Dual-site Mechanism Research Articles

The key role of adsorbate-catalyst interactions into catalytic activity of [CTA+]-Si-MCM-41 from electron density analysis

Abstract In this work, we analyzed the role of the interactions involved in the reaction mechanism for the transesterification of ethyl acetate and methanol on the pore mouth of [CTA+]-Si-MCM-41 catalyst. The Quantum Theory of Atoms in Molecules (QTAIM) was applied for the analysis of adsorbate-catalyst interactions in order to gain a deeper understanding about the relationship between bonding and catalytic properties along the reaction coordinate and the role of weak interactions in the catalytic activity. Experimental FT-IR spectrum was supported by the theoretical model for the coadsorption of both reagents following a dual-site mechanism. Our results reveal that the key role of the (CTA+)(SiO−) ion pair is to stabilize the reactant species. During the reaction coordinate, the silica and the head of the surfactant are bonded through several O···H(CH3) interactions forming the bifunctional active site on the surface of the solid catalyst. Four interactions are associated with the reaction mechanism. The rest of weak adsorbate-catalysts interactions along the reaction coordinate are related to the additional stabilization of the reactants on the pore mouth of the catalyst.

Totally-green Fuels via CO2 Hydrogenation

Hydrogen is the cleanest energy vector among any fuels, nevertheless, many aspects related to its distribution and storage still raise serious questions concerning costs, infrastructure and safety. On this account, the chemical storage of renewable-hydrogen by conversion into green-fuels, such as: methanol, via CO2 hydrogenation assumes a role of primary importance, also in the light of a cost-to-benefit analysis. Therefore, this paper investigates the effects of chemical composition on the structural properties, surface reactivity and catalytic pathway of ternary CuO-ZnO-CeO2 systems, shedding light on the structure-activity relationships. Thus, a series of CuZnCeO2 catalysts, at different CuO/CeO2 ratio (i.e. 0.2-1.2) were performed in the CO2 hydrogenation reactions at 20 bar and 200-300 °C, (GHSV of 4800 STP L∙kg∙cat-1∙h-1). Catalysts were characterized by several techniques including X-ray Diffraction (XRD), N2-physisorption, single-pulse N2O titrations, X-ray Photoelectron Spectroscopy (XPS), and Temperature-programmed Reduction with H2 (H2-TPR). Depending on preparation method, the results clearly diagnostics the occurrence of synergistic structural-electronic effects of cerium oxide on copper activity, with an optimal 0.5 copper-to-cerium content. The rise of CuO loading up to 30% drives to a considerable increase of hydrogenation activity: C2Z1-C catalyst obtains the best catalytic performance, reaching methanol yield value of 12% at 300 °C. Catalyst activity proceeds according to volcano-shaped relationships, in agreement with a dual sites mechanism. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Vacancy-enabled N2 activation for ammonia synthesis on an Ni-loaded catalyst

Ammonia (NH3) is pivotal to the fertilizer industry and one of the most commonly produced chemicals1. The direct use of atmospheric nitrogen (N2) had been challenging, owing to its large bond energy (945 kilojoules per mole)2,3, until the development of the Haber-Bosch process. Subsequently, many strategies have been explored to reduce the activation barrier of the N≡N bond and make the process more efficient. These include using alkali and alkaline earth metal oxides as promoters to boost the performance of traditional iron- and ruthenium-based catalysts4-6 via electron transfer from the promoters to the antibonding bonds of N2 through transition metals7,8. An electride support further lowers the activation barrier because its low work function and high electron density enhance electron transfer to transition metals9,10. This strategy has facilitated ammonia synthesis from N2 dissociation11 and enabled catalytic operation under mild conditions; however, it requires the use of ruthenium, which is expensive. Alternatively, it has been shown that nitrides containing surface nitrogen vacancies can activate N2 (refs. 12-15). Here we report that nickel-loaded lanthanum nitride (LaN) enables stable and highly efficient ammonia synthesis, owing to a dual-site mechanism that avoids commonly encountered scaling relations. Kinetic and isotope-labelling experiments, as well as density functional theory calculations, confirm that nitrogen vacancies are generated on LaN with low formation energy, and efficiently bind and activate N2. In addition, the nickel metal loaded onto the nitride dissociates H2. The use of distinct sites for activating the two reactants, and the synergy between them, results in the nickel-loaded LaN catalyst exhibiting an activity that far exceeds that of more conventional cobalt- and nickel-based catalysts, and that is comparable to that of ruthenium-based catalysts. Our results illustrate the potential of using vacancy sites in reaction cycles, and introduce a design concept for catalysts for ammonia synthesis, using naturallyabundant elements.

