Oxidative Dehydrogenation Of Ethanol Research Articles

H2 from biofuels and carriers: A concerted homo-heterogeneous kinetic model of ethanol partial oxidation and steam reforming on Rh/Al2O3

Investigating bioethanol as a renewable energy source is crucial in the context of H2-based economy. Ethanol partial oxidation and steam reforming on Rh/Al2O3 represent promising processes that have already proved to be highly tangled reacting systems.In this work, a significant step forward has been done towards the development of an engineering tool that can capture all the relevant features of the process; a combined homo-heterogeneous kinetic scheme was developed and validated against experimental data, informative of the catalytic and thermal activation of the C2-alcohol.In particular, a 36-species reduced homogeneous scheme was developed, able to capture observed trends with a limited computational load. On the other side, a macro-kinetic heterogeneous scheme with six molecular reactions (ethanol oxidative dehydrogenation, total oxidation, decomposition, dehydrogenation, steam reforming and acetaldehyde post-reforming) was tuned to accurately describe ethanol/O2 and ethanol/H2O reacting systems.

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

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

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

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

H2 from biofuels and carriers: gas-phase and surface ethanol conversion pathways on Rh/Al2O3 investigated by annular microreactor coupled with Raman and FTIR spectroscopy

Catalytic Partial Oxidation (CPO) and Steam Reforming of ethanol are studied on Rh/Al2O3. The main goal of the work is the development of a comprehensive methodological approach coupling catalytic activity testing and surface characterization, in order to investigate both ethanol-to-H2 conversion pathways and C-deposits formation.Experiments are performed in an annular reactor and four reaction regimes in CPO are identified: ethanol oxidative dehydrogenation to acetaldehyde (T < 200 °C); total oxidation and initial ethanol O2-assisted ethanol decomposition (200 °C < T < 300 °C); early H2 and CO production for reforming of surface CHx fragments (300 °C < T < 500 °C); development of ethanol steam reforming (T > 500 °C).Adsorbed species and C-deposits are characterized via operando FTIR, ex-situ Raman and TPO. These analyses proved that the different reaction regimes are reflected in continuous changes of catalytic surface coverage, passing from the co-existence of ethanol and O2 at low temperature, to wide C-coverage when O2 is consumed. At 700 °C gasification is favoured and promotes surface cleaning.

Activity, Selectivity and Initial Degradation of Iron Molybdate in the Oxidative Dehydrogenation of Ethanol

AbstractIron molybdate catalysts are applied in the industrial FormOx process to produce formaldehyde by oxidative dehydrogenation (ODH) of methanol. Only few studies are available about the applicability of iron molybdate catalysts for the ODH of ethanol to produce acetaldehyde. Herein, an iron molybdate synthesized by co‐precipitation (p) and an iron molybdate prepared by a ball‐milling solid‐state synthesis (bm) are applied as ethanol ODH catalysts. Both materials show attractive acetaldehyde selectivites of &gt;90 % (280 °C: p‐Fe2(MoO4)3: YAcH=90.3 %; bm‐Fe2(MoO4)3: YAcH=60.4 %) and a stable performance. The bulk composition and crystal structure could be confirmed by various characterization techniques and is maintained during ethanol ODH. XPS reveals an enrichment of Mo on the catalyst surface which is slightly decreasing after the catalytic tests. This observation could be a first sign of long‐term deactivation like known from methanol ODH. Comparing the performance of both materials, p‐Fe2(MoO4)3 shows higher activity and aldehyde selectivity. We propose the higher Mo/Fe surface ratio and the lower acidity to be the reasons for these differences.

