Catalyst Pretreatment Research Articles

Dynamic Formation of Brønsted Acid Sites over Supported WOx/Pt on SiO2 Inverse Catalysts─Spectroscopy, Probe Chemistry, and Calculations

Platinum-tungsten oxides are among the most studied metal–metal oxide pair catalysts for C–O hydrogenolysis reactions. The Brønsted acid density and synergy between Pt and WOx, especially in the inverse structure, are critical to reactivity and selectivity. However, a clear molecular-level understanding of the formation and dynamics of Brønsted acid sites (BAS) is lacking. Here, using in situ spectroscopic characterizations (Raman and FTIR), chemical probing (CO chemisorption and pyridine titration), density functional theory (DFT) calculations, and a model reaction (tert-butanol dehydration), we demonstrate the structural evolution of WOx species and associated BAS dynamics in various environments. In situ Raman and DFT calculations show that below monolayer coverage, the WOx species stay as isolated monomers on the SiO2 support and W3Ox trimers on Pt. The W3Ox trimers on Pt are dynamic and 10× more active toward dehydration than the WOx species on the SiO2 support. H2 plays a complex role: at low temperatures (<473 K), it creates more BAS in the form of W3O7H on Pt by reversible hydrogen spillover, and at higher temperatures (>573 K), it partially reduces the W3Ox. We further show that the inverse configuration allows changes in the BAS density via catalyst pretreatments. This study provides a strategy for tuning Brønsted acid density and regenerating sites by pretreatment and catalyst composition.

Significantly Improving the Activity of Methane Oxidation over a Pd-based Catalyst for Lean Natural Gas Vehicles by Catalyst Pre-treatment

The activity of methane oxidation on the Pd/10YZ (10 wt.% Yttria-stabilized Zirconia) catalyst was significantly improved by pretreatment with a simulated emission gas mixture. The 90% methane conversion temperature T90 on the pre-treated Pd/10YZ-P was decreased by 49 °C. It was found that the pretreatment increased the content of PdO and active oxygen species on the catalyst surface. Meanwhile, larger crystalline PdO particles were formed after pretreatment. This enhanced the reducing property of the catalyst, resulting in a significant improvement of methane oxidation activity. The simulated exhaust gas pretreatment significantly improved the methane combustion activity of Pd-based catalysts. It is found that the pretreatment increases the content of PdO and active oxygen species on the catalyst surface. In addition, this pretreatment promotes the growth of Pd particles to form crystalline PdO, which is highly active for methane combustion.

Effects of Different Reductive Agents on Zn-Promoted Iron Oxide Phases in the CO2–Fischer–Tropsch to Linear α-Olefins

The pretreatment atmosphere has a significant impact on the performance of iron-based catalysts in carbon dioxide (CO2) hydrogenation. In this study, we investigated the effects of carbon monoxide (CO), syngas (H2/CO), and hydrogen (H2) on the performance of iron-based catalysts during the pretreatment process. To evaluate the structural changes in catalysts after activation and reaction, we analyzed their morphology and particle size, the surface and bulk phase composition, carbon deposition, the desorption of linear α-olefins and reaction intermediates using transmission electron microscope (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Mössbauer spectroscopy (MES), temperature-programmed desorption (TPD), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). Raman and XPS showed that the H2 pretreatment catalyst caused the absence of iron carbides due to the lack of carbon source, and the CO and syngas pretreatment catalysts promoted the formation of carbon deposits and iron carbides. While the bulk phase of the CO and syngas pretreatment catalyst mainly consists of iron carbide (FeCx), XRD and MES revealed that the bulk phase of the H2 pretreatment catalyst primarily consisted of metallic iron (Fe) and iron oxide (FeOx). The composition of the phase is closely associated with its performance at the initial stage of the reaction. The formation of olefins and C5+ products is more encouraged by CO pretreatment catalysts than by H2 and syngas pretreatment catalysts, according to in situ DRIFTS evidence. Ethylene (C2H4)/propylene (C3H6)-TPD indicates that the CO pretreatment catalyst is more favorable for the desorption of olefins which improves the olefins selectivity. Based on the analysis of the TEM images, H2 pretreatment stimulated particle agglomeration and sintering. In conclusion, the results show that the CO-pretreatment catalyst has higher activity due to the inclusion of more FeOX and Fe3C. In particular, the presence of Fe3C was found to be more favorable for the formation of olefins and C5+ hydrocarbons. Furthermore, carbon deposition was relatively mild and more conducive to maintaining the balance of FeOx/FeCx on the catalyst surface.