Highly Dispersed Ni–Fe Alloy Catalysts on MgAl2O4 Derived from Hydrotalcite for Direct Ethanol Synthesis from Syngas

In view of the dual active sites mechanism of direct ethanol synthesis and the excellent catalytic performance of bimetallic catalysts, a series of Ni–Fe alloy catalysts with different Ni/Fe molar ratios derived from layered double hydroxides (LDHs) precursors are synthesized. During the calcination and reduction process of LDHs precursors, the Ni–Fe alloy is obtained, and attributed to all the elements being evenly dispersed at the atomic level in the LDHs precursors; meanwhile, a strong interaction between Ni–Fe alloy and MgAl2O4 support exists. As a result, Ni–Fe alloy nanoparticles are highly dispersed on the MgAl2O4 surface. The high CO adsorption ability on the Ni–Fe alloy and synergism catalysis between Ni and Fe result in excellent catalytic activity and high selectivity to ethanol on the bimetallic Ni–Fe alloy. In addition, the strong antisintering ability and stable alloy structure bring about a good catalytic stability. This research proposes a new catalytic system for direct ethanol synthesis from syngas.

Spectroscopic and kinetic insights into the methane reforming over Ce-pyrochlores

High thermal stability and oxygen conductivity of pyrochlores makes them a potential catalyst for the dry reforming of methane (DRM). In this study, noble metal (Pt, Ru) substituted Ce2Zr2O7 and Ce2Ti2O7 pyrochlores have been synthesized by modified Pechini method. The effect of variation of dopant concentration and position was examined to achieve strong metal-support interaction. Ce2Zr1.96Pt0.04O7-δ exhibited the best catalytic activity towards DRM and hence, been studied for partial oxidation (POM) and autothermal reforming of methane (ATR). Syngas ratio (H2/CO) was tuned by varying the O2 concentration in the feed. Insights obtained from both ex-situ and in situ characterization were exploited to discern the reaction mechanism. The surface intermediates were examined by DRIFTS on Ce2Zr1.96Pt0.04O7-δ for DRM, POM and ATR. Besides adsorbed CH4 and CO on Pt, the presence of carbonate and formate species were also identified. Thus, a dual-site mechanism via carbonate and formate formation was proposed for DRM over Ce2Zr1.96Pt0.04O7-δ.

Bovine serum albumin templated porous CeO2 to support Au catalyst for benzene oxidation

Bovine serum albumin (BSA)-templated CeO2 was prepared by citrate sol-gel method and used as a support to synthesize Au catalyst for benzene oxidation. It was found that the Au/BSA-CeO2 with 3.2 nm Au nanoparticles (NPs) gave rise to superior catalytic performance for benzene oxidation in which the temperature for 90 % benzene conversion was only 210 °C. In addition, the catalytic activity of Au/BSA-CeO2 remained stable for 140 h of on-stream reaction. Besides, density functional theory calculation demonstrated how the porous structure of CeO2 influenced the oxygen vacancy generation, and the synergetic effects of Au NPs and CeO2 support facilitated the activation of benzene which was adsorbed on Au NPs prior to benzene oxidation. The catalysis of benzene oxidation over Au/CeO2 catalyst follows the dual-site mechanism. BAS-templated CeO2 support possessed hierarchical structure, abundant adsorbed oxygen species and synergic interaction with Au that determined the performance of Au/BSA-CeO2.

Amine-based CO2 capture aided by acid-basic bifunctional catalyst: Advancement of amine regeneration using metal modified MCM-41

