Dehydrogenation Of Ethanol Research Articles

Bimetallic NiCu catalysts supported on a Metal-Organic framework for Non-oxidative ethanol dehydrogenation

Non-oxidative ethanol dehydrogenation is a promising route to produce acetaldehyde and hydrogen from sustainable feedstock. Bimetallic NiCu catalysts have shown high efficiency and selectivity for this chemical transformation. In this study, we leverage the high porosity and uniform catalyst deposition sites on a Zr-based metal–organic framework (MOF) catalyst support, NU-1000, to understand how the changes in Cu:Ni ratio affects the reactivity for non-oxidative ethanol dehydrogenation. We found that increasing the Ni2+ concentration significantly reduces the activation energy of the reaction due to the role of Ni2+ in suppressing the onset of Cu reduction. This study illustrates how MOFs can be used as catalyst supports to fine-tune the catalyst compositions and understand their effect on the overall catalytic performances.

Computational Study of Dehydration and Dehydrogenation of Ethanol on (TiO2)n (n = 2–4) Nanoclusters

Dehydration and dehydrogenation of an ethanol molecule on (TiO2)n, n = 2-4, nanoclusters were studied at the correlated molecular orbital theory CCSD(T)/aug-cc-pVDZ(-PP(Ti)) level using density functional theory B3LYP/DZVP2-optimized geometries. Physisorption and chemisorption of ethanol at the bridge Ti site on the trimer and tetramer are thermodynamically preferred over these reactions at the Ti site with a terminal Ti═O. Two possible lowest energy reaction coordinates of dehydration were predicted for the dimer and trimer where the β hydrogen on ethanol transfers to the adjacent terminal oxygen, or to the adjacent bidentate oxygen. Only the latter reaction coordinate was predicted to be the lowest energy one for the tetramer. Removal of ethylene from the (TiO2)nOH2-C2H4 complex for n = 2-4 at 0 K requires 2-7 kcal/mol. For dehydrogenation, transfer of the α hydrogen to the adjacent Ti atom results in the lowest energy reaction coordinate following a proton-coupled electron-transfer (PCET) process. Removal of the acetaldehyde molecule requires 14-26 kcal/mol from the (TiO2)nH2-C2H4O complex. Loss of H2 from the (TiO2)nH2 complex requires 5-8 kcal/mol. Dehydration and dehydrogenation of one ethanol molecule occur below the reactant asymptote for (TiO2)n, n = 2-4, whereas for (WO3)3 and (MoO3)3, two ethanol molecules are required for this process to be below the reactant asymptote. Dehydration of ethanol is thermodynamically preferred over dehydrogenation on (TiO2)n, n = 2-4. There is an approximate linear correlation of metal Lewis acidity with physisorption of ethanol. A quadratic correlation is predicted between the chemisorption barrier of ethanol and the corresponding proton affinity of oxygen to which the proton is being transferred. There are linear correlations between the basicity of the oxygen site and the acidity of the OH group versus the energy to remove C2H4 from that site. The results for the nanoclusters for n = 3 and 4 are consistent with the experimental results for the reactivity of ethanol on Ti5c4+ rutile TiO2 (110) surface sites.

