Catalytic Oxidation Of Carbon Monoxide Research Articles

Synthesis and carbon monoxide purification performance of ZSM-5 molecular sieve Co-doped Mn/V catalytic material

Trackless, rubber-tired, diesel-powered vehicles are widely used in the mining industry. In recent years, the use of high-performance catalysts to remove carbon monoxide (CO) from diesel vehicle exhaust has attracted much attention. In this paper, a series of manganese-vanadium doped ZSM-5 molecular sieve catalysts were prepared by an impregnation method. The structures of the catalysts were characterized and experiments were conducted to evaluate their performance. The CO catalytic oxidation performance experiments revealed that Mn0.6-V0.4-ZSM-5 had the best performance, with a conversion rate of 97.5 % at 300 °C. The catalyst was also tested for water resistance and stability. Kinetic measurements were performed and the fitted activation energy was 22.68 kJ/mol. Characterization studies revealed that the surface defects formed by Mn and V doping provided a large number of active sites and oxygen vacancies for CO oxidation, increased the number of adsorbed oxygen species on the surface, and enhanced the redox capacity through the interaction of Mn4+ and V5+ to improve the catalytic oxidation performance of the catalyst. The adsorption configurations, adsorption energy (Ebin), and formation energy of oxygen vacancies of CO at different adsorption sites and different active fractions were calculated with density functional theory. The Ebin of CO on Mn2V2O7, the active fraction of Mn0.6-V0.4-ZSM-5, was −1.29 eV, which was the most stable adsorption configuration. This configuration had good oxygen mobility, and was conducive to CO catalysis, confirming the characterization and performance experiments.

A Comparative Study of Hydrothermally Leached Al3TM and Al3TM-Rh (TM=Zr, V, Ce) Intermetallic Compounds for Catalytic Oxidation of Carbon Monoxide.

Rise of the mute assassin "carbon monoxide (CO)" levels impact all aerobic life. The elevated rates of CO concentration endure climatic and geographical characteristics that exacerbate air pollution. Herein, a simple approach for hydrothermal leaching (HyTL) of Al3TM-Rh0.5 (Target material (TM)=Zr, V, Ce) and Al3TM (TM=Zr, V, Ce) intermetallic compounds produces leached products of ZrO2, VO2, and CeO2 with Rhodium (Rh) as an active component. The characterization result reveals the HyTL process and the presence of the active Rh element that elevated the performance of HyTL-Al3Zr-Rh0.5 towards CO conversion compared to other samples. Further, the cubic ZrO2 phase selectively forms after HyTL at 130 °C even though the formation of the cubic ZrO2 phase takes place at a high temperature. Moreover, the presence of Rh promotes higher catalytic activity in all the cases with low temperatures. The advancement in the present study towards the catalytic oxidation of CO over the hydrothermally leached ZrO2-Rh nanocatalyst guarantees the perspective of the aggregation-activation process.

Advances in Catalytic Oxidation of Methane and Carbon Monoxide (2nd Edition)

Advances in Catalytic Oxidation of Methane and Carbon Monoxide (2nd Edition)

Catalytic Decontamination of Carbon Monoxide Using Strong Metal–Support Interactions on TiO2 Microparticles

The traditional catalytic oxidation of carbon monoxide (CO) using metal oxide catalysts often requires either high temperatures (thermocatalysis) or ultraviolet light (UV) excitation (photocatalysis), limiting practical applications under ambient conditions. Our research aimed to develop a catalytic system capable of oxidizing CO to CO2 at room temperature and in the dark. Using the Strong Metal–Support Interaction (SMSI) methodology, several titanium oxide (TiO2)-complexed metals were prepared (Ag, Au, Pd, and Pt). The highest catalytic efficiency of CO oxidation at room temperature was demonstrated for the TiO2-Pt complex. Therefore, this complex was further examined structurally and functionally. Two modes of operation were addressed. The first involved applying the catalytic system to remove CO from an individual’s environment (environmental system), while the second involved the installation of the catalysis chamber as a part of a personal protection unit (e.g., a mask). The catalytic activity exhibited a significant reduction in CO levels in both the environmental and personal protection scenarios. The practical application of the system was demonstrated through efficient CO oxidation in air emitted from a controlled fire experiment conducted in collaboration with the Israel Fire and Rescue Authority.

