Catalysts For Methanol Decomposition Research Articles

Impact of preparation methods on the performance of Cu/Ni/Zr catalysts for methanol decomposition

Utilizing waste heat from engine exhausts to decompose methanol into a hydrogen (H2) and carbon monoxide (CO) mixture, subsequently reintroduced into the engine, offers a significant potential to enhance engine efficiency and reduce emissions. The efficacy of the catalyst is crucial, as it directly influences the composition of the decomposition gases, thereby impacting energy conservation and emissions reduction. This study investigates the impact of various preparation methods for the self-developed Cu/Ni/Zr catalyst for methanol hydrogenation decomposition. These techniques include the co-precipitation method, co-impregnation method, and citrate complexation method, evaluated within a temperature spectrum of 220 °C–320 °C. Employing analytical methods such as x-ray Photoelectron Spectroscopy (XPS), x-ray Diffraction (XRD), Thermogravimetric Analysis-Differential Scanning Calorimetry (TGA-DSC), Brunauer–Emmett–Teller (BET), Temperature-Programmed Reduction (TPR), and Scanning Electron Microscopy (SEM) analysis, the study elucidates the mechanism of methanol decomposition catalyzed by Cu/Ni/Zr. The findings indicate that the catalyst’s activity, in terms of decomposition rate and hydrogen content, ranks in descending order from the co-impregnation method, followed by the citrate complexation method, to the co-precipitation method.

Methanol Fueled Low Temperature Solid Oxide Fuel Cell with Pt-SDC Anodes

A low-temperature solid oxide fuel cell (LT-SOFC) is a next-generation energy conversion device and has advantages of high energy efficiency, fast start up and shut down and eco-friendliness. In addition, since it has the advantage of being able to use various fuels such as hydrogen, alcohol, and methane gas, research is being actively conducted in recent years. However, LT-SOFC using hydrogen as a fuel has difficulties in storing and transporting fuel, making it difficult to apply as a portable device. On the other hand, methanol fuel is an attractive alternative fuel because it is easier to transport and store than hydrogen fuel and has a high volumetric energy density. However, when methanol is applied to LT-SOFC, there is a disadvantage in performance due to the complicated oxidation process and CO poisoning. Complex methanol oxidation reaction (MOR) and CO poisoning reduce the performance and durability of fuel cells. Therefore, it is important to use a catalyst that can prevent CO poisoning and improve the oxidation reaction of methanol. Pt is an effective catalyst for methanol decomposition and is one of the materials widely used in direct methanol fuel cell (DMFC). However, there is a problem in that it is vulnerable to CO generated during the methanol oxidation process. It is known that CO is adsorbed on the Pt surface, blocks the active site, and reduces catalytic activity. Therefore, alloying Pt with samaria-doped ceria (SDC) with high oxygen storage capacity (OSC) and good OH generation capacity can be effective to reduce CO poisoning and coking.In this study, we prepared the cells with Pt-SDC cermet anodes with the Pt volume percent of 69 (Pt 0.69), 83 (Pt 0.83), 92 (Pt 0.92), and 95 (Pt 0.95) volume% by varying Pt and SDC powers in the co-sputtering process. In the electrochemical impedance spectroscopy (EIS), ohmic resistance was similar between all samples; on the other hand, activation resistance was measured to be 24.0, 19.5, 31.8, 30.8, and 53.0 Ω∙cm2 at Pt 0.69, Pt 0.83, Pt 0.92, Pt 0.95, and Pt 1 samples, respectively, confirming the lowest activation resistance at Pt 0.83. We speculate that the MOR is improved by the increase of triple phase boundary (TPB) sites and the facilitation of bifunctional CO oxidation mechanisms with higher content of SDC up to 17 mol% (Pt 0.83). However, in the anode with excessive SDC content (31 mol%, Pt 0.69), the Pt is oxidized to form PtO2, lowering the catalytic activity.

Novel Ceria and Ceria-based Nanocomposites as Potential Catalysts for Methanol Decomposition and Total Oxidation of Ethyl Acetate

The focus of our study is the development of novel ceria-based materials that can be successfully used as catalysts in various environmentally friendly processes due to a significant improvement of ceria intrinsic characteristics. In particular, the combination of ceria with low-dimensional carbon materials such as graphene oxide (GO) and nanodiamond (ND) appears as a very promising approach. Actually, the decrease of ceria crystallite sizes deep in the nanoscale have been found to convert them into highly effective destructive adsorbent materials owing to their high surface area, strong adsorbability, and large number of highly reactive sites. Besides, the addition of a nanostructured carbon containing component (nanodiamond or graphene oxide) contributes to both mechanical and catalytic properties of the obtained nanocomposite hybrids. The results show that the novel ceria and ceria-based composite materials significantly outperform the hydrothermally obtained ceria catalyst used for comparison in both activity and selectivity to CO and hydrogen in the methanol decomposition reaction, and in the process of total oxidation of ethyl acetate due to their significantly improved redox behaviour and textural characteristics.