Insights into the Role of Defects in Fe2(MoO4)3 Catalysts

The catalytic activity and selectivity of Fe2(MoO4)3 obtained from solid-state synthesis protocols is investigated for the oxidative dehydrogenation (ODH) of ethanol to acetaldehyde. While Fe2(MoO4)3 annealed in a MoO3 atmosphere is found to be inactive, ball-milling of such solid-state synthesis precursors leads to an increase in activity, which cannot be attributed purely to the change in the specific surface area nor to a geometric effect of smaller particles. In a systematic study of the synthesis of Fe2O3-free Fe2(MoO4)3 samples, the correlation of ball-milling time, defect concentration, and catalytic activity is presented. In-depth X-ray diffraction studies, magnetic susceptibility, and 57Fe-Mössbauer spectroscopic measurements disclose characteristic signatures of the defect sites in the solid materials introduced by ball-milling and indicate: (i) MoO3-enriched amorphous layers of variable thickness (shell-like) and (ii) crystalline bulk defects corresponding to a reduction in the molar volume of the solid. The onset of recrystallization processes sets in around 300 °C and is accompanied by an enhanced MoO3 mobility in the particles, which adds to an increase in activity and a decreasing selectivity under catalytic conditions. Accordingly, the defects associated with the decreasing amorphous fraction are converted to crystalline bulk defects, which are monitored by the magnetic hyperfine field distribution of the respective Fe sites. Overall, this study shows the importance of the amorphous layer thickness with a sufficient defect concentration and of the bulk defects’ contribution to the chemical gradients, important for the MoO3 mobility and reduction of the MoO3 loss as a volatile species at the solid/gas phase boundary in ODH catalysis.

Ethanol dehydrogenation to acetaldehyde with mesoporous Cu-SiO2 catalysts prepared by aerosol-assisted sol–gel

Copper based catalysts are central for carrying dehydrogenation reactions. However, these materials are prone to deactivation by sintering and coke deposition. Irreversible sintering occurring during reaction (under the effect of temperature) is known to decrease both activity and selectivity, where the unwanted dehydration activity of the support might also play an important role. From this perspective, the quite unreactive silica supports may be attractive. However, using classical catalyst preparation methods (e.g. impregnation), it is a challenge to obtain a stable and homogeneous dispersion of Cu over SiO2 owing to the weak support-active phase interactions. Taking a sidestep, aerosol-assisted sol–gel is a promising alternative for the facile preparation of mesostructured metallosilicates with high metal dispersion. Here we report Cu-SiO2 made by the aerosol-assisted sol–gel method and exploited in the ethanol non-oxidative dehydrogenation to acetaldehyde. These catalysts are compared with a series of catalysts made by impregnation to investigate, through a thorough characterization survey, the effect of the synthesis procedure as well as the effect of Cu loading. We show that aerosol-made catalysts do not suffer heavy sintering, reach high ethanol conversions with acetaldehyde selectivity above 75%, and only slowly deactivate upon time due to a (reversible) coking phenomenon.

Ionic liquid supported on mesoporous Pd/SBA-15 during the manufacture of 1,3-butadiene using ethanol at lower temperature reaction

Investigating the heterogeneous organo-catalysts such as 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate upon SBA-15, which includes one percent palladium, and their ability to produce 1,3-butadiene from ethanol while supporting them on mesoporous materials. SBA-15 and metal precursors were mixed together and crushed in solid state. By using the TGA, N2 adsorption–desorption, TEM, and XRD procedures, the produced catalysts were studied. Once an organic motif was added to SBA-15, the solid-state grinding procedure produced more accessible acid sites on the catalyst and increased the dispersion of Pd metal. In a fixed-bed reactor, the catalytic performance was assessed, and a selectivity of up to 82% for 1,3-butadiene was achieved. This is brought on by the coupling activity of Pd and ionic liquid species in the porous structure of SBA-15, where the ionic liquid catalyst promotes ethanol dehydrogenation while Pd promotes aldol condensation The solvent-free method also served as the inspiration for a fresh way of synthesizing catalysts for the formation of 1,3-butadiene using ethanol.

