Detailed Reaction Mechanism Research Articles

Evaluating the selectivity of CO2 reduction reaction on elementary metal particles with DFT calculations

Electrocatalytic CO2 reduction reaction (CO2RR) towards two-electron products is a competent technique to convert renewable electricity into chemical energy at ambient conditions. Poly-crystalline metals are well-known electrocatalysts for CO2RR. However, no theoretical research was reported to date that evaluates the selectivity of two-electron CO2RR on metal particles. In this work, we proposed a paradigm to evaluate the product selectivity of CO2RR on metal particles. The product selectivity on three low-index surfaces of six metals (In, Pb, Ag, Au, Ni, and Pt) was firstly determined based on the detailed reaction mechanisms established for CO2RR to products of HCOOH and CO. Then, the product selectivity of CO2RR on the first four metal particles was evaluated using the effective free energy barrier which accounts for the facet dependence of CO2RR on the metal particles. The computational results well rationalize the experimental observations, namely preference of HCOOH to CO on the In and Pb particles with higher HCOOH selectivity on the Pb particle, while CO preferred to HCOOH on the Ag and Au particles with higher CO selectivity on the Au particle.

Gasification characteristics and sulfur migration mechanism during supercritical water partial oxidation of 2-methylthiophene

Supercritical water partial oxidation (SCWPO), as a clean and efficient energy conversion technology, offers new insights for the clean treatment of thiophene compounds, which are a significant source of potential pollutants. However, the detailed reaction mechanism of thiophene compounds in the SCWPO process is still unclear. Therefore, the effects of parameters on gasification characteristics and sulfur migration were investigated in the quartz tube reactor during the SCWPO of 2-methylthiophene (2-MT). The results demonstrated that extending the reaction time, increasing the reaction temperature, and reducing the feed concentration favored gaseous product generation. The SCWPO environment with the low equivalent ratio (ER) was favorable for the generation of hydrogen-rich gas. When the conditions were 750 °C, 4 wt%, 15 min, ER = 0.2, the highest H2 yield was 18.59 mol kg−1. With the addition of oxidants, the SCWPO environment promoted the conversion of sulfur from S-2, S-o to S+4, S+6. This conversion reduced the sulfur content in the gas, making it stored in a more environmentally friendly form. Notably, the presence of SOx was not detected during the SCWPO process. Finally, a detailed reaction mechanism for the SCWPO of 2-MT was proposed based on the comprehensive analysis of experimental products.

Theoretical and Experimental Study on Carbodiimide Formation.

Carbodiimides are important crosslinkers in organic synthesis and are used in the isocyanate industry as modifier additives. Therefore, the understanding of their formation is of high importance. In this work, we present a theoretical B3LYP/6-31G(d) and SMD solvent model and experimental investigation of the formation of diphenylcarbodiimide (CDI) from phenyl isocyanate using a phosphorus-based catalyst (MPPO) in ortho-dichlorobenzene (ODCB) solvent. Kinetic experiments were based on the volumetric quantitation of CO2 evolved, at different temperatures between 40 and 80 °C. Based on DFT calculations, we managed to construct a more detailed reaction mechanism compared to previous studies which is supported by experimental results. DFT calculations revealed that the mechanism is composed of two main parts, and the rate determining step of the first part, controlling the CO2 formation, is the first transition state with a 52.9 kJ mol-1 enthalpy barrier. The experimental activation energy was obtained from the Arrhenius plot (ln k vs. 1/T) using the observed second-order kinetics, and the obtained 55.8 ± 2.1 kJ mol-1 was in excellent agreement with the computational one, validating the complete mechanism, giving a better understanding of carbodiimide production from isocyanates.

Manganese-rhodium nanoparticles: Adsorption on titanium oxide surfaces and catalyst for syngas reactions.

Manganese-rhodium (Mn-Rh) nanoparticles have emerged as a promising candidate for catalytic applications in the production of syngas, a critical precursor for a wide range of industrial processes. This study employs a comprehensive, theoretical, and computational approach to investigate the structural and electronic properties of Mn-Rh nanoparticles, with a specific focus on their interaction with titanium oxide (TiO2) surfaces and their potential as catalysts for syngas reactions. The density functional theory calculations are employed to explore the adsorption behavior of Mn-Rh nanoparticles on TiO2 surfaces. By analyzing the adsorption energies, geometries, and electronic structure at the nanoscale interface, we provide valuable insights into the stability and reactivity of Mn-Rh nanoparticles when immobilized on TiO2 supports. Furthermore, the catalytic performance of Mn-Rh nanoparticles in syngas production is thoroughly examined. Through detailed reaction mechanism studies and kinetic analysis, we elucidate the role of Mn and Rh in promoting syngas generation via carbon dioxide reforming and partial oxidation reactions. The findings demonstrate the potential of Mn-Rh nanoparticles as efficient catalysts for these crucial syngas reactions. This research work not only enhances our understanding of the fundamental properties of Mn-Rh nanoparticles but also highlights their application as catalysts for sustainable and industrially significant syngas production.

