Liquid Methanol Research Articles

Ab initio molecular dynamics simulation of methanol and acetonitrile: The effect of van der Waals interactions

We employed PBE and BLYP semi-local functionals and the van der Waals density functional of Dion et al. (2004) (vdW-DF) to investigate structural properties of liquid acetonitrile and methanol. Among those functionals the vdW-DF is the only one that correctly predicts energy minima in inter-molecular interactions between acetonitrile molecules. We found that van der Waals interactions have a negligible effect on H-bonds in methanol chains. However, it significantly increases chain packing resulting in a more dense liquid in comparison to the other two functionals. The overall trend is that the vdW-DF tends to overestimate density and bulk modulus, meanwhile the semi-local functionals tend to underestimate density. Thus, van der Waals interactions play an important role in the properties of liquids in which much stronger dipole-dipole interactions are present.

Ethanol and Methanol Burn Risks in the Home Environment.

Biofuel heaters and fireplaces have in recent years been introduced for indoor and outdoor use. Due to their simplicity, they are usually equipped with few or no safety features. Worldwide, incidents resulting in major skin burn injury and long hospitalization periods have occurred when using such biofuel units. The present study analyses the characteristics of the liquids ethanol and methanol to get a scientific background for understanding related accidents. The comparably heavy vapors, especially from ethanol, may generate a pillow of combustible gas in the vicinity of the unit, particularly in quiescent indoor air conditions. It is also revealed that these fuels represent a potential severe risk, since the equilibrium vapor pressures are close to the stoichiometric fuel–air composition at normal room temperatures. Selected incidents were reviewed to understand the mechanisms involved when severe burns were received by the users. It turns out that the most severe incidents were related to refilling operations and included ignition of the fuel container vapor phase. When ignited, the container gas phase expansion propelled burning fuel from the bottle or container onto the user or other persons in the vicinity. Similar incidents involving refilling methanol for chemistry demonstrations and ethanol for endodontic (dentistry) treatment were also studied and it was shown that these accidents followed similar accident mechanisms. It may be concluded that the main contributors to burn risk are the near-stoichiometric vapor pressure of these liquids at room temperature and the close proximity of the fuel container to burning fuel. Research needs and possible technical barriers are suggested to reduce this risk for the future.

Liquid media regulated growth of cinnamon nanoparticles: Absorption and emission traits

Customized cinnamon-based nanostructures are of great demand for broad arrays of nanomedical, biomedical and photocatalytic purposes. Conventional methods for cinnamon nanomaterials production with desirable optical absorption and emission properties are still limited. This communication elucidates the role of growth media (liquid ethanol and methanol) in controlling the optical qualities of cinnamon nanoparticles (CNPs). Such CNPs of varied morphologies were prepared using pulsed laser ablation in liquid (PLAL) technique (a simple, an inexpensive, and an eco-friendly approach). In the PLAL process, clean cinnamon sticks (as target material purchased from supermarket) were ablated via Q-switched Nd:YAG laser pulse of wavelength 532 nm operated at optimum fluence of 5.73 J/cm2. As-synthesized CNPs were characterized at room temperature using ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) emission spectroscopy. Uniformly dispersed high purity colloidal CNPs with narrow size distribution was achieved. The UV-Vis absorption and the PL spectra of CNPs revealed prominent peaks. These observed distinctive absorption and emission traits of studied CNPs were ascribed to the effects of oxygen deficiency, quantum confinement, crystal defects and existence of cinnamaldehyde compounds. In short, the nucleation and growth of CNPs was significantly sensitive to the chemical character of liquid suspension that provided a favorable thermodynamic condition via entropy driven free energy minimization. It was demonstrated that the structural, morphological, physical, optical properties of such CNPs can be tailored by intuitively selecting the liquid growth media. This disclosure affirmed that the present systematic approach can constitute a basis for the large-scale production of CNPs effective for widespread applications.

