CO Consumption Research Articles

LHHW/RSM reaction rate modeling for Co-Mn/SiO2 nanocatalyst in Fishcher-Tropsch synthesis

This study aims to assess the kinetics of Fischer–Tropsch (FT) reaction over the cobalt-manganese nanoparticles supported by silica oxide. Nanoparticles were synthesized by the thermal decomposition method using "[Co(NH3)4CO3]MnO4" complex and characterized by XRD, TEM, and BET techniques. The kinetics of the process were evaluated using a combination of Langmuir–Hinshelwood-Hougen-Watson (LHHW) and response surface methodology. Correlation factors of 0.9902 and 0.962 were obtained for the response surface method (RSM) and LHHW, respectively. The two methods were in good agreement, and the results showed that the rate-determining step was the reaction of the adsorbed methylene with the adsorbed hydrogen atom, and only carbon monoxide molecules were the most active species on the catalyst surface. A temperature of 502.53 K and a CO partial pressure of 2.76 bar are proposed as the optimal conditions by RSM analysis. The activation energy of CO consumption reaction was estimated to be 61.06 kJ/mol.

Simultaneous Formate and Syngas Conversion Boosts Growth and Product Formation by Clostridium ragsdalei.

Electrocatalytic CO2 reduction to CO and formate can be coupled to gas fermentation with anaerobic microorganisms. In combination with a competing hydrogen evolution reaction in the cathode in aqueous medium, the in situ, electrocatalytic produced syngas components can be converted by an acetogenic bacterium, such as Clostridium ragsdalei, into acetate, ethanol, and 2,3-butanediol. In order to study the simultaneous conversion of CO, CO2, and formate together with H2 with C. ragsdalei, fed-batch processes were conducted with continuous gassing using a fully controlled stirred tank bioreactor. Formate was added continuously, and various initial CO partial pressures (pCO0) were applied. C. ragsdalei utilized CO as the favored substrate for growth and product formation, but below a partial pressure of 30 mbar CO in the bioreactor, a simultaneous CO2/H2 conversion was observed. Formate supplementation enabled 20-50% higher growth rates independent of the partial pressure of CO and improved the acetate and 2,3-butanediol production. Finally, the reaction conditions were identified, allowing the parallel CO, CO2, formate, and H2 consumption with C. ragsdalei at a limiting CO partial pressure below 30 mbar, pH 5.5, n = 1200 min-1, and T = 32 °C. Thus, improved carbon and electron conversion is possible to establish efficient and sustainable processes with acetogenic bacteria, as shown in the example of C. ragsdalei.

Simulating biosignatures from pre-oxygen photosynthesizing life on TRAPPIST-1e

ABSTRACT In order to assess observational evidence for potential atmospheric biosignatures on exoplanets, it will be essential to test whether spectral fingerprints from multiple gases can be explained by abiotic or biotic-only processes. Here, we develop and apply a coupled 1D atmosphere-ocean-ecosystem model to understand how primitive biospheres, which exploit abiotic sources of H$_2$, CO, and O$_2$, could influence the atmospheric composition of rocky terrestrial exoplanets. We apply this to the Earth at 3.8 Ga and to TRAPPIST-1e. We focus on metabolisms that evolved before the evolution of oxygenic photosynthesis, which consume H$_2$ and CO and produce potentially detectable levels of CH$_4$. O$_2$-consuming metabolisms are also considered for TRAPPIST-1e, as abiotic O$_2$ production is predicted on M-dwarf orbiting planets. We show that these biospheres can lead to high levels of surface O$_2$ (approximately 1–5 per cent) as a result of CO consumption, which could allow high O$_2$ scenarios, by removing the main loss mechanisms of atomic oxygen. Increasing stratospheric temperatures, which increases atmospheric OH can reduce the likelihood of such a state forming. O$_2$-consuming metabolisms could also lower O$_2$ levels to around 10 ppm and support a productive biosphere at low reductant inputs. Using predicted transmission spectral features from CH$_4$, CO, O$_2$/O$_3$, and CO$_2$ across the hypothesis space for tectonic reductant input, we show that biotically produced CH$_4$ may only be detectable at high reductant inputs. CO is also likely to be a dominant feature in transmission spectra for planets orbiting M-dwarfs, which could reduce the confidence in any potential biosignature observations linked to these biospheres.

