the support. Cobalt precursor is reduced completely to metal within 2 h in typical activation conditions for FTS cobalt catalysts: H2 flow, 450 °C. Activity in CO hydrogenation decreases while selectivity to higher hydrocarbons increases with carbon content. High proportion of olefins in synthesized light hydrocarbons (> 65%) is a remarkable feature of the elaborated catalysts. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of γ-alumina pore size on the ability of alumina-supported cobalt (Co/Al2O3) catalysts in Fischer–Tropsch synthesis (FTS), ordered mesoporous alumina (OMA) samples with different pore sizes (4.8, 7.2, 9.7 and 12.6 nm) were synthesized by various methods. Co/OMA catalysts with a Co loading of 15 wt% were prepared by the impregnation method. N2 physisorption, X-Ray Diffraction (XRD), H2-Temperature-Programmed Reduction (H2-TPR), and H2 Temperature-Programmed desorption (H2-TPD) experiments were conducted to characterize the structure and properties of these catalysts, and the catalyst structure–FTS performance relationships were also analyzed. The TOF increases with OMA pore size increase from 4.8 to 9.7 nm and decreased when the OMA pore size increased further to 12.6 nm. The C5+ selectivity of catalysts increases with OMA pore size, while the CH4 selectivity decreased with which. The Co3O4 particle size of catalysts were depended highly on the OMA pore size, which was the vital factor affecting the performance of catalyst. [ABSTRACT FROM AUTHOR]

A series of supported alumina were synthesized using two methods of sol–gel and oil drop. In this work, the process of γ-alumina, γ-alumina + glucose supported granules and the simultaneous effects of glucose surfactant and the promoter (cerium and boron) on catalytic activity for the Fischer–Tropsch synthesis (FTS) were studied. The prepared cobalt catalysts are using the incipient wetness impregnation method on γ-alumina granules for FTS in a fixed-bed reactor. All the prepared granules Co catalysts using BET, XRD, TPR, FTIR, FESEM and ICP techniques. All conditions of the FTS operation were carried out at T = 503K, P = 15 bar, H2/CO = 2 with the space velocity of 5.1 NL·g−1·h−1. The obtained results clearly showed that the catalytic evaluation of the Co catalysts supported on γ-alumina, with respect to the activity and selectivity of C5+ products, was increased by the addition of cerium and boron promoters in FTS. Also, the Co catalysts supported with γ-alumina glucose surfactant were more active than the Co catalysts supported with γ-alumina. Furthermore, the morphologies of the γ-alumina supported granules were changed by surfactant and promoters and the presence of CeO2 on the surface of the supports favors the reducibility of cobalt oxide with a shift down in reduction temperature of about 60 °C. Meanwhile, the addition of glucose surfactant and cerium promoter remarkably influenced the improvement of activity, selectivity and stability of the catalyst as well. Ce promoter reduced the methane selectivity by increasing the chain-growth probability (α-value). [ABSTRACT FROM AUTHOR]

Electrocatalytic phosphorylation of terminal acetylenes with diarylphosphine oxides in the presence of a bpyCo(BF4)2 catalyst was first implemented under electrochemical reducing conditions with yields up to 75%. The nature of the solvent and the supporting electrolyte, the presence of oxygen and water determine the formation of certain products of the acetylenes' phosphorylation. The varying of the above factors was carried out in order to select optimal conditions for electrosynthesis to achieve stereo- and chemo-selectivity. Voltammetric studies were used to establish redox properties of participants, to optimize processes involving the cobalt catalyst. [ABSTRACT FROM AUTHOR]

Cobalt complexes carrying 2‐acetyl‐6‐iminopyridine ligand are synthesized and characterized. Single‐crystal X‐ray diffraction reveals the cobalt ion is chelated with two nitrogen atoms and an acetyl oxygen atom additionally. A significant prolonged Co–O distance (2.3960(57) Å) is found, indicative of a labile character. Activated by diethylchloroaluminum, all complexes show high conversion rates for isoprene and myrcene polymerizations, affording cis‐1,4/3,4 regulated 1,3‐diene polymers. The polymerization of butadiene, interestingly, gives predominant cis‐1,4 selectivity (>99.2%) with moderate activity. The substituent at ortho‐position of arylimine plays a minor role in controlling activity and selectivity as well as the molecular weight of the resultant polymers. The properties of resultant poly(1,3‐diene)s are stable even in a wide range of operational conditions, such as [Al]/[Co] varied from 20 to 600, temperature spanning from 0°C to 60°C, and monomer–catalyst ratio from 1000 to 4000. These additional benefits of minimum fluctuation in catalytic performances may be suitable for industrial polymerization process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crucial counterion-effect of organozinc pivalates steering cobalt-catalyzed selective 1,4-carbosulfonylation of 1,3-enynes via radical reply coupling pathway. • Both aryl and alkyl zinc pivalates can undergo sequential C–C/C–S bond formation which provides an expedient access to the preparation of highly functionalized α-allenyl sulfones. • Versatile late-stage modifications of drug-like compounds and facile transformations of the resulting allenes illustrate the potential applications of this technology in organic syntheses and medicinal chemistry. Salt-stabilized organozinc pivalates display crucial counterion-effect by OPiv-coordination, which steer an efficient cobalt-catalyzed 1,4-carbosulfonylation of 1,3-enynes with sulfonyl chlorides under simple and mild reaction conditions. Notably, both aryl and alkyl zinc pivalates show superior reactivity compared to conventional halide-supported organozinc reagents, thus providing an expedient access to the preparation of highly functionalized α-allenyl sulfones via cascade C–C/C–S bond formation. Moreover, late-stage modifications of drug-like compounds and facile transformations of the resulting allenes illustrate the synthetic utility of this protocol. [ABSTRACT FROM AUTHOR]