LES of Premixed Turbulent Combustion Using Filtered Tabulated Chemistry

AbstractThe filtered tabulated chemistry (FTACLES) approach utilizes data from pre-tabulated explicitly filtered 1D flame profiles for closure of the LES-filtered transport terms. Different methodologies are discussed to obtain a suitable progress variable c from detailed chemistry calculations of a methane/air flame. In this context, special focus is placed on the analytical modeling of the reaction source term using series of parameterized Gaussians. For increasing effective filter sizes in LES (i.e. including the flame thickening) the precise shape of the reaction rate profile becomes less and less relevant. In particular, it is shown that for one-step chemistry, a single Gaussian is sufficient to derive an explicitly expressible 1D flame profile with a prescribed laminar flame speed and thermal flame thickness. The resulting artificial flame profile is shown to have similarities with profiles based on carbon chemistry and detailed reaction mechanisms. Next, the behavior of the filtered c-transport equation is analyzed and several possible closure methods are compared for a wide range of filter widths. It is shown that the unclosed contribution of the filtered diffusion term can be combined with the subgrid convection term, thus simplifying the FTACLES formulation. The model is implemented in OpenFOAM and validated in 1D for a variety of LES filter sizes in combination with artificial flame thickening. A power-law-based wrinkling model is modified for use with artificial flame thickening and combined with the FTACLES model to enable 3D simulations of a premixed turbulent Bunsen burner. The comparison of 3D Large Eddy Bunsen flame simulations at increasing levels of turbulence intensity shows a good match to experimental results for most investigated cases. In addition, the results are mostly insensitive to the variation of the mesh size.

Enhanced mass transfer by 3D printing to promote the degradation of organic pollutants in electro-Fenton system

In this study, researchers constructed a monolithic 3D-FeO/C electrode with a macro-ordered pore structure using direct-write 3D printing technology. Experimental results showed that the 3D-FeO/C electrode possessed excellent degradation performance for ornidazole (ONZ) (complete degradation within 120 min) and pharmaceutical wastewater (51.13 % in TOC and 63.72 % in COD removal within 420 min). The detailed reaction mechanism of the EF system was revealed through characterization analysis, mass transfer simulation, and experimental results, in which the excellent EF performance is mainly due to the confinement effect of FeO active sites encapsulated in the carbon layer, as well as the enhancement of mass transfer induced by 3D printing macro-ordered structure network. In addition, the degradation pathway of ONZ, the toxicity of its degradation intermediates, and the degradation pathway of actual pharmaceutical wastewater were revealed in detail. This study proposes a new 3D printing method to enhance the mass transfer of electrode materials in EF systems, which has good potential for application to real wastewater.

Pyrolysis mechanistic study on sulfated polysaccharide from marine algal biomass with density functional theory method

Sulfated polysaccharide (SPS) derived from marine algae represents a promising renewable carbon biomass source. Through pyrolysis, SPS can be converted into C5 platform chemicals, including furfural (FF) and 5-methylfurura (5-MF). Understanding the fundamental reaction mechanisms during pyrolysis is essential for the advancing pyrolysis techniques. This work presents a detailed reaction mechanism that reveal new pathways leading to the most important products and intermediates. Simulations focusing on the initial steps in SPS pyrolysis showed that the unimolecular degradation of SPS is dominated by SO3 elimination, with a barrier height of 157.2 kJ/mol; ring-opening and glycosidic bond fission were identified as important competitive reactions, both of which have a barrier height of 207.6 kJ/mol and 260.1 kJ/mol, respectively. The 4,5-unsaturated acyclic rhamnose derived from the glycosidic bond fission of acyclic reducing end group can transform into 5-MF with high selectivity. In addition, the acyclic reducing end group is readily dehydrated to form a 2,3-unsaturated acyclic reducing end group, a reactive unsaturated intermediate. Its decomposition involves an 8-membered ring transition state that requires a low barrier height and results in the formation of a C5 fragment, which can be cyclized directly and dehydrated to form 5-MF. The majority of CO2 is mostly formed by the synergistic breakage of C-Ccarboxyl bonds and glycosidic bonds, with a barrier height of 197.9 kJ/mol. Moreover, a mechanism is uncovered for the formation of formic acid (FA) from a 4,5-unsaturated no-reducing end group. The major pyrolysis channel is initiated by a retro Diels-Alder reaction and followed by a retro-ene reaction to produce a 3,4-unsaturated non-reducing end group, which further decomposes into FA and a new 4,5-unsaturated non-reducing end group.