Reaction kinetics of a NiO-based oxygen carrier with ethanol to be applied in chemical looping processes

The use of bio-ethanol in chemical looping combustion (CLC) and reforming (CLR) has the potential to produce energy and/or hydrogen and, as a negative-emissions technology (NET), to remove CO2 from the atmosphere at low cost following the principles of bio-energy with CO2 capture and storage (BECCS). The determination of the rate of the chemical processes involving the fuel conversion with the oxygen carrier is required for the modelling and design of a chemical looping unit. In this work, a kinetic study of ethanol conversion is performed considering a NiO-based material as the oxygen carrier. Combined experiments in TGA and fixed bed were conducted. TGA tests confirmed that the oxygen carrier was reduced by a ethanol-containing gaseous stream at temperatures higher than 773 K. An apparent reaction kinetics for the NiO reduction with ethanol was determined, which might be used in simplified fuel reactor models. However, tests performed in a fixed bed revealed that products derived of the ethanol decomposition, such as CH4, CO, H2 were responsible for NiO reduction, instead of the direct reduction with ethanol. High temperature kinetics of processes involved in ethanol conversion, namely dehydration, dehydrogenation and decomposition, were determined. Both, non-catalytic and Ni-catalytic reactions were of relevance under chemical looping conditions. A reaction pathway was described to be used in detailed fuel reactor models of chemical looping units.

Origin of the Activity Trend in the Oxidative Dehydrogenation of Ethanol over VOx /CeO2.

Supported vanadia (VOx ) is a versatile catalyst for various redox processes where ceria-supported VOx have shown to be particularly active in the oxidative dehydrogenation (ODH) of alcohols. In this work, we clarify the origin of the volcano-shaped ethanol ODH activity trend for VOx /CeOx catalysts using operando quick V K- and Ce L3 - edge XAS experiments performed under transient conditions. We quantitatively demonstrate that both vanadium and cerium are synergistically involved in alcohol ODH. The concentration of reversible Ce4+ /Ce3+ species was identified as the main descriptor of the alcohol ODH activity. The activity drop in the volcano plot, observed at above ca. 3 V nm-2 surface loading (ca. 30 % of VOx monolayer coverage), is related to the formation of spectator V4+ and Ce3+ species, which were identified here for the first time. These results might prove to be helpful for the rational optimization of VOx /CeO2 catalysts and the refinement of the theoretical models.

Map of 20 reactions that take place during vapor–solid phase photocatalytic dehydrogenation of ethanol on metal‐loaded TiO2

AbstractWe report the map of 20 reactions that take place during vapor‐phase photochemical dehydrogenation of ethanol on four metal‐doped TiO2 (Mn/TiO2, Mn = nanoparticles of Pd, Pt, Au, and Cu) under solar simulated light. The reactions are sensitively affected by the moisture amount and the nature of the carrier gas. To construct the above map, we also used CH3CHO, CH3CO2H, (C2H5O)2CHCH3, and CH3CO2C2H5, respectively, as an independent starting reagent. Amazingly, Mn/TiO2 not only serves as photocatalysts but also as thermocatalysts for various reactions that appear in the above map. The reaction is proposed to proceed by a radical mechanism in which photoinduced electron transfer from the valence band to the conduction band of TiO2 is the initial step and the subsequent electron injection from organic reactants to the hole in the TiO2 valence band. This report also features highly valuable unprecedented reactions, which bear great potential to be commercialized.

Mechanistic Insights into Nonoxidative Ethanol Dehydrogenation on NiCu Single-Atom Alloys

Ethanol dehydrogenation presents a promising pathway toward the production of acetaldehyde, a valuable building block in chemicals production. Under nonoxidative conditions, the reaction is facilitated by supported Cu nanoparticles, which afford reasonable activity and high selectivity. The stability issues associated with Cu nanoparticle sintering can be addressed by the addition of small amounts of Ni, which further boost reactivity while retaining selectivity. Despite the promise of NiCu single-atom alloys for nonoxidative ethanol dehydrogenation, little is known about the role of each component and the pathway of this mechanistically complex process. Herein, kinetic investigations from reactor tests identify C–H bond scission as the rate-limiting step, while 1-hydroxyethyl is detected as the intermediate via IR spectroscopy. Temperature-programmed desorption studies are employed to examine the effect of Ni coverage and to demonstrate that Ni atoms activate ethanol selectively at lower temperatures, resulting in higher acetaldehyde yield than pure Cu. Temperature-programmed desorption experiments also reveal the spillover of intermediates from the Ni atom to neighboring Cu sites as a relevant step in the reaction pathway. Density functional theory calculations are used to investigate the reaction energetics and to confirm that C–H bond scission is the initial reaction step, while a clear effect of H2 partial pressure on the reaction pathway is realized. Further, counter to the expected behavior that all reaction steps take place on the Ni atoms, our degree of rate control analysis reveals that a mechanism involving spillover of the 1-hydroxyethyl intermediate from the Ni atom to the Cu surface, where it will dehydrogenate further, is more likely. Our combined kinetic, spectroscopic, and theoretical approach sheds light on this complex reaction mechanism and represents a promising method for the understanding and designing of highly active, selective, and stable single-atom alloys for other multistep catalytic processes.

