Dry Reforming of Methane on a Highly‐Active Ni‐CeO2 Catalyst: Effects of Metal‐Support Interactions on C−H Bond Breaking

Ni‐CeO₂ is a highly efficient, stable and non‐expensive catalyst for methane dry reforming at relative low temperatures (700 K). The active phase of the catalyst consists of small nanoparticles of nickel dispersed on partially reduced ceria. Experiments of ambient pressure XPS indicate that methane dissociates on Ni/CeO₂ at temperatures as low as 300 K, generating CH_x and CO_x species on the surface of the catalyst. Strong metal–support interactions activate Ni for the dissociation of methane. The results of density‐functional calculations show a drop in the effective barrier for methane activation from 0.9 eV on Ni(111) to only 0.15 eV on Ni/CeO_2?x(111). At 700 K, under methane dry reforming conditions, no signals for adsorbed CH_x or C species are detected in the C 1s XPS region. The reforming of methane proceeds in a clean and efficient way.     

Interaction of Hydrogen with Ceria: Hydroxylation,Reduction, and Hydride Formation on the Surface and in the Bulk

The study reports the first attempt to address the interplay between surface and bulk in hydride formation in ceria (CeO₂) by combining experiment, using surface sensitive and bulk sensitive spectroscopic techniques on the two sample systems, i.e., CeO₂(111) thin films and CeO₂ powders, and theoretical calculations of CeO₂(111) surfaces with oxygen vacancies (O_v) at the surface and in the bulk. We show that, on a stoichiometric CeO₂(111) surface, H₂ dissociates and forms surface hydroxyls (OH). On the pre-reduced CeO_2−x samples, both films and powders, hydroxyls and hydrides (Ce−H) are formed on the surface as well as in the bulk, accompanied by the Ce³⁺ ↔ Ce⁴⁺ redox reaction. As the O_v concentration increases, hydroxyl is destabilized and hydride becomes more stable. Surface hydroxyl is more stable than bulk hydroxyl, whereas bulk hydride is more stable than surface hydride. The surface hydride formation is the kinetically favorable process at relatively low temperatures, and the resulting surface hydride may diffuse into the bulk region and be stabilized therein. At higher temperatures, surface hydroxyls can react to produce water and create additional oxygen vacancies, increasing its concentration, which controls the H₂/CeO₂ interaction. The results demonstrate a large diversity of reaction pathways, which have to be taken into account for better understanding of reactivity of ceria-based catalysts in a hydrogen-rich atmosphere.     

In Situ and Theoretical Studies for the Dissociation of Water on an Active Ni/CeO2 Catalyst: Importance of Strong Metal–Support Interactions for the Cleavage of O–H Bonds

Water dissociation is crucial in many catalytic reactions on oxide‐supported transition‐metal catalysts. Supported by experimental and density‐functional theory results, the effect of the support on O? H bond cleavage activity is elucidated for nickel/ceria systems. Ambient‐pressure O 1s photoemission spectra at low Ni loadings on CeO₂(111) reveal a substantially larger amount of OH groups as compared to the bare support. Computed activation energy barriers for water dissociation show an enhanced reactivity of Ni adatoms on CeO₂(111) compared with pyramidal Ni₄ particles with one Ni atom not in contact with the support, and extended Ni(111) surfaces. At the origin of this support effect is the ability of ceria to stabilize oxidized Ni²⁺ species by accommodating electrons in localized f‐states. The fast dissociation of water on Ni/CeO₂ has a dramatic effect on the activity and stability of this system as a catalyst for the water‐gas shift and ethanol steam reforming reactions.     

