Pure LaFeO3@C and LaCoO3@C and substituted LaFe1-xCoxO3 and LaCo1-xFexO3 perovskites (x = 0.10; 0.30) were used as catalysts for the liquid-phase oxidation of furfural at 150 °C and 30 bar of O2 pressure. The perovskites were characterized by XRD, H2-TPR, N2 physisorption, TPR-MeOH, and XPS. The carbon in situ incorporation (@C) increases the surface area, favoring oxygen mobility leading to LaFeO3@C stabilizing the redox pair Fe3+/Fe2+. In contrast, no evidence of the formation of a LaCoO3@C perovskite structure through @C incorporation was observed. The gradual substitution of Fe with Co (10 and 30%) in LaFeO3@C decreases the crystallinity, redox and basic properties, and surface area. For LaCoO3@C, after the substitution of Co with 10 and 30% of Fe, only metal (La, Fe, Co) oxides as segregated phases were observed. The highest catalytic activity and selectivity to maleic acid of LaFeO3@C is attributed to the higher surface area, crystalline structure, and surface-reducible Fe3+ species, favoring oxygen mobility and promoting their more oxidizing capacity. The lower catalytic activity of LaCoO3@C, the Co- and Fe-substituted LaFeO3@C and LaCoO3@C catalysts, is attributed to the smaller surface area, and the similar selectivity towards maleic acid, 5-hydroxy-2(5H) and furanone indicates that the active site type is not modified in comparison to LaFeO3@C.

The establishment of a carbon-neutral society is one of humanity's top priorities. However, the inertness of CO2 imposes a barrier to its transformation to distinct added-value products at appreciable reaction rates. Therefore, catalysts with improved properties must be developed. Herein, 0.4 wt% Ru catalysts supported on ZrO2 and La promoted ZrO2 with different La loadings were prepared by wet impregnation and systematically investigated for CO2 methanation. Catalytic testing showed that La incorporation enhanced activity, with 0.4Ru/1.5La-ZrO2 achieving the highest CH4 formation rate, while maintaining 100% CH4 selectivity and stable conversion over 72 h. The structural and surface properties of the catalysts were examined by ex-situ techniques (BET, CO2-TPD, H2-TPR, XPS). Complementary in-situ studies provided mechanistic insights. EPR showed that La stabilized Ru3+ species that were gradually reduced into active Ru0/Ru+ clusters during reaction. In-situ DRIFTS analysis revealed adsorbed CO on Ru sites as the main reaction intermediate, with formates and carbonates acting as spectator species, and demonstrated that 1.5 wt% La optimized intermediate coverage, whereas higher La loadings diminished CO adsorption and surface-accessible Ru. The combined ex-situ and in-situ characterization demonstrated that tuning La loading is important to balance basicity and metal-support interactions, offering a clear design strategy for efficient and stable Ru-based CO2 methanation catalysts.

The selective hydrogenation of the C=O bond over the C=C bond in α,β-unsaturated aldehydes remains a well-known challenge. This work investigates the liquid-phase catalytic transfer hydrogenation of crotonaldehyde to crotyl alcohol over ReOx-based catalysts, using formic acid (FA) as an in situ hydrogen donor. A series of 10 wt% Re catalysts supported on G200, g-C3N4, TiO2, and ZrO2 were synthesized and tested in a batch reactor at 20 bar and temperatures of 140–180 °C. Catalysts were characterized by XRD, BET, NH3-TPD, and XPS to correlate their physicochemical properties with catalytic behavior. Among the studied materials, ReOx/ZrO2 and ReOx/g-C3N4 exhibited the highest crotyl alcohol selectivity above 57% for all reaction temperatures, evaluated at crotonaldehyde conversion of 25%. The nature of the support strongly influenced the dispersion and oxidation state of Re species, as well as the surface acidity, which governed the activation of both the carbonyl group and the FA decomposition. Compared with molecular hydrogen, FA improved both conversion and selectivity due to its superior hydrogen-donating ability in the aqueous phase. These findings demonstrate that tailoring the acid–base characteristics of ReOx catalysts and employing biomass-derived hydrogen donors represent an effective strategy for selective hydrogenation of α,β-unsaturated aldehydes.