Ultrathin wavy Rh nanowires as highly effective electrocatalysts for methanol oxidation reaction with ultrahigh ECSA

Direct methanol fuel cells (DMFCs) have received tremendous research interests because of the facile storage of liquid methanol vs. hydrogen. However, the DMFC today is severely plagued by the poor kinetics and rather high overpotential in methanol oxidation reaction (MOR). Here we report the investigation of the ultrathin Rh wavy nanowires as a highly effective MOR electrocatalyst. We show that ultrathin wavy Rh nanowires can be robustly synthesized with 2–3 nm diameters. Electrochemical studies show a current peak at the potential of 0.61 V vs. reversible hydrogen electrode (RHE), considerably lower than that of Pt based catalysts (~ 0.8–0.9 V vs. RHE). Importantly, with ultrathin diameters and favorable charge transport, the Rh nanowires catalysts exhibit an ultrahigh electrochemically active surface area determined from CO-stripping (ECSACO) of 144.2 m2/g, far exceeding that of the commercial Rh black samples (20 m2/g). Together, the Rh nanowire catalysts deliver a mass activity of 722 mA/mg at 0.61 V, considerably higher than many previously reported electrocatalysts at the same potential. The chronoamperometry studies also demonstrate good stability and CO-tolerance compared with the Rh black control sample, making ultrathin Rh wavy nanowires an attractive electrocatalyst for MOR.

Passive production of synthesis gas from liquid methanol using a packed bed of porous material particles

The passive production of synthesis gas from liquid methanol using a packed bed of porous material particles supporting a catalyst is investigated. Heating of the upper portion of a vertical tube packed with the porous particles where the bottom is immersed in liquid methanol is expected to cause steady upward fluid flow due to capillary action enhanced by evaporation. The emergence of a dry region and a resulting increase in temperature can produce synthesis gas due to catalytic reaction, which then flows out of the top end of the tube. In the proposed process, the capillary force, which is dependent on the local liquid content in the porous bed, is balanced locally with the gravitational force and the viscous forces acting on the liquid and vapor. The distributions of the liquid content, flow rates, pressures, and temperatures of liquid and vapor along the tube axis are calculated using a one-dimensional model based on the mass, force, and energy balances for each phase. The experimental results indicate the validity of the process, that is, the induction of steady fluid flow, the emergence of a dry region, temperature increase to the reaction level, and the products of the reacted gases. The behavior of liquid-vapor flow induced by phase-change in a packed bed and the factors that characterize the process and affect the performance are discussed.

Solubility and Molecular Interactions of Trimetazidine Hydrochloride in 12 Monosolvents and Solvent Mixtures of Methanol + (Ethanol, N,N-Dimethylformamide or Ethyl Acetate)

The solubility of trimetazidine hydrochloride in 12 neat solvents namely ethanol, methanol, isopropyl alcohol, n-propanol, acetone, toluene, 2-butanone, ethyl acetate, n-butanol, acetonitrile, N,N-dimethylformamide (DMF), and 1,4-dioxane and binary liquid mixtures methanol + (ethanol, DMF, or ethyl acetate) was measured using the isothermal method over the temperature range from 278.15 to 323.15 K under local atmospheric pressure of 101.2 kPa. The observed mole fraction solubility was the largest in methanol and smallest in toluene. The experimental data in monosolvents was correlated through the Apelblat equation; while in mixed solvents, by the van’t Hoff–Jouyban–Acree model, Jouyban–Acree model and Apelblat–Jouyban–Acree model. Consequently, for the selected monosolvents, the largest relative average and root-mean-square deviations were 0.79% and 0.227 × 10–4, respectively; and for the binary solvent mixtures, 3.00% and 2.22 × 10–4. Solvent–solvent and solute–solvent interactions were analyzed in the 1...

Hydrogen-bond network in liquid Formamide Methanol mixture as studied by neutron scattering and density functional theory

In this work, a hydrogen-bond network in an equimolar Formamide-Methanol (FA-MeOH) mixture was investigated by means of neutron scattering combined with Density Functional Theory (DFT). Original neutron scattering data were analyzed in order to deduce the structure factor SM(Q) and the intermolecular pair correlation function gL(r). To describe the intermolecular associations in this mixture liquid, different H-bonded clusters: dimer, trimers and tetramer are considered. Our investigation shows that the local order of FA-MeOH mixture is better described by a trimer T1 and tetramer T3 where two FA molecules are connected to one or two methanol molecules. Topological analysis AIM was performed to examine the electronic densities and the strength of hydrogen-bond network involved in the more probable clusters T1 and T3. Good correlations have been obtained between hydrogen bond lengths versus AIM topological parameters like electron density ρ(r) and its correspondent Laplacian ∇2ρ(r) at the bond critical points. Natural Bond Orbital (NBO) analysis was performed in order to explore interactions and charge transfer among different orbitals and lone pairs taking place within the T1 and T3 clusters.