A Priori Design of Dual-Atom Alloy Sites and Experimental Demonstration of Ethanol Dehydrogenation and Dehydration on PtCrAg.

Single-atom catalysts have received significant attention for their ability to enable highly selective reactions. However, many reactions require more than one adjacent site to align reactants or break specific bonds. For example, breaking a C-O or O-H bond may be facilitated by a dual site containing an oxophilic element and a carbophilic or "hydrogenphilic" element that binds each molecular fragment. However, design of stable and well-defined dual-atom sites with desirable reactivity is difficult due to the complexity of multicomponent catalytic surfaces. Here, we describe a new type of dual-atom system, trimetallic dual-atom alloys, which were designed via computation of the alloying energetics. Through a broad computational screening we discovered that Pt-Cr dimers embedded in Ag(111) can be formed by virtue of the negative mixing enthalpy of Pt and Cr in Ag and the favorable interaction between Pt and Cr. These dual-atom alloy sites were then realized experimentally through surface science experiments that enabled the active sites to be imaged and their reactivity related to their atomic-scale structure. Specifically, Pt-Cr sites in Ag(111) can convert ethanol, whereas PtAg and CrAg are unreactive toward ethanol. Calculations show that the oxophilic Cr atom and the hydrogenphilic Pt atom act synergistically to break the O-H bond. Furthermore, ensembles with more than one Cr atom, present at higher dopant loadings, produce ethylene. Our calculations have identified many other thermodynamically favorable dual-atom alloy sites, and hence this work highlights a new class of materials that should offer new and useful chemical reactivity beyond the single-atom paradigm.

The Perspective of Using the System Ethanol-Ethyl Acetate in a Liquid Organic Hydrogen Carrier (LOHC) Cycle

Starting from bioethanol it is possible, by using an appropriate catalyst, to produce ethyl acetate in a single reaction step and pure hydrogen as a by-product. Two molecules of hydrogen can be obtained for each molecule of ethyl acetate produced. The mentioned reaction is reversible, therefore, it is possible to hydrogenate ethyl acetate to reobtain ethanol, so closing the chemical cycle of a Liquid Organic Hydrogen Carrier (LOHC) process. In other words, bioethanol can be conveniently used as a hydrogen carrier. Many papers have been published in the literature dealing with both the ethanol dehydrogenation and the ethyl acetate hydrogenation to ethanol so demonstrating the feasibility of this process. In this review all the aspects of the entire LOHC cycle are considered and discussed. We examined in particular: the most convenient catalysts for the two main reactions, the best operative conditions, the kinetics of all the reactions involved in the process, the scaling up of both ethanol dehydrogenation and ethyl acetate hydrogenation from the laboratory to industrial plant, the techno-economic aspects of the process and the perspective for improvements. In particular, the use of bioethanol in a LOHC process has three main advantages: (1) the hydrogen carrier is a renewable resource; (2) ethanol and ethyl acetate are both green products benign for both the environment and human safety; (3) the processes of hydrogenation and dehydrogenation occur in relatively mild operative conditions of temperature and pressure and with high energetic efficiency. The main disadvantage with respect to other more conventional LOHC systems is the relatively low hydrogen storage density.

