Pt encapsulated hollow mesoporous SiO2 sphere catalyst for sulfuric acid decomposition reaction in SI cycle

Sulfuric acid (SA) decomposition is one of three key reactions in sulfur Iodine (SI) cycle to produce hydrogen. The catalysts for the decomposition should be active and stable in a wide temperature range of 550–900 °C. Pt based catalysts have been explored for the application, but suffered from the Pt loss in high temperature (∼850 °C). TiO₂ and Al₂O₃ are used as a support. They can stabilize Pt metal at higher temperature, but are degraded at the temperature lower than 700 °C. SiO₂ supports with a high surface area are relatively stable in a sulfuric acid vapor stream, but the lower interaction with Pt results in high Pt sintering and Pt loss. Both Pt loss and Pt sintering at the high temperature are originated from Pt vaporization. Here, Pt metallic components are placed at the inner wall of hollow mesoporous SiO₂ spheres (Pt-HMSS) to preserve Pt components even at 850 °C. PtOx vapor vaporized during the SA decomposition can be re-dispersed on the inner wall of mesoporous SiO₂ shell, which can suppress the Pt loss; (1) temperature at outer wall is higher than temperature at inner wall during the endothermic reaction on Pt at the inner wall, (2) the mesoporous shell afford the long path to suppress the diffusion of PtOx vapor at the inner wall to the outer wall. Pt catalyst at the outer walls of hollow mesoporous SiO₂ spheres (HMSS-Pt) is prepared and tested for clarifying the hypothesis. Additionally, TiO₂-Pt catalyst, one of highly stable catalytic systems for the SA decomposition, is also prepared and compared with the Pt-HMSS catalyst.     

Electrospun NiMn2O4 and NiCo2O4 spinel oxides supported on carbon nanofibers as electrocatalysts for the oxygen evolution reaction in an anion exchange membrane-based electrolysis cell

Spinel oxide electrocatalysts supported on carbon nanofibers (CNFs), denoted as and NiMn₂O₄/CNF and NiCo₂O₄/CNF, are investigated for the oxygen evolution reaction (OER) in alkaline electrolyte. NiCo₂O₄/CNF and NiMn₂O₄/CNF are prepared according to an optimized electrospinning method using polyacrylonitrile (PAN) as carbon nanofibers precursor. After the thermal treatment at 900 °C for 1 h in the presence of helium and the subsequent one at 350 °C for 1 h in air, nanosized metal oxides with a spinel structure supported on carbon nanofibers are obtained. The physico-chemical investigation shows relevant difference in the crystallite size (9 nm for the NiCo₂O₄/CNF and 20 nm for the NiMn₂O₄/CNF) and a more homogeneous distribution for NiMn₂O₄ supported on carbon nanofibers. These characteristics derive from the different catalytic effects of Co and Mn during the thermal treatment as demonstrated by thermal analysis. The OER activity of NiCo₂O₄/CNF and NiMn₂O₄/CNF is studied in a single cell based on a zero gap anion-exchange membrane-electrode assembly (MEA). The NiMn₂O₄/CNF shows a better mass activity than NiCo₂O₄/CNF at 50 °C (116 A g⁻¹ @ 1.5 V and 362 A g⁻¹ @ 1.8 V vs. 39 A g⁻¹ @ 1.5 V and 253 A g⁻¹ @ 1.8 V) but lower current density at specific potentials. This is the consequence of a lower concentration of the active phase on the support resulting from the need to mitigate the particle growth in NiMn₂O₄/CNF.     