Rhenium and copper catalysts supported on high surface area graphite have been studied for the hydrogenation of crotonaldehyde using formic acid and pure hydrogen as hydrogen sources in the gas phase. The resulting catalysts were characterized using various techniques, such as Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and X-ray Photoelectron Spectrosocpy (XPS), Fluorescence TXRF and Temperature programmed surface reaction (TPSR). Catalytic reaction tests were carried out at the temperatures of 140 degrees C and 180 degrees C and ambient pressure, showing good conversion levels for all the catalysts and with remarkable variations in selectivity values. So, with the monometallic rhenium catalyst the desired selectivity to crotyl alcohol when using formic acid is achieved. However, it was unable to carry out such as hydrogenation with pure hydrogen. To better understand these modifications in selectivity depending on the different hydrogen sources, both theoretical and experimental studies of the different surfaces were performed using Density Functional Theory (DFT) and Temperature-Programmed Desorption (TPD). Theoretical studies reveal the different adsorption modes of crotonaldehyde, formic acid and hydrogen depending on the metallic surface centers. Finally, the high conversions obtained with these catalysts confirms the promising future of using alternative molecules, such as formic acid, instead of molecular hydrogen as hydrogenation reactant.

The effect of different supports (SiO2, Al2O3, TiO2, and ZrO2) on nickel phosphide as an active phase in the reductive amination reaction (using aniline and octylamine) for the synthesis of 5-methyl-N-alkyl-2-pyrrolidone was studied. The experiments were conducted at 200 degrees C and 50 bar H-2, using dioxane as the reactive solvent. Various techniques were employed to characterize the catalysts, including N-2 adsorption-desorption, H-2-temperature-programmed reduction (H-2-TPR), X-ray diffraction (XRD), pyridine-FTIR, and X-ray photoelectron spectroscopy (XPS). Firstly, the supports influenced the nickel species present on the surface and the number of acidic sites in each catalyst. Secondly, in the reaction between levulinic acid and aniline, the turnover frequency (TOFM2 -> 5MPanilina ) for 5-methyl-1-phenyl-2-pyrrolidone production followed the order: NiP/Al2O3 > NiP/ZrO2> NiP/SiO2> NiP/TiO2. Regarding the reaction between levulinic acid and 1-octylamine, the TOFL1 -> 5MPoctylamine for 5-methyl-N-octyl-2-pyrrolidone production followed the order: NiP/ZrO2> NiP/Al2O3 > NiP/SiO2> NiP/TiO2. Finally, the supports influenced the type of nickel phosphide species present on the catalyst surface and, consequently, the hydrogenation rate to pyrrolidone molecules.

Formic acid is obtained as a byproduct of biomass pyrolysis and is used as a liquid organic hydrogen carrier due to its low decomposition temperature, enabling hydrogen production under mild conditions with noble metals. The decomposition of FA in the vapor phase using different rhenium phases (metal, carbide, and oxide) supported on graphite and carbon nanotubes was studied within a temperature range of 80–220 °C, in a fixed‐bed reactor with a space velocity of 651 mL gcat h−1. The catalysts were characterized by N2 adsorption–desorption, H2‐temperature‐programmed reduction, transmission electron microscopy, temperature programmed desorption‐ammonia, temperature programmed reaction‐methanol, X‐ray diffraction, and X‐ray photoelectron spectroscopy. Graphite‐supported catalysts achieved higher activity than carbon nanotube‐supported ones, due to the higher rhenium dispersion on graphite. Catalytic reactions revealed that ReC/G exhibited superior performance at lower temperatures per active site, attributed to the rhenium carbide phase. High selectivity toward CO2 was observed across all catalysts, except for ReOx/G at lower temperatures, where differences in active site characteristics likely influenced performance. ReC/G displayed the highest intrinsic activity, highlighting rhenium carbide as a more active phase than metallic or oxide rhenium.