The most critical challenge for the industrial implementation of amine solution CO2 capture is the high heat duty of rich solvent thermal regeneration. Despite significant efforts to lower energy consumption, including employing new amine solvents and process intensification, a novel approach of overcoming this challenge is still demanded. Here, we introduce a novel acid-basic bifunctional catalyst system to reducing the regeneration heat duty by adding metal modified MCM-41 catalyst into amine-based solution. MCM-41 was modified with three metals (Fe, Al, Mo) as well as with different Fe content for catalysis of the rich monoethanolamine (MEA) solvent regeneration process at 98 °C. Results reveal that all the catalysts accelerated regeneration process, and Fe2O3 modified MCM-41 (MFe) catalysts exhibited superior catalytic performance. Notably, the addition of MFe greatly improved the CO2 desorption performance (desorption factor) to 206.3–337.1% compared to the catalyst-free run. The excellent catalytic performance of MFe is ascribed to its improved Brϕnsted acid sites and increased basic sites. Additionally, MFe showed good cyclic stability and its use in the regeneration process enhanced the subsequent CO2 absorption performance. Furthermore, a plausible dual sites mechanism of catalytic amine solvent regeneration over MFe was proposed. Our results demonstrate that the acid-basic bifunctional catalyst plays significant role in developing the amine-based post-combustion CO2 capture technology and has important promise for real-world application.

Molecular Insights on the Role of (CTA+)(SiO−) Ion Pair into the Catalytic Activity of [CTA+]–Si–MCM-41

In this work, a theoretical study in conjunction with a spectroscopic analysis by FTIR were carried out in order to obtain molecular insights on the role of (CTA+)(≡SiO−) ion pair into the catalytic activity of [CTA+]–Si–MCM-41, the non-calcined form of Si–MCM-41. The reaction of transesterification of ethyl acetate with methanol was used as a model of transesterification of vegetal oils using the mesoporous heterogeneous catalyst. The theoretical study was performed in the framework of density functional theory (DFT) in order to provide new insights that could be helpful in the understanding of these chemical reactions on solid surfaces. It is found that the most favorable reaction mechanism is the dual site mechanism and that the presence of the (CTA+)(≡SiO−) ionic pair is fundamental for the catalytic activity. The basic center of [CTA+]–Si–MCM-41 catalyst polarizes the adsorbed methanol and the acid center polarizes the carbonyl of adsorbed ethyl acetate. Thus, this bifunctional catalytic site makes possible the concerted adsorption of both reactants at the pore mouth and generates a concerted transition state that gives rise to the beginning of the transesterification reaction and the formation of the unstable tetrahedral intermediate which will give rise to the products.

Synthesis of 3-aminocoumarin-N-benzylpyridinium conjugates with nanomolar inhibitory activity against acetylcholinesterase.

A series of 3-amino-6,7-dimethoxycoumarins conjugated with the N-benzylpyridinium moiety through an amide-bond linkage was synthesized and evaluated for their acetylcholinesterase inhibitory activity. A number of the benzylpyridinium derivatives exhibited potent activities with inhibitory concentration (IC50) values in the nanomolar concentration range. Among them, the 2,3-difluorobenzylpyridinium-containing compound was the most potent inhibitor with an IC50 value of 1.53 ± 0.01 nM. Docking studies revealed that the synthesized compounds inhibit the target enzyme by a dual binding site mechanism whereby the coumarin portion binds with the peripheral anionic site while the N-benzylpyridinium residue binds with the catalytic anionic site of the enzyme.

Reducing energy consumption of CO2 desorption in CO2-loaded aqueous amine solution using Al2O3/HZSM-5 bifunctional catalysts

The aim of this work is to find a potential way for great decrease in CO2 capture energy requirement. Here, for the first time, a series of bifunctional Al2O3/HZSM-5 catalysts (Al-ZSM) were prepared by the combined precipitation ultrasound method and used for the CO2 desorption process. All the investigated catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), N2 adsorption–desorption, ammonia and CO2 temperature programmed desorption (NH3/CO2-TPD) and pyridine-adsorption infrared spectroscopy (Py-IR). The regeneration behaviors of a 5 M monoethanolamine (MEA) solvent with four Al-ZSM catalysts were studied at an initial CO2 loading of 0.5 mol CO2/mol amine and the temperature of 96 °C. The results reveal that all the catalysts improve the CO2 desorption performance, the Al-ZSM catalysts show higher catalytic performance than the single catalysts Al2O3 and HZSM-5, and the Al-ZSM can reduce the heat duty by 23.3–34.2% as compared with the catalyst-free test. The use of Al-ZSM in the MEA regeneration process improves the desorption performance by 2–3 times in comparison with the blank run. A possible dual sites mechanism of CO2 desorption with Al-ZSM is suggested. The excellent performance of Al-ZSM can be attributed to their enhanced Brϕnsted acid sites (BAS), mesopore surface area (MSA) and basic sites, which resulted from the good synergistic reaction between the Al2O3 and HZSM-5, and the base treatment for HZSM-5. Besides, the stability test of the Al-ZSM was conducted. Based on the results, the Al-ZSM demonstrate a superior catalytic performance for the rich amine regeneration process, and present an excellent cyclic stability, explicitly have the potential to be a promising industrial catalyst for CO2 capture. Furthermore, the dual sites catalytic CO2 desorption over bifunctional catalysts will open a new path to design better catalysts for the rich amine solution regeneration process to increase the desorption performance, reduce the regeneration energy consumption, and thus further decreasing the operation costs of CO2 capture.

