Ni/Photoredox Dual Catalysis Sulfone Compounds Synthesised with Carbon Nitride as the Semiheterogeneous Photocatalyst

An easily available heterogeneous semiconductor material, g-CN, proved to be feasible when combined with homogeneous nickel catalysts for light-mediated C(sp2)-SO2Ar bond formation of aryl bromides with aryl sulfinates under mild conditions and base-free, unlocking a variety of cross-couplings. The metal-free heterogeneous semiconductor is totally recyclable from reaction system, and experimental results demonstrated a series of differently substituted substrates including electron donating groups and electron withdrawing groups can be tolerated with a satisfactory result. The method could even pro-duce the classic drug Dapsone in large scale, showing strong practical application potential.

The Effects of Ce and W Promoters on the Performance of Alumina-Supported Nickel Catalysts in CO2 Methanation Reaction

The influence of Ce and W promoters on the performance of alumina-supported nickel catalysts in the CO2 methanation reaction was investigated. The catalysts were obtained by the co-impregnation method. Nitrogen low-temperature adsorption, temperature-programmed reduction, hydrogen desorption, transmission electron microscopy, X-ray diffraction, and photoelectron spectroscopy studies were used for catalyst characterization. An introduction of Ce and W promoters (1–5 wt %) led to the decrease in mean Ni crystallite size. Gradual increase in the active surface area was observed only for Ce-promoted catalysts. The increase in CO2 conversion in methanation reaction at low-reaction temperatures carried out over Ce-promoted catalysts was attributed to the increase in the active surface area and changes in the redox properties. The introduction of small amounts of tungsten led to an increase in the activity of catalysts, although a decrease in the active surface area was observed. Quasi in situ XPS studies revealed changes in the oxidation state of tungsten under CO2 methanation reaction conditions, indicating the participation of redox promoter changes in the course of surface reactions, leading to an improvement in the activity of the catalyst.

New Solvent-Free Melting-Assisted Preparation of Energetic Compound of Nickel with Imidazole for Combustion Synthesis of Ni-Based Materials

In this work two approaches to the synthesis of energetic complex compound Ni(Im)6(NO3)2 from imidazole and nicklel (II) nitrate were applied: a traditional synthesis from solution and a solvent-free melting-assisted method. According to infrared spectroscopy, X-ray diffraction, elemental and thermal analysis data, it was shown that the solvent-free melt synthesis is a faster, simpler and environmentally friendly method of Ni(Im)6(NO3)2 preparation. The results show that this compound is a promising precursor for the production of nanocrystalline Ni-NiO materials by air-assisted combustion method. The combustion of this complex together with inorganic supports makes it possible to synthesize supported nickel catalysts for different catalytic processes.

Hydrogen from Ammonia by Catalytic Spillover Membrane

<p>One of the major challenges to be overcome before hydrogen fuelled vehicles can become commonplace is to store hydrogen with sufficient storage density to be practical. One approach to overcoming this challenge involves converting the hydrogen into a secondary fuel that can be stored more easily, such as ammonia. This introduces the challenge of efficiently retrieving the hydrogen from the secondary fuel with sufficient purity to be used in a polymer electrolyte membrane fuel cell. Putting the hydrogen producing reaction inside a membrane which is capable of filtering out hydrogen creates a membrane reactor which can increase hydrogen purity and can accelerate the reaction both kinetically and thermodynamically. The most effective materials currently known for hydrogen membranes are high palladium alloys of copper and silver. These are able to absorb hydrogen on the side with high hydrogen partial pressure and desorb that hydrogen on the side with low hydrogen pressure. Palladium metal is also able to interact with some catalysts by hydrogen spillover. Hydrogen is transported from the surface of the catalyst to the palladium surface more quickly than the hydrogen can desorb from the catalyst, this potentially accelerates both the catalysis and the hydrogen filtration. This research aimed to create a catalytic spillover membrane to extend the possibility of ammonia as a secondary fuel for hydrogen transport. In this research, several methods to produce a nickel catalyst on the surface of the palladium were explored: electrodeposition with and without a lithographic template; spray coating with nanoparticles; and preshaped nickel mesh and nickel foam. These potential catalysts were tested for ammonia decomposition. Templated electrodeposition created the most effective catalyst, but the nickel foam was most easily applied to the next stage of the research. The nickel foam catalyst was subsequently retested for ammonia decomposition in three scenarios: in contact with palladium foil; in a reactor with a palladium membrane; and in contact with a palladium membrane. The presence of a palladium membrane improved decomposition more than spillover contact between nickel foam catalyst and palladium, however, the combination of spillover contact with a palladium membrane increased the ammonia decomposition further. The rate of hydrogen flux through the palladium membranes was calculated for the experimental results. These were compared to flux values predicted by a model equation. The results showed that spillover contact between nickel catalyst and palladium membrane increased the hydrogen flux through the membrane.. The research outcomes have generated new knowledge and improved understanding of the morphology and role of nickel catalysts in accelerating ammonia decomposition. The research highlights the complex relationship between reactor design, gas flow paths, catalyst presentation and catalysis chemistry, suggesting promising areas for future research.</p>