Design Control of Copper-Doped Titania–Zirconia Catalysts for Methanol Decomposition and Total Oxidation of Ethyl Acetate

This study is focused on the design control of Cu–Zr–Ti oxide composites by the variation of the Zr/Ti ratio and the copper deposition procedure used. For the first time, these ternary composites were obtained by a combination of template-assisted hydrothermal techniques for the preparation of mesoporous ZrO2–TiO2 mixed oxides with diverse compositions, followed by the consecutive chemisorption and hydrolysis of copper ammonia complexes on them. The nitrogen physisorption, XRD, SEM, HRTEM, TPR, XPS, UV-Vis, and Raman spectroscopies were applied for the catalysts’ characterization. Methanol decomposition and the total oxidation of ethyl acetate, both of which with potential for sustainable environmental protection, were used as catalytic tests. The complex relationship between the phase composition, structure, and morphology of titania–zirconia mixed oxides and the state and catalytic behavior of the copper oxide species supported on them was investigated. In comparison with the conventional impregnation technique, the novel preparation procedure revealed the generation of more uniform and homogeneously dispersed needle-like copper oxide crystallites in the mesoporous TiO2–ZrO2 host matrix, which typically ensure improved catalytic performance. The synergistic activity between the loaded copper species and TiO2–ZrO2 support was discussed. All ternary composites exhibited superior catalytic activity in total oxidation of ethyl acetate. The specific behavior of the catalysts in methanol decomposition was related to the irreversible phase transformations by the influence of the reaction medium.

Promoting Effect of Ce Doping on the CuZn/ZnAl2O4 Catalysts for Methanol Decomposition to Hydrogen and Carbon Monoxide

Promoting Effect of Ce Doping on the CuZn/ZnAl2O4 Catalysts for Methanol Decomposition to Hydrogen and Carbon Monoxide

Formation of Catalytic Active Sites in Hydrothermally Obtained Binary Ceria-Iron Oxides: Composition and Preparation Effects.

A series of mesoporous cerium-iron binary oxides was prepared by a hydrothermal technique using CTAB as a template. The influence of the Fe/Ce ratio and the variations in the preparation techniques such as the type of solvent and the precipitation agent, the approach of the template release, and the temperature of calcination on the phase composition, textural, structural, surface, and redox properties of the obtained materials was studied in details by XRD, nitrogen physisorption, TPR, FTIR, UV-vis, XPS, Raman, and Moessbauer spectroscopies. The materials were tested as catalysts in methanol decomposition and total oxidation of ethyl acetate. It was assumed that the binary materials represented a complex mixture of differently substituted ceria- and hematite-like phases. Critical assessment of their formation on the base of a common mechanism scheme was proposed. This scheme declares the key role of the formation of shared Ce-O-Fe structures by insertion of Fe3+ in the ceria lattice and further competitive compensation of the lattice charge balance by the existing in the system ions, which could be controlled by the Fe/Ce ratio and the hydrothermal synthesis procedure used. This mechanism provides proper understanding and regulation of the catalytic behavior of cerium-iron oxide composites in methanol decomposition with a potential for hydrogen production and total oxidation of ethyl acetate as a model of VOCs.

Carbon deposition–resistant Ni3Sn nanoparticles with highly stable catalytic activity for methanol decomposition

Ni3Sn intermetallic compound has the potential to serve as a catalyst for methanol decomposition. However, the catalytic stability of Ni3Sn and the resulting mechanism that governs methanol decomposition has not been elucidated thoroughly. Herein, isothermal tests were conducted to probe the methanol decomposition on unsupported Ni3Sn and Ni nanoparticles synthesized by a thermal plasma process. Ni3Sn exhibited higher selectivities for H2 and CO, more stable catalytic activity, and a higher resistance to carbon deposition than Ni. Synchrotron radiation X-ray diffraction and surface analyses revealed the high phase stability of Ni3Sn during methanol decomposition. Density functional theory calculations indicated that methanol decomposition on Ni3Sn surface preferentially proceeded through OH bond cleavage, followed by CH bond cleavage in the produced intermediates. The activation energies of CH3O and CO dissociation were higher on Ni3Sn than that on Ni surface, which was believed to account for the higher selectivity of Ni3Sn toward methanol decomposition.