Aqueous-phase hydrodechlorination of model chlorinated organic compounds over Ru/C catalyst

ABSTRACTEffluents from the pharmaceutical and dye industries contain chlorinated organic pollutants. The effective treatment of such effluents constitutes a challenging task. In this work, 4-chlororesorcinol (PCRE) and 4-chloro-2-aminophenol (PCAP) were selected as model chloro-organic compounds. Catalytic hydrodechlorination (HDC) of PCRE and PCAP in the aqueous phase was investigated in a slurry reactor using commercial carbon supported ruthenium catalyst. HDC reactions of PCRE and PCAP were studied over the ranges in temperature, 313–353 K, H2 partial pressure, 0.69–2.76 MPa, and catalyst loading, 0.2–1.2 kg/m3. The performance of Ru/C catalyst for hydrodechlorination and ring saturation was promising. The kinetic data were modeled using Langmuir–Hinshelwood–Hougen–Watson kinetics. The HDC reaction of PCRE and PCAP using Ru/C catalyst proceeds via a dual-site mechanism, wherein atomic H2 reacts with the adsorbed organic substrate. The activation energy for the hydrodechlorination reactions of PCRE and PCAP was 41.6 and 49.4 kJ/mol, respectively.

Simultaneous production of oil enriched in ω-3 polyunsaturated fatty acids and biodiesel from fish wastes

The waste resulted from fish processing industries are discarded into the environment around the world, causing environmental pollution. The main problem of fish oil extracted from waste is the high content in free fatty acids (FFA) which decrease the yield in fatty acids esters during transesterification reactions. Therefore, to correct the fish-oil properties, a new environmentally friendly heterogeneous superacid catalyst (SO42−/SnO2-ZrO2) was tested in the esterification reaction of FFA with ethanol. The catalyst was characterized by different techniques (XRD, FT-IR, FT-IR of adsorbed pyridine, BET, SEM-EDX, TGA and acidity measurements). The reaction was found to follow a Langmuir–Hinshelwood (L-H) dual-site mechanism with the novelty that both Brönsted and Lewis acid centers participate equally in the esterification reaction. The pre-treated oil was subjected to transesterification reaction with ethanol over a heterogeneous base catalyst and then, the saturated and unsaturated fractions of fatty acid ethyl esters (FAEE) were separated using a vacuum rectification unit with falling film. The saturated content can be used as biofuel, while the unsaturated FAEE are further transesterified with glycerol in order to obtain oil with high content in polyunsaturated fatty acids (PUFA). A detailed study of the intrinsic kinetic process at the surface of the superacid catalyst and a thorough mathematical model of the fixed bed reactor were written and validated by an experimental program, designed according to the D-optimal methodology.

Copper-cobalt catalyzed liquid phase hydrogenation of furfural to 2-methylfuran: An optimization, kinetics and reaction mechanism study

In the present work, the hydro-conversion of biomass derived furfural (FAL) into fuel additive 2-methylfuran (2-MF) is studied over Cu–Co/Al2O3 catalyst. The influence of various operating parameters such as temperature, pressure, catalyst amount, time and FAL concentration on the conversion of FAL to 2-MF was optimized using well known Taguchi method as statistical tool. According to Taguchi method, under optimum reaction conditions viz. temperature 220°C, pressure 40bar, reaction time 5h, catalyst loading 0.75g, and FAL concentration of 1.75M, maximum 2-MF yield (87%) was obtained. The detailed kinetics of the liquid-phase hydrogenation of FAL to 2-MF in two steps was also studied in the range of temperatures from 200 to 220°C and in the range of pressures from 20 to 40bar. The initial rate of reaction for both conversion of FAL to FOL and FOL to 2-MF varied linearly with hydrogen pressure at various temperature and the catalyst loading, however, effect of reactant substrate behave distinctly. In case of FAL, rate of reaction varied linearly and order of reaction is found to be almost one, whereas, for FOL disappearance, order of reaction found to be almost zero beyond 2.25gmol/L of FOL concentration. The experimental data could also be explained using Langmuir–Hinshelwood kinetics. A dual-site mechanism with dissociative adsorption of hydrogen and surface reaction as the rate-controlling step provided the best fit for the experimental data.