Selective syngas fermentation to acetate under acidic and psychrophilic conditions using mixed anaerobic culture

Syngas fermentation to acetate offers a promising solution for its valorisation, particularly when syngas contains a high N2 concentration, which otherwise impedes the utilisation of syngas biomethanation gaseous product in cogeneration or upgrading units. In this study, continuous lab-scale syngas fermentation assessing the effects of acidic pH and psychrophilic conditions (28 °C and 20 °C) on bioconversion efficiency and anaerobic consortium diversity was studied. The results showed that as temperature and pH decrease, acetate yield increases. The highest H2 and CO consumption rates were observed at 20 °C and pH 4.5, reaching 48.4 mmol/(L·d) and 31.5 mmol/(L·d), respectively, and methanogenic activity was not completely suppressed. The microbial community composition indicated an enhanced abundance of acetate-producing bacteria and hydrogenotrophic methanogens at 28 °C. The PICRUSt2 prediction of metabolic potential indicated that temperature and pH changes appear to have a more pronounced impact on acetotrophic methanogenesis genes than carbon dioxide-based methanogenesis genes.

Insights to the reaction kinetics of Fischer-Tropsch synthesis using an integral system over Cu-Mo promoted Fe catalyst

This work focused on the design and kinetics study of the Cu-Mo promoted Fe catalyst supported on biomass-derived carbon material with engineered surface chemistry and textural properties for Fischer-Tropsch synthesis (FTS). The kinetics tests were carried out at different operational conditions including temperature in the range of 280–310 °C, pressures: 20.6–41.3 bar, and gas hourly space velocity (GHSV): 1500–3000 h−1. The reaction rate was evaluated based on the enol mechanism using Eley–Rideal theory. To study the reaction rates along the catalytic bed, the reactor was assumed as an integral system. The production rates of the hydrocarbons were estimated by introducing a mathematical expression based on the lumped reaction network. The kinetics parameters, profiles of the partial pressures for the reactants and products were optimized using genetic algorithm. The proposed reaction mechanism proceeded with associative adsorption of CO, followed by hydrogenation to an oxygenated intermediate (CHO*); and the activation energy for CO consumption rate model was obtained as 51.90 kJ. mol−1. The provided one-dimensional model can lead to better understanding of the reaction mechanism of FTS as a sustainable energy resource with a novel catalyst design.

Plasmonic-Assisted Water–Gas Shift Reaction of Gold Particles on TiO2

The Localized Surface Plasmon (LSP) effect of 5 nm mean size Au particles deposited on TiO2 P25 was investigated during the photo-thermal water gas shift reaction (WGSR). The effects of CO concentration, excitation light flux and energy, and molecular oxygen addition during the reaction were investigated. The photocatalytic WGSR rate under light excitation with wavelengths extending from 320 to 1100 nm was found to be higher than the thermal reaction alone at the same temperature (85 °C). A H2/CO2 ratio of near unity was found at high concentrations of CO. The addition of molecular oxygen during the reaction resulted in a slight decrease in molecular hydrogen production, while the rates of CO2 formation and CO consumption changed by one order of magnitude. More importantly, it was found that the WGSR rates were still high under only visible light excitation (600–700 nm). The results prove that Au LSP alone triggers this chemical reaction without requiring the excitation of the semiconductor on which they are deposited.