Interface-controlled synthesis of CeO2(111) and CeO2(100) and their structural transition on Pt(111)

Ceria-based catalytic materials are known for their crystal-face-dependent catalytic properties. To obtain a molecular-level understanding of their surface chemistry, controlled synthesis of ceria with well-defined surface structures is required. We have thus studied the growth of CeO_x nanostructures (NSs) and thin films on Pt(111). The strong metal-oxide interaction has often been invoked to explain catalytic processes over the Pt/CeO_x catalysts. However, the Pt-CeO_x interaction has not been understood at the atomic level. We show here that the interfacial interaction between Pt and ceria could indeed affect the surface structures of ceria, which could subsequently determine their catalytic chemistry. While ceria on Pt(111) typically exposes the CeO₂(111) surface, we found that the structures of ceria layers with a thickness of three layers or less are highly dynamic and dependent on the annealing temperatures, owing to the electronic interaction between Pt and CeO_x. A two-step kinetically limited growth procedure was used to prepare the ceria film that fully covers the Pt(111) substrate. For a ceria film of ~3–4 monolayer (ML) thickness on Pt(111), annealing in ultrahigh vacuum (UHV) at 1000 K results in a surface of CeO₂ (100), stabilized by a c-Ce₂O₃(100) buffer layer. Further oxidation at 900 K transforms the surface of the CeO₂(100) thin film into a hexagonal CeO₂(111) surface.     

Water Adsorption and Dissociation on Ceria‐Supported Single‐Atom Catalysts: A First‐Principles DFT+U Investigation

Single‐atom catalysts have attracted wide attention owing to their extremely high atom efficiency and activities. In this paper, we applied density functional theory with the inclusion of the on‐site Coulomb interaction (DFT+U) to investigate water adsorption and dissociation on clean CeO₂(111) surfaces and single transition metal atoms (STMAs) adsorbed on the CeO₂(111) surface. It is found that the most stable water configuration is molecular adsorption on the clean CeO₂(111) surface and dissociative adsorption on STMA/CeO₂(111) surfaces, respectively. In addition, our results indicate that the more the electrons that transfer from STMA to the ceria substrate, the stronger the binding energies between the STMA and ceria surfaces. A linear relationship is identified between the water dissociation barriers and the d band centers of STMA, known as the generalized Brønsted–Evans–Polanyi principle. By combining the oxygen spillovers, single‐atom dispersion stabilities, and water dissociation barriers, Zn, Cr, and V are identified as potential candidates for the future design of ceria‐supported single‐atom catalysts for reactions in which the dissociation of water plays an important role, such as the water–gas shift reaction.     

Growth and Electronic Properties of Ag Nanoparticles on Reduced CeO2-x(111) Films

Ag nanoparticles grown on reduced CeO_2-x thin films have been studied by X-ray photoelec-tron spectroscopy and resonant photoelectron spectroscopy of the valence band to understand the effect of oxygen vacancies in the CeO_2-x thin films on the growth and interfacial elec-tronic properties of Ag. Ag grows as three-dimensional particles on the CeO_2-x(111) surface at 300 K. Compared to the fully oxidized ceria substrate surface, Ag favors the growth of smaller particles with a larger particle density on the reduced ceria substrate surface, which can be attributed to the nucleation of Ag on oxygen vacancies. The binding energy of Ag3d increases when the Ag particle size decreases, which is mainly attributed to the final-state screening. The interfacial interaction between Ag and CeO_2-x(111) is weak. The resonant enhancement of the 4f level of Ce³⁺ species in RPES indicates a partial Ce⁴⁺→Ce³⁺ re-duction after Ag deposited on reduced ceria surface. The sintering temperature of Ag on CeO_1.85(111) surface during annealing is a little higher than that of Ag on CeO₂(111) surface, indicating that Ag nanoparticles are more stable on the reduced ceria surface.     