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO3

AbstractBackgroundAcetaldehyde is a main organic intermediate for manifold chemical products. In the near future, its production using renewable raw materials is rapidly becoming highly desirable. In this paper, investigations on pure and silica‐supported molybdenum oxide (MoO3) as catalysts for the ethanol oxidative dehydrogenation process to acetaldehyde are reported.ResultsAcicular pure α‐MoO3 crystals and silica‐gel supported MoO3 (1, 5 and 12% wtMoO3/wtsupport) were prepared by the thermal decomposition method and by incipient wetness impregnation, respectively. Catalysts were studied and extensively characterized assessing structural, morphological and chemical properties. The samples were tested in ethanol oxidative dehydrogenation through Temperature Programmed Surface Reaction (TPSR) and steady‐state measurements. MoO3/SiO2 samples were constituted by MoO3 particles weakly interacting with the support, but also by some molybdate species entering the silica framework and significantly modifying the silica morphology. High catalyst acidity limits oxydehydrogenation yield, catalyzing the competitive dehydration reaction to ethylene. Thus, the highest obtained acetaldehyde yield was ≈60%. Molybdenum loss by MoO3 volatilization was found on MoO3/SiO2.ConclusionThe produced and characterized catalysts are active, and allow quite a high yield to acetaldehyde. Slight deactivation was observed and also investigated. © 2021 Society of Chemical Industry (SCI).

A study of molybdena catalysts in ethanol oxidation. Part 2. Alumina‐supported and silica‐doped alumina‐supported MoO3

AbstractBACKGROUNDγ‐Al2O3 and silica‐doped aluminas are largely used supports for industrial catalysts. The addition of silica to alumina modifies its acid–base properties, also affecting its dispersion ability of supported species. In this paper, investigations on the silica doping effect in alumina‐supported MoO3 catalysts, developed for the oxidative dehydrogenation process of ethanol to acetaldehyde, are reported.RESULTSMoO3 (1÷12% wtMoO3/wtsupport) supported over pure γ‐Al2O3, SiO2 (1 and 5 wt.%) doped γ‐Al2O3 were prepared by incipient wetness impregnation. Catalysts were studied and extensively characterized structurally, morphologically, and chemically. All samples were tested in ethanol oxidative dehydrogenation in Temperature Programmed Surface Reaction conditions. Best performing catalysts were also tested in steady‐state and time‐on‐stream experiments. At 573 K, the best acetaldehyde yield (60% in steady state conditions) was found on 12 wt.% MoO3 over 1 wt.% SiO2 on alumina. The slight deactivation after 8 h on stream (10% activity loss) is attributed to a limited MoO3 loss by volatilization.CONCLUSIONThe investigated catalysts are active and allow quite a high yield to acetaldehyde. The addition of silica to alumina increases both the conversion of ethanol and the selectivity to acetaldehyde, and reduces MoO3 volatilization, due to the higher activity of monomeric molybdates with respect to polymeric ones. The high acidity of the catalysts limits oxydehydrogenation yield, catalyzing competitive reaction to ethylene. © 2021 Society of Chemical Industry (SCI).

Modification of the properties of γ-alumina as a support for nickel and molybdate catalysts by addition of silica

Commercial pure γ-Al2O3 and SiO2 (1−30 wt.%) doped γ-Al2O3 were characterized as acid catalysts in ethanol conversion and used as supports for NiO and MoO3. Supported catalysts were prepared by incipient wetness impregnation. All catalytic materials were characterized by BET, XRD, FE-SEM microscopy, UV–vis and IR spectroscopies. Pure and silica-doped NiO/Al2O3 materials were used as precursors of metal catalysts for CO2 hydrogenation. Pure and silica-doped MoO3/Al2O3 materials were used as catalysts for ethanol oxidative dehydrogenation to acetaldehyde.These data show that the addition of silica in moderate amounts selectively influences a part of the alumina surface and strongly modifies the dispersing properties of alumina support. In particular, silica preferentially bonds over the strongest Lewis acid-base sites of γ-Al2O3, where also Ni2+ and molybdate species tend to interact. Being the SiO2-Al2O3 interaction stronger than the NiO-Al2O3 interaction and the MoO3-Al2O3 interaction, silica displaces nickel and molybdate species to less preferential sites where their interaction with exposed alumina is weaker. This results in more easily reducible Ni2+ species and larger Ni metal particles for silica doped Ni/Al2O3, and more monomeric and less polymeric molybdate species for silica doped MoO3/Al2O3.