Analysis of the performance and emissions generation mechanism of natural gas/diesel dual-fuel under different strategies by combining experiments and mechanisms

In natural gas/diesel dual-fuel engines, natural gas (NG) still produces some emissions during combustion, especially at high NG substitution rates. In order to reduce the emissions and to clarify the emissions formation mechanism. In this work, the performance and emission characteristics of the dual-fuel engine under different diesel injection strategies, as well as the formation mechanism of emissions (NOx, CO, THC and soot) were analyzed by combining bench test and chemical mechanism. The results showed that compared with diesel single injection, the diesel pilot injection strategy (PIS) could effectively improve the engine BTE (22.6%), CO and THC emissions were reduced by 87.8% and 76.1%, respectively. By advancing the diesel pilot injection timing (PIT), the combustion efficiency and BTE increased by 5.1% and 10.9%, respectively; the soot, THC, and CO emissions reduced by 63.9%, 69.4% and 76.9%, respectively. Increasing the diesel pilot injection ratio (PIR) could improve the combustion efficiency and reduce CO and THC emissions. According to the path analysis, the CO consumption was mainly the reaction R120: HO2+COOH + CO2, the generation of THC were mainly affected by path 1: CH3→CH3O→CH2O→HCO→CO and path 2: CH3→C2H6→C2H5→C2H4, and the soot was mainly related to C2H2, but it was mainly affected by the synergistic effect of multi-step reaction. Therefore, through the analysis of different diesel injection strategies, advanced the MIT and PIT of diesel and the medium PIR of diesel, the pressure and temperature of the engine were within the appropriate range, and the reactivity was kept in a good state, which could achieve low NOx, soot and THC emissions, high BTE and low BSEC from the engine.

Influence of Sapwood/Heartwood and Drying Temperature on Off-Gassing of Scots Pine Wood Pellets

Wood pellets produced from fresh sawdust can form and release uncontrolled gases during bulk storage, a tendency referred to as off-gassing. This study investigated the off-gassing tendencies of Scots pine wood pellets made from separated sapwood and heartwood sawdust. The effects of drying temperature, raw material storage, as well as varying proportions of sapwood and heartwood were also investigated. There was a strong linear correlation between off-gassing and sapwood content, with correlation coefficient (R) values greater than 0.9 at p < 0.001 for all the off-gases. An increase in sapwood content of the feedstock led to a significant increase in off-gassing of CO2, CO, and CH4, and O2 consumption. The drying temperature of the raw material had a significant effect on off-gassing of both sapwood (F(8, 26) = 51.32, p < 0.05) and heartwood (F(8, 26) = 334.1, p < 0.05) pellets. Increasing the drying temperature for heartwood resulted in increased off-gassing, while for sapwood, the off-gassing reduced. Storage of sapwood raw material before pelletization reduced the off-gassing of wood pellets, whereas for heartwood, it had no significant impact. Based on the results, it is suggested that a biological process, in combination with the chemical oxidation of fatty acids, lay behind the off-gassing of wood pellets.

Mid-infrared absorption spectroscopy measurements and model improvements during the oxidation of ammonia/ethanol and ammonia/diethyl ether blends in a shock tube

Blending ammonia with highly active fuels (hydrogen, hydrocarbons, oxygenated hydrocarbons, etc.) has been identified as an efficient way to improve the mixture's reactivity. In this study, the temperature, CO, CO2, H2O, NH3, and NO time-histories were measured simultaneously during the oxidation of ammonia/ethanol and ammonia/diethyl ether (DEE) blends (equivalence ratio ϕ ∼ 1.2) using mid-infrared laser absorption spectroscopy behind reflected shock waves. Various models (ten for ammonia/ethanol and three for ammonia/DEE) were selected to perform the simulation and compared with the measurements. The predictions are very different for both mixtures, among which the CRECK model was selected to perform discussion and kinetics analyses for the ammonia/ethanol mixture and the Shrestha 2022 model was selected for the ammonia/DEE mixture. The CRECK model performs well in predicting the temperature rise/plateau, H2O formation rate/plateau, CO consumption rate/plateau, and CO2 formation rate. However, it underpredicts the CO formation rate and slightly overpredicts the CO2 plateau and NH3 consumption rate; for the NO time-history, the CRECK model well captures the rapid NO formation but underpredicts the near-equilibrium NO concentration and gives an unnormal initial NO production. The Shrestha 2022 model accurately predicts the plateaus of temperature and H2O, but significantly underpredicts the reactivity of the ammonia/DEE mixture and overpredicts the near-equilibrium NO concentration. According to the kinetics analyses, key reactions affecting the species' time-histories were selected. Fourteen reactions in the CRECK model and eight reactions in the Shrestha 2022 model were updated by the reported data or estimations to improve the predictions. However, discrepancies still exist, which are mainly located in the CO formation and NH3 consumption rates. Further effort should mainly focus on these two aspects, as well as the interactions between oxygenated hydrocarbons and ammonia at high temperatures.