Cross-aldol condensation reaction study using a family of UiO-66 MOFs between benzaldehyde and acetone to produce benzalacetone.

The hydrogenation of 4-(2-furyl)-3-buten-2-one (FAc), derived from biomass through the aldol condensation of furfural and acetone, to obtain jet-fuel precursors and high-value products has been primarily performed using noble metals. In this study, the hydrogenation of FAc was studied using modified catalysts in which aluminum in CuMgAl double-layered hydroxides was partially or fully substituted with cerium (Ce) and zirconium (Zr) to induce oxygen vacancies. These vacancies were introduced to enhance catalytic performance by modifying the hydroxide structure. Characterization techniques, including N2adsorption-desorption, H2-temperature-programmed reduction (TPR-H2), N2O-chemisorption, O2-temperature-programmed desorption (TPD-O2), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were employed to characterize catalysts. The complete substitution of the Al layer with Ce or Zr significantly enhanced activity due to increased oxygen vacancy formation and improved electronic density at copper sites, resulting from variations in electronegativity. A similar product distribution at iso-conversions suggests consistent active sites across catalysts. Additionally, the Ce-and Zr-modified catalysts (CuMgCe and CuMgZr) increased selectivity toward 4-(2-furyl)-butan-2-ol, which subsequently led to the formation of 2-methyl-1,6-dioxaspiro[4,4]nonane through an intermolecular addition reaction was observed at 6 h reaction time.

In this study, we report the synthesis and characterization of MOF-808-SO4-M (M = Zr(IV), Hf(IV)), derived from MOF-808-M precursors. The introduction of sulfate groups enhances the Brønsted acidity of these materials, significantly improving their catalytic performance in the benzaldehyde acetalization reaction. The materials were characterized using powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), nitrogen adsorption-desorption analysis, thermogravimetric analysis (TGA), energy-dispersive spectroscopy (EDS), and Hammett indicator tests. Catalytic evaluation revealed that MOF-808-SO4-Zr exhibited significantly higher conversion compared to its Hf-based analogue, a difference attributed to its greater density of acid sites, as confirmed by temperature-programmed surface reaction (TPSR) analysis. These experimental results were further supported by density functional theory (DFT) calculations, which provided insights into the acidic properties and catalytic behavior of the materials.

This work reviews the application of Analysis of Variance (ANOVA), Design of Experiments (DOE), and Response Surface Methodology (RSM) in heterogeneous catalysis, based on an analysis of recent scientific literature. Heterogeneous catalysis plays a key role in various industries, guiding chemical reactions, optimizing the performance of different processes and/or prioritizing products, and ANOVA, DOE and RSM are valuable tools to understand the intricate relationships between catalyst properties, process variables and reaction responses. This understanding facilitates improvements in catalysts performance and selectivity, thereby optimizing processes. Drawing insights from recent studies, this minireview highlights the different applications of ANOVA-based experimental designs and RSM optimization techniques in catalytic process evaluation. Therefore, this review provides valuable insights into these current statistical methodologies applied to heterogeneous catalysis research, informing the relevance and future directions of the research in the field.

Methanol is considered a key and platform compound to produce high value-added chemicals, and it could contribute to energy transition, decreasing the dependence of fossil fuels. This paper presents a methanol synthesis simulation over a commercial Cu/ZnO/Al2O3, which is used at industrial scale. With the aim of exploring renewable raw materials as alternative to synthesize this alcohol, synthesis gas was obtained as a starting mixture from gasification of residual coffee pulp, which is an agro-industrial waste widely generated in coffee producing countries. Currently, the raw materials most used to obtain methanol are natural gas and coal, so the use of agro-industrial waste as a raw material would achieve greener methanol production. Design of experiments and ANOVA were applied to obtain results with statistical significance. Residual coffee pulp gasification conditions and reaction temperature were the controlled variables, while methanol production was selected as a response one. The simulation runs and ANOVA were analyzed and compared with the literature reports, and it was observed that methanol production is possible avoiding the catalyst deactivation. For the best obtained conditions, the profiles along the reactor of chemical species molar fraction, stochiometric number, methanol production and pressure drop were shown.