Reaction Mechanism in Standardized α-Cellulose Content Test: Study from Boehmeria nivea Fiber

In defense industry, α-cellulose is the main component of nitrocellulose propellant. However, a detailed description of the reaction mechanism of each treatment step in SNI 0444-2009 is still very scarce. This study addresses this gap by presenting the reaction mechanisms of each treatment and the symbols used in the SNI 0444-2009 procedure. The separation of lignin from α-cellulose occurred by breaking the C‒O bond linking them. This bond was broken by the ‒OH group of NaOH via a hydrolysis reaction. The reaction was initiated with the elimination of a hydrogen atom from the lignin structure by the hydroxyl ion (‒OH), and the C‒O bond was broken by a hydrolysis reaction. The breaking of this bond was indicated by the disappearance of the IR peaks at wavenumbers 1049 and 1190 cm–1 in the filtrate after extraction. The SNI 0444-2009 method for the α-cellulose content test was carried out by a redox back titration of Cr(VI) with Fe(II) from ferrous ammonium sulfate. This titration was conducted to calculate the amount of Cr(VI) ions in potassium dichromate or Cr(VI) that did not react with lignin or beta cellulose in the filtrate. Understanding the contribution and reaction mechanisms of each compound involved in the SNI 0444-2009 procedure contributed to obtaining accurate data on α-cellulose content. In this study, the calculated α-cellulose content of the flax fiber was 96.75%. Furthermore, the detailed mechanism of the redox reaction was discussed in detail in this paper.

Unraveling the activity trends of T-C2N based Single-Atom catalysts for electrocatalytic nitrate reduction via high-throughput screening

Electrochemical nitrate reduction reaction (NO3RR) offers a cost-effective and environmentally friendly method to simultaneously yield valuable NH3and alleviate NO3−pollution under mild operating conditions.However, this complicated eight-electron reaction suffers from low selectivity and Faradaic efficiency, which highlight the importance of developing efficient catalysts, but still a critical challenge. Here, a theoretical screening is performed on transition metal-tetragonal carbon nitride (TM@T-C2N) as active and selective electrocatalysts for NO3RR, where detailed reaction mechanisms and activity origins are explored. In addition, five-step screening criteria and volcano plots enable fast prescreening among numerous candidates.We identify that V@T-C2N and Cr@T-C2N are promising candidates with low overpotentials and high selectivity and stability. In particular, a significant negative correlation between the adsorption strength ofnitrate and the Gibbs free energy for the last proton-electron coupling step (*NH2→*NH3) was existed, which is considerably advantaged to track the activity trend and reveal the origin of activity. This work provides theoretical insights into the rational design of TM–N4/C catalysts for NO3RR andpaves a valuable electrochemical screening framework for other multi-step reactions.

Optimized global reaction mechanism for H2+NH3+N2 mixtures

Hydrogen and ammonia are playing an increasingly vital role in combustion technologies. Recently, some detailed reaction mechanisms (DRMs) can predict reliable laminar burning velocities (LBVs). Meanwhile, despite their broad applicability in practical combustion engineering, global reaction mechanisms (GRMs) suitable for ammonia and its mixtures with hydrogen or nitrogen have yet to be reported. This study aims to address this gap by investigating new GRMs. Five DRMs were used to calculate the LBVs, and their average values were employed as a reference. First, a single-step GRM was developed for hydrogen (H2 + 0.5O2 → H2O), and another single-step GRM was developed for ammonia (NH3 + 0.75O2 → 0.5N2 + 1.5H2O). However, their combined GRM did not provide reasonable predictions of LBVs for the H2+NH3 mixtures. Therefore, a 4-step GRM was developed consisting of the single-step hydrogen and three additional reactions, i.e., an endothermic ammonia decomposition (NH3 + 0.5O2 → NO + 3H), an exothermic NO reduction (NO + 2H → 0.5N2 + H2O), and an exothermic H recombination (H + H → H2). In conclusion, this 4-step GRM and its revisions could predict reasonable LBVs, flame temperatures, and primary product compositions for mixtures of hydrogen, ammonia, and cracked ammonia gas over a wide range of temperatures (300–600 K) and pressures (1–5 atm).