The Surface/Interface Modulation of Platinum Group Metal (PGM)-Free Catalysts for VOCs and CO Catalytic Oxidation.

Effective management of volatile organic compounds (VOCs) and carbon monoxide (CO) is critical to human health and the ecological environment. Catalytic oxidation is one of the most promising technologies for achieving efficient VOCs and CO emission control. Platinum group metal (PGM)-free catalysts are recently receiving sustainable attention in catalyzing VOCs and CO removal due to their low cost, superior catalytic activity, and excellent stability, but PGM-free catalysts face challenges in low-temperature catalytic efficiency. In this mini-review, starting with discussing the catalytic mechanism of VOCs and CO oxidation, we summarize the surface/interface modulation strategies of PGM-free catalysts to promote oxygen and VOCs/CO molecule activation for enhanced low-temperature oxidation activity, including oxygen vacancy engineering, heteroatom doping, surface acidity modification, and active interface construction. We highlight the currently remaining challenges and prospects of advanced PGM-free catalyst development for highly efficient VOCs and CO emission control in practical applications.

Ultralow doping of Zr species into Co3O4 catalyst enhance the CO oxidation performance

The oxidation of carbon monoxide (CO) has garnered significant interest for its application in treating automobile exhaust. In this study, we employed the sol-gel method to synthesize a series of cobalt-zirconium oxide catalysts with various Co/Zr ratios, aiming to catalyze the oxidation of CO effectively. The findings showed that the Co90Zr10 catalyst, with a cobalt-to-zirconium ratio of 90:10, not only exhibited exceptional catalytic efficiency, achieving a 90 % conversion of CO at 94 °C, but also sustained superior thermal stability and resistance to water. The presence of both cobalt defects and oxygen vacancies significantly enhances the catalytic activity, which is attributed to the doping of zirconium. The characterization analyses indicated the incorporation of zirconium into the Co3O4 spinel lattice modifies the valence states (Co3+/Co2+) and geometries (CoOh/CoTd) of the cobalt cations. This alteration results from a variety of partial electron transfers and substitution sites. Enhanced ratios of Co3+/Co2+ and CoOh/CoTd in the CoxZry catalysts lead to improved reducibility and oxygen mobility. Consequently, this facilitates the lower-temperature oxidation of intermediates during the catalytic conversion of CO. DFT result showed that the Co3O4 after Zr doped has lower adsorption energy and revealed the reaction mechanism of CO catalytic oxidation.

Realizing the high loading amount of active Cu on Al2O3 to boost its CO catalytic oxidation

Catalytic oxidation of carbon monoxide (CO) by Cu/Al2O3 has garnered increasing interest in recent years due to its promising application prospects. Numerous investigations conducted on the Cu/Al2O3 system, but its catalytic performance for CO oxidation is still not as promising as that of precious metal catalysts. Increasing the loading amount of the active Cu on Al2O3 surface is a feasible method for improving its activity. However, with the increase of Cu loading, the agglomeration and enlargement of Cu particles is inevitable, which reduces the active Cu amount. Therefore, the utilization rate of Cu atoms is not high and the catalytic performance often can not further rise. Enhancing active Cu loading amount as high as possible is a prerequisite to further enlarge the activity of Cu/Al2O3 catalyst. Herein, self-synthesized Al2O3 nanofibers (Al2O3-nf) with high specific surface area and abundant penta-coordinated aluminum (AlV) are used as the support to maximize the Cu loading amount by chemical vapor deposition (CVD). And commercially available α-Al2O3 is used for comparative experiment. The high specific surface area could make Cu high dispersion on Al2O3, even at 20 wt% Cu loads, which is beneficial to high concentration load of active Cu. The catalytic activity of Cu/Al2O3-nf-CVD gradually increases with the increase of Cu loading from 2 wt% to 20 wt%, exhibiting a clear linear correlation with the surface content of Cu0 on the catalyst. Meanwhile, this result confirms that Cu0 plays a crucial role in CO oxidation of Cu/Al2O3. However, commercial α-Al2O3 reaches its highest activity when the Cu load is 5%, and then its activity begins to decrease due to the agglomeration of particles. Moreover, Cu/Al2O3-nf-CVD also exhibits remarkable thermal stability for CO oxidation. This work highlights a new strategy to synthesis of high Cu loading amount, high activity and thermostable Cu/Al2O3 catalyst for low-temperature oxidation of CO.