The development of the synthesis of 1,3‐diarylpropanes is important because some of them have been reported to have biological activities. We report herein the synthesis of two types of 1,3‐diarylpropane derivatives by using cobalt‐catalyzed cycloaddition of 1,6‐diynes. CoCl(PPh3)3‐catalyzed cyclotrimerization of 1,6‐diynes afforded a series of 1,3‐diarylpropane derivatives. Furthermore, double [4+2]‐cycloaddition between 1,6‐diynes and 1,3‐dienes proceeded in the presence of CoBr2−DPPE−Zn−ZnBr2, and the successive oxidation by 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) afforded another type of 1,3‐diarylpropane derivatives. [ABSTRACT FROM AUTHOR]

Ni and Co catalysts supported on ITQ-6 zeolite have been synthesized and evaluated in the steam reforming of ethanol (SRE). Catalysts were also characterized by means of N 2 adsorption-desorption, XRD, H 2 -TPR, and H 2 -chemisorption. ITQ-6 containing Co (Co/ITQ-6) presented a higher conversion of ethanol and production of hydrogen than ITQ-6 containing Ni (Ni/ITQ-6). The lower size of the metallic cobalt particles shown in Co/ITQ-6 seems to be the major responsible of its higher catalytic performance. Regarding the reaction by-products (CO, CH 4 , C 2 H 4 O and CO 2), Co/ITQ-6 showed the lowest selectivity at medium and high temperatures (773 and 873 K). At low reaction temperatures (673 K) the dehydrogenation reaction predominates in the Co/ITQ-6, what it is supported by the high concentration of acetaldehyde detected at this temperature. In the case of the Ni/ITQ-6 the main side reaction at 673 K seems to be the methanation reaction since large concentrations of methane are detected. Stability studies were also carried out showing lower deactivation of Co/ITQ-6 at large reaction times (24 h). Characterization of the exhausted catalysts after reaction showed the presence of coke in both catalysts. Nevertheless, Co/ITQ-6 presented the lowest coke deposition. In addition, Co/ITQ-6 exhibited the lowest metal sinterization, what could be also account for the lower deactivation exhibited by this sample. This fact could be related to the higher interaction between the cobalt metallic particles and the ITQ-6 support as the H 2 -TPR studies demonstrate. • Ethanol steam reforming catalysts based on Co or Ni supported on ITQ-6 zeolite is prepared by the first time. • Higher ethanol conversion and hydrogen selectivity is exhibited by the catalyst with Co. • The lower size of the metal Co particles is the major responsible of its higher catalytic activity. • Higher stability is exhibited by the Co catalyst (lower coke deposition and sinterization of the metallic particles). [ABSTRACT FROM AUTHOR]

The deposition of nanostructured carbon particles on the surface of a catalyst (carburization) is routinely considered an inalienable and undesirable secondary process in Fischer–Tropsch synthesis. However, very little is known about the actual role of the nanocarbon particles and how they influence catalysis. This paper reports research on the influence of carbon deposition on the performance of a cobalt-based Fischer–Tropsch-synthesized catalyst in an industrial-scale fixed-bed reactor (length—6000 mm, inner diameter—16.5 mm). The comparison of the structure and catalytic performance of a pelletized cobalt catalyst with the same catalyst, which was preliminary carburized, is presented. Pellet pore structure, catalyst surface, cobalt cluster morphology and the main catalytic properties (CO conversion, C5+ hydrocarbon productivity and selectivity to C5+ hydrocarbons and CH4 formation) were investigated. It is shown that the primary pre-carburization effect is a result of the physical blockage of the catalyst pore structure not followed by drastic changes in the cobalt cluster's structure. [ABSTRACT FROM AUTHOR]

The use of waste tires for producing valuable chemicals via fast pyrolysis necessarily involves the understanding and synthesis of catalysts. Therefore, here, a statistical-based screening of SiO2-supported metal catalysts (Ni, Pd, Co, and Fe) to produce limonene from waste tire pyrolysis (WTP) is presented. The response surface method (RSM) was integrated into a principal component analysis (PCA) to identify the catalyst and reaction conditions that maximize the limonene yields for the experiments performed in an analytical pyrolyzer. The experiments were performed in an analytical pyrolysis unit coupled to a mass spectrometer (Py-GC/MS) using the temperature, the tire-to-catalyst ratio, and the type of catalyst as independent variables. The samples were grouped using PCA into 4 clusters according to the studied experimental conditions. The RSM model demonstrates that Co/SiO2 generates the most positive influence on the selectivity towards limonene under the following operating conditions: 370 °C and a tire-to-catalyst ratio of 1:5. Furthermore, it is possible to maintain a high selectivity to limonene and reduce the optimal catalyst load by slightly increasing the reaction temperature. [ABSTRACT FROM AUTHOR]