Production of Acetaldehyde via Oxidative Dehydrogenation of Ethanol over AgLi/SiO2 Catalysts

Three AgLi/SiO2 catalysts containing different types of silica supports [small particle size (SPS), medium particle size (MPS) and large particle size (LPS)] were prepared by incipient wetness co-impregnation techniques and tested in oxidative dehydrogenation of ethanol into acetaldehyde. The catalysts were characterized and evaluated by various characterization techniques (e.g. XRD, N2 physisorption, SEM-EDX, UV-Visible spectroscopy, H2-TPR, and CO2-TPD). This study reveals that the catalyst with the best performance is AgLi/SiO2-LPS with a yield in acetaldehyde of 76.8% at 300 °C. The results obtained with the tested catalysts are discussed, and the reasons of performance improvement caused by the presence of the dispersion of active components, the interaction between active components and silica supports, the textural properties of catalysts and reducibility, are raised. Besides, the cooperation of redox properties (Agnδ+ cluster and Ag0) and weak basic density played a pivotal role in promoting the formation of acetaldehyde from ethanol oxidative dehydrogenation. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Oxidative dehydrogenation of ethanol on gold: Combination of kinetic experiments and computation approach to unravel the reaction mechanism

Selective alcohol dehydrogenation on heterogeneous catalysts is a key industrial reaction for production of aldehydes, ketones, and carboxylic compounds. Design of catalysts with improved activity and selectivity requires understanding of the reaction mechanism and kinetics. Herein, experiments, density functional theory (DFT) and kinetic modelling were combined to elucidate the mechanism and kinetics of ethanol oxidative dehydrogenation to acetaldehyde on gold catalysts. Catalytic experiments clearly emphasized the role of oxygen in this reaction. Ethanol conversion was rather independent on the gold cluster size. Formation of minor products, acetic acid and ethyl acetate was structure sensitive as on smaller clusters ethanol is less prone to oxidation reacting more efficiently with acetic acid to ethyl acetate. DFT calculations indicated that the activation of molecular oxygen is facilitated by the hydrogen bond donor e.g., ethanol, leading to hydrogen abstraction from the bond donor and formation of an OOH intermediate followed by its facile dissociation. Furthermore, the calculations show that ethanol oxidation along such pathway is thermodynamically feasible on smooth Au(111) facets. The kinetic model developed based on the concept of ethanol mediated activation of oxygen derived from DFT studies, qualitatively and quantitatively by data fitting reproduces experimental observations on ethanol oxidative dehydrogenation over gold on alumina catalyst. The concentration profiles in the catalyst particle were calculated numerically to evaluate the role of diffusion in the catalyst pores. Combining experiments and DFT with kinetic modelling provides a powerful way to unravel the mechanisms and kinetics of heterogeneous catalytic reactions.

Oxidative dehydrogenation of ethanol over Cu/Mg-Al catalyst derived from hydrotalcite: effect of ethanol concentration and reduction conditions