Enhanced CO hydrogenation performance via two-dimensional NiAl-layered double oxide decorated by SiO2 nanoparticles

The CO methanation reaction has been widely used in the fields of synthetic natural gas and ammonia (NH₃). This study improves the CO methanation performance using a two-dimensional NiAl-layered double oxide (2D NiAl-LDO) decorated by SiO₂ nanoparticles and reduced under hydrogen atmosphere. The as-obtained H–NiAl-LDO/SiO₂ exhibited a high specific surface area of 240.5 m²/g and high surface-adsorbed oxygen of 20.77%. Furthermore, it had an excellent CO conversion of 100% at 300 °C and 96.87% at 250 °C, which was much better than those of H–NiAl-LDO (84.03% at 300 °C and 0% at 250 °C). We believe that it provides an additional strategy to easily and effectively improve CO methanation performance and shows potential for the application of similar catalysts.     

Investigation on NO reduction by CO and H2 over metal oxide catalysts Cu2M9CeOx

Composite metal oxide catalyst Cu₂M₉CeOx (M = Fe, Co, Ni) was prepared by citric acid complexation method for NOx reduction. Prepared catalysts activities were tested in a fixed bed reactor for NOx reduction by CO and H₂. The sequence of activity of the three catalysts for NOx reduction by CO is: Cu₂Co₉CeOx > Cu₂Fe₉CeOx > Cu₂Ni₉CeOx. The catalytic efficiency of Cu₂Co₉CeOx increased to 100% at 250 °C. For NO reduction by H₂, the sequence of activity follows: Cu₂Fe₉CeOx > Cu₂Co₉CeOx > Cu₂Ni₉CeOx. The catalytic activity of Cu₂Fe₉CeOx was ranged from 60% to 100% during 250–325 °C. Additionally, characterization was conducted to investigate the physical and chemical properties of Cu₂M₉CeOx catalysts. In-situ Fourier transform-infrared spectra was also used to study the mechanism of the reaction. The results indicated that Cu-□-Co synergistic oxygen vacancies in Cu₂Co₉CeOx and unstable CuFe₂O₄ (spinel) in Cu₂Fe₉CeOx promote NO reduction. The reasons of activities over different Cu₂M₉CeOx catalysts were then carefully explored.     

Physical and sealing properties of BaO–Al2O3–SiO2–CaO–V2O5 glasses for solid oxide fuel cell applications

In this study, the properties of BaO–Al₂O₃–SiO₂ (SAB) glasses incorporated with CaO and V₂O₅ as the network modifier and additive, respectively, are evaluated. The electrical resistivities of the glasses decrease upon the addition of CaO but increase upon increasing their V₂O₅ content because the V⁵⁺ species lower the ionic mobility of the glasses. The addition of V₂O₅ improves the wettability of the glasses on the Crofer 22 APU substrate, and thus, increases the fracture strength at the glass–Crofer 22 APU couple. Among the glasses evaluated, the SAB glass with a CaO content of 20 wt% and V₂O₅ content of 2 wt% (SAB-Ca20V2) present excellent sealing properties because it adheres well to both the Zr_0·92Y_0·08O_2-δ (YSZ) and Crofer 22 APU substrates; no pores, cracks, or interfacial phases are present at the interfaces, confirming the good chemical and thermal compatibility of the glass–substrate pairs at high temperatures. After SAB-Ca20V2 is sealed on the Crofer 22 APU substrate at 850 °C, the leakage rate of the glass is low (<0.015 sccm?cm^?1 at 800 °C for 200 h), indicating negligible deterioration of its sealing efficiency and revealing its remarkable potential for use in solid oxide fuel cell applications.     

Preparation of Cu0.1-xNixCe0.9O2-y catalyst by ball milling and its CO catalytic oxidation performance

A series of Cu_0.1-xNi_xCe_0.9O_2-y catalysts with different Cu/Ni molar ratios were prepared by the ball milling method. The obtained catalytic materials were characterized by XRD, H₂-TPR, BET, XPS and Ramen and the effects of different Cu/Ni content on the structure, properties and CO catalytic oxidation performance of the catalysts were explored. The results evidenced the formation of Cu–Ni–Ce mixed oxide solid solution in all ternary catalysts. In addition, there is a synergistic interaction between Cu and Ni in ternary catalysts, resulting in more oxygen vacancies and improved reduction performance, and hence demonstrating better CO catalytic oxidation activity in the ternary catalysts than binary ones. Under a GHSV of 60000 mL·g_cat⁻¹·h⁻¹, the required reaction temperature for reaching less than 10 ppm CO is lowed from 160 °C with Cu_0·1Ce_0·9O_2-y to 130 °C with Cu_0·07Ni_0·03Ce_0·9O_2-y.     