Effects of in-process cryocooling on metallurgical and mechanical properties of friction stir processed Al7075 alloy

Friction stir processing (FSP) of heat treatable aluminum alloys is reported to deteriorate strength and hardness properties in spite of huge grain size refinement. The improvement in strength due to the grain size refinement after FSP could not be able to offset the reduction in strength due to coarsening or dissolution of the strengthening precipitate(s). To overcome this, the present work investigates an effective way of heat rejection from the FSP zone to control the precipitate evolution besides the grain size refinement during FSP of Al7075 alloy. The FSP was carried out with standardized process parameters (i.e. 720 rpm, 65 mm/min traverse speed) under two different cooling environments: (i) at normal air cooling and (ii) by rushing a chilled mixture (−30 °C) of liquid nitrogen and methanol through the bottom of the backing plate. Microstructural evolution was examined through optical, scanning and transmission electron microscopy and electron backscatter diffraction to confirm the grain size and morphology of precipitate(s) formed. The in-process cryocooling during the FSP led to 65 and 72% improvement in the Vickers hardness and tensile strength, respectively, in comparison to the solutionized base metal. The results have been analyzed in terms of precipitate interface characteristics and its strengthening effect, Hall–Petch strengthening due to grain size reduction and tradeoff between them.

Preparation of the Multicomponent High Temperature Proton Exchange Membranes with Layer by Layer Self-assembly Technique

Layer by layer (LBL) self-assembly technique has been proved to be a feasible method that enables to accomplish the preparation of functional membranes with multilayered structure. In this research, the polymer of sulfonated polyetheretherketone (SPEEK) and thioglycolic acid capping of cadmium telluride (CdTe) nanocrystals as polyanion, the polymer of polyurethane (PU) as polycation have been used to prepare membrane electrolytes. These multilayered membranes showed good thermal stability and exhibited low liquid methanol permeability, which provided a possibility for the prepared membranes as proton exchange membranes (PEMs) to apply in direct methanol fuel cells (DMFCs). We have also demonstrated that the multicomponent (SPEEK/PU/CdTe/PU)100 membranes favored to combine more phosphoric acid (PA) molecules and possessed a higher proton conductivity comparing to the bicomponent (SPEEK/PU)210 membranes. So PA doped (SPEEK/PU/CdTe/PU)100 membrane presented a maximum proton conductivity up to 8.6×10-2 S/cm at 160 °C under anhydrous conditions. However, PA doped (SPEEK/PU)210 membranes underwent a drop on proton conductivity while the temperature exceeded 120 °C.

Continuous flow HER and MOR evaluation of a new Pt/Pd/Co nano electrocatalyst

A new protocol of synthesis (e.g. choose of the solvent, precursors and amount and type of reducing agents) has been designed to prepare a Pt/Pd/Co alloy with a desired metals ratio. The stability of the alloy has been monitored after an acidic washing, to remove, if present, unalloyed metals and pre-leach the surface. An excellent combination of performance, e.g. Tafel slope lower than 30 mV/dec and a negligible overpotential, were measured for our Pt/Pd/Co NPs, with an atomic ratio (7:3:3) in a flow system. Very high hydrogen production rate of 7.09 mL cm−2 h−1 at −0.05 V was measured. The electrochemical production of hydrogen from liquid methanol in acidic solution was also investigated. The Pt/Pd/Co NPs exhibit an anodic current density of 560 mA/mgPt during methanol oxidation in acidic solution at 0.45 V and an If/Ib ratio of 1.96. A quantitative evaluation of the performance of the electrode in the two different processes has been made, too.