Salicylic acid as a cobalt-based catalyst modifier enhances the activity with increased selectivity towards cyclohexanol. This is linked to changes induced by the modifier over the cobalt surface, allowing for tuning of the catalytic activity.

4-(2-furyl)-3-buten-2-one (FAc) is obtained by aldol condensation of furfural and acetone and has been used in hydrodeoxygenation reactions to obtain fuel products using noble metal catalysts. The hydrogenation of FAc in the aqueous phase using metallic- and Re oxide-supported catalysts on graphite was studied, within a temperature range of 200–240 °C, in a batch reactor over a 6 h reaction period. The catalysts were characterized using N2 adsorption–desorption, TPR-H2, TPD-NH3, XRD, and XPS analyses. Catalytic reactions revealed that metallic rhenium and rhenium oxide-supported catalysts are active for the hydrogenation and Piancatelli rearrangement of FAc. Notably, metallic rhenium exhibited a fourfold higher initial rate than rhenium oxide, which was attributed to the higher dispersion of Re in the Re/G catalyst over graphite. Re/G and ReOx/G catalysts tended to rearrange and hydrogenate FAc to 2-(2-oxopropyl)cyclopenta-1-one in water.

Mono-and bimetallic UiO-66 nanocatalysts were synthesized using the solvothermal synthesis method and evaluated in the aldol condensation reaction of benzaldehyde and acetone in a batch reactor. N2 physisorption, thermogravimetric analysis, temperature-programmed desorption of ammonia, X-ray diffraction, field-emission scanning electron microscopy-energy-disper-sive X-ray, X-ray photoelectron spectroscopy, potentiometric titration, and Fourier transform infrared were used to characterize the nanocatalysts. The higher activity exhibited by the Zr/Hf-UiO66 catalyst could be attributed to the lower orbital energy interaction with benzaldehyde, as shown by density functional theory. A synergetic effect is observed for the bimetallic UiO-66 nanocatalyst between Zr and Hf, obtaining a higher reaction rate than the monometallic nanocatalysts. Meanwhile, this antagonistic effect was shown in the bimetallic catalysts between Zr and Ce, which was less active than the monometallic UiO-66 catalyst due to free COOH generated during the synthesis. Finally, the selectivity results showed that incorporating Hf and Ce on Zr-UiO-66 favors benzalacetone formation by cross-coupling condensation of benzaldehyde and acetone at isoconversion conditions.

The effect of the choice of carbon support (activated carbon, carbon nanofiber, graphite, and multiwalled carbon nanotube) on the formation of rhenium carbide was evaluated in the hydrodeoxygenation of guaiacol, a pyrolysis oil model compound. Catalysts were prepared by incipient wetness impregnation, carburized at 650ºC under a 25/75 mixture of ethylene/hydrogen, and characterized by XRD, N2-physisorption, TPD, TPR, NH3-TPD, and XPS. The characterization results gave evidence that the choice of support affected the carburization of rhenium, a likely consequence of the nature of oxygen function groups on the supports. Indeed, poor carburization of Re occurred over the carbon nanofiber support, which was rationalized by a lack of carboxylic groups on the support. The study showed that the sites mainly responsible for converting guaiacol could be identified by quantification of CH4 mass signals during TPR measurements. This is an important finding to unravel the critical properties responsible for the HDO catalysis of carburized Re. Most of the catalysts were effective at converting guaiacol to phenol and a few, especially Re/MWCNT-O+ and Re/HSAG, were active for the hydrogenolysis of phenol to benzene (with benzene selectivity reaching 50% at guaiacol conversion of 98%). This indicates that this class of catalysts show great promise in converting guaiacol to desirable aromatic hydrocarbons.