NixZn1-xFe2O4 modified activated carbons from industrial waste as catalysts for hydrogen production

Abstract This study is aimed at the development of intelligent approach for clean energy production via valorization of industrial waste by-products. The proposed scheme is based on the preparation of activated carbon based catalysts for methanol decomposition as a source of hydrogen. Peach stones from the canning industry and by-products from low-rank coals treatment, all of them widely available in the Balkan region, are used as activated carbon precursors. The specific effect of carbon support on the formation of the loaded active NixZn1-xFe2O4 (x = 0; 0.2; 0.8; 1) ferrite phase are studied by nitrogen physisorption, XRD, HRTEM, FTIR, Moessbauer spectroscopy, TPR with hydrogen and Boehm method. To precise the discussion, analogues KIT-6 silica modifications are used as reference samples. It was found that the hosted in the activated carbon metal containing phase represents a complex mixture of Ni and/or Zn substituted magnetite, NiFe alloys, metallic Fe and ZnO. Its composition and dispersion is controlled by the variation of the Ni/Zn ratio and the texture peculiarities of the carbon support, the latter being easily tuned by the waste precursor used. The NixZn1-xFe2O4 modified activated carbons obtained from peach stones and coal treatment by-products possess a significant potential for sustainable environmental protection as cheap and effective catalysts for hydrogen production.

Synthesis of Cu–Co Catalysts for Methanol Decomposition to Hydrogen Production via Deposition–Precipitation with Urea Method

A series of CuxCoy catalysts were successfully synthesized by deposition–precipitation with urea method and their catalytic performance was investigated for methanol decomposition to hydrogen. These as-prepared samples were characterized by ICP-OES, XRD, SEM, BET, H2-TPR and XPS. The characterization results indicate that the bimetallic catalysts exhibit better dispersion and reducibility as compared with the monometallic catalysts, and the strong interaction between copper and cobalt can promote the formation of Cu+. Among the fabricated materials, the Cu0.5Co0.5 presents the best catalytic activity and H2 selectivity. Moreover, its catalytic performance is higher than the commercial catalyst at the same test conditions. The catalytic performance of bimetallic CuxCoy catalytic is better than that of monometallic catalysts. Meanwhile, the optimized catalyst prepared exhibits excellent catalytic activity and selectivity compared with the commercial catalysts at the same reaction conditions, which is due to the coexist of Cu+ and Cu2+ after reduction.

Morphology and Size Effect of Ceria Nanostructures on the Catalytic Performances of Pd/CeO2 Catalysts for Methanol Decomposition to Syngas

Palladium is an active catalyst for the decomposition of methanol to syngas, and its chemical activity is largely affected by the interaction with the supporting substrate. Nanostructured cerium oxide can establish strong electronic interactions with finely dispersed palladium nanoparticles (NPs) leading to a substantial enhancement of their catalytic performance. To study this synergistic effect and connect it to structural parameters, we deposited Pd NPs on nanostructured cerium oxide particles exposing mainly the same (100) surface, but with different nanoshape and average dimension, and we have investigated their activity toward the methanol decomposition reaction. A systematic comparison of photoemission measurements taken at every step of the catalytic cycle allowed us to identify the most important factors that control the redox properties of the Pd/CeO2 systems and therefore the overall catalytic activity. Capitalizing on this knowledge it was possible to synthesize synergistic nanocatalysts with ...

Activated carbon from Bulgarian peach stones as a support of catalysts for methanol decomposition