Experimental and kinetic modeling study on the oxidation and laminar combustion characteristics of natural gas

The oxidation process in the flow tube reactor and the laminar combustion process in the constant volume combustion bomb of natural gas (0.9 methane/0.07 ethane/0.03 propane, mole fraction) were experimental tested. Furthermore, a reduced reaction mechanism (including 40 species and 189 reactions) of natural gas was developed based on the Aramco 2.0 mechanism by combining the path sensitivity analysis, rate of production analysis, reaction path analysis and the decoupling method. The results show that, in the oxidation process of natural gas, with the equivalence ratio increasing, the starting and ending temperatures for oxidation reaction of natural gas are increased, the reaction temperatures corresponding to CO generation and consumption are higher, and the amount of NO production is decreased. In the the laminar combustion process of natural gas, with the initial temperature and oxygen content increasing or the initial pressure, CO2 and H2O contents decreasing, the laminar flame speed is increased. Through comparing with the calculated results by the Aramco 2.0 mechanism and the corresponding test data, the reduced reaction mechanism can well predict the oxidation, ignition delay and laminar combustion characteristics of natural gas under various conditions.

Comprehensive kinetic study for Fischer–Tropsch reaction over KMoFe/CNTs nano‐structured catalyst

AbstractThe kinetics of the Fischer–Tropsch (FT) reaction was evaluated through detailed experimentation with a KMo bimetallic promoted Fe catalyst supported on carbon nanotubes (CNTs). The kinetic tests were conducted in a fixed‐bed reactor under operating conditions of P = 6.9–41.3 bar, T = 543–563 K, H2/CO = 1, gas hourly specific velocity (GHSV) = 2000 h−1. This study aimed to investigate the mechanism prevailing in CO activation and the rate equation for CO consumption during FT reactions over a 0.5K5Mo10Fe/CNTs catalyst. To evaluate the synergistic effects of Fe, Mo, and K phases on the catalyst activity, both fresh and spent catalysts were thoroughly characterized using X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy and energy‐dispersive spectroscopy (SEM‐EDS), X‐ray absorption near edge structure (XANES), and extended X‐ray absorption fine structure (EXAFS) to ascertain the different phases (active sites) present and relevant interactions. Based on the adsorption of carbon monoxide and hydrogen, 22 possible mechanisms for monomer formation were proposed for FT synthesis in accordance with the Langmuir–Hinshelwood–Hougen–Watson (LHHW) and Eley–Rideal (ER) adsorption theories. The best fit kinetic model was identified through a multi‐variable non‐linear regression analysis. The selected mechanistic model was based on carbide formation approach, where H2‐assisted adsorption of CO was considered for the derivation. Kinetic parameters such as activation energy, adsorption enthalpies of H2, and CO were estimated to be 65.0, −13.0, and −54.0 kJ/mol, respectively. Considering the developed kinetic model, the effects of reaction temperature and pressure were assessed on Fischer–Tropsch synthesis (FTS) product distribution. Additionally, the kinetic model was compared with the typical Anderson–Schulz–Flory model, suggesting the effects of water‐gas‐shift and the existence of additional formation pathway such as secondary re‐adsorption of olefins for heavier hydrocarbons.