Active Exsolved Metal–Oxide Interfaces in Porous Single-Crystalline Ceria Monoliths for Efficient and Durable CH4/CO2 Reforming

Dry reforming of CH₄/CO₂ provides an attractive route to convert greenhouse gas into syngas; however, the resistance to sintering and coking of catalyst remains a fundamental challenge at high operation temperatures. Here we create active and durable metal–oxide interfaces in porous single-crystalline (PSC) CeO₂ monoliths with in situ exsolved single-crystalline (SC) Ni particles and show efficient dry reforming of CH₄/CO₂ at temperatures as low as 450 °C. We show the excellent and durable performance with ≈20 % of CH₄ conversion and ≈30 % of CO₂ conversion even in a continuous operation of 240 hours. The well-defined active metal–oxide interfaces, created by exsolving SC Ni nanoparticles from PSC Ni_xCe_1?xO₂ to anchor them on PSC CeO₂ scaffolds, prevent nanoparticle sintering and enhance the coking resistance due to the stronger metal–support interactions. Our work would enable an industrially and economically viable path for carbon reclamation, and the technique of creating active and durable metal–oxide interfaces in PSC monoliths could lead to stable catalyst designs for many challenging reactions.     

Infrared spectroscopic study on the reaction mechanism of CO hydrogenation over Pd/CeO2

In situ infrared spectroscopy was applied to elucidate the reaction mechanism of CO hydrogenation over Pd/CeO₂. Instead of direct dissociation of CO, a new reaction pathway is proposed for methane formation, involving geminal dicarbonyl intermediates and (HCO)₂(a) intermediates, which may be located on the surface of Pd covered with thin layers of reduced ceria (SMST effect). Transformation of methane formation sites into methanol formation ones by the oxidation with water vapor formed during the CO-H₂ reaction is proposed, which may be located on the Pd (111) planes adjacent to ceria support.     

A Cobalt(I) Pincer Complex with an η2‐Caryl−H Agostic Bond: Facile C−H Bond Cleavage through Deprotonation,Radical Abstraction,and Oxidative Addition

The synthesis and reactivity of a Co^I pincer complex [Co(ϰ³P,CH,P‐P(CH)P^NMe‐iPr)(CO)₂]⁺ featuring an η²‐ C_aryl−H agostic bond is described. This complex was obtained by protonation of the Co^I complex [Co(PCP^NMe‐iPr)(CO)₂]. The Co^III hydride complex [Co(PCP^NMe‐iPr)(CNtBu)₂(H)]⁺ was obtained upon protonation of [Co(PCP^NMe‐iPr)(CNtBu)₂]. Three ways to cleave the agostic C−H bond are presented. First, owing to the acidity of the agostic proton, treatment with pyridine results in facile deprotonation (C−H bond cleavage) and reformation of [Co(PCP^NMe‐iPr)(CO)₂]. Second, C−H bond cleavage is achieved upon exposure of [Co(ϰ³P,CH,P‐P(CH)P^NMe‐iPr)(CO)₂]⁺ to oxygen or TEMPO to yield the paramagnetic Co^II PCP complex [Co(PCP^NMe‐iPr)(CO)₂]⁺. Finally, replacement of one CO ligand in [Co(ϰ³P,CH,P‐P(CH)P^NMe‐iPr)(CO)₂]⁺ by CNtBu promotes the rapid oxidative addition of the agostic η²‐C_aryl−H bond to give two isomeric hydride complexes of the type [Co(PCP^NMe‐iPr)(CNtBu)(CO)(H)]⁺.     