Mechanochemical preparation,sintering aids and hybrid microwave sintering in the proton conductor Sr0.02La0.98Nb1-xVxO4-δ, x = 0, 0.15

Mechanochemical preparation of Sr_0.02La_0.98Nb_1-xV_xO_4-δ was demonstrated for values of x = 0 and 0.15. Crystallinity could be improved by calcining at 1073 K. On cooling, the high temperature scheelite phase was retained to room temperature. Several novel sintering additives for LaNbO₄ materials have been tested. The most successful were Cu₃Nb₂O₈ and CuV₂O₆, which reduced the temperature of maximum shrinkage rate to temperatures ∼1173 K. The additive CuV₂O₆ was shown to increase densification and promote grain growth. A mechanosynthesised sample of Sr_0.02La_0.98Nb_0.85V_0.15O_4-δ + 2 mol% CuV₂O₆ could be densified to ∼ 90% that of the theoretical by hybrid microwave sintering at 1168 K for 5 min. The scheelite phase in this material was retained to room temperature, against the normal thermodynamic tendency. Impedance spectroscopy in wet and dry, nitrogen and oxygen atmospheres suggested that the bulk conductivity of this material is unaffected by the sintering aid, whereas the grain boundary conductivity was impaired and exhibited n-type conductivity behaviour, characteristic of the additive. The concentration of this promising additive should be reduced in further work.     

Investigation on the combustion behaviors of coke and biomass char in quasi-granule with CuO–CeO2 catalysts in iron ore sintering

To thoroughly understand the combustion behaviors of coke and biomass char based on its physiochemical characteristics and distribution states in iron ore sintering, three types of single, composite and pellet quasi-granules of coke and biomass char were prepared carefully, catalytic potential of Cu_0.1Ce_0.9O₂ to increase quasi-granule combustion efficiency defined by the extent of CO destruction in flue gas was investigated. The results showed that biomass char is combusted at relative low temperature in the range of 350–800 °C because it has higher volatiles and porosity, exhibiting high reactivity compared to coke which combusts from 650 °C to 1030 °C. Pellet type has an intrinsic high combustion efficiency due to its fine fuel size and the neighboring compounds effect. Single coarse type granules have a high CO concentration in flue gas and have the highest combustion efficiency improvement by Cu_0.1Ce_0.9O₂ loading among all the types, which is mainly attributed to CO catalytic oxidation following Mars-van Krevelen path rather than the carbon oxidation. Through intentionally producing more coarse single type and composite type granules with 3 wt% Cu_0.1Ce_0.9O₂ in granulation, substitution ratio of biomass for coke can be increased, leading to improved combustion efficiency of ~98% without deterioration of sintering performance.     

Cobalt oxide as photocatalyst for water splitting: Temperature-dependent phase structures

This study investigated the best phases of cobalt oxide for the photochemical and photoelectrochemical (PEC) water-splitting reaction. Cobalt oxide was produced via a hydrothermal process of cobalt nitrate hexahydrate and then annealed at different temperatures from 450 °C to 950 °C. The Co₃O₄ phase was produced during pre-annealing and annealing at 450 °C. The mixed phase of Co₃O₄ and CoO was produced during annealing at 550 °C and 650 °C, and pure CoO was produced during annealing from 750 °C to 950 °C. The Co₃O₄ phase produced the highest photocurrent density with a value of 1.15 mA cm⁻² at a −0.4 V potential bias vs. Ag/AgCl. This value two times higher than that reported by other researchers at the same potential bias. Furthermore, the highest rate of hydrogen collected by Co₃O₄ was ~272.6 μmol h⁻¹ g⁻¹ after 8 h photocatalytic process. The amount of collected hydrogen was stable until 12 h of the process.     