The hydrogen bonding enthalpies of water and methanol in ionic liquids

The thermochemical study of hydrogen bonding of water with different proton acceptor ionic liquids was carried out. Along with the available experimental data, the solution enthalpies of water in [BMIM][TfO], [BMIM][BF4] and [BMIM][PF6] were measured. The hydrogen bonding enthalpies of water with various ionic liquids were determined by using previously developed method of solvation enthalpy separation into the nonspecific solvation enthalpy and the specific solute-solvent interaction enthalpy (hydrogen bonding). The findings indicate the formation of a complex, where one molecule of water is bound to two molecules of ionic liquids. Similarly, hydrogen bonding enthalpies of methanol with the same proton acceptor ionic liquids were determined.

Comparative analysis of liquid versus vapor-feed passive direct methanol fuel cells

Abstract Passive direct methanol fuel cells (pDMFCs) have several advantages such as high theoretical energy density, quick refueling and environmentally safe. However, methanol crossover (MCO) is one of the major challenges to the commercialization of pDMFCs. Significant progress has been achieved over the last few years in controlling MCO through different approaches, such as applying porous plate, pervaporative membranes, and so forth. These methods are mainly based on supplying methanol to the anode surface in vapor phase. Thus, two types of pDMFCs are available: low methanol concentration (liquid-feed pDMFC) and high methanol concentration (vapor-feed pDMFC). The methanol and water transports are different in these two types of cells. Moreover, under low operating temperature and at high methanol concentration (i.e., above 50 mol%) in the vapor-feed pDMFC, the possibility for chemical intermediate to form increases. Such intermediates not only decrease the efficiency of the cell but are also harmful for the health and the environment. The aim of this review is to highlight and clarify the differences between liquid and vapor-feed pDMFCs. Moreover, the mechanism of intermediates formation in vapor-feed pDMFC and the different approaches to controlling it are presented. Finally, we present recommendations for designing safe and high performance pDMFCs.

The ability of ionic liquids to form hydrogen bonds with organic solutes evaluated by different experimental techniques. Part I. Alkyl substituted imidazolium and sulfonium based ionic liquids

This work is devoted to the quantitative study of hydrogen bond formation of N-alkyl substituted ionic liquids with proton acceptor and proton donor organic solvents. 1-Butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [BMIM][NTf2], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4], 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO], 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], triethylsulfonium bis(trifluoromethylsulfonyl)imide [Et3S][NTf2], 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM], 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF4] were investigated by solution calorimetry and FTIR-spectroscopy techniques. The stretching vibration region of CO group of 2-pentanone in mixture with N-alkyl substituted ionic liquid in inert solvent carbon tetrachloride was analyzed at different concentrations of components for the estimation of proton donor ability of ionic liquids. Also, the stretching vibration region of the OH-group of methanol was studied in a ternary system carbon tetrachloride (inert solvent), methanol (proton donor) and N-alkyl substituted ionic liquid for the estimation of proton acceptor ability of ionic liquids. The hydrogen bond enthalpy of methanol in ionic liquids was calculated using data of measured solution enthalpies and data extracted from the literature. The frequency shifts of the OH-group of methanol induced by intermolecular interactions within ionic liquids in a carbon tetrachloride solution were compared with the hydrogen bonding enthalpies of methanol with ionic liquids. A linear relationship between the frequency shifts of the OH-groups and hydrogen binding enthalpies of methanol in ionic liquids were found. According to measured FTIR-spectroscopy data, the N-alkyl substituted ionic liquids analyzed in this work possess weak proton donor properties, and at the same time their proton acceptor ability (basicity) is much higher and shows dependency on anion structure.

Magnetic Metal-Organic Framework Exhibiting Quick and Selective Solvatochromic Behavior along with Reversible Crystal-to-Amorphous-to-Crystal Transformation.

By utilizing a flexible tetrapyridinate ligand, tetrakis(4-pyridyloxymethylene) methane(L), a novel multifunctional soft porous framework, [Co(NCS)2(L)]·2H2O·CH3OH (1), was constructed. This framework exhibits quick and selective solvatochromic and vapochromic behavior during a reversible crystal-to-amorphous-to-crystal (CAC) transformation. Importantly, the rapid CAC transition can selectively be triggered by methanol molecules, even at low concentrations of liquid or gaseous methanol. This reproducible transition can be monitored by single-crystal and power X-ray analysis, IR, and UV-vis, which all powerfully illustrate the selectivity and sensitivity of this system. In addition, the typical magnetic behavior of single ion magnets (SIMs) has been successfully introduced into this 3D framework, and the modified dynamic relaxations have been investigated via experimental and theoretical analysis. The consistent observations of both experimental and theoretical results support that the distortions of the metal coordination environments should be responsible for the finely tuned SIM behavior.