Structure Sensitivity of CO Oxidation on Co3O4: A DFT Study

The reaction mechanism of CO oxidation on the Co₃O₄ (110) and Co₃O₄ (111) surfaces is investigated by means of spin‐polarized density functional theory (DFT) within the GGA+U framework. Adsorption situation and complete reaction cycles for CO oxidation are clarified. The results indicate that 1) the U value can affect the calculated energetic result significantly, not only the absolute adsorption energy but also the trend in adsorption energy; 2) CO can directly react with surface lattice oxygen atoms (O_2f/O_3f) to form CO₂ via the Mars–van Krevelen reaction mechanism on both (110)‐B and (111)‐B; 3) pre‐adsorbed molecular O₂ can enhance CO oxidation through the channel in which it directly reacts with molecular CO to form CO₂ [O₂(a)+CO(g)→CO₂(g)+O(a)] on (110)‐A/(111)‐A; 4) CO oxidation is a structure‐sensitive reaction, and the activation energy of CO oxidation follows the order of Co₃O₄ (111)‐A(0.78 eV)>Co₃O₄ (111)‐B (0.68 eV)>Co₃O₄ (110)‐A (0.51 eV)>Co₃O₄ (110)‐B (0.41 eV), that is, the (110) surface shows higher reactivity for CO oxidation than the (111) surface; 5) in addition to the O_2f, it was also found that Co³⁺ is more active than Co²⁺, so both O_2f and Co³⁺ control the catalytic activity of CO oxidation on Co₃O₄, as opposed to a previous DFT study which concluded that either Co³⁺ or O_2f is the active site.     

A novel two‐dimensional cobalt(II) complex composed of one‐dimensional twisted pair‐like chains: poly[[tetraaquabis(μ3‐pyridine‐2,5‐dicarboxylato‐κ4N,O2:O5:O5′)dicobalt(II)] dihydrate]

A novel neutral polymer, {[Co₂(C₇H₃NO₄)₂(H₂O)₄]·2H₂O}_n, was hydrothermally synthesized using pyridine‐2,5‐dicarboxylate (2,5‐PDC²⁻) as the organic linker. It features a two‐dimensional layer structure constructed from one‐dimensional {[Co(2,5‐PDC)₂]²⁻}_n chains interlinked by [Co(H₂O)₄]⁺ units. The two Co^II cations occupy special positions, sitting on inversion centres. Each 2,5‐PDC²⁻ anion chelates to one Co^II cation via the pyridine N atom and an O atom of the adjacent carboxylate group, and links to two other Co^II cations in a bridging mode via the O atoms of the other carboxylate group. In this way, the 2,5‐PDC²⁻ ligand connects three neighbouring Co^II centres to form a two‐dimensional network. The two‐dimensional undulating layers are linked by extensive hydrogen bonds to form a three‐dimensional supramolecular structure, with the uncoordinated solvent molecules occupying the interlamellar region.     

Influence of MgO/CeO2 ratio on CO2-oxidative transformation of C2H6 to C2H4 over highly active and stable Cr/MgO(x)–CeO2(100−x) nanocatalysts

Cr/MgO(x)–CeO₂(100?x) nanocatalysts were synthesized by a coprecipitation method and characterized by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), energy-dispersive x-ray (EDX) spectroscopy, diffuse reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller (BET) analysis. The effect of ceria addition on their physicochemical characteristics was investigated, and the results were correlated with their catalytic performance in oxidative dehydrogenation of ethane. A decrease in the size of the metal particles was found when adding a suitable content of ceria to the support. Crystalline Cr₂O₃ was not found in the calcined samples, indicating good dispersion of Cr species on the support. All samples showed nanosized particles with uniform morphology, with the best surface morphology for the Cr/MgO(50)–CeO₂(50) sample, on which the particle distribution mainly lay in the range of 40–60 nm. Variation of the amount of Ce in the support led to an enhancement of the Cr⁶⁺/Cr³⁺ ratio, with the highest value for the Cr/MgO(50)–CeO₂(50) sample. This catalyst effectively dehydrogenated ethane to ethylene with CO₂ at 700 °C even after 5 h on-stream, giving 42.76 % ethylene yield.