Interfacial engineering of nickel/vanadium based two-dimensional layered double hydroxide for solid-state hydrogen storage in MgH2

As a high-density solid-state hydrogen storage material, magnesium hydride (MgH₂) is promising for hydrogen transportation and storage. Yet, its stable thermodynamics and sluggish kinetics are unfavorable for that required for commercial application. Herein, nickel/vanadium trioxide (Ni/V₂O₃) nanoparticles with heterostructures were successfully prepared via hydrogenating the NiV-based two-dimensional layered double hydroxide (NiV-LDH). MgH₂ + 7 wt% Ni/V₂O₃ presented more superior hydrogen absorption and desorption performances than pure MgH₂ and MgH₂ + 7 wt% NiV-LDH. The initial discharging temperature of MgH₂ was significantly reduced to 190 °C after adding 7 wt% Ni/V₂O₃, which was 22 and 128 °C lower than that of 7 wt% NiV-LDH modified MgH₂ and additive-free MgH₂, respectively. The completely dehydrogenated MgH₂ + 7 wt% Ni/V₂O₃ charged 5.25 wt% H₂ in 20 min at 125 °C, while the hydrogen absorption capacity of pure MgH₂ only amounted to 4.82 wt% H₂ at a higher temperature of 200 °C for a longer time of 60 min. Moreover, compared with MgH₂ + 7 wt% NiV-LDH, MgH₂ + 7 wt% Ni/V₂O₃ shows better cycling performance. The microstructure analysis indicated the heterostructural Ni/V₂O₃ nanoparticles were uniformly distributed. Mg₂Ni/Mg₂NiH₄ and metallic V were formed in-situ during cycling, which synergistically tuned the hydrogen storage process in MgH₂. Our work presents a facile interfacial engineering method to enhance the catalytic activity by constructing a heterostructure, which may provide the mentality of designing efficient catalysts for hydrogen storage.     

Fabricating carbon nanocages as ORR catalysts in alkaline electrolyte from F127 self-assemble core-shell micelle

In order to reduce the cost of oxygen reduction reaction (ORR) catalyst in fuel cell, polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) three-block copolymer (F127) and Zn(OH)₂ were used as carbon resource and morphology retaining agent to prepare porous nanocages for ORR catalyst in alkaline solution. Its composition and microstructure were characterized by X-ray diffraction Raman spectroscopy (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) method. Electrochemical properties were evaluated in O₂ saturated alkaline solution. Results showed the sample obtained at 700 °C (C-700) was composed of porous carbon nanocages with diameter of 50 nm and shell thickness of 4 nm. C-700 had the maximum surface area (1011 m² g⁻¹) and the best ORR catalytic performance. The main reason is that polypropylene oxide (PPO) group at the lipophilic end begins to decompose at 500 °C, and the polyethylene oxide (PEO) group at the lipophilic end at 700 °C decomposes completely. In O₂ saturated 0.1 M KOH solution, C-700's oneset potential, limit current density and half-wave potential, which were 0.89 V, 5.59 mA/cm²@0.45 V and 0.71 V, respectively, were close to that of commercial 20% Pt/C catalyst. It was noted that the oneset potential and half-wave potential of C-700 had barely change, and limit current density attenuated about 87.8% after 2000 CV cycle. The obtained catalyst behaved good catalytic activity and stability for ORR in alkaline solution and a potential application prospect in fuel cells.     