This study is aimed at the development of intelligent integrated scheme for full utilization of biomass for clean energy production. The proposed approach includes production of activated carbon based catalysts for methanol decomposition as a source of hydrogen, where both activated carbon and methanol, could be produced from biomass. In order to elucidate the impact of different activated carbon characteristics on the formation of the catalytic active phase, carbons with different texture and surface functionality are purposely obtained by changes in the activation temperature during the carbon preparation and its post-synthetic treatment with nitric acid. Peach stones, widely available in Bulgaria and Balkans region, are chosen as activated carbons precursor. Iron, zinc and ferrite modifications of thus obtained carbons are prepared by incipient wetness impregnation technique and nitrogen physisorption, XRD, HRTEM, UV-Vis, FTIR, Moessbauer spectroscopy, TPR with hydrogen and Boehm method are used for samples characterization. It is established that the state and catalytic activity of the supported metal oxide particles could be easily controlled by the procedure of the activated carbon preparation and this effect strongly depends on the nature of the loaded metal oxide. In case of iron modifications, the increase of the activation temperature during the carbon preparation promotes the formation of more finely dispersed, accessible for the reactants and active in methanol decomposition magnetite particles. The dispersion and the accessibility of the zinc oxide species in zinc modifications are improved by the formation of additional amount of surface acidic groups during the carbon pre-treatment with nitric acid. The combination of lower temperature of carbon activation with nitric acid pre-treatment promotes the formation of highly active ferrite nanoparticles in the binary modifications.

Porosity distribution optimization catalyst for methanol decomposition in solar parabolic trough receiver-reactors by the variational method

Decomposing methanol to hydrogen and carbon monoxide in solar parabolic trough receiver-reactors is a promising way for solar energy utilization, which converts solar energy to chemical energy. Due to the non-uniform boundary heat flux of receivers and the varying concentration of methanol, the porosity distribution of catalyst should be carefully designed to improve the thermochemical reaction performance. In this contribution, we theoretically analyze the relations of such factors as temperature, mass fraction of gas mixture, porosity distribution, and reaction rate, establish a optimization model by adapting the largest conversion rate of methanol as an optimization objective together with such constraints as the continuity equation, the momentum equation, the energy conservation equation, the species equations, and the fixed total mass of catalyst, apply the variational principle to derive the governing equations for optimization of catalyst porosity distribution, and finally take a solar parabolic trough receiver–reactor with methanol decomposition reaction as an example to show the applications. When the surface heat flux as well as the total mass of porous catalyst are given, solving the newly deduced governing equations directly gives the optimal porosity distribution of catalyst under different working conditions. Meanwhile, the optimized non-uniform porosity distribution of catalyst will effectively improve the conversion rate of the methanol, e.g. from 52.3% to 72.3% when E = 40, which provide a guidance for catalyst design to improve the thermochemical reactions performance.

5-1.Cu/ZnO系メタノール分解触媒における第三成分添加の影響(Session 2.5.6 バイオマス・新エネルギー・リサイクル)

5-1.Cu/ZnO系メタノール分解触媒における第三成分添加の影響(Session 2.5.6 バイオマス・新エネルギー・リサイクル)

Catalytic properties of Ni-Fe-Mg alloy nanoparticle catalysts for methanol decomposition

Ni-25Fe and Ni-15Fe-13Mg (at.%) alloy nanoparticles were fabricated by a thermal plasma method, and their catalytic properties for methanol decomposition were examined in the 513–793K temperature range. Both nanoparticles started showing activity for methanol decomposition above 593K, with activity rapidly increasing with temperature. Ni-15Fe-13Mg showed much higher activity and less carbon deposition than Ni-25Fe. These results indicated that the addition of Mg in the Ni-Fe alloy significantly increased the activity, but suppressed carbon deposition. Characterization of the nanoparticles revealed that the Mg was segregated and a thin layer of MgO was formed on the surface of the nanoparticles. It is likely that the formation of MgO suppressed carbon deposition, but enhanced the activity by delaying the coarsening of nanoparticles during the reaction.

Zinc ferrites hosted in activated carbon from waste precursors as catalysts in methanol decomposition

Activated carbons from peach stones and waste polyolefin wax were prepared and tested as a host matrix of nanodispersed zinc ferrite. Nitrogen physisorption, Boehm method, XRD, TPR with hydrogen, FTIR, UV–Vis and Moessbauer spectroscopy were applied to investigate the activated carbon characteristics and the state of loaded on it metal oxide particles. The higher microporosity and lower surface functionality, typical of activated carbon from waste biomass, facilitated the formation of more finely dispersed, located into the micropores iron and zinc oxide nanoparticles. This promoted formation of Zn rich ferrite phase which ensures high catalytic activity in methanol decomposition.