Synthesis of green solvents from bio-based lactones using heterogeneous copper catalysts

In this paper, the synthesis of green solvents N-alkyl-pyrrolidinones starting from γ-valerolactone using non-noble, supported copper catalysts is proposed. The reaction setup has been improved to limit both harsh conditions and auxiliaries and to avoid any catalyst pretreatment or a too high hydrogen pressure use. A CuO/Al2O3 catalyst with a high dispersion of the metal phase combined with a low Cu nanoparticle size proved to be the best for the process. The catalytic system has proven to be suitable for other lactones such as γ-butyrolactone, γ-caprolactone, ε-caprolactone and dihydrocoumarin.

Design and techno–economic analysis of levulinic acid production process from biomass by using co-product formic acid as a catalyst with minimal waste generation

Levulinic acid (LA) is an essential biomass-derived platform chemical that can be converted into value–added chemicals such as polymers, fertilisers, and pharmaceuticals. However, the high energy demand and cost required in the separation process are significant issues in the LA production process. Recently, formic acid (FA), the co–product in biomass–LA reaction, has been focused on as a catalyst for both biomass pretreatment and LA production. This study designed and numerically simulated a novel process for producing LA from wheat straw (feed rate: 100 kg/h) using an FA aqueous catalyst system (60, 70, and 80 wt%). The reaction data were referred to previous kinetics studies in order to evaluate the feasible reaction time from an economic perspective. The minimised waste generation process was designed by recovering the FA catalyst and using solid residues (lignin and humins) as heat sources. Another byproduct, furfural, was utilised as an extractant for purifying the LA and recovering unreacted products. The minimum selling price (MSP) of the LA and furfural was calculated with an internal rate of return of 6.1% for 20 years. The MSPs were calculated to be 9.59–12.8 USD/kg–products, which was higher than the market price and previous studies. However, the net required energy in this process was − 5.37 to − 32.1 MJ/kg–LA, indicating that the combustion of the solid residue can supply all of the energy required for the process. Our novel concept based on the byproduct utilisation for heat source and extractant can be an effective strategy for an implication of the biorefinery process that can circulate energy with minimum waste generation.

NOx storage and reduction by H2 over highly dispersed Pt on Co1Mg2Al1Ox-LDO for stationary applications: A transient kinetic study

The performance of a highly dispersed Pt/Co1Mg2Al1Ox-LDO catalyst towards NOx-storage and reduction by H2 for NOx control in stationary applications was investigated under forced feed composition cycling (“swing-reactor” system). The influence of 7 vol% CO2 and 5 vol% H2O in the NO-containing and H2-containing feeds on the dynamic evolution of adsorbed NOx-s and their reduction performance (conversion and N2-selectvity) were determined in the 200–400 oC range. The effects of catalyst pretreatment with 20 or 50 ppm SO2/He gas mixture on its NOx-s storage and reduction by hydrogen dynamics were also investigated. Reduction of NOx-s formed on the support involves a hydrogen spillover effect from Pt to the metal-support interface and support NOx-s sites. A very stable NSR performance was obtained at 350 oC for 2 h of successive NOx-adsorption (3 min)/reduction by H2 (1 min) steps. The nature of active and inactive NOx-s in H2 was probed by in-situ DRIFTS.

Efficient co-production of fermentable sugars and biobutanol from corn stover based on a novel butyric acid pretreatment strategy