Transient HCO/HCOO− species formation during Fischer–Tropsch over an Fe–Co spinel using low Ribblet ratio syngas: a combined operando IR and kinetic study

The comprehensive kinetics of simultaneous CO consumption in a Fischer–Tropsch and water–gas shift reaction network was systematically investigated over a supported FeCo2O4 spinel catalyst.

Heterogeneous and Combined Heterogeneous/Homogeneous Combustion Modeling of SOFC Off-Gases.

The heterogeneous (catalytic) and the hetero-/homogeneous (catalytic and gas-phase) combustion processes of solid oxide fuel cell (SOFC) off-gases with compositions typical of a high cell utilization rate are investigated with high-fidelity 2D simulations in a platinum-coated planar channel using detailed hetero-/homogeneous chemistry. The pressures are 1-8 bar; the reactant streams have volumetric H2 and CO contents 0.7-1.5 and 5.3-9.7%, respectively; H2O and CO2 dilutions are ∼40 and ∼50%, respectively; and the global fuel/air equivalence ratio is 0.90. Water inhibits chemically the catalytic oxidation of H2, as it leads to high H(s) surface coverage that favors the recombinative desorption of H(s) to H2. On the other hand, H2O promotes chemically the catalytic oxidation of CO by creating high OH(s) coverage that in turn accelerates the CO consumption. Strong flames are established at the highest H2 content cases and for pressures p ≥ 3 bar. For all cases with vigorous homogeneous combustion, the catalytic and gas-phase reaction pathways coexist and compete with each other for the consumption of H2 and CO. The large H2O content leads to gas-phase production of H2 via the reaction H2O + H = H2 + OH. However, the gas-phase produced H2 is subsequently consumed by the catalytic pathway, such that nearly complete H2 conversion is attained at the reactor outlet. Gaseous chemistry does not affect the reactor lengths required for complete H2 conversion but substantially reduces the corresponding lengths for CO conversion. The H2 emissions decrease with increasing pressure and are in the range 8-110 ppmv, while the CO emissions increase with rising pressure and span the range 0.3-52 ppmv, thus leading to corrected CO emissions (at 15% O2) of less than 15 ppmv. Finally, the peak wall temperatures are largely acceptable in terms of catalyst thermal stability.

Effective hexanol production from carbon monoxide using extractive fermentation with Clostridium carboxidivorans P7

This study achieved high production of hexanol via gas fermentation using Clostridium carboxidivorans P7 by extracting hexanol from the fermentation broth. The hexanol extraction efficiency and inhibitory effects on C. carboxidivorans P7 of 2-butyl-1-octanol, hexyl hexanoate and oleyl alcohol were examined, and oleyl alcohol was selected as the extraction solvent. Oleyl alcohol was added at the beginning of fermentation and during fermentation or a small volume of oleyl alcohol was repeatedly added during fermentation. The addition of a small volume of oleyl alcohol during fermentation was the most effective for CO consumption and hexanol production (5.06 g/L), yielding the highest known hexanol titer through any type of fermentation including gas fermentation. Hexanol production was further enhanced to 8.45 g/L with the repeated addition of oleyl alcohol and ethanol during gas fermentation. The results of this study will enable sustainable and carbon–neutral hexanol production via gas fermentation.

Co-Fermenting Pyrolysis Aqueous Condensate and Pyrolysis Syngas with Anaerobic Microbial Communities Enables L-Malate Production in a Secondary Fermentative Stage