Steam-promoted Methane-CO2 reforming by NiPdCeOx@SiO2 nanoparticle clusters for syngas production

We demonstrate a facile aerosol-based approach to fabricate hybrid nanostrcutures, NiPdO_x-CeO₂ nanoparticles deposited on the SiO₂ nanoparticle clusters, for the catalysis of steam-promoted CO₂ reforming with methane. Ultrafine crystallites of active metal and promoter (≈5 nm) are created with tunable cluster sizes and chemical compositions. A superior catalytic performance achieves at low temperature (550 °C): remarkable turnover frequency (≈2 s^?1), tunable H₂/CO ratio (1.1–1.9) and high 100-h operation stability. Incorporation of SiO₂ nanoparticle cluster as support material increases dispersion of active metals and suppresses metal sintering during material synthesis and catalysis. Hybridization with Pd significantly improves the activity of Ni-based catalyst especially ≤600 °C. Addition of steam suppresses the coke formation by > 10 times. The work demonstrates a prototype study of developing bimetallic hybrid nanocatalysts homogeneously dispersed with promoter on the NPC mesoporous support by design, showing promise for the syngas production via synergistic catalysis of methane-CO₂ reforming.     

Catalytic properties of dispersed iron oxides Fe2O3/MO2 (M = Zr,Ce, Ti and Si) for sulfuric acid decomposition reaction: Role of support

Supported iron oxides have been established as an important class of catalyst for high temperature sulfuric acid decomposition. With an objective to elucidate the role of support in modifying the overall catalytic properties of dispersed iron oxide catalysts, a series of supported iron oxide based catalysts, Fe₂O₃ (15 wt%)/MO₂ (M = Zr, Ce, Ti and Si), synthesized by adsorption-equilibrium method, is investigated for sulfuric acid decomposition reaction. The structure of dispersed iron oxide phases largely depended on the nature of the support oxide as revealed by the XRD and Mössbauer studies. α-Fe₂O₃ is found to be present as a major phase on ZrO₂ and CeO₂ support while ε-Fe₂O₃ was the major phase on silica supported iron oxide. On the other hand, presence of mixed oxide Fe₂TiO₅ was revealed over TiO₂ support. Strong dispersed metal oxide-support interactions inhibited the total reduction of the dispersed phase on SiO₂ and TiO₂ as compared to complete reduction of dispersed iron oxide on CeO₂ and ZrO₂ supports during temperature programmed reduction upto 1000 °C. The order of catalytic activity at a temperature of ～750 °C is observed as Fe₂O₃/SiO₂ > Fe₂TiO₅/TiO₂ > Fe₂O₃/ZrO₂ > Fe₂O₃/CeO₂, while at higher temperatures of ～900 °C the SO₂ yield is found to be comparable for all catalysts. A relationship between the rate of sulfate decomposition and catalytic activity is established through detailed TG-DTA investigations of sulfated catalyst and support. Considerable influence of the support oxide on the composition, structure, redox properties, morphology and catalytic activities of the active iron oxide dispersed phase has been observed. Thus, the support oxides operate as a critical component in the complex supported metal oxide catalysts and these findings might influence the design and development of future high temperature sulfuric acid decomposition catalysts.     

Green synthesis of MCM-41 derived from renewable biomass and construction of VOx-Modified nickel phyllosilicate catalyst for CO2 methanation