New insights and reaction mechanisms on ZrO2 (110) surface enhanced catalytic hydrolysis of CFC-12: a density functional theory study.

Freon, a greenhouse gas that contributes to the depletion of the ozone layer, has been the subject of investigation in this study. The catalytic hydrolysis enhancement of CFC-12 by ZrO2 was examined using a density functional theory approach. A detailed reaction mechanism and a new reaction pathway were proposed. The study found that CFC-12 is more likely to be adsorbed on the ZrO2 surface in the CFC-12-TO(F) configuration, while H2O is more likely to be adsorbed on the ZrO2 surface in the H2O-TO(H) configuration. Additionally, H2O replaces CFC-12 on the surface of ZrO2. The hydrolysis of CFC-12 is primarily determined by the first dechlorination process, while the defluorination process is comparatively easier. ZrO2 has a catalytic effect on both dechlorination and defluorination processes, with a more pronounced effect on the former. The production of C-OH bonds is inhibited, which facilitates the dechlorination and defluoridation processes. This work was carried out in the Dmol3 program in the Material Studio 2017, including the geometric structure optimization and energy calculations. The GGA/PBE method was used in this work, along with the DNP basis, spin-polarized set, and DFT-D correction. The possible TSs were guessed based on the linear synchronous transit/quadratic synchronous transit/conjugate gradient (LST/QST/CG) method, and they were further confirmed and reoptimized to ensure that the only one imaginary frequency exists in the TSs.

Thermal decomposition mechanism of lithium methyl carbonate in solid electrolyte interphase layer of lithium-ion battery

To predict the early stages of thermal runaway and improve the safety of lithium-ion batteries, it is necessary to examine the elementary reaction steps for the thermal decomposition of individual solid electrolyte interphase (SEI) components. This study elucidates a detailed decomposition mechanism of lithium methyl carbonate (LMC) which is one of SEI components and accounts for the majority of SEI components formed in commercial electrolytes. The detailed reaction mechanism for the thermal decomposition of LMC is proposed based on the in-situ/ex-situ experiments and density functional theory calculations. LMC underwent six reactions before finally converting to Li2CO3 at 300 °C. To supplement the reliability of the proposed reaction mechanism, the actual gas composition measured using mass spectrometry (MS) are compared with the chain reactions of radicals generated through the thermal decomposition reactions, which is calculated using GRI-MECH 3.0, a gas-phase reaction mechanism. The methodology proposed in this study can be used both for analyzing the reaction mechanisms of different SEI components and their coupling effects with the electrolyte in the future. Understanding these reaction mechanism sets will help us to understand the degradation reactions of real complex SEI and the initial self-heating stage during thermal runaway.

Experimental and Numerical Investigation of Methane/Air and Biogas/Air Coflow Flames in a Confined Coaxial Burner

Abstract The present experimental-cum-numerical work reports three different types of transitions (Type I, Type II, and Type III) observed in the flame topology of non-premixed methane/air and biogas/air coflow flames as the co-annular air Reynolds number (Rea) is varied from zero to maximum limit or till flame blows off/blows out for a given range of fuel Reynolds number (Ref). Type I transition represents the transformation from burner lip-attached flame to lifted flame and then backward propagation towards the burner exit plane as Rea is increased. In Type II transition, the burner lip-attached flame lifts off from the burner exit, stabilizes at a new location, and then extinguishes as Rea is increased. In Type III transition, the burner lip-attached flame directly extinguishes as Rea is increased. RANS-Based 3D numerical simulations are performed to simulate these three types of transitions (Type I, Type II, and Type III) using GRI 2.11 detailed reaction mechanism. Flow turbulence is modeled by employing the standard k−ɛ turbulent model. Flamelet-Generated Manifold (FGM) approach is used as the turbulent-combustion model. To validate the numerical method/models, the numerical temperature profiles have been compared against the experimental temperature measurements as a part of the present work. The numerical results are employed to gain further insights to understand flame–flow interactions.