Production of Acetaldehyde via Oxidative Dehydrogenation of Ethanol in a Chemical Looping Setup.

A novel chemical looping (CL) process was demonstrated to produce acetaldehyde (AA) via oxidative dehydrogenation (ODH) of ethanol. Here, the ODH of ethanol takes place in the absence of a gaseous oxygen stream; instead, oxygen is supplied from a metal oxide, an active support for an ODH catalyst. The support material reduces as the reaction takes place and needs to be regenerated in air in a separate step, resulting in a CL process. Here, strontium ferrite perovskite (SrFeO3-δ) was used as the active support, with both silver and copper as the ODH catalysts. The performance of Ag/SrFeO3-δ and Cu/SrFeO3-δ was investigated in a packed bed reactor, operated at temperatures from 200 to 270 °C and a gas hourly space velocity of 9600 h-1. The CL capability to produce AA was then compared to the performance of bare SrFeO3-δ (no catalysts) and materials comprising a catalyst on an inert support, Cu or Ag on Al2O3. The Ag/Al2O3 catalyst was completely inactive in the absence of air, confirming that oxygen supplied from the support is required to oxidize ethanol to AA and water, while Cu/Al2O3 gradually got covered in coke, indicating cracking of ethanol. The bare SrFeO3-δ achieved a similar selectivity to AA as Ag/SrFeO3-δ but at a greatly reduced activity. For the best performing catalyst, Ag/SrFeO3-δ, the obtained selectivity to AA reached 92-98% at yields of up to 70%, comparable to the incumbent Veba-Chemie process for ethanol ODH, but at around 250 °C lower temperature. The CL-ODH setup was operated at high effective production times (i.e., the time spent producing AA to the time spent regenerating SrFeO3-δ). In the investigated configuration with 2 g of the CLC catalyst and 200 mL/min feed flowrate ∼5.8 vol % ethanol, only three reactors would be required for the pseudo-continuous production of AA via CL-ODH.

Production of hydrogen from gas-phase ethanol dehydrogenation over iron-grafted mesoporous Pt/TiO2 photocatalysts

Production of hydrogen from gas-phase ethanol dehydrogenation over iron-grafted mesoporous Pt/TiO2 photocatalysts

Design of Multicationic Copper‐Bearing Layered Double Hydroxides for Catalytic Application in Biorefinery

AbstractEthanol has been used as a renewable hydrogen‐donor in the conversion of a lignin model molecule in subcritical conditions. Noble metal‐free porous mixed oxides, obtained by activation of Cu−Ni−Al and Cu−Ni−Fe layered double hydroxide (LDH) precursors, have been used as heterogeneous catalysts for Meerwein‐Ponndorf‐Verley (MPV) hydrogen transfer and further hydrogenation by ethanol dehydrogenation products. Both the Cu/(Cu+Ni) ratio and the nature of the trivalent cation (Al or Fe) affect the activity of the catalysts, as well as the selectivity towards the different steps of the hydrogenation reactions and the cleavage of lignin‐like phenylether bonds. Accounting for the peculiar behaviour of Cu2+ and M(III) cations in the synthesis of LDHs, the coprecipitation of the precursors has been monitored by titration experiments. Structural and textural properties of the catalysts are closely related to the composition of the LDH precursors.

Redispersion and Stabilization of Cu/MFI Catalysts by the Encapsulation Method for Ethanol Dehydrogenation

Encapsulation of metal particles with ordered porous zeolite is a promising method to stabilize nanoparticles. In this work, Cu/MFI catalysts prepared by the impregnation method were encapsulated with MFI to yield (Cu/MFI)@MFI catalysts for ethanol dehydrogenation. The encapsulation process not only anchored Cu particles into MFI but also redispersed Cu with decreased particle sizes and newly formed Cu+ species. During the ethanol dehydrogenation reaction, the Cu+ and Cu0 species confined in (Cu/MFI)@MFI catalysts demonstrated synergistic effects and afforded 95.7% acetaldehyde selectivity, 97.2% ethanol conversion at 523 K, and a weight hourly space velocity (WHSV) of 0.53 h–1 in the 200 h time on stream over the optimized (Cu/MFI)@MFI 100% catalyst, which is significantly better than the counterpart of the Cu/MFI catalyst.