Special issue: Plasma and Liquids

Special issue: Plasma and Liquids

­­Chemical reaction mechanisms accompanying pulsed electrical discharges in liquid methanol

The primary goal of this study was to explore the fundamental chemical processes occurring during a pulsed electrical discharge in liquid methanol. To this end, advanced analytical techniques were used to identify and, when possible, quantify gas and liquid methanol decomposition products. The effects of applied voltage, voltage polarity, and presence of water on the reaction stoichiometry and the selectivity for the identified gas products were also studied. Density Functional Theory (DFT) simulations were used to determine the most feasible thermal reaction pathways between 300 and 4000 K responsible for the formation of experimentally identified gas and liquid products. From these results, the key chemical reaction pathways were theorized and a reaction mechanism was developed. Gas products of plasma‐induced decomposition of methanol that were detected and quantified include hydrogen, carbon monoxide, carbon dioxide, methane, acetylene, ethylene, and ethane. The reaction selectivity was the highest for the former two compounds regardless of the applied voltage, discharge polarity or presence of water in the starting solution. Results also showed that the applied voltage, discharge polarity and presence of water had no effect on the types of reaction products. Liquid methanol decomposition products that where identified include ethanol, ethylene glycol, formaldehyde, acetic acid, allyl alcohol, 1‐propanol, 3‐buten‐1‐ol, 3‐butyn‐1‐ol, glycolaldehyde, and methyl glycolate. The chemical reaction mechanism that was proposed to explain the formation of the experimentally verified gas products offers specific pathways for the production of carbon monoxide and short‐chained hydrocarbons. In contrast, the reactions leading to the formation of hydrogen, carbon dioxide, and liquid products appear to be random. In general, recombination reactions of direct methanol decomposition products are largely responsible for the formation of C1 and C2 liquid products. Step‐wise reactions of those compounds with single or multiple carbon‐based radicals grow the molecular chain length to up to four carbon atoms thereby producing C4 compounds.

(Invited) Kinetic Characterization of Ir, Pt, and Irpt-Alloy Nanocatalysts for Ammonia Oxidation Reaction

Direct ammonia fuel cells (DAFC) is an attractive alternative of hydrogen fuel cells because of lower cost in storage and distribution of liquid fuel than hydrogen gas. A drawback is the sluggish kinetics of ammonia oxidation reaction (AOR). Based on previous DAFC studies and measurements using rotating disk electrodes (RDEs), Ir, Pt, and IrPt-alloy nanoparticles are considered as the most active AOR catalysts. However, many questions remain open in correlating RDE results obtained at ambient temperature with the catalysts’ performance in DAFC at elevated temperatures. This is due to low sustainable AOR currents at sufficiently low potentials at ambient temperature and complicated temperature effect on AOR kinetics. Here, we report an AOR study using gas diffusion electrode (GDE) in 1 M KOH solution at temperatures up to 60 oC. We kept ammonia concentration constant with time at temperatures higher than the boiling point of ammonia by saturating the solution with argon gas that bubbled through concentrated ammonia before entering the electrochemical cell. Three commercial nanocatalysts, Ir, Pt, and PtIr 1:1 alloy particles with 40 wt% metal on carbon support, were used to establish test protocol and to benchmark the platinum group metal (PGM) mass activity. The three catalysts exhibited distinct kinetic behaviors in terms of onset potential, maximum current, and activity enhancement factor with increasing temperature. Clearly characterized AOR kinetic behavior can be explained using the reaction pathways proposed based on previous DFT calculations. We’ll discuss in detail why Ir has lower onset potential, but lower peak current than Pt does, why temperature enhancement factor is higher for Ir than Pt, what are the inactive intermediates and how catalysts deactivated due to increased coverage of less active AOR intermediates at potentials above and below 0.6 V. New insights can help developing advanced AOR catalysts and making effective DAFCs. The method and concepts developed are generally applicable for studying oxidation of other liquid fuels, such as, methanol and ethanol as their oxidation reactions also involve multiple intermediates and pathways. Acknowledgements This research was funded by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000805 and by the Division of Chemical Sciences, Geosciences and Biosciences Division, US Department of Energy under contract DE-SC0012704.