Hydrogen from Ammonia by Catalytic Spillover Membrane

<p>One of the major challenges to be overcome before hydrogen fuelled vehicles can become commonplace is to store hydrogen with sufficient storage density to be practical. One approach to overcoming this challenge involves converting the hydrogen into a secondary fuel that can be stored more easily, such as ammonia. This introduces the challenge of efficiently retrieving the hydrogen from the secondary fuel with sufficient purity to be used in a polymer electrolyte membrane fuel cell. Putting the hydrogen producing reaction inside a membrane which is capable of filtering out hydrogen creates a membrane reactor which can increase hydrogen purity and can accelerate the reaction both kinetically and thermodynamically. The most effective materials currently known for hydrogen membranes are high palladium alloys of copper and silver. These are able to absorb hydrogen on the side with high hydrogen partial pressure and desorb that hydrogen on the side with low hydrogen pressure. Palladium metal is also able to interact with some catalysts by hydrogen spillover. Hydrogen is transported from the surface of the catalyst to the palladium surface more quickly than the hydrogen can desorb from the catalyst, this potentially accelerates both the catalysis and the hydrogen filtration. This research aimed to create a catalytic spillover membrane to extend the possibility of ammonia as a secondary fuel for hydrogen transport. In this research, several methods to produce a nickel catalyst on the surface of the palladium were explored: electrodeposition with and without a lithographic template; spray coating with nanoparticles; and preshaped nickel mesh and nickel foam. These potential catalysts were tested for ammonia decomposition. Templated electrodeposition created the most effective catalyst, but the nickel foam was most easily applied to the next stage of the research. The nickel foam catalyst was subsequently retested for ammonia decomposition in three scenarios: in contact with palladium foil; in a reactor with a palladium membrane; and in contact with a palladium membrane. The presence of a palladium membrane improved decomposition more than spillover contact between nickel foam catalyst and palladium, however, the combination of spillover contact with a palladium membrane increased the ammonia decomposition further. The rate of hydrogen flux through the palladium membranes was calculated for the experimental results. These were compared to flux values predicted by a model equation. The results showed that spillover contact between nickel catalyst and palladium membrane increased the hydrogen flux through the membrane.. The research outcomes have generated new knowledge and improved understanding of the morphology and role of nickel catalysts in accelerating ammonia decomposition. The research highlights the complex relationship between reactor design, gas flow paths, catalyst presentation and catalysis chemistry, suggesting promising areas for future research.</p>

Co/Ba/La2O3 catalyst for ammonia synthesis under mild reaction conditions

Ruthenium catalysts may allow realization of renewable energy–based ammonia synthesis processes using mild reaction conditions (<400 °C, <10 MPa). However, ruthenium is relatively rare and therefore expensive. Here, we report a Co nanoparticle catalyst loaded on a basic Ba/La2O3 support and pre-reduced at 700 °C (Co/Ba/La2O3_700red) that showed higher ammonia synthesis activity at 350 °C and 1.0–3.0 MPa than two benchmark Ru catalysts, Cs+/Ru/MgO and Ru/CeO2. The synthesis rate of the catalyst at 350 °C and 1.0 MPa (19.3 mmol h−1g−1) was 8.0 times that of Co/Ba/La2O3_500red and 6.9 times that of Co/La2O3_700red. The catalyst showed activity at temperatures down to 200 °C. High-temperature reduction induced formation of a BaO-La2O3 nano-fraction around the Co nanoparticles, which increased turnover frequency, inhibited Co nanoparticle sintering, and suppressed ammonia poisoning. These strategies may also be appliable to nickel catalysts.