In order to achieve green synthesis of MCM-41 and address the sintering problem of Ni-based catalyst supported on silica material, MCM-41 with regular spherical morphology was prepared using sodium silicate extracted from renewable equisetum fluviatile as silicon source, and then a group of nickel phyllosilicates were synthesized via the reaction of MCM-41 sphere and nickel nitrate under hydrothermal condition. Much denser nanosheets corresponding to lamellar nickel phyllosilicate were formed on the surface of MCM-41 sphere with the raise of hydrothermal temperature in the range of 180–220 °C, resulting in the nickel content varying from 17.2 to 41.8 wt%. Fine Ni particles with size smaller than 6 nm could be obtained on the 750^oC-reduced catalyst owing to the strong nickel-silica interaction derived from Ni-phyllosilicate. After the addition of V₂O₅ promoter, Ni particle size was further reduced to around 4.5 nm at high Ni loading above 30 wt%. Vanadium species was in the mixed valence state of V(III), V(IV) and V(V) after reduction, which increased the electron cloud density of Ni⁰, resulting in high catalytic activity of the VO_x-modified Ni-phyllosilicate catalyst for CO₂ methanation. In a 100 h-400^oC-lifetime test and 600 °C-steam hydrothermal treatment, the VO_x-modified Ni-phyllosilicate catalyst also showed high long-term stability, excellent sintering resistance of metallic nickel particles and high hydrothermal stability due to the strong surface confinement effect of nickel phyllosilicate and promotion of VO_x species. In all, this work provided a green synthesis of MCM-41 as well as an efficient Ni/SiO₂ catalyst derived from nickel phyllosilicate for CO₂ methanation.     

Al2O3 based Co-Schiff Base complex catalyst in hydrogen generation

This work presents the study of the catalytic activity of aluminum oxide supported Co-Schiff Base complex derived from 4,4′-Methylenebis(2,6-diethylaniline)-3,5-ditertbutylsalicylaldimine-Co-Schiff Base complex in sodium borohydride hydrolysis. This catalyst is characterized with XRD, FT-IR, SEM, TEM, and BET. The respective reaction kinetics have been calculated. With the catalyst condition, maximum reaction (initial) rate is 106540 and 147193,3 mL H₂/g_cat.^.min. at 30 °C and 50 °C. For this reaction apparent activation energy is 44,7792 kJ^.mol⁻¹ with 20–50 °C. The reaction order value (n) for this catalytic system is 0,31. Additionally when Al₂O₃ supported Co-Schiff Base complex compared with pure Co-Schiff Base complex, the experimental results show that the aluminum oxide support exhibits enhancing effect with 106540 and 64147 mL H₂/g_cat. min respectively in sodium borohydride hydrolysis to Hydrogen production.     

Catalytic characteristics of CexCu1-xO1.9 catalysts formed by solid state method for MTS and OMTS reactions

Ce_xCu_1-xO_1.9 (x = 0.3, 0.5, 0.8 and 0.9) catalysts were synthesized by solid state method, using ball mill apparatus, and evaluated in medium temperature shift (MTS), as well as oxygen assisted MTS (OMTS) reactions at temperature range of 300–390 °C. Catalysts were characterized by X-Ray Diffraction (XRD), Temperature Programmed Reduction (TPR), Scanning Electron Microscopy (SEM), and N₂ adsorption-desorption (BET) analysis. Ce_0.9Cu_0.1O_1.9 sample showed the best catalytic activity and structural properties. Decrease in proportion of Cu to Ce, leads to increase in the Cu-Ce mixed oxide formation (according to TPR analysis), significant increase in BET surface area (from 18 m²/g for Ce_0.3Cu_0.7O_1.9–48 m²/g for Ce_0.9Cu_0.1O_1.9), and decrease in CuO crystalline size (XRD). Moreover, the effect of oxygen addition to the feed (O₂/CO ratio = 0, 0.3, 0.5, 0.7 and 1), on the catalytic performance was evaluated. CO conversion was increased by enhancing the amount of oxygen (from 60% to 80% at 360 °C). CO and H₂ oxidations are occurring as competitive parallel reactions in which CO oxidation is dominant at low O₂/CO ratios (<0.5) and H₂ oxidation (undesirable for MTS reaction) at high O₂/CO ratios (>0.5). Furthermore, molar ratios of steam to CO at ranges of 2–4 were compared in OMTS reaction. According to the obtained results, the magnitudes of O₂/CO ratio and S/C ratio which were 0.5 and 4, respectively, were selected as the best values for OMTS reaction.     