Model simplification and sensitivity analysis of chemical species for oxidation behavior in multi route complex chemical mechanism

This study employs a Model Reduction Technique (MRT) to simplify the four-step catalytic carbon monoxide (CO) oxidation reaction. The C-matrix method identifies key elements, key/non key components, and key reactions, while the Intrinsic Low-Dimensional Manifold (ILDM) pinpoints a Slow-Invariant Manifold (SIM) important for understanding key species behavior. Sensitivity analysis can be considered for measuring the efficiency of the chemical species in detailed mechanism. This systematic approach contributes to optimizing and controlling complex reactions offering broad application potential. In addition to the mathematical proof, the validation of the given chemical model is rectified. The comparison between the slow invariant manifold of both reaction routes is reported and the computational based results performed in this study are obtained through MATLAB.

Oxygen vacancies promote the activation of O2 in transition metal oxide doped ε-MnO2 for low-temperature CO oxidation

Carbon monoxide (CO), a toxic pollutant usually formed from incomprehensive combustion especially at low temperature, has harmful effects on human health. Therefore, the catalytic oxidation of CO always receives widespread attention. Herein, we reported transition metal (Cu, Co, Ni, Fe) doped ε-MnO2 as CO catalysts using a hydrothermal-deposition method. Physiochemical properties for CO oxidation were meticulously analyzed employing characterization techniques such as SEM, XRD, BET, XPS, EPR, CO-TPR. The doped ε-MnO2 catalyst showed expanded BET surface area, increased oxygen vacancy defects, more active sites, enhanced adsorption, and faster electron transfer. Catalytic activity tests indicated that the ε-MnO2 catalyst doped with transition metals exhibited exceptionally high catalytic activity, with the Cu-doped catalyst showing the fastest chemical reaction rate and the lowest complete conversion reaction temperature (TOF of 9.92 × 10−3 s−1, at 65℃). Density Functional Theory (DFT) calculations indicated that Cu doping more effectively induced oxygen vacancy defects compared to Co, Ni, Fe, and raw ε-MnO2 catalysts. It identifies the CO oxidation reaction and improved the CO adsorption capacity of the catalyst. Furthermore, a novel potential reaction pathway for the M-vK mechanism in transition metal oxides was proposed.

Catalytic oxidation of carbon monoxide at low temperature using AuRh/TiO2 bimetallic catalysts: Effect of the synthesis method

AuRh nanoparticles supported on TiO2 P25 were synthesized by two sequential deposition methods: sequential deposition-precipitation with urea (DPU) and impregnation (IMP)-DPU. Segregated nanoparticles (RhcoreAushell ball-cup-type, and Janus-type arrangements) were observed in gold-rhodium bimetallic catalysts, but mainly ball-cup-type and Janus-type nanoparticles were found on catalysts prepared by IMP-DPU. XPS analysis of gold-rhodium bimetallic catalysts, before and after reaction allowed concluding that gold-rhodium interaction on metallic state was an important factor to avoid the oxidation of rhodium during CO oxidation. However, this effect of stabilization of the rhodium metallic phase by gold does not fully explain the promoting effect observed for some bimetallic catalysts on CO oxidation. Some structural aspects such as the atomic arrangement of the bimetallic nanoparticles and the type of active sites, determined by DRIFTS-CO, were also considered. TPR and UV–visible DR spectroscopy characterizations also showed differences in the gold-rhodium interactions.

Enhanced Catalytic Performance and Tolerance to Carbon Monoxide Poisoning of CoO/PtPd/r‐GO Nanocomposite Thin Film for Methanol Fuel Cells