Bifunctional materials based on Ru nanoparticles and an alkaline metal (K, Na or Ba) have been scrutinized for several cycles of CO2 capture and subsequent methanation at different temperatures from 250 ºC to 450 ºC. The optimum performance in terms of stable cyclic operation, amount of captured CO2 and relevant methane productivity was attained at different temperature window for each material. For the materials here prepared, the limiting lower operation temperature of stable cyclic performance was determined by the methanation kinetics, which depended on reactivity of COx ad-species captured with each alkaline metal. The highest activity was found with Ba-containing materials, which exhibited a stable and relevant cyclic CH4 productivity at 250 ºC, being one of the lowest operation temperatures reported for a dual functional material to date. This material exhibited stable cyclic performance also in the presence of O2 and H2O, although the CH4 productivity decreases slightly and reversibly compared to that using CO2 containing gas free of O2 and H2O.

Catalytic hydrodeoxygenation (HDO) is a critical technique for upgrading biomass derivatives to deoxygenated fuels or other high-value compounds. Phenol, guaiacol, anisole, p-cresol, m-cresol and vanillin are all monomeric phenolics produced from lignin. Guaiacol is often utilised as a model lignin compound to deduce mechanistic information about the bio-oil upgrading process. Typically, a source of H2 is supplied as reactant for the HDO reaction. However, the H2 supply, due to the high cost of production and additional safety precautions needed for storage and transportation, imposes significant economic infeasibilities on the HDO process's scaling up. We investigated a novel H2-free hydrodeoxygenation (HDO) reaction of guaiacol at low temperatures and pressures, using water as both a reaction medium and hydrogen source. A variety of Ni catalysts supported on zirconia/ graphene/with/without nitrogen doping were synthesised and evaluated at 250 degrees C and 300 degrees C in a batch reactor, with the goal of performing a multi-step tandem reaction including water splitting followed by HDO. The catalysts were characterised using H2-TPR, XRD, TEM and XPS to better understand the physicochemical properties and their correlation with catalytic performance of the samples in the HDO process. Indeed, our NiZr2O/Gr-n present the best activity/selectivity balance and it is deemed as a promising catalyst to conduct the H2-free HDO reaction. The catalyst reached commendable conversion levels and selectivity to mono-oxygenated compounds considering the very challenging reaction conditions. This innovative HDO approach provides a new avenue for cost-effective biomass upgrading.

Conversion of 1-butene was studied over Mo carbides and Ni, Co and Mo phosphides, under continuous gas phase operating conditions at atmospheric pressure and 100 degrees C, using 1-butene/helium mixture in a molar ratio of 4:1. The conversion was in the range 30-44% and the values were quite stable except for (1:2)CoP, (1:2)NiP, (1:2) MoP-and MoxC supported catalysts. The main reaction was isomerization of 1-butene, and the selectivity to dimerization was observed in a higher ratio on (1:2)MoP and MoxC supported on high surface area graphite. In situ XRD, XPS, NH3-TPD and thermogravimetry (TG) have been used to assess for the formed species on the surface.

The present study evaluates the effect of heteroatom doping (N and B) and thermal treatment modification of activated carbon, in different sequences over hydrogen storage capacity. All the materials were characterized by N2-physisorption, XRD, TPD, and XPS. H2 adsorption was measured at-196 degrees C and correlated with physico-chemical properties, while a density-functional theory model was employed to analyze the hydrogen adsorp-tion. Results have shown that there is an effect of the modification order on the storage capacity, which was related to increments of the specific surface area or the nature of the functional groups. An optimum nitrogen doping temperature was detected at 500 degrees C and was associated with the presence of pyridone groups. This sample had the highest hydrogen capacity ca. 2.34 % at 0.93 bar. Such value was extrapolated to 7.86 wt% at 30 bar using the Dubinin-Astakhov adsorption model, making it a promising material for hydrogen storage.