Efficient deconstruction of lignocellulosic biomass by pretreatment is important for the production of fermentable sugars and biofuels. This study used butyric acid as a novel catalyst for corn stover pretreatment. The effects of butyric acid pretreatments on chemical composition and enzymatic digestibility were systematically investigated. The results indicate that a high linear correlation between xylan removal and fermentable sugars yield (r2 = 0.91) was found. Pretreatment of corn stover with 50 g/L butyric acid at 180 °C for 0.5 h removed 83.17% of xylan and recovered 86.99% of glucan, and fermentable sugars yield of pretreated corn stover reached 97.16%. The physiochemical characterization results show that crystalline index (CrI) of corn stover was increased from 30.13% to 45.04%−48.38% after pretreatments, and the chemical structure and morphological features also exhibited positive changes for enhancing enzymatic hydrolysis. Meanwhile, the liquid fraction of pretreated slurry can be used for recycled pretreatment with 73.81% of fermentable sugars yield after four cycles. Additionally, the residual butyric acid was re-utilized as the co-substrate for Clostridium acetobutylicum ATCC 824 to produce biobutanol via acetone-butanol-ethanol (ABE) fermentation. The final production of butanol and solvents reached 8.38 g/L and 12.63 g/L under an optimized intermittent feeding strategy with a higher butanol/acetone ratio of 2.40 g/g. Overall, this work presents a novel pretreatment strategy to co-produce fermentable sugars and advanced biofuel from abundant lignocellulosic biomass.

Effect of reduction pretreatment on the structure and catalytic performance of Ir-In2O3 catalysts for CO2 hydrogenation to methanol

In2O3 has been found a promising application in CO2 hydrogenation to methanol, which is beneficial to the utilization of CO2. The oxygen vacancy (Ov) site is identified as the catalytic active center of this reaction. However, there remains a great challenge to understand the relations between the state of oxygen species in In2O3 and the catalytic performance for CO2 hydrogenation to methanol. In the present work, we compare the properties of multiple In2O3 and Ir-promoted In2O3 (Ir-In2O3) catalysts with different Ir loadings and after being pretreated under different reduction temperatures. The CO2 conversion rate of Ir-In2O3 is more promoted than that of pure In2O3. With only a small amount of Ir loading, the highly dispersed Ir species on In2O3 increase the concentration of Ov sites and enhance the activity. By finely tuning the catalyst structure, Ir-In2O3 with an Ir loading of 0.16 wt.% and pre-reduction treatment under 300°C exhibits the highest methanol yield of 146 mgCH3OH/(gcat·hr). Characterizations of Raman, electron paramagnetic resonance, X-ray photoelectron spectroscopy, CO2-temperature programmed desorption and CO2-pulse adsorption for the catalysts confirm that more Ov sites can be generated under higher reduction temperature, which will induce a facile CO2 adsorption and desorption cycle. Higher performance for methanol production requires an adequate dynamic balance among the surface oxygen atoms and vacancies, which guides us to find more suitable conditions for catalyst pretreatment and reaction.

Active sites formation of molybdenum oxide catalyst for hydrocarbon conversion

The catalytic properties of molybdenum-alumina systems depend on the synthesis conditions. Herein, we considered the effect of MoO3/Al2O3 catalyst pretreatment conditions on their activity in propylene and propane conversion. MoO3/Al2O3 catalysts were synthesized by wetness impregnation of the support with a solution of molybdenum citrate complex and activated in different atmospheres at 550–590 °С. The maximum conversion of propylene and yields of metathesis products were observed for the sample activated in an inert gas flow. This is caused by the formation of precursors of the metathesis active sites in this sample, i.e. isolated surface monomolybdate species. Activation of the catalyst in hydrogen leads to the reduction of Mo6+ to Mo5+/Mo4+, which ensure the increased activity and selectivity in propane dehydrogenation. Therefore, it was shown that make it possible to purposefully change the properties of the same molybdenum-alumina catalyst to suit the problems of the specific reaction (metathesis, oligomerization, dehydrogenation, aromatization, cracking).

H2 Production by Methane Oxy-Reforming: Effect of Catalyst Pretreatment on the Properties and Activity of Rh-Ce0.5Zr0.5O2 Synthetized by Microemulsion

Green hydrogen introduction in hard-to-abate processes is held back by the cost of substituting steam reforming plants with electrolyzers. However, green hydrogen can be integrated in properly modified reforming processes. The process proposed here involves the substitution of steam reforming with oxy-reforming, which is the coupling of the former with catalytic partial oxidation (CPO), exploiting the pure oxygen coproduced during electrolysis to feed CPO, which allows for better heat exchange thanks to its exothermic nature. With the aim of developing tailored catalysts for the oxy-reforming process, Ce0.5Zr0.5O2 was synthetized by microemulsion and impregnated with Rh. The Ce-based supports were calcined at different temperatures (750 and 900 °C) and the catalysts were reduced at 750 °C or 500 °C. Tuning the calcination temperature allowed for an increase in the support surface area, resulting in well-dispersed Rh species that provided a high reducibility for both the metal active phase and the Ce-based support. This allowed for an increase in methane conversion under different conditions of contact time and pressure and the outperformance of the other catalysts. The higher activity was related to well-dispersed Rh species interacting with the support that provided a high concentration of surface OH* on the Ce-based support and increased methane dissociation. This anticipated the occurrence and the extent of steam reforming over the catalytic bed, producing a smoother thermal profile.