     

Front Cover: Water-Solvation-Dependent Spin Transitions in Cobalt(II)-Octacyanidometallate Complexes (Eur. J. Inorg. Chem. 30/2023)

The spin-crossover (SCO) and charge-transfer (CT) phenomena, the switching processes between two distinguishable magnetic states, are promising for developing materials capable of sophisticated memory and sensing functionalities. The majority of SCO systems are based on iron(II) complexes. However, cobalt(II)-2,2′:6′,2′′-terpyridine (terpy) systems emerge as a promising alternative. In this work, new complex salts [Co^II(terpy)₂]₂[Mo^IV(CN)₈] ⋅ 15H₂O, Co₂Mo (H₂O), and [Co^II(terpy)₂]₃[W^V(CN)₈]₂ ⋅ 12H₂O, Co₃W₂ (H₂O) were synthesized and physiochemically characterized. Structural studies for both compounds revealed [Co(terpy)₂]²⁺ layers pillared by octacyanidometallate anions and completed with water molecules between them. Magnetic studies confirmed that the (de)solvated phases of both complexes exhibit partial SCO on the cobalt(II) centers: Co^II−LS (S_Co(II)-LS=¹/₂)↔Co^II−HS (S_Co(II)-HS=³/₂). Moreover, handling dehydrated samples in a high-humidity environment leads to partial recovery of previous magnetic properties via humidity-induced SCO for Co₂Mo : Co^II−HS→Co^II−LS, and the new phenomenon of isothermal humidity-activated charge-transfer-induced spin transition, which we define here as HACTIST, for Co₃W₂ : Co^II−HS⋅⋅⋅W^V (S_Co(II)-HS=³/₂ and S_W(V)=¹/₂)→Co^III−LS⋅⋅⋅W^IV (S_W(IV)=0 and S_Co(III)-LS=0). These comprehensive studies shed light on the water-solvation-dependent spin transitions in Co(II)-octacyanidometallate(IV/V) complexes.     

助剂对NiMgAl催化剂的结构和甲烷二氧化碳重整反应性能的影响(英文)

向担载镍基催化剂NiMgAl中添加助剂(Co,Ir或Pt)制备了三种助剂促进型催化剂,通过氢气程序升温还原(H2-TPR),CO2/CH4程序升温表面反应(CO2/CH4-TPSR)和CO2程序升温脱附(CO2-TPD)等方法对催化剂进行表征.助剂对催化剂性能的影响通过甲烷干重整实验进行评价.添加少量的Pt或Ir助剂可以降低Ni活性组分的还原温度和提高反应性能.添加助剂的样品与原始NiMgAl催化剂相比能够降低反应的活化能,添加Co或Ir助剂的催化剂与NiMgAl催化剂相比活化能有了明显的降低.NiMgAl催化剂的活化能为51.8 kJ·mol-1,添加Pt助剂的NiPtMgAl催化剂活化能降至26.4 kJ·mol-1.NiMgAl催化剂中添加Pt助剂制备的催化剂具有较好的催化活性和较低的活化能.CH4-TPSR和CO2-TPSR结果表明添加Pt助剂可以在更低的温度下(与NiMgAl催化剂相比)提高CH4的活化能力,并在催化剂表面形成更多的碳物种.CO2-TPD结果显示,添加助剂的催化剂与NiMgAl样品相比在反应温度区间内增加了CO2的吸附/脱附量.     

Pt overlayer for direct oxidation of CH4 to CH3OH

Highly selective conversion of methane (CH₄) to methanol (CH₃OH) is an emerging attractive but challenging process for future development of hydrogen economy, which requires efficient catalysts. Herein, we systematically explore the catalytic properties of Pt(111) overlayer on transition metal oxides (TMOs) for CH₄ conversion by first principles calculations. The Pt(111) monolayer supported by Ce-terminated CeO₂(111) substrate exhibits high activity and selectivity for CH₄ conversion to CH₃OH, with the kinetic barrier of rate-limiting step of 1.05 eV. Intriguingly, the surface activity of Pt overlayer is governed by its d-band center relative to the energy of bonding states of adsorbed molecules, which in turn depends on the number of charge transfer between Pt(111) monolayer and underlying TMOs substrates. These results provide useful insights in the design of metal overlayers as catalysts with high-ultra performance and atomic utilization.     