The copper-modified Mg-Al catalyst (Cu/Mg-Al) was synthesized using the incipient wetness impregnation of copper onto the Mg-Al hydrotalcite derived from co-precipitation method. The effects of copper on the characteristics of catalyst were obtained using several characterization techniques. We found that only copper (I) oxide (CuO) species were obtained on the surface after calcination in air by X-ray Diffraction (XRD). However, the basicity of the base decreases slightly, while the density of the base increases due to the decrease in Brunauer-Emmett-Teller (BET) surface area. We carried out the catalytic activity of the Cu/Mg-Al catalyst in the continuous flow reactor through oxidative dehydrogenation of ethanol. We obtained that the copper enhances the catalytic activity in this reaction, and the ethanol conversion increases with increase in temperature, while the acetaldehyde selectivity decreases because of the decomposition of acetaldehyde to carbon dioxide. The highest acetaldehyde yield of 41.8% was at 350 °C. Moreover, we studied the effects of the ethanol concentration by varying the ethanol feed concentrations (99.9%, 75%, and 50%). The ethanol conversion decreases with a decrease in the ethanol concentration due to the high adsorption of water molecules on the catalyst surface. Thus, the negative effect decreases at higher reaction temperature (350–400 °C). Furthermore, we investigated the effect of the reduction condition of catalyst by varying the reduction temperature (300 and 400 °C). The reduction process affects the catalytic activity. The Cu/Mg-Al was comparatively stable for 10 h upon time-on-stream test. It is used as a promising catalyst in oxidative dehydrogenation of ethanol without any reduction step.

Lithium promotion in ethanol oxidative dehydrogenation over Al- modified Ag/Montmorillonite clays

The oxidative dehydrogenation (ODH) of ethanol over Ag and AgLi catalyst anchored on unmodified and modified (aluminated) montmorillonite (MT) clay was studied. The results indicate that AgLi formulations anchored on aluminated MT were effective for acetaldehyde production, while unmodified formulations favored ethylene production. Characterization studies indicate that the catalyst activity is regulated by the crystalline size of the silver clusters and the amount of weak basic sites present in the support. The synergism observed is rationalized in terms of a Ag re-dispersion mechanism probed through operando and in situ UV–vis analysis.

Oxidative Dehydrogenation of Ethanol over Vanadium- and Molybdenum-modified Mg-Al Mixed Oxide Derived from Hydrotalcite

Hydrotalcite or Mg-Al LDHs were synthesized by co-precipitation method. The Mg-Al mixed oxide was then derived by calcination of hydrotalcite at 450°C. The metal modified catalysts (Mo/Mg-Al and V/Mg-Al) were prepared by incipient wetness impregnation method. The obtained catalysts were characterized by several useful techniques and tested the reactivity for dehydrogenation and oxidative dehydrogenation of ethanol (gas-phase) to produce acetaldehyde. The catalytic reactions were performed at temperature range from 200 to 400°C for both non-oxidative and oxidative atmospheres. The results showed that the vanadium-modified hydrotalcite (V/Mg-Al) exhibited the highest ethanol conversion (34.3%) and acetaldehyde yield (15.5%) at 400℃ in the non-oxidative atmosphere. For the oxidative dehydrogenation of ethanol, the V/Mg-Al catalyst showed the highest activity at 400°C giving the ethanol conversion and acetaldehyde yield of 73.7% and 29.5%, respectively. This result probably related to the highest base density of V/Mg-Al catalyst (6.13 µmol CO2/m2) measured by CO2-TPD. The catalytic activity of Mg-Al catalyst and metal modified catalyst slightly decreased upon time-on-stream test for 10 h on oxidative dehydrogenation of ethanol due to carbon deposition.

Efficient oxidative dehydrogenation of ethanol by VOx@MIL-101: On par with VOx/ZrO2 and much better than MIL-47(V)

The possibility to apply metal organic framework (MOF) based catalysts for oxidation reaction in gas phase was explored. Catalytic activity of the vanadium oxide catalyst incorporated in MIL-101(Cr) as support was investigated in gas phase ethanol oxidative dehydrogenation (EtOH-ODH) and compared to that of MIL-47(V) metal organic framework material containing vanadium as central metal in the framework structure and to a classical VOx/ZrO2 supported vanadium oxide catalyst. It was found that vanadium species, incorporated in MIL-101(Cr) support by a variant of vapor deposition method, are stabilized in the form of well dispersed VOx species (no vanadium pentoxide clusters was detected in the catalyst). The obtained VOx@MIL-101(Cr) catalyst exhibited high selectivity towards acetaldehyde (up to 99%) at reaction temperatures not exceeding 200 °C. The catalytic activity of VOx@MIL-101(Cr) catalyst reached an activity level comparable to that of the classical VOx/ZrO2 catalyst, but the specific productivity of acetaldehyde (3 kgAA kgcat−1 h−1) was higher by 75% compared with productivity on VOx/ZrO2 due to much higher content of vanadium species, which could be hosted by the MOF. On the other hand, MIL-47(V) catalyst exhibited negligible activity seemingly due to coordinatively saturated character of the vanadium centers and/or too high stability of the VIV oxidation state. This proof-of-concept study proved that application of MOF materials as host matrices for heterogeneous catalysts aiming oxidation reaction in gas phase could be efficient as demonstrated on the example of oxidative dehydrogenation of ethanol.