This study presents the facile synthesis of CoO/PtPd and CoO/PtPd/reduced‐graphene oxide (r‐GO) nanocomposites, highlighting their significant role in methanol fuel cells. To create a CoO/PtPd thin film at the toluene/water interface, we employed NaBH4 to effectively reduce PtCl2(COD), PdCl2(COD), and Co (acac)3 (COD = cis,cis‐1,5‐ cyclooctadiene, acac = acetylacetonate). The two nanocomposites were analyzed using XRD, FE‐SEM, AFM, XPS, BET, and TEM techniques. In the electrooxidation of methanol in the anodic part of fuel cell, cobalt (II) oxide can serve as an oxygen source in the catalytic oxidation of carbon monoxide (CO) or it can play a role in producing the HO‐CoO intermediate to facilitate the oxidation of CO‐PtPd to carbon dioxide (CO2). This reaction can help eliminate CO, which is a common poison for Pt‐based catalysts in methanol oxidation. Our research reveals significant improvements in current densities and catalyst tolerance when using the CoO/PtPd/r‐GO nanocomposite thin film. The observed current density for CoO/PtPd/r‐GO is 263.33 mA.cm−2, surpassing the reported value of 30.00 mA.cm−2 for PtPd/r‐GO. The jf/jb ratios, commonly used to evaluate catalyst tolerance, are approximately 2.80 for CoO/PtPd and 4.98 for CoO/PtPd/r‐GO, in contrast to ratios larger than 0.99 for ETEK Pt and 0.58 for other types of commercial Pt/C. These findings indicate that the CoO/PtPd/r‐GO thin film exhibits enhanced catalytic performance and improved tolerance to CO poisoning. Furthermore, the power output calculated for CoO/PtPd/r‐GO is 104.5 mW·cm−2, which is comparable to the reported value of 48.03 mW·cm−2 for commercial Pt/C. These results demonstrate the potential of the CoO/PtPd/r‐GO nanocomposite thin film as a promising alternative to traditional catalyst materials in methanol fuel cells.

Simultaneous catalytic oxidation of toluene and CO over Cu-V/Al-Ce catalysts: Physicochemical properties-activity relationship and simultaneous oxidation mechanism

Cu-V/Al-Ce with varying ratios of Al2O3/CeO2 were prepared to study the simultaneous catalytic oxidation of toluene and CO. Experimental results show that Cu-V/20Al-80Ce exhibits optimal simultaneous oxidation activity and good durability. This superior performance is related to Cu-Ce, V-Ce, and Al-Ce interactions, which facilitate the exposure of active centers, the creation of oxygen vacanicies, and efficient electron transfer. The mutual influence between toluene and CO during the simultaneous oxidation is then demonstrated. Toluene hinders CO oxidation through the competitive adsorption and the consumption of reactive oxygen species. CO enhances toluene oxidation, which is comprehensively explained by affecting the competition between the desorption and oxidation of benzaldehyde. Despite the mutual influence between toluene and CO, the pathways of CO and toluene oxidation are mutually independent. Toluene oxidation proceeds sequentially from toluene to benzyl alcohol, benzaldehyde, benzoate, and finally to CO2. Before being completely oxidized to CO2, CO is initially converted to carboxylic acid, hydrogen carbonate, free carbonate ion, bidentate formate, and monodentate carbonate.

Enhancing the Catalytic Oxidation of Carbon Monoxide Using K-OMS-2 by Surface Modification with Binary Oxides of Copper and Other Metals

Enhancing the Catalytic Oxidation of Carbon Monoxide Using K-OMS-2 by Surface Modification with Binary Oxides of Copper and Other Metals

Revealing the intrinsic nature of Cu- and Ce-doped Mn3O4 catalysts with positive and negative effects on CO oxidation using operando DRIFTS-MS.

Aiming at the problem of the poor performance of an Mn-MOF-74-derived Mn3O4 catalyst in low-temperature carbon monoxide (CO) oxidation, copper (Cu) and cerium (Ce) elements were used to modify the Mn3O4 catalyst to improve its performance in low-temperature CO oxidation. According to the results of catalytic performance testing, the CO oxidation activity of the Cu0.3Mn2.7O4 catalyst was significantly improved compared with that of the pristine Mn3O4 catalyst, when a CO conversion rate of 90% was achieved at 118 °C. According to X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller analyses, the (Mn2+ + Mn3+)/(Mn2+ + Mn3+ + Mn4+) ratio and the Oads/Ototal ratio increased after Cu doping, indicating promoted oxygen vacancy generation. In addition, the increased specific surface area was beneficial for the adsorption of reactant molecules and the exposure of active sites. According to H2-temperature-programmed reduction characterization, Cu doping significantly enhanced the performance of the Cu0.3Mn2.7O4 catalyst during low-temperature redox. Finally, these factors synergistically promoted the degradation of CO over the Cu0.3Mn2.7O4 catalyst. In addition, operando diffuse reflectance Fourier transform infrared spectroscopy results suggested the presence of more terminal-type oxygen, which is essential for the catalytic oxidation of CO on the surface of the Cu0.3Mn2.7O4 catalyst. Moreover, the Cu0.3Mn2.7O4 catalyst also showed excellent resistance to carbonate, and remarkable stability.