Sorption-enhanced methanol steam reforming for hydrogen production by combined copper-based catalysts with hydrotalcites

Hydrogen is stored in liquid methanol to ensure safe transportation, and when needed, hydrogen is produced in situ through methanol steam reforming at a relatively low temperature (about 473 K–573 K), which is considered as a significant breakthrough in the storage and transport system of hydrogen energy. To improve methanol conversion, the process intensification technology, called as sorption enhanced methanol steam reforming, is developed, where the configuration between catalyst and sorbent is investigated experimentally in this work. Catalyst is commercial CuO/ZnO/Al2O3 catalyst, and sorbent is K2CO3 promoted hydrotalcite (K-hydrotalcite). Two kinds of packed modes in the reactor are tested and compared with each other, one packed mode with the mixture of catalyst particles and sorbent particles, and the other packed mode with composite sorbent-catalyst particles pelleted with the mixture of catalyst powders and sorbent powders. According to the experimental results, it is found that CO2 adsorption by K-hydrotalcites enhances significantly methanol steam reforming in both packing modes. When combined CuO/ZnO/Al2O3 catalyst with K-hydrotalcite into one-body composite pellet, the methanol conversion reduces due to the loss of catalytic activities under the alkaline atmosphere of K-hydrotalcites. Therefore, attention should be paid on the synergic relationship between catalysts and sorbents for sorption enhanced reaction.

Direct Synthesis of Hydrogen and Dimethoxylmethane from Methanol on Copper/Silica Catalysts with Optimal Cu+/Cu0 Sites

AbstractHydrogen is an important sustainable resource, and here we report a catalytic route for the direct production of hydrogen (with a purity of 95 %) and dimethoxylmethane (DMM) from supercritical methanol over a Cu/SiO2 catalyst prepared by deposition–precipitation with ammonia (DPA) at 240°C in a one‐pot process. The procedure starts with methanol dehydrogenation to hydrogen and formaldehyde at the interface of the Cu2O⋅SiO2–Cu0 particle mixture, and subsequently, the formaldehyde intermediate condenses with substantial methanol to form DMM in the liquid phase. The Cu0, CuO, and chrysocolla species are inactive for hydrogen generation from methanol, and the intrinsic active species for methanol decomposition is the Cu2O⋅SiO2–Cu0 nanoparticle interface, which is produced from the hydrogen reduction of Cu2Si2O5(OH)2 or from the methanol reduction of Cu−O−Si moieties. A correlation between the structure and activity on reduced Cu/SiO2 (DPA) suggested that only Cu0 was not active, but the combined Cu0 and Cu+ sites with interfaces on SiO2 with an optimal Cu+/Cu0 ratio of 1.56 were highly active for methanol dehydrogenation and subsequent condensation steps. The developed new catalytic system offers a facile and atom‐economical way to generate pure hydrogen (almost CO free) from liquid methanol that can be used in fuel cell and hydrogen‐involved biomass reactions.

Preparation of bifunctional Au-Pd/TiO2 catalysts and research on methanol liquid phase one-step oxidation to methyl formate

A series of Au-Pd/TiO2 bifunctional catalysts with different Au, Pd loading percents have been prepared by sol-immobilization method. The related XRD, HR-TEM and XPS characterizations have been undertaken to uderstand the structure of catalysts. Catalytic activity in methanol liquid phase one-step oxidation to methyl formate have been studied in batch reactor. Results show that the nanoparticles are highly dispersed on TiO2 with 6.4 nm mean size. Also, bifunctional catalysts could catalyse the conversion of methanol to methyl formate with high efficiency. With 1wt%Au-1wt%Pd/TiO2 catalysts, when the molar ratio between active components and methanol is 1/2000, the conversion of methanol is 55.7% for 4 h under 100 °C and 25 bar. At the same time, the selectivity of methyl formate is up to 74.2%. The Au-Pd/TiO2 bifunctional catalysts also shows great stability for the reaction with stable conversion and selectivity after 5 cycles.