Anodic Behavior of Hafnium in Anhydrous Electrodissolution-Coupled Hafnium Alkoxide Synthesis

The electrodissolution-coupled hafnium alkoxide (Hf(OR)4, R is alkyl) synthesis (EHS) system, which has significant environmental and economic advantages over conventional thermal methods, serves as a promising system for green and efficient Hf(OR)4 electro-synthesis. The EHS system is operated based on the simultaneous heterogeneous reactions of hafnium dissolution and ethanol dehydrogenation, as well as the spontaneous solution-based reaction of Hf4+ and OR−. Employing green ethanol and Hf as feedstocks, the anodic hafnium corrosion/dissolution electrochemical behavior of the Et4NCl or Et4NHSO4 based anhydrous system was investigated through electrochemical measurements combined with SEM observations. The results demonstrated that the Et4NCl-based anhydrous ethanol system exhibited an efficient mechanism of passive film pitting corrosion breakdown and metal hafnium dissolution, while the Et4NHSO4-based anhydrous ethanol system reflected the weak corrosion mechanism of the anodic hafnium under the passive film. The polarization resistance of the Et4NCl system was dramatically lower than that of the Et4NHSO4 system, which indicated that the Et4NCl system had superior anodic hafnium corrosion performance compared to the Et4NHSO4 system. Overall, the investigation of the electrochemical behaviors of anodic hafnium corrosion/dissolution provides theoretical guidance for the efficient operation of EHS electrolysis.

Effect of Sr Substitution on the Novel La1-xSrxCo0.5Ni0.5O3-δ Perovskite-Type Catalysts for Hydrogen Production in Ethanol Steam Reforming

La1-xSrxCo0.5Ni0.5O3-δ perovskites with different substitution of La by Sr have been firstly synthesized and applied as catalysts for ethanol steam reforming (ESR). The effect of partial Sr substitution on the performance and stability of La1-xSrxCo0.5Ni0.5O3-δ for ESR was investigated. The synthesized samples were characterized by XRD, SEM, BET, and EDS techniques. The results show that with the increase of substitution of La by Sr, the pore size and surface area of La1-xSrxCo0.5Ni0.5O3-δ perovskite increase. The doping of Sr causes changes in the specific surface area, pore volume, and pore size of the catalyst, which in turn causes changes in its catalytic activity. Meanwhile, La0.1Sr0.9Co0.5Ni0.5O3-δ with a highest SBET presents the highest ethanol conversion rate among all the samples. The modifications of catalyst characteristics caused by the Sr substitution in La1-xSrxCo0.5Ni0.5O3-δ directly affect its catalytic performance in the ESR. What is more, the influences of operating parameters on the catalytic activity of La0.1Sr0.9Co0.5Ni0.5O3-δ were studied in detail, and the optimum conditions were determined and applied for stability experiments. When the temperature is lower than 500°C, the selectivity of gas products is most likely affected by the dehydrogenation of ethanol and the decomposition of acetaldehyde. Meanwhile, the improving hydrogen selectivity and reducing the formation of by-products can be achieved by increasing the reaction temperature. The best catalytic performance for hydrogen production was achieved with La0.1Sr0.9Co0.5Ni0.5O3-δ which presented the highest ethanol conversion (98.7%) under the optimal reaction conditions. La0.1Sr0.9Co0.5Ni0.5O3-δ perovskites with higher strontium degree of substitution exhibited an excellent activity and stability of the catalysts derived.