Pretreatment with fermentable and recyclable deep eutectic solvent (DES) for improving resource utilization of biomass

A series of acidic FDES were prepared to pretreat lignocellulose. After pretreatment, solid product containing 82% cellulose, high quality lignin and liquid product containing hemicellulose were obtained, respectively. The enzymatic hydrolysis of the solid product could reach 84.5%. The enzymatic hydrolysate with the was used as feedstock for ethanol fermentation using commercial Saccharomyces cerevisiae live preparation instead of genetically engineered strains that can use 5-carbon sugars. The pretreatment solution was used as a raw material to culture Rhodotorula glutinis for microbial lipid production. phosphoric acid (PA) as a pretreatment catalyst could ensure the enzymatic efficiency compared with other acids, while more polysaccharide fractions could be formed. At the end of fermentation, the biomass could reach 30 g/L, and the lipid concentration could reach 7 g/L. In addition, the lignin prepared in this study has a consistent structure and low molecular weight, showing high potential for bio-based chemicals and materials conversion. According to the results of FDES reutilization, the pretreatment effect and fermentation effect of the FDES prepared here did not decrease significantly with the increase in the reutilization. The biomass pretreatment process developed in this study realized the full utilization of cellulose, hemicellulose, lignin and pretreatment solvent. It is innovative compared with the genetically engineered strain which mainly rely on the co-fermentation of glucose and xylose for cellulosic ethanol fermentation.

Low-temperature CO oxidation by silver nanoparticles in silica aerogel mesoreactors

Low-temperature carbon monoxide (CO) oxidation on silver/silica aerogel (Ag/SiO2 AG) catalyst prepared by one-pot sol–gel synthesis followed by supercritical ethanol drying method is reported. Highly stable and sinter-proof catalyst led to easy reactant diffusion to the active sites. The Ag/SiO2 AG catalyst showed enhanced catalytic activity toward low-temperature CO oxidation by preventing agglomeration of silver nanoparticles inside pores and facilitating well-dispersed active sites to enhance the mass heat transfer in the mesopores. Catalyst pre-treatment conditions were found to play a crucial role in achieving high CO conversion efficiency at low light-off temperatures. Inverse counter-clockwise CO oxidation hysteresis was found to occur after the first run. The active sites contributing to this enhanced catalytic behavior were confirmed to be Ag0 from XPS, XRD, and TEM analysis. The catalyst exhibited good thermal stability up to 450 °C over repeated number of cycles.

Optimization of process parameters at direct liquefaction of waste PETs

Waste polyethylene terephthalate (wPET) was converted to liquid fuel by direct liquefaction method. Additionally, how the catalyst (sodium borohydride) and microwave pre-treatment affect the total conversion and the char yield were investigated. Direct liquefaction experiments were carried out in a batch reactor under non-catalytic/catalytic conditions, and reaction temperature of 325–425 °C, and solid/solvent ratio of ¼, and reaction time of 15–90 min, and microwave pre-treatment time of 3–10 min, and an initial nitrogen pressure of 20 bar. Both the microwave pre-treatment and sodium borohydride (NaBH4) increased the total conversion in the direct liquefaction of wPETs. According to fourier transform infrared spectroscopy (FTIR) and X-Ray diffraction (XRD) analysis of char samples obtained in the direct liquefaction process, the NaBH4 was converted to sodium borate (Na2B8O13). NaBH4 made both hydrogen (H) donating and catalytic effect. The highest total conversion in direct liquefaction of wPETs, which has at the reaction time of 30 min, and the reaction temperature of 400 °C, and in presence of NaBH4, and the microwave pre-treatment of 3 and 8 min, was 62%. The optimum process parameters in direct liquefaction of wPETs are the reaction time of 30 min, and reaction temperature of 400 °C, and the microwave pre-treatment time of 3 min.