Preparation of LiMn2O4 at the low temperature of 250 °C using eutectic self-mixing method

Spinel LiMn₂O₄ as a cathode material for lithium rechargeable batteries is prepared at the low temperature of 250 °C without any artificial mixing procedures of reactants. The phase transitions of lithium manganese oxide are found three times on heating at 250 °C. The prepared material exhibits the initial discharge capacity of 85.5 mAh g⁻¹ and the discharge capacity retention of 91.5% after 50 cycles.     

Synergistic enhancement of hydrogen storage properties in MgH2 using LiNbO3 catalyst

Extensive researches are being conducted to improve the high dehydrogenation temperature and sluggish hydrogen release rate of magnesium hydride (MgH₂) for better industrial application. In this study, LiNbO₃, a catalyst composed of alkali metal Li and transition metal Nb, was prepared through a direct one-step hydrothermal synthesis, which remarkably improved the hydrogen storage performance of MgH₂. With the addition of 6 wt% LiNbO₃ in MgH₂, the initial dehydrogenation temperature decreases from 300 °C to 228 °C, representing a drop of almost 72 °C compared to milled MgH₂. Additionally, the MgH₂-6 wt.% LiNbO₃ composite can quickly release 5.45 wt% of H₂ within 13 min at 250 °C, and absorbed about 3.5 wt% of H₂ within 30 min at 100 °C. It is also note that LiNbO₃ shows better catalytic effect compared to solely adding Li₂O or Nb₂O₅. Furthermore, the activation energy of MgH₂-6 wt.% LiNbO₃ decreased by 44.37% compared to milled MgH₂. The enhanced hydrogen storage performance of MgH₂ is attributed to the in situ formation of Nb-based oxides in the presence of LiNbO₃, which creates a multielement and multivalent chemical environment.     

Large scale hydrothermal synthesis and electrochemistry of ammonium vanadium bronze nanobelts

Single crystalline ammonium vanadium oxide bronze NH₄V₄O₁₀ nanobelts were synthesized by the hydrothermal treatment of H₂C₂O₄·2H₂O and NH₄VO₃ at 140 °C for 48 h. The NH₄V₄O₁₀ nanobelts were characterized using a combination of techniques including X-ray diffraction, transmission electron microscopy, selected area electronic diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy techniques. The as-obtained nanobelts are several microns long, typically 30–40 nm wide, and 10–20 nm thick. The electrochemical properties of the nanobelts were tested in cells with metallic lithium as the negative electrode, the first discharge capacity of 171.8 mAh g⁻¹ was achieved.     

Remarkable activity of Pd catalyst supported on alumina synthesized via a hydrothermal route for hydrogen release of perhydro-N-propylcarbazole

The investigation of dehydrogenation catalysts to achieve rapidly hydrogen release of Liquid Organic Hydrogen Carriers (LOHCs) are of crucial importance for large-scale applications. The catalyst supports with bulk surface area and decent acid-base nature is a key parameter for catalyst to improve its catalytic performance as well as reduce precious metal dosage. Herein, alumina was chosen as a support for Pd loading and prepared through hydrothermal route at different temperatures. The morphology and surface acid property of the alumina supports were investigated in detail. The results revealed that the hydrothermal temperature had a closely effect on the morphology, surface acidity and specific surface area of alumina, resulting in a further impact on Pd dispersion and particle size associated tightly with catalytic activity of Pd/Al₂O₃. The catalyst with 1 wt% Pd loaded on alumina carrier prepared via hydrothermal treatment at 120 °C showed the best catalytic performance for dehydrogenation of perhydro-N-propylcarbazole (12H-NPCZ). Full dehydrogenation with 100% conversion to N-propylcarbazole (NPCZ) could be achieved after 360 min at 180 °C and 101 kPa, which is higher than that of commercial 5 wt% Pd/Al₂O₃ catalyst. The catalyst has potential commercial application value in large-scale application of LOHC technology.