Activation of Ethanol Transformation on Copper-Containing SBA-15 and MnSBA-15 Catalysts by the Presence of Oxygen in the Reaction Mixture.

The aim of this study was to get insight into the pathway of the acetaldehyde formation from ethanol (the rate-limiting step in the production of 1,3-butadiene) on Cu-SBA-15 and Cu-MnSBA-15 mesoporous molecular sieves. Physicochemical properties of the catalysts were investigated by XRD, N2 ads/des, Uv-vis, XPS, EPR, pyridine adsorption combined with FTIR, 2-propanol decomposition and 2,5-hexanedione cyclization and dehydration test reactions. Ethanol dehydrogenation to acetaldehyde (without and with oxygen) was studied in a flow system using the FTIR technique. In particular, the effect of Lewis acid and basic (Lewis and BrØnsted) sites, and the oxygen presence in the gas reaction mixture with ethanol on the activity and selectivity of copper catalysts, was assessed and discussed. Two different reaction pathways have been proposed depending on the reaction temperature and the presence or absence of oxygen in the flow of the reagents (via ethoxy intermediate way at 593 K, in ethanol flow, or ethoxide intermediate way at 473 K in the presence of ethanol and oxygen in the reaction mixture).

Управление морфологией и поверхностной энергией электрода для создания этанольных топливных элементов на основе пористого кремния, сформированного Pd-стимулированным травлением

The evolution of macro- and mesoporous layers of porous silicon formed by Pd-assisted etching with different duration of formation and temperature of the etching solution from 25 to 75 °С, which have the property of ethanol electrooxidation, has been studied. High values of the dissolution rate of porous silicon at a temperature of 75 °С are shown, leading to a significant loss of thickness and specific surface area of the macro- and mesoporous layer, respectively. The obtained porous layers with different surface energy and surface area, show different rates of ethanol dehydrogenation and the number of dehydrogenated ethanol molecules, which allows you to control the activity of the electrode material for ethanol fuel cells.

Ethanol Electrooxidation on an Island-Like Nanoporous Gold/Palladium Electrocatalyst in Alkaline Media: Electrocatalytic Properties and an In Situ Surface-Enhanced Raman Spectroscopy Study.

The design of electrocatalysts with high activity and the understanding of the reaction mechanism for the ethanol oxidation reaction (EOR) are pivotal for commercializing direct ethanol fuel cells (DEFCs). Herein, island-like nanoporous gold/palladium (INPG/Pd) is designed as a highly efficient EOR electrocatalyst. For a better understanding of the reaction mechanism, in situ surface-enhanced Raman spectroscopy (SERS) in conjunction with H-D isotope replacement is used to investigate the dissociation and oxidation of CH3CH2OH on the INPG/Pd electrode, with a focus on identifying significant intermediate species in the reaction process. The results show that INPG/Pd has a higher electrocatalytic performance than INPG and indium-tin oxide (ITO) glass/palladium (Pd) due to the synergistic effect of NPG and Pd. INPG/Pd-10 shows the highest specific activity, the strongest charge-transfer ability, and relatively good stability. INPG/Pd presents better SERS sensitivity than ITO glass/Pd because of the plasma enhancement effect of nanoporous Au. The in situ Raman spectral results suggest that the oxidation of ethanol proceeds via a dual-pathway (C1 and C2) reaction mechanism. Dehydrogenation of ethanol can form acetaldehyde (CH3CHO) at -0.4 V. Meanwhile, the adsorbed acetaldehyde is oxidized to acetate from approximately -0.4 V, with the potential moving positively, which is the so-called C2 pathway. Alternatively, in the C1 pathway, CH3CHO and CH3CH2OH decomposed to intermediate species (adsorbed CO) on the INPG/Pd electrode due to C-C bond breaking at potentials of approximately -0.2 V. Subsequently, the CO species is oxidized to CO2 at more positive potentials.