The pyrolytic conversion of lignocellulosic biomass into fuels and chemicals is a promising option for the valorization of agricultural and forestry residues. However, technological developments are still needed to maximize product recovery and carbon fixation of the pyrolysis process. The pyrolysis aqueous condensate (PAC), a pyrolysis by-product, has a high water content and is highly toxic, hampering its use. The anaerobic digestion of PAC from different biomasses has been proven a viable technology for PAC valorization and detoxification, but its toxicity limits the methanogenic potential. Alternatively, methanation or VFA production from syngas by anaerobic mixed cultures are technologies of scientific interest. This study investigates the potential of a two-stage process to convert the carbon and energy in syngas and PAC into L-malate. PAC and syngas were co-fermented by two mixed cultures at 37 and 55 °C, identifying kinetic inhibitions and the effects of increasing PAC concentrations on the product pool. The media from selected mixed culture fermentations were then inoculated with Aspergillus oryzae for L-malate production. The results show that mixed cultures can perform simultaneous syngas fermentation and PAC detoxification. While PAC concentrations above 2% completely inhibited methanogenesis, CO consumption was inhibited at PAC concentrations above 5%, regardless of the temperature. In fermentations where PAC inhibited methanation, the mixed cultures channelled the carbon and electrons from syngas and PAC to volatile fatty acids or acetate/H2 production, depending on the incubation temperature. Substantial detoxification of PAC was observed under PAC concentrations up to 10% independently of the rates of syngas metabolism. PAC detoxification enabled the further valorization of the acetate produced via syngas and PAC fermentations into L-malate, achieving yields up to 0.17 mM/mM. These results are promising for the development of an integrated process that simultaneously detoxifies and recovers value from gaseous and aqueous waste streams originating from pyrolysis.

The water assisted vinylene mechanism for cobalt Fischer-Tropsch synthesis assessed by multi-catalyst modelling of kinetics and deactivation

The paper describes development of a mechanism and a consistent rate expression for Fischer-Tropsch (FT) synthesis over cobalt-based catalysts. The developed mechanism relies on a two-step hydrogen assisted activation of CO. The carbon atom of CO is first hydrogenated by surface hydrogen to formyl; followed by the rate-limiting step whereby the oxygen atom is hydrogenated by adsorbed water. The produced CH* monomer is incorporated into the growing chain giving vinylene intermediate. The vinylene intermediate is either terminated to an olefin by adding hydrogen to the α-carbon atom or propagates by adding hydrogen to the β-carbon position. The resulting expression for CO consumption, the Fischer-Tropsch rate, can respond positively or negatively to the partial pressure of water, in agreement with experimental observations. A special feature is that the chain propagation probability does not depend on the partial pressure of hydrogen. The resulting kinetic model is tested on several cobalt catalysts supported on alumina; spanning from γ-alumina with average pore sizes ranging from 6.1 to 18.3 nm to α-alumina with a wide pore structure; and with cobalt particle sizes from 8 to 19 nm. Water was added sequentially to the syngas feed, causing enhanced deactivation, for testing the water response on activity and selectivity. A deactivation model comprising sintering and cobalt oxidation, and the FT-kinetics, describe the observed CO conversions with great precision for all catalysts. Selectivities are also well described, but with slight deviations at least partly due the effect of deactivation. Trends in some of the kinetic parameters are rationalized in terms of cobalt crystallite and pore sizes.

Efficient Utilization of Siderite- and Hematite-Mixed Ore by Suspension Magnetization Roasting: A Pilot-Scale Study

Steel is an important industrial raw material and plays an important role in industrial construction. Studying the efficient utilization of complex refractory iron ore with large reserves is of great significance to ensure the strategic safety of China’s iron and steel industry. Focusing on the typical mixed iron ore of siderite (FeCO3) and hematite (Fe2O3), this paper analyzes the possible ways of magnetization roasting from the perspective of thermodynamics and highlights that oxidation–reduction roasting is an easy way to realize industrial application. On this basis, a pilot-scale test of suspension magnetization roasting followed by low-intensity magnetic separation is carried out by using a newly developed suspension magnetization roasting furnace. The effects of roasting temperature, CO consumption, and N2 consumption on the magnetization roasting process are investigated, and 24 h continuous tests are carried out. Here, we find continuous suspension magnetization roasting followed by low-intensity magnetic separation can obtain a total iron grade of over 56% with an average value of 57.18% and a total iron recovery rate of over 91% with an average value of 92.22%. Product analysis shows that after SMR, iron minerals such as siderite and hematite transform into magnetite, with a substantial increase in magnetism, which is conducive to the separation of iron ore. The results provide a reference for the development and utilization of siderite- and hematite-mixed iron ore.