Parametric Study of Flow and Combustion Characteristic in a Cavitied Scramjet with Multi-Position Injection

This study focuses on the three-dimensional flow and combustion characteristics of a cavitied scramjet engine with multi-position injection. A single-equation large eddy simulation (LES) turbulence model is employed, with a detailed reaction mechanism for hydrogen combustion, as described by Jachimowski. The combustion characteristics of hydrogen in the scramjet combustion chamber are analyzed. Based on the combustion chamber model, the influence of different equivalence ratios, injection timing, injection positions, and injection pressures on the flame formation and propagation process are compared. The results indicate that within a certain range, an increase in the equivalence ratio enhances the combustion intensity and chamber pressure. In the case of multi-position injection, the order of injection from different nozzles has little effect on the final flame stabilization mode and pressure distribution. The opposite-side distribution of nozzles can effectively improve the fuel efficiency and the internal pressure. Furthermore, when the nozzles are closely placed in the opposite-side distribution, the combustion efficiency increases, although this leads to a higher total pressure loss. In scenarios where the fuel injection duration is short, an increase in the injection pressure at the upstream nozzles of the cavity results in a higher local equivalence ratio, as well as reduced fuel mixing and ignition time.

Formation of nanophase metallic iron through charge disproportionation of ferrous iron during micrometeoroid impact‐induced splash melting

AbstractCharge disproportionation of ferrous iron has been considered as one of the mechanisms for the formation of metallic iron on the lunar surface. However, the detailed mechanism of the disproportionation reaction on the Moon is yet to be elucidated. We provide direct evidence for the ferrous disproportionation reaction that produces nano phase metallic iron (npFe0) during a rapid cooling process after splash melting from a lunar sample returned by China's Chang'e‐5 mission. Space weathering processes have resulted in the formation of three distinct zones at the rim of a pyroxene fragment, as observed through transmission electron microscopy. These zones, made up of splashed melts, newly formed melts from the substrate, and the mineral, are distinguished as I, II, and III. Quantitative analyses of the iron valence state by electron energy loss spectroscopy show that disproportionation reactions occurred in zone II at a low temperature of <570°C during a rapid cooling process. The reaction led to the production of α‐structure npFe0 and Fe3+ reserve in the glass phase. The npFe0 produced by the disproportionation reaction has a larger grain size than those formed from solar wind irradiation, implying that micrometeoroid impacts mainly contribute to the darkening of visible and near‐infrared reflectance. These findings reveal a novel rim structure by repeated space weathering and a universal formation mechanism of npFe0 during micrometeoroid impacts, suggesting that the disproportionation reaction could be widespread on airless bodies with impact‐induced splash processes.

Mechanistic Insights into the Excited-State Intramolecular Proton Transfer (ESIPT) Process of 2-(2-Aminophenyl)naphthalene.

The 2-(2-aminophenyl)naphthalene molecule attracted much attention due to excited-state intramolecular proton transfer (ESIPT) from an amino NH2 group to a carbon atom of an adjacent aromatic ring. The ESIPT mechanisms of 2-(2-aminophenyl)naphthalene are still unclear. Herein, the decay pathways of this molecule in vacuum were investigated by combining static electronic structure calculations and nonadiabatic dynamics simulations. The calculations indicated the existence of two stable structures (S0-1 and S0-2) in the S0 and S1 states. For the S0-1 isomer, upon excitation to the Franck-Condon point, the system relaxed to the S1 minimum quickly, and then there exist four decay pathways (two ESIPT ones and two decay channels with C atom pyramidalization). In the ESIPT decay pathways, the system encounters the S1S0-PT-1 or S1S0-PT-2 conical intersection, which funnels the system rapidly to the S0 state. In the other two pathways, the system de-excited from the S1 to the S0 state via the S1S0-1 or S1S0-2 conical intersection. For the S0-2 structure, the decay pathways were similar to those of S0-1. The dynamics simulations showed that 75 and 69% of trajectories experienced the two ESIPT conical intersections for the S0-1 and S0-2 structures, respectively. Our simulations showed that the lifetime of the S1 state of S0-1 (S0-2) is estimated to be 358 (400) fs. Notably, we not only found the detailed reaction mechanism of the system but also found that the different ground-state configurations of this system have little effect on the reaction mechanism in vacuum.