In this study, a series of Co-based catalysts with alkali metal carbonate promoters were prepared to investigate the interrelation between promotion effect of these carbonates and catalytic performance for aniline hydrogenation to cyclohexylamine in vapour phase. The chemical promoters Li2CO3 and Na2CO3 leading to decrease in catalytic activity of cobalt catalysts for aniline hydrogenation. Catalysts with K2CO3 and Cs2CO3 loadings have practically no catalytic activity for hydrogenation of aniline. Results of TPD of aniline proved that presence of alkali metals carbonates restricts the adsorption of aniline on the surface of cobalt catalysts. Further, it was found that the addition of Na2CO3 greatly enhances the catalytic selectivity towards the cyclohexylamine and inhibits the consecutive reactions of cyclohexylamine leading to formation of by-products such as dicyclohexylamine and N-phenylcyclohexylamine.

The cobalt catalysts supported on perovskite-type XCeO3 (X: Mg, Ca, Sr, Ba) oxide were prepared for the decomposition of ammonia. The influence of different alkaline earth metals in support composition on the catalytic activity of Co/XCeO3 catalysts has been studied. A nominal 5 wt% Co loading was maintained over these perovskite supports. The catalytic ammonia decomposition performance was studied in the temperature range 300–600 °C. The catalyst 5Co–BaCeO (5 wt% Co impregnated on BaCeO3 support) showed the highest activity among the all other catalysts and the sequential order of exhibited NH3 conversion was as follows: 5Co–MgCeO < 5Co–CaCeO ≤ 5Co–SrCeO < 5Co–BaCeO. The synthesized catalysts were characterized by BET, XRD, TPR, CO2-TPD and SEM techniques. The results showed that the interaction between BaCeO3 and Co is beneficial to electron conductivity that promotes the catalytic activity of 5Co–BaCeO. The basicity of 5Co–BaCeO catalysts facilitates the re-combinative desorption of surface N atoms which help in enriching the ammonia decomposition. [ABSTRACT FROM AUTHOR]

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A number of catalysts were synthesized from a composite mixture consisting of a metal component (specifically, a Co–Al2O3/SiO2 catalyst in an amount of 20–40% for the synthesis of long-chain hydrocarbons), an acid component (Beta zeolite in the H-form, 20–50%), and a binder (boehmite). The catalysts were characterized by XRD, low-temperature argon adsorption/desorption, and TPR, and tested in Fischer–Tropsch synthesis at 2.0 MPa, 240°C, and GHSV 1000 h–1. The activity and selectivity of the catalysts were compared, and the composition of the synthetic products was investigated. The content of the zeolite component was found to be critical to the cracking and isomerization activity of the catalysts. It was further shown that the ratio between the active components correlates with the C5+ productivity and the selectivity towards fuel-range hydrocarbons. The catalysts with Co–Al2O3/SiO2 to HBeta ratios of 0.75 and 1.3 were found to be optimal for high-performance synthesis of gasoline-range (C5–C10) and diesel-range (C11–C18) hydrocarbons, respectively. [ABSTRACT FROM AUTHOR]

Co – CeO 2 /MgAl 2 O 4 catalysts were obtained by varying the impregnation order (sequential or co‒impregnation) of active phase (Co) and Ce and were evaluated in the ethanol steam reforming (ESR) reaction. Results from TPR and XPS revealed that the impregnation order influenced the metal‒metal and/or metal‒support interactions and Co0/Con+, Ce3+/Ce4+ and the Co/Ce surface molar ratio, affecting the catalyst behavior in the ESR reaction. The solids prepared by sequential impregnation, Co/Ce/S and Ce/Co/S exhibited a greater degree of reduction than the solid obtained by co‒impregnation (CoCe/S), though these systems displayed low dispersion of Co species and low content of surface Co°. The solid CoCe/S showed the highest dispersion (68.5%) and greater presence of Co0 on the surface. The effect of the cobalt content (4, 8 and 12 wt%) was also examined in catalysts prepared using the co‒impregnation method. With the increase in cobalt content, a greater loss of stability and a greater amount of carbon deposits were observed. The highest H 2 yield (5.3 mol H 2 /mol C 2 H 5 OH) and stability were achieved over the solid obtained by co‒impregnation with 8 wt% Co, which was attributed to the high dispersion of the active phase and its high content of surface metallic cobalt. [Display omitted] • Impregnation order of Co and Ce influences on the final properties of solids. • The co‒impregnation method results in greater dispersion of Co species. • Highest content of superficial Co0 is obtained by the co‒impregnation method. • Highest H 2 yield was achieved from solid obtained by co‒impregnation. • The best performance was exhibited from the catalyst containing 8 wt% Co. [ABSTRACT FROM AUTHOR]