Production of Hexanol as the Main Product Through Syngas Fermentation by Clostridium carboxidivorans P7.

The production of hexanol from syngas by acetogens has gained attention as a replacement for petroleum-derived hexanol, which is widely used in the chemical synthesis and plastic industries. However, acetogenic bacteria generally produce C2 compounds (e.g., acetate and ethanol) as the main products. In this study, the gas fermentation conditions favorable for hexanol production were investigated at different temperatures (30–37°C) and CO gas contents (30–70%) in batch gas fermentation. Hexanol production increased from 0.02 to 0.09 g/L when the cultivation temperature was lowered from 37 to 30°C. As the CO content increased from 30 to 70%, the CO consumption rate and hexanol production (yield, titer, and ratio of C6 compound to total products) increased with the CO content. When 70% CO gas was repeatedly provided by flushing the headspace of the bottles at 30°C, the total alcohol production increased to 4.32 g/L at the expense of acids. Notably, hexanol production (1.90 g/L) was higher than that of ethanol (1.20 g/L) and butanol (1.20 g/L); this is the highest level of hexanol produced in gas fermentation to date and the first report of hexanol as the main product. Hexanol production was further enhanced to 2.34 g/L when 2 g/L ethanol was supplemented at the beginning of 70% CO gas refeeding fermentation. Particularly, hexanol productivity was significantly enhanced to 0.18 g/L/day while the supplemented ethanol was consumed, indicating that the conversion of ethanol to acetyl-CoA and reducing equivalents positively affected hexanol production. These optimized culture conditions (gas fermentation at 30°C and refeeding with 70% CO gas) and ethanol supplementation provide an effective and sustainable approach for bio-hexanol production.

Synthesis of CuO‐Loaded Ceria Hollow Spheres for Catalytic CO Oxidation

AbstractCopper‐ceria has been widely investigated as an active heterogeneous catalyst for CO oxidation reaction. Herein we report a reliable synthesis of CuO loaded ceria hollow spheres (CHS‐CuO) which show an outstanding performance of 6.1712 μmolCO⋅gcat−1⋅s−1 CO consumption rate at 120 °C over other reported ceria‐based catalysts for the CO oxidation reaction. The performance is superior to CuO loaded ceria nanoparticles (CNP‐CuO) and ceria hollow spheres (CHS), due to hollow structure, large surface area, more adsorptive oxygen and subsequent lower activation energy. TEM images reveal CuO nanoparticles are uniformly dispersed on the surface of ceria hollow spheres. XPS investigation shows that Cu2+ is the dominant copper species in CHS‐CuO. The synthesis reliability is demonstrated with the case of Ag loaded CHS fabrication. The reported strategy enables the fabrication of similar bimetal hollow spheres, holding good promise for various heterogeneous catalysis.

Very high loading oxidized copper supported on ceria to catalyze the water-gas shift reaction

To prepare supported catalysts with high loading and high dispersion of active metals is a crucial challenge in heterogeneous catalysis. Here we report the fabrication of very reactive catalyst that contains finely dispersed copper with 20 wt% content supported on high-surface area CeO2 for the water–gas shift (WGS) reaction. This copper-ceria catalyst shows superb activity with a CO consumption rate of 116.7 μmolCO gcat-1 s−1 at 300 ℃, nearly one order of magnitude more active than other copper-based catalysts ever reported. Based on the precise and integratedcharacterizations, the oxidized not the metallic Cu are proved to be active centers where the adsorbed CO directly reacted with bridged —OH groups to finish the WGS reaction. The oxidized Cu sites are confirmed to be originated from the activation effect from Cu to CeO2, which promotes the oxygen of CeO2 diffuse from the bulk to surface, making Cu oxidized even under reductive atmosphere.