Incorporation of Epoxy Carbon onto CeO2-Supported Pt to Tackle the CO Self-Poisoning Issue.

The catalytic oxidation of carbon monoxide (CO) under ambient conditions plays a crucial role in the abatement of indoor CO, which poses risks to human health. Despite the notable activity exhibited by Pt-based catalysts in CO oxidation, their efficacy is usually diminished by the CO self-poisoning issue. In this work, three different Pt/CeO2-based catalysts, which have distinct coordinative environments of Pt but an identical Pt/CeO2 substrate structure, were synthesized by activating the catalyst with CO using different temperatures and durations. Compared with clean and graphite-covered Pt on CeO2, the one modified by epoxy carbon showed higher activity and stability. The combination of characterizations and density functional theory modeling demonstrated that the clean Pt on CeO2 rapidly deactivated due to the CO self-poisoning albeit high initial activity, and conversely, low initial activity was observed for the more stable graphite-covered catalyst due to the obstruction of the Pt site. In contrast, epoxy carbon species on Pt shifted the d-band of Pt to lower energy, weakening the Pt-CO binding strength. Such a modification mitigated the self-poisoning effect while maintaining ample active sites and enabling the complete oxidative removal of CO under ambient conditions. This work may provide a general approach to tackling the self-poisoning issue.

Simultaneously accomplishing selective catalytic reduction of NO and catalytic oxidation of CO in a catalyst coupling system

Considering that nitrogen oxides (NOx) and carbon monoxide (CO) usually meantime exist in industrial flue gas, it is meaningful to develop a collaborative control technology for the simultaneous purification of NOx and CO. In this work, the catalysts xCu-1V-5W/Ti were evaluated in the simultaneously selective catalytic reduction by NH3 (NH3-SCR) and CO oxidation. The introduction of CuO provided the active sites for the oxidation of CO, while inhibited the NH3-SCR process and facilitated the generation of N2O by-product at high temperature. Accordingly, a catalyst coupling system was designed by employing 1V-5W/Ti and 2Cu-1V-5W/Ti catalysts in one reactor, and high NO conversion (>90 %) and CO removal efficiency (>80 %) could be simultaneously realized within 350–500 °C. This work would provide valuable insights for achieving simultaneous removal of NOx and CO using the catalyst coupling method.

Catalytic oxidation of carbon monoxide over copper oxide with interfering gases involved for industrial buildings: An experimental and theoretical study

With the intention of thoroughly eliminating carbon monoxide (CO) from indoor environment, it is one of the most promising methods of converting it into carbon dioxide (CO2) via catalytic oxidation processes. Therefore, in this study, catalytic oxidation mechanisms of CO over copper oxide (CuO) with interfering gases involved are investigated via theoretical calculations and experimental verification, which mainly include basic catalytic oxidation processes over CuO, effects of different interfering gases and analyses of thermodynamic features. According to results, catalytic oxidation of CO over CuO can be performed in three different routes and rate-determining transition-state (TS) energy barriers vary a lot from route to route at high temperature owing to different thermal stability. In the meantime, SO2, H2O and NO are theoretically proved to affect catalytic oxidation of CO via competitive adsorption, high oxidizability and hydrogen bonds, which are accompanied with different sensitivities to changes of temperature or temperature power exponents. In experiments, it is found that impurity of lattice planes and small specific surface areas in CuO are key to restricting catalytic oxidation performances. What is more, some extra chemical reactions in experiments (e.g. SO2 + O2 + CuO → CuSO4, NO + O2 + CO → CO2 + NO) caused by interfering gases colossally affect catalytic oxidation performances of CuO. The whole study provides crucial information for indoor air purification in industrial buildings by using cheap adsorbents/catalysts.