CO oxidation over supported gold nanoparticles as revealed by operando grazing incidence X-ray scattering analysis.

The mechanism of carbon monoxide oxidation over gold was explored using a model planar catalyst consisting of monodisperse gold nanoparticles periodically arranged on single crystal SiO2/Si(111) substrates using a combination of Grazing Incidence Small Angle X-ray Scattering and Grazing Incidence X-ray Diffraction (GISAXS/GIXD) under reaction conditions. It is shown that nanoparticle composition, size and shape change when the catalyst is exposed to reactive gases. During CO oxidation, the particle's submergence depth with respect to the surface decreases due to the removal of gold oxide at the metal-support edge, meanwhile the particle 'flattens' to maximise the number of the reaction sites along its perimeter. The effect of the CO concentration on the catalyst structure is also discussed. Our results support the dual catalytic sites mechanism whereby CO is activated on the gold surface whereas molecular oxygen is dissociating at the gold-support interface.

Effect of supports over Pd/Fe2O3 on CO oxidation at low temperature

Pd/Fe2O3 catalysts were prepared by deposition-precipitation method and investigated for CO oxidation. Compared with Pd/α-Fe2O3, Pd/γ-Fe2O3 exhibited the higher CO oxidation activity, and CO completely oxidation temperature was obtained at 0°C. CO oxidation occurred through the dual sites mechanism, namely CO adsorbed on Pd species and O activation on the support. The close contact between Pd and γ-Fe2O3 enhanced the redox recycle between Fe3+and Fe2+ species, which played a decisive role in oxygen activation. The excellent performance in oxygen activation efficiently accelerated the rate-determining step in CO oxidation. The accumulated carbonate and hydrocarbonate species on α-Fe2O3 blocked the oxygen activation which resulted in the low activity of Pd/α-Fe2O3 in CO oxidation.

Novel mechanistic view of catalytic ozonation of gaseous toluene by dual-site kinetic modelling

Abstract The catalytic ozonation of VOCs is a promising approach for degradation of indoor VOCs, such as gaseous toluene. However, the mechanism and relevant kinetic steps involved in this reaction remain unclear. In this study, the catalytic ozonation of toluene over MnO 2 /graphene was investigated using the empirical power law model and classic Langmuir-Hinshelwood single-site (denoted as L-H s ) mechanism. The apparent activation energy determined using the power law model was 29.3 ± 2.5 kJ mol −1 . This finding indicated that the catalytic ozonation of toluene over MnO 2 /graphene was a heterogeneous reaction, and the Langmuir-Hinshelwood mechanism was applicable. However, the L-H s mechanism did not fit the experimental data, suggesting that the reaction was non-single-site governed. A novel Langmuir-Hinshelwood dual-site (denoted as L-H d ) mechanism was then proposed to explain the experimental observations of the catalytic ozonation of toluene over MnO 2 /graphene through a steady-state kinetic study. This mechanism was based on the hypothesis that MnO 2 was responsible for ozone decomposition and toluene adsorption on graphene; these two types of adsorption were coupled by an adjacent attack. Furthermore, XPS results confirmed the presence of a strong connection between MnO 2 and graphene sites on the surface of MnO 2 /graphene. This connection allowed the adjacent attack and validated the dual-site mechanism. The L-H d model was consistent with the predicted reaction rate of toluene removal with a correlation coefficient near unity (r 2 = 0.9165). Moreover, the physical criterion was in accordance with both enthalpy and entropy of toluene adsorption constraints. Fulfillment of mathematical and physical criteria indicated the catalytic ozonation of toluene over MnO 2 /graphene can be well described by the L-H d mechanism. This study helps understand the catalytic ozonation of toluene over MnO 2 /graphene in a closely mechanistic view.