Influence of incorporating a small amount of silica on the catalytic performance of a MoO3/Al2O3 catalyst in ethanol oxidative dehydrogenation

The influence of incorporating a small amount of silica on the catalytic performance of MoO3/Al2O3 catalyst was studied. Molybdenum supported on pure alumina and 5% SiO2-Al2O3 supports were synthesized. The catalysts were characterized by XRD, Raman, UV-Vis and IR spectroscopies, FE-SEM microscopy, and their activity was evaluated in the oxidative dehydrogenation of ethanol to acetaldehyde. Molybdenum supported on pure alumina gives a 74% yield to acetaldehyde (at 573 K) due to the generation of oxy-dehydrogenation active sites by molybdenum and to the decrement of the alumina dehydration sites. For the molybdenum catalyst supported on silica-containing alumina, the molybdenum species were displaced from the strongest alumina’s acid-base couples, located on nanoparticles edges, corners and defects, to weaker ones located on plane faces causing the rise of weakly bonded species with less active redox behavior.

Structural Dynamics of Dispersed Titania During Dehydration and Oxidative Dehydrogenation Studied by In Situ UV Raman Spectroscopy

The structural dynamics of dispersed titania, i.e., silica supported titania, is investigated during dehydration and oxidative dehydrogenation (ODH) of ethanol using optical spectroscopy. UV Raman spectroscopy enabling resonance enhancements proves to be a valuable tool to identify Ti–OH, Ti–O–Si, and Ti–O–Ti groups. Upon dehydration, a transformation of Ti–OH into Ti–O–Si and Ti–O–Ti groups is observed. Two types of Ti–OH vibrations (isolated, geminal) are identified at around 700 and 800 cm− 1 in agreement with theoretical models. Dispersed titania is catalytically active in ethanol ODH with a performance comparable to dispersed vanadia. In situ UV Raman spectra reveal a consumption of Ti–O–Ti, Ti–O–Si, and Ti–OH groups during ethanol adsorption to the titania surface. The presented results are consistent with an ODH reaction mechanism involving a structural transformation of oligomerized or closely neighbored monomeric TiOX structures. The relevance of the proposed mechanism is discussed in the context of other supported transition metal oxide catalysts.

Design of Ag-CeO2/SiO2 catalyst for oxidative dehydrogenation of ethanol: Control of Ag–CeO2 interfacial interaction

Three Ag-CeO2/SiO2 catalysts were prepared by different methods, namely, sequential impregnation, co-impregnation and impregnation of pre-reduced CeO2/SiO2 and are tested in the oxidative dehydrogenation of ethanol. The order of introduction of silver and ceria precursors is found to influence the catalytic activity that increases in the order of preparation method: sequential impregnation < co-impregnation < impregnation of pre-reduced CeO2/SiO2. Results of TPR-H2, TEM HR, XPS and Raman characterizations show the best interfacial Ag–CeO2 interaction and highest defectiveness of CeO2 nanoparticles in the catalyst prepared by impregnation of pre-reduced CeO2/SiO2. A correlation between Ag–CeO2 interaction and catalytic activity is found in the series of Ag-CeO2/SiO2 catalysts depending on the preparation method. Enhanced Ag–CeO2 interfacial interaction leads to increased activity in oxidative dehydrogenation of ethanol.

