The future of green ammonia as long-term energy storage relies on the replacement of the conventional CO₂ intensive methane-fed Haber–Bosch process by distributed and agile ones aligned to the geographically isolated and intermittent renewable energy.

a b s t r a c tLow temperature hydrogen production via ammonia decomposition is achieved by the synergetic combination of a highly conductive support and an electron donating promoter in a ruthenium-based system, with activity at temperatures as low as 450 K. The high conductivity of graphitized carbon nanotubes allows for greater electronic modification of the ruthenium nanoparticles by cesium located in close proximity but without direct contact, avoiding the blockage of the active sites. This development of low temperature catalytic activity represents a breakthrough toward the use of ammonia as chemical storage for in-situ hydrogen production in fuel cells.

RutheniumCesium Promoter a b s t r a c t Cesium-promoted ruthenium nanoparticles supported on multi-walled carbon nanotubes catalysts are shown to be highly active for hydrogen production by ammonia decomposition. Its low temperature activity is significantly improved as the cesium loading increases, reducing the activation energy from 96.7 kJ/mol in the absence of cesium to 59.3 kJ/ mol with a cesium/ruthenium molar ratio of 3. Hydrogen production was observed to proceed below 590 K which represents a breakthrough towards the use of ammonia as chemical storage for in-situ hydrogen production on fuel cells. The catalytic enhancement is shown to be due to the electronic modification of ruthenium by the electron donating cesium promoter located on the ruthenium surface and in close proximity on the CNT surface. However, higher promoter loadings above a cesium/ruthenium ratio of 3 leads to ammonia inaccessibility to the catalytic active sites.