Ultrathin 3D CoMn nanoflowers coupled diatomite for highly efficient catalytic oxidation of CO and propane

Manganese oxides are promising catalysts for the treatment of VOC gas pollutants due to variable valences and abundant oxygen vacancies. The surface properties of manganese oxides significantly affect their catalytic activity. Thus, the development of appropriate modulation strategies for manganese oxides is of great significance. Herein, ultrathin (1–2 nm) three-dimensional (3D) CoMn nanoflowers have been in-situ planted on the surface of a naturally abundant resource – diatomite. Due to the open diffusion channels of diatomite and 3D coordination of CoMn nanoparticles, more open space and exposed sites are created for the transport and migration of O2, CO and propane. Compared to the pure CoMn, the obtained cobalt-manganese/diatomite (CoMn/Dia) composite contains more surface defect sites and oxygen vacancies, resulting in 90 % of carbon monoxide (CO) and propane (C3H8) conversion at as low as 108 °C and 250 °C, respectively. Density functional theory (DFT) results demonstrate that the doping of Co elements and the ultrathin structure of CoMn nanoflowers induce the formation of oxygen vacancies and weaken the Mn-O-Co bond in CoMn/Dia composites, which significantly accelerate the oxygen cycling during the oxidation reactions of CO and propane. In addition, the prepared CoMn/Dia catalyst exhibits excellent stability with consistent catalytic efficiency achieved for 70 h. Due to the simple synthesis method and lower cost raw materials, this research provides new insight into the scale-up production of efficient and economical Mn-based catalysts.

Enhanced CO oxidation performance over hierarchical flower-like Co3O4 based nanosheets via optimizing oxygen activation and CO chemisorption

Enhancing low-temperature activity is a focus for carbon monoxide (CO) elimination by catalytic oxidation. In this work, the hierarchical flower-like silver (Ag) modified cobalt oxides (Co3O4) nanosheets were prepared by solvothermal method and applied into catalytic CO oxidation. The doped Ag species in the form of AgCoO2 induced the prolongated surface Co–O bond and weaker bond intensity. Consequently, the oxygen activation/migration ability and redox capacity of Ag0.02Co were enhanced with more oxygen vacancies. The chemisorbed CO was preferentially converted to CO2 but not carbonates. The inhibited carbonates accumulation could avoid the coverage of active sites. According to Density functional theory (DFT) calculations, the electron transfer from AgCoO2 to Co3O4 promote electron donation ability of Co3O4 layer, benefiting for oxygen activation. Moreover, the longer Co–C and C–O bond length suggest the weakened chemisorption strength and higher active of CO molecule. The Ag modified Co3O4 exhibited more satisfactory activity at lower temperature. Typically, it realized 100% CO conversion at 90 °C, and displayed 6.3-fold higher reaction rate than pristine Co3O4 at 40 °C. Moreover, the Ag0.02Co exhibited outstanding long-term stability and water resistance. In summary, the optimized oxygen activation, CO chemisorption and interfacial electron transfer synergistically boosted the CO oxidation activity on Ag modified Co3O4.

Synthesis of Inexpensive Ternary Metal Oxides by a Co-Precipitation Method for Catalytic Oxidation of Carbon Monoxide.

By using a simple co-precipitation method, new Fe2 O3 -based nanocatalysts (samples) were synthesized. The samples were composites of two or three transition metal oxides, MOx (M=Fe, Mn, Co, Ni, and Cu). The average size of CuO crystallites in the composites composed of two oxide components (CuO-Fe2 O3 ) was about 14.3 nm, while in those composed of three (CuO-MnOx -Fe2 O3 ), the composite's phase compositions were almost in the amorphous form when annealing the sample at 300 °C. The latter sample had a specific surface area higher than that of the former, 207.9 and 142.1 g/m2 , respectively, explaining its higher catalytic CO oxidation. The CO conversion over the CuO-MnOx -Fe2 O3 -300 catalyst (1 g of catalyst, 2600 ppm of CO concentration in air, and 1.0 L/min of gas flow rate) begins at about 40 °C; the temperature for 50 % CO conversion (t50 ) is near 82 °C; and CO removal is almost complete at t99 ≈110 °C. The activity of the optimal sample was tested in different catalytic conditions, thereby observing a high durability of 99-100 % CO conversion at 130 °C. The obtained results were derived from XRD, FTIR, BET, SEM, elemental analysis and mapping, as well as catalytic experiments.