Surface Fe clusters promote syngas reaction to oxygenates on Rh catalysts modified by atomic layer deposition

Converting syngas to higher oxygenates is a promising strategy for sustainably producing fuels and chemicals used every day. Rh-based catalysts promoted with metal oxides have long been of interest for oxygenate synthesis, but the role of promoters and the structure of the catalyst during reaction are often not well understood. In this work, we characterize a Rh/SiO2 catalyst modified by Fe2O3 deposited by atomic layer deposition (ALD). We show that Fe2O3 deposits selectively on the Rh nanoparticles and enhances both the turnover frequency and the oxygenate selectivity of the catalysts. A maximum 29% selectivity towards higher oxygenates is achieved with just 1 cycle of Fe2O3 ALD, and we relate the trends in selectivity to the changing availability of surface sites that drive higher alcohol (e.g., ethanol and propanol) formation. Further, we show that the ALD promoter mitigates catalyst sintering, improving the stability of these materials. In-situ X-ray absorption spectroscopy experiments reveal that the Fe2O3 undergoes reduction during the catalyst pretreatment and forms Fe clusters on the surface of the Rh that migrate but remain stable under syngas reaction conditions. We find that modification of the Rh with these surface Fe species is key to the enhanced alcohol production observed in these materials.

Unveiling the effect of metallic and oxidized phases of cobalt on acetone hydrodeoxygenation

The impact of metallic and oxidized phases of cobalt and the nature of different catalytic sites in the gas-phase acetone hydrodeoxygenation were evaluated using Co3O4 nanopowder as catalyst. Mild pretreatments (reduction/oxidation up to 400 °C) were performed to vary the oxidation degree of the catalyst, aiming to favor the selective CO bond cleavage. We found that the Co3O4 nanopowder was not able to deoxygenate acetone at 200 °C, even by halving the acetone weight hourly space velocity (WHSV). At this temperature, only products of hydrogenation (isopropanol) and condensation (mesityl oxide) were obtained. A different selectivity was achieved by the pretreated catalysts. Methane formation was enhanced in the prereduced catalyst whereas isopropanol was the favored product after reoxidizing the catalyst at 400 °C. The best compromise was achieved when the prereduced catalyst was calcined at a lower temperature, 200 °C, achieving about 1:1 CC: CO bond cleavage ratio. The results pointed out the nature of different catalytic sites, and their correlation with the reaction pathways was proposed.

Impact of nanoparticle exsolution on dry reforming of methane: Improving catalytic activity by reductive pre-treatment of perovskite-type catalysts

Nanoparticle exsolution is regarded as a promising alternative to classical catalyst synthesis routes. In this work, we compare the catalytic performance of nanoparticles formed by in-situ exsolution during dry reforming of methane with particles pre-formed by reductive pre-treatment. The experiments were conducted on three perovskite-type oxides. Using a combination of in-situ and operando spectroscopic investigations (x-ray diffraction, near ambient pressure x-ray photoelectron spectroscopy) and the correlation to the obtained catalytic results, we could highlight that pre-formed nanoparticles strongly enhance the activity compared to in-situ exsolution. Scanning electron microscope images recorded after catalytic tests revealed that nanoparticles formed during reductive pre-treatment are bigger on average than particles formed in-situ. Furthermore, B-site doping with Co or Ni significantly enhanced the catalytic activity. Importantly, the perovskite host lattice was stable in all experiments, thus providing the necessary enhanced oxygen surface chemistry which is the key to the coking resistance of the investigated materials. Additionally, we observe a temperature dependent change of mechanism leading to different product ratios.

Dynamical Study of Adsorbate-Induced Restructuring Kinetics in Bimetallic Catalysts Using the PdAu(111) Model System.