Reactivity and detailed reaction mechanism of quasi‐tetrahedral o‐azophenylboronic acid

AbstractQuasi‐tetrahedral o‐azophenylboronic acid (azoB‐ROH), which contains the protic solvent ROH, is a key species in the colorimetric sensing of saccharides by o‐azophenylboronic acid (azoB). In this study, we compared the reactivity of azoB‐ROH with that of trigonal azoB and tetrahedral o‐azophenylboronate (azoB‐OH−), and clarified the reaction mechanism of azoB‐ROH with cis‐1,2‐cyclopentanediol and D‐glucose. Analysis of the kinetics of the reactions of azoB with cis‐1,2‐cyclopentanediol and D‐glucose in DMSO:water = 1:9 and azoB with cis‐1,2‐cyclopentanediol in tetrahydrofuran containing a small amount of methanol revealed that there was not much difference in the reactivity of azoB‐H2O and azoB‐OH−, although the reactivity of azoB was higher than that of azoB‐MeOH, that is, the reaction mechanism of azoB‐H2O was essentially the same as that of azoB‐OH−.

State-to-state dynamics and machine learning predictions of inelastic and reactive O(3P) + CO(1∑+) collisions relevant to hypersonic flows.

The state-to-state (STS) inelastic energy transfer and O-atom exchange reaction between O and CO(v), as two fundamental processes in non-equilibrium air flow around spacecraft entering Mars' atmosphere, yield the same products and both make significant contributions to the O + CO(v) → O + CO(v') collisions. The inelastic energy transfer competes with the O-atom exchange reaction. The detailed reaction mechanisms of these two elementary processes and their specific contributions to the CO relaxation process are still unclear. To address these concerns, we performed systematic investigations on the 3A' and 3A″ potential energy surfaces (PESs) of CO2 using quasi-classical trajectory (QCT) calculations. Analysis of the collision mechanisms reveals that inelastic collisions have an apparent PES preference (i.e., they tend to occur on the 3A' PES), while reactive collisions do not. Reactive rates decrease significantly when the total collision energy approaches dissociation energy, which differs from the inelastic process. Inelastic rates are generally lower than the reactive rates below ∼10 000K, except for single quantum jumps, whereas the reverse is observed above ∼10 000K. In addition, by combining QCT with convolutional neural networks, we have established neural network (NN)-STS1 (inelastic) and NN-STS2 (reactive) models to generate all possible STS cross sections. The NN-based models accurately reproduce the results calculated from QCT calculations. In this study, all calculations have been focused on analyzing collisions at the ground rotational level.

Effect of key structure parameters of passive pre-chamber on in-cylinder combustion processes and emissions within a gasoline engine

Due to increasingly strict global emission regulations and energy conservation policies, gasoline engines are facing significant challenges. Achieving high efficiency and ultra-low emissions in gasoline engines has become a critical technical challenge that requires attention. Pre-chamber (PC) Turbulent Jet Ignition (TJI) is a highly promising technology for improving thermal efficiency and reducing emissions in gasoline engines. This study employs a three-dimensional flow simulation analysis combined with a detailed chemical reaction mechanism. The investigation is based on eight distinct passive PC structural configurations. The effects of various structural parameters, including the orifice number (ON), orifice axis angle (OAA), orifice diameter (OD), and volume ratio (VR), on the in-cylinder combustion process and emission characteristics are investigated, in which the formation of the fire nucleus and the propagation of the flame are intensively involved. The investigation is conducted under equivalence ratio working condition. Among these, the ITE of the best configuration is relatively 5.46% higher than the baseline engine. The combustion duration decreased by 55.95% to 7.4 °CA compared to the baseline engine, while particulate soot emissions also decreased by 51.22%.

Photogenerated carriers transfer in Pd/TiO2-AgO heterojunction and its photocatalytic behaviors on oxidative dehydrogenation of ethane to ethylene

Photocatalytic oxidative dehydrogenation of ethane to ethylene with a high selectivity is an attractive reaction. In this study, different types of heterojunctions between Pd/TiO2 and a second metal oxide semiconductor were designed and synthesized to realize high activity conversion of C2H6 to C2H4. Pd/TiO2-AgO heterojunction was proved with best reaction performance. The addition of AgO facilitated the activation of reactant molecules. It enhanced directional transfer of electron-hole pairs and separation efficiency of photogenerated carriers. Pd/TiO2-5 % AgO heterojunction was proved with the best separation ability of photogenerated carriers and the largest number of surface hydroxyl groups. Detailed charge transfer path and reaction mechanism were proposed and discussed.