New Insights in the Treatment of Waste Water with Graphene: Dual-Site Adsorption by Sodium Dodecylbenzenesulfonate

For the adsorption of sodium dodecylbenzenesulfonate (SDBS) in aqueous solution on reduced graphene oxide (rGO), it is demonstrated that the dual-site mechanism is strongly favored over the conventional single-site one. The dual-site adsorption isotherm is derived, and regression analysis is successfully applied to experimental UV–vis data (1 g L–1 rGO; 298–318 K; 100–900 mg L–1 SDBS; pH: 4–11), considering reparametrization to minimize the correlation between the parameter estimates (dual site: ΔH° = −37.1 ± 1.3 kJ mol–1; ΔS° = 35.5 ± 4.1 J mol–1 K–1; q∞ = 546.9 ± 8.6 mgSDBS grGO–1). A temperature of 298 K is identified as the optimal operating temperature with contact times of ca. 30 h (700 mg L–1 SDBS). An improved regression analysis strategy, carefully selecting only low contact times (maximal 10 h), allowed assessment of the dual-site adsorption and desorption coefficient as (1.2 ± 0.3) × 10–4 L mgSDBS–1 h–1 and (2.8 ± 0.7) × 10–3 h–1. Moreover, by the additional presence of sodium chloride (1.2 × 1...

Microkinetic Modeling of CO Oxidation on Ionic Palladium-Substituted Ceria

This study presents a plausible dual-site mechanism and microkinetic model for CO oxidation over palladium-substituted ceria incorporating the theoretical oxygen storage capacity of different catalysts into the kinetic model. A rate expression without prior assumption of rate-determining steps has been developed for the proposed microkinetic model using reaction route analysis. Experiments were conducted using various percentages of palladium in ceria that were synthesized by solution combustion. Obtained catalysts were characterized by X-ray diffraction, X-ray photoelectron spectra, and Brunauer–Emmett–Teller surface area measurements. A detailed mechanism was developed, and the kinetic parameters and rate expression were validated with the conversion data obtained in the presence of the catalysts. Furthermore, a reduced rate expression based on rate-determining step and most abundant reactive intermediate approximation was obtained and tested against the original rate expression for different experiment...

Shape-selective synthesis of para-diethylbenzene over pore-engineered ZSM-5: A kinetic study

Alkylation of ethylbenzene (EB) with ethanol was carried out in a fixed bed, continuous, down-flow, tubular reactor at atmospheric pressure and hydrogen as a carrier gas in vapor phase. A detailed kinetic study was conducted over ZSM-5 zeolite extrudates pore-engineered by phosphate modification. The reaction was performed at EB: ethanol mole ratio of 4:1 and with varying contact time at temperatures of 613, 633 and 653K. Due to the induced shape-selectivity in ZSM-5 by phosphate modification, para-diethylbenzene (PDEB) was formed as a major product and side products like benzene, meta-diethylbenzene (MDEB) and other isomers were formed in minor quantity. Langmuir–Hinselwood–Hougen–Watson (LHHW) method for dual site mechanism with an assumption of surface reaction controlling was applied to derive the rate equations. Activation energies for the ethylation of EB, dealkylation of EB and isomerization of PDEB were found to be 117.2, 186.0 and 298.6kJ/mol respectively. Adsorption energetics showed that EB is weakly adsorbed, whereas ethanol is strongly adsorbed over the catalyst surface. Activation energy of PDEB formation was found to be lower than that of MDEB. Considering that the alkylation takes place mostly inside the zeolite channels, the results support restricted transition state selective mechanism for EB alkylation with ethanol over phosphate modified ZSM-5. Based on the proposed kinetic model, calculated values of EB conversion and PDEB formation were found to be in good agreement with the experimental results.

Interfacial Effects of CeO2-Supported Pd Nanorod in Catalytic CO Oxidation: A Theoretical Study

Understanding the interfacial effects of metal/support catalysts is of great significance in heterogeneous catalysis. In this work, we performed density functional theory calculations corrected by on-site Coulomb interactions (DFT+U) to study CO oxidation on a CeO2(111)-supported Pd nanorod. Three different reaction mechanisms for CO oxidation were systematically studied, namely the Pd–Ce3+ dual sites mechanism, the Mars-van Krevelen (M-vK) mechanism, and the Pd-only mechanism. On the basis of energetic analysis, we concluded that the dominant reaction pathway at low temperatures is the Pd–Ce3+ dual sites mechanism, whereas the M-vK mechanism would be dominant at higher temperatures. The interfacial effects play a crucial role and strongly affect the catalytic activity in these two mechanisms. The origin of the interfacial effects can be understood by analyzing the geometric and electronic properties. From the geometric perspective, the interaction between Pd nanorod and ceria support elongates the Ce–O b...