Dynamic restructuring of bimetallic catalysts plays a crucial role in their catalytic activity and selectivity. In particular, catalyst pretreatment with species such as carbon monoxide and oxygen has been shown to be an effective strategy for tuning the surface composition and morphology. Mechanistic and kinetic understanding of such restructuring is fundamental to the chemistry and engineering of surface active sites but has remained challenging due to the large structural, chemical, and temporal degrees of freedom. Here, we combine time-resolved temperature-programmed infrared reflection absorption spectroscopy, ab initio thermodynamics, and machine-learning molecular dynamics to uncover previously unidentified timescale and kinetic parameters of in situ restructuring in Pd/Au(111), a highly relevant model system for dilute Pd-in-Au nanoparticle catalysts. The key innovation lies in utilizing CO not only as a chemically sensitive probe of surface Pd but also as an agent that induces restructuring of the surface. Upon annealing in vacuum, as-deposited Pd islands became encapsulated by Au and partially dissolved into the subsurface, leaving behind isolated Pd monomers on the surface. Subsequent exposure to 0.1 mbar CO enabled Pd monomers to repopulate the surface up to 373 K, above which complete Pd dissolution occurred by 473 K, with apparent activation energies of 0.14 and 0.48 eV, respectively. These restructuring processes occurred over the span of ∼1000 s at a given temperature. Such a minute-timescale dynamics not only elucidates the fluxional nature of alloy catalysts but also presents an opportunity to fine-tune the surface under moderate temperature and pressure conditions.

Effect of dry torrefaction pretreatment of the microwave-assisted catalytic pyrolysis of biomass using the machine learning approach

This study employs the Leave-One-Out cross-validation approach to build a machine-learning model using polynomial regression to predict pyro product yield through microwave-assisted pyrolysis of sawdust over KOH catalyst and graphite powder a susceptor. The determination of coefficient (R2) validates the developed models. All the developed models achieved a high prediction accuracy with R2 > 0.93, which signifies that the experimental values are in good agreement with the predicted one. The dependence of the catalyst loading and pretreatment temperature on dominating process parameters such as heating rate, pyrolysis temperature, susceptor thermal energy, and pyro products, namely bio-oil, biochar, and biogas, are explored. The yield of biochar is reduced; however, bio-oil and biogas are enhanced as the catalyst loading increased. On the other hand, increasing the temperature of pretreated sawdust decreased bio-oil and biogas yields while increasing biochar yields. Further, microwave conversion efficiency, and susceptor thermal energy increased with increased catalyst quantity and pretreatment temperatures of sawdust. It was observed that the average heating rate was increased by increasing the catalyst quantity while maintaining the same pyrolysis time until pretreatment temperatures of 150 °C were reached, after which the heating rate dropped due to the continuous microwave energy input to the system.

Facile synthesis of multi-layered nanostructured Ni/CeO2 catalyst plus in-situ pre-treatment for efficient dry reforming of methane

A multi-layered nanostructured Ni/CeO2 catalyst was synthesized through a facile one-pot hydrothermal reaction. The influence of catalyst pre-treatment was investigated as an efficient and easy strategy to improve its catalytic activity. The catalyst exhibited stable above 90% CO2 and 85% CH4 reactant conversions and high product H2/CO ratio (close to 0.95) for DRM at 700 °C for 24 h, with a two-step pre-treatment of the catalyst (H2 reduction followed by CO2 oxidation). This can be ascribed to the multi-layered structure of CeO2 support, enhancing of exposed metal-support interface between Ni and the CeO2 and formation of carbon and oxygen species on the catalyst surface, as indicated by characterizations of H2-TPR, XPS, XRD, FTIR and HAADF-STEM. The simple synthesis and pre-treatment method of such Ni/CeO2 catalyst with high DRM performance offers new opportunities for CeO2 application into DRM reaction as a promising support material.

Effect of support and reduction temperature in the hydrogenation of CO2 over the Cu–Pd bimetallic catalyst with high Cu/Pd ratio

Metal-support interaction and catalyst pretreatment are important for industrial catalysis. This work investigated the effect of supports (SiO2, CeO2, TiO2 and ZrO2) for Cu–Pd catalyst with high Cu/Pd ratio (Cu/Pd = 33.5) regarding catalyst cost, and the reduction temperatures of 350 °C and 550 °C were compared. The activity based on catalyst weight follows the order of Si > Ce > Zr > Ti when reduced at 350 °C. The reduction temperature leads to the surface reconstruction over the SiO2, CeO2 and TiO2 catalysts, while results in phase transition over Cu–Pd/ZrO2. The effect of reduction temperature on catalytic performance is prominent for the SiO2 and ZrO2 supported catalysts but not for the CeO2 and TiO2 ones. Among the investigated catalysts, Zr-350 exhibits the highest methanol yield. This work reveals the importance of the supports and pretreatment conditions on the physical-chemical properties and the catalytic performance of the Cu–Pd bimetallic catalysts.