Co3(HCOO)6 microporous metal-organic framework membrane for separation of CO2/CH4 mixtures

Continuous metal–organic framework‐type Co₃(HCOO)₆ intergrown films with a one‐dimensional zigzag channel system and pore aperture of 5.5 Å are prepared by secondary growth on preseeded macroporous glass‐frit disks and silicon wafers. The adsorption behavior of CO₂ or CH₄ single gases on the Co₃(HCOO)₆ membrane is investigated by in situ IR spectroscopy. It is shown that the isosteric heats of adsorption for CO₂ (17.7 kJ mol^?1) and CH₄ (14.4 kJ mol^?1) do not vary with increasing amount of adsorbed gases. The higher value of isosteric heat for CO₂ is an indication of the stronger interaction between the CO₂ and the Co₃(HCOO)₆ membrane. The Co₃(HCOO)₆ membrane is studied by binary gas permeation of CO₂ and CH₄ at different temperatures (0, 25, and 60 °C). The membrane has CO₂/CH₄ selectivity with a separation factor higher than 10, which is due to the unique structure and molecular sieving effect. Upon increasing the temperature from 0 to 60 °C, the preferred permeance of CO₂ over CH₄ is increased from 1.70×10^?6 to 2.09×10^?6 mol m^?2 s^?1 Pa^?1, while the separation factor for CO₂/CH₄ shows a corresponding decrease from 15.95 to 10.37. The effective pore size of the Co₃(HCOO)₆ material combined with the pore shape do not allow the two molecules to pass simultaneously, and once the CO₂ molecules are diffused in the micropores, the CH₄ is blocked. The supported Co₃(HCOO)₆ membrane retains high mechanical stability after a number of thermal cycles.     

3D Metal–Organic Frameworks Based on Co(II) and Bithiophendicarboxylate: Synthesis,Crystal Structures,Gas Adsorption,and Magnetic Properties

Three new 3D metal-organic porous frameworks based on Co(II) and 2,2′-bithiophen-5,5′-dicarboxylate (btdc²⁻) [Co₃(btdc)₃(bpy)₂]·4DMF, 1; [Co₃(btdc)₃(pz)(dmf)₂]·4DMF·1.5H₂O, 2; [Co₃(btdc)₃(dmf)₄]∙2DMF∙2H₂O, 3 (bpy = 2,2′-bipyridyl, pz = pyrazine, dmf = N,N-dimethylformamide) were synthesized and structurally characterized. All compounds share the same trinuclear carboxylate building units {Co₃(RCOO)₆}, connected either by btdc^2– ligands (1, 3) or by both btdc^2– and pz bridging ligands (2). The permanent porosity of 1 was confirmed by N₂, O₂, CO, CO₂, CH₄ adsorption measurements at various temperatures (77 K, 273 K, 298 K), resulted in BET surface area 667 m²⋅g⁻¹ and promising gas separation performance with selectivity factors up to 35.7 for CO₂/N₂, 45.4 for CO₂/O₂, 20.8 for CO₂/CO, and 4.8 for CO₂/CH₄. The molar magnetic susceptibilities χ_p(T) were measured for 1 and 2 in the temperature range 1.77–330 K at magnetic fields up to 10 kOe. The room-temperature values of the effective magnetic moments for compounds 1 and 2 are μ_eff (300 K) ≈ 4.93 μ_B. The obtained results confirm the mainly paramagnetic nature of both compounds with some antiferromagnetic interactions at low-temperatures T < 20 K in 2 between the Co(II) cations separated by short pz linkers. Similar conclusions were also derived from the field-depending magnetization data of 1 and 2.     