Formation of catalytic active sites in iron modified activated carbons from agriculture residues

Agriculture residues (grape seeds, peach, apricot and olive stones) were used as a precursor of activated carbons with tunable textural characteristics and relatively low surface functionalities (predominantly carbonyl and hydroxyl groups). Thus obtained activated carbons were modified with iron species and tested as catalysts in methanol decomposition. Nitrogen physisorption, XRD, UV–Vis, FTIR, Moessbauer spectroscopy, TPR with hydrogen and Boehm method were applied for complex characterization of the initial activated carbon supports, their iron modifications and the transformations during the catalytic process. The final phase composition and the related with this catalytic activity and selectivity of these materials was considered as a result of complex transformations of active phase by the influence of activated carbon support and reaction medium and this is in close relation with the dispersion and location of iron species into the porous matrix. The decisive role of activated carbon texture characteristics, which is much more significant than the surface functionalities, on the formation of iron catalytic sites is established, and the variation in the nature of the agriculture precursor is assumed as a simple approach for tailoring their properties.

Activated carbon from waste biomass as catalyst support: formation of active phase in copper and cobalt catalysts for methanol decomposition

Activated carbons (AC) from various waste agriculture precursors with different texture and surface characteristics were obtained by different preparation procedures. These AC were used as a host matrix of mono- and bi-component copper and cobalt nanoparticles. The effect of carbon properties on the formation of copper/cobalt phases was studied by Boehm method, XRD, nitrogen physisorption, UV–Vis, FTIR, TPR–TG analysis and methanol decomposition as a catalytic test. The elucidation of activated carbons from waste biomass as catalyst support was based on the comparative study with similar materials supported on mesoporous silica KIT-6. It was demonstrated that contrary to KIT-6, the reduction properties of AC support hinders the formation of spinel CuCo2O4 phase in the bi-component materials, but provides formation of mixture of finely dispersed and highly active and selective in methanol decomposition Cu2O and CoO nanoparticles.

Nanostructured copper-zirconia composites as catalysts for methanol decomposition

Nanostructured mesoporous ZrO2 was obtained by hydrothermal synthesis using surfactant assisted approach. Copper modifications of thus obtained ZrO2 (4–25wt.% copper) were prepared by incipient wetness impregnation with the corresponding nitrate or acetyl acetonate precursors and further treatment in oxidative or reduction atmosphere. The obtained materials were characterized by N2 physisorption, XRD, UV–vis, FTIR, XPS and temperature programmed reduction with hydrogen and tested as catalysts in methanol decomposition to hydrogen and CO. Selected samples were investigated after partial coverage of the surface with 11C-labeled methanol and 11C-labeled methyl formate. The formation of monolayer of finely dispersed copper oxide species on zirconia at about 4wt.% copper loading and bulk copper nanoparticles at higher one is observed. It was assumed that zirconia support provides the formation of two types of catalytic sites: the first ones strongly adsorb methanol and exhibit predominantly dehydrogenation activity, while the others, possess acidic function. The modification of zirconia with copper significantly improves the catalytic activity and selectivity in methanol decomposition via (i) creation of additional surface acidic sites which contribute to generation of methoxy intermediates; (ii) stabilization of Cu2+-Cu+ and Cu+-Cu0 redox pairs where the electron transfer is facilitated by zirconia support and (iii) assisting the recombination and release of hydrogen during the transformation of produced on zirconia surface intermediates.

Cobalt ferrite nanoparticles hosted in activated carbon from renewable sources as catalyst for methanol decomposition

High quality micro-mesoporous activated carbon was prepared from waste bio-mass (peach shells) and used as a host matrix of cobalt ferrite nanoparticles. The obtained materials were characterized by N2 physisorption, XRD, FTIR and Moessbauer spectroscopy and tested as catalysts for hydrogen production from methanol. Depending on the Co/Fe ratio formation of pure CoFe2O4 or a mixture of CoO and ferrite phases were observed for carbon supported bi-component materials, while under the same condition the silica support provides the formation of non-stoichiometric ferrite phase. The catalytic active phase which is formed by the influence of the reaction medium represents a complex mixture of non-changed ferrite, magnetite, Co–Fe alloy and/or Fe3C in different proportions.

Cobalt and iron modified activated carbon from coal tar pitch: preparation and application as catalysts for methanol decomposition

Activated carbons were prepared from waste coal treatment by-products by different preparation and activation procedures and applied as a host matrix of nanodispersed cobalt and iron species. Thus obtained composites were characterized by nitrogen physisorption, XRD, UV–Vis, FTIR, TPR and tested as catalysts in methanol decomposition to hydrogen and CO. It was established that the activated carbon, prepared from waste coal treatment by-products could be successfully used for the preparation of highly active catalysts for methanol decomposition. The facilitated effect of surface functionality decrease on the dispersion and catalytic activity of loaded metal species was demonstrated.