VOx/Zr–SBA-15 catalysts for selective oxidation of ethanol to acetaldehyde

Effect of zirconium presence in the silica framework and content and speciation of vanadium surface oxo-complexes on the catalytic behavior of VOx/Zr–SBA-15 catalysts in oxidative dehydrogenation of ethanol was investigated. Experimental results bring evidence of successful incorporation of zirconium into ordered mesoporous silica framework with the preservation of ordered mesoporosity by hydrothermal template base synthesis method. The presence of zirconium in the SBA-15 framework increases reducibility of vanadium species and acidity of the catalysts. It is reflected in higher activity of vanadium species expressed as turn-over frequency (e.g., TOF of 20 h−1 for 5%VOx/Zr–SBA-15 sample in comparison with TOF of 12 h−1 for 5%VOx/SBA-15 sample) and also in significant decrease of selectivity to acetaldehyde (65% in comparison with 90% for mentioned samples) followed by increase in selectivity to ethylene (25% in comparison with 5%). This change in distribution of reaction products is related to stronger acidity character of surface OH groups and inhibition effect of formed water vapours on the oxidative dehydrogenation products (acetaldehyde). Catalytic data also reveal that oligomeric/polymeric tetrahedrally coordinated vanadium species exhibit higher activity in ethanol oxidative dehydrogenation than monomeric complexes. In addition, comparison of the catalytic performance of VOx/Zr–SBA-15 catalysts with VOx/SBA-15 catalysts showed that catalytic properties of VOx/Zr–SBA-15 catalysts can be tuned by incorporation of controlled amount of zirconium into silica framework.

Effect of the metal−support interaction in Ag/CeO2 catalysts on their activity in ethanol oxidation

The interaction of silver with the surface of CeO2 in the Ag/CeO2 catalysts prepared by coprecipitation and impregnation techniques was studied by temperature-programmed reduction, X-ray diffraction, and high-resolution transmission electron microscopy. It was shown that coprecipitation technique led to formation of strong silver–support interaction and the epitaxy of silver particles (d 111 = 2.35 A) on the surface of CeO2 (d 111 = 3.1 A). This provided incresed catalytic activity in the oxidative dehydrogenation of ethanol at relatively low temperatures (a 15% conversion of ethanol with 100% selectivity for the formation of acetaldehyde was reached at 85°C). Above 130°C, the deep oxidation of ethanol to CO2 becomes the predominant direction of a catalytic reaction, and the Ag/CеО2 catalyst obtained by impregnation technique was most active in this region as a consequence of the weaker metal–support interaction.

Surfactant templated synthesis of porous VOx-ZrO2 catalysts for ethanol conversion to acetaldehyde

Synthesis of VOx-ZrO2 catalysts with hierarchical porosity is reported here for first time. Surface areas of prepared materials reached values up to 211m2/g with the intrinsic porosity on the border between micro- and mesopores. Physico-chemical properties and catalytic activity in ethanol oxidative dehydrogenation to acetaldehyde of these materials are compared with VOx/ZrO2 catalyst obtained by vanadia deposition on the surface of the already synthesized zirconia support with the hierarchical micro-meso-macroporosity with macrochannels of 200–500nm in size. The VOx/ZrO2 sample prepared by deposition of vanadium on hierarchical zirconia exhibits high catalytic activity (TOF=106.9h−1 at 200°C), and especially high selectivity towards acetaldehyde. Acetaldehyde selectivity under reaction conditions varied between 99 and 92%. Directly synthesized VOx-ZrO2 catalysts showed higher selectivity to acetaldehyde compared to VOx/ZrO2 catalyst obtained by vanadia deposition on the surface of the already synthesized zirconia, but significantly lower activity probably due to incorporation of vanadium during the synthesis inside the channel walls where vanadium is not accessible to the gas molecules.