Cobalt Carbonate as an Electrocatalyst for Water Oxidation

Co^II salts in the presence of HCO₃⁻/CO₃²⁻ in aqueous solutions act as electrocatalysts for water oxidation. It comprises of several key steps: (i) A relatively small wave at E_pa≈0.71 V (vs. Ag/AgCl) owing to the Co^III/II redox couple. (ii) A second wave is observed at E_pa≈1.10 V with a considerably larger current. In which the Co^III undergoes oxidation to form a Co^IV species. The large current is attributed to catalytic oxidation of HCO₃⁻/CO₃²⁻ to HCO₄⁻. (iii) A process with very large currents at >1.2 V owing to the formation of Co^V(CO₃)₃⁻, which oxidizes both water and HCO₃⁻/CO₃²⁻. These processes depend on [Co^II], [NaHCO₃], and pH. Chronoamperometry at 1.3 V gives a green deposit. It acts as a heterogeneous catalyst for water oxidation. DFT calculations point out that Coⁿ(CO₃)₃ⁿ⁻⁶, n=4, 5 are attainable at potentials similar to those experimentally observed.     

Nestlike Silver(I) Thiolate Clusters with Tunable Emission Color Templated by Heteroanions

Four silver thiolate clusters, [H₃O][(Ag₃S₃)(BF₄)@Ag₂₇(tBuS)₁₈(hfac)₆H₂O] ⋅ H₂O ( 1 ; hfac = hexafluoroacetylacetone), [(Ag₃S₃)(CF₃CO₂)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ CF₃CO₂ ⋅ 4 CH₃CN ( 2 ), [(Ag₃S₃)(MoO₄)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ 2 CH₃CN ( 3 ), and [(Ag₃S₃)(CrO₄)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ 4 CH₃CN ( 4 ), were isolated. They have similar nestlike structures assembled by an [Ag₃S₃]³⁻ template together with one of the BF₄⁻, CF₃CO₂⁻, MoO₄²⁻, or CrO₄²⁻ anions. Interestingly, the solid-state emissions of 2 – 4 are dependent on the templating anions and are tunable from green to orange and then to red by changing the template from CF₃CO₂⁻ to MoO₄²⁻ and to CrO₄²⁻, and this may be correlated to the charge transfer between these templates to metal atoms. This work helps to understand the templating role of heteroanions and the relationship between structure and properties.     

Hydrogen Production by Catalytic Reforming of Gaseous Hydrocarbons (Methane &; LPG)

Hydrogen has been attracting great interest as a major energy source in near future. The lack of an infrastructure has led to a research effort to develop fuel processing technology for production of hydrogen. In this review, we are reporting the catalytic reforming of gaseous hydrocarbons carried out in our research group, covering dry-reforming of CH₄, tri-reforming of CH₄, the electrocatalytic reforming of CH₄ by CO₂ in the SOFC (solid oxide fuel cell) system and steam reforming of LPG. Especially, we have focused on our work, though the related work from other researchers is also discussed wherever necessary. It was found that tri-reforming of CH₄ over NiO–YSZ–CeO₂ catalyst was more desirable than dry-reforming of CH₄ due to higher reforming activity and less carbon formation. The synthesis gas produced by tri-reforming of CH₄ can be used for the production of dimethyl ether, Fischer–Tropsch synthesis fuels and high valued chemicals. To improve the problem of deactivation of catalyst due to carbon formation in the dry reforming of CH_4, the internal reforming of CH₄ by CO₂ in SOFC system with NiO–YSZ–CeO₂ anode catalyst was suggested for cogeneration of a syngas and electricity. It was found that Rh-spc-Ni/MgAl catalyst showed long term stability for 1,100 h in the steam reforming of LPG under the tested conditions. The addition of Rh to spc-Ni/MgAl catalyst restricted the deactivation of catalyst due to carbon formation in the steam reforming of LPG and diesel under the tested conditions. The result suggested that the developed reforming catalysts can be used in the reforming process of CH₄, LNG and LPG for application to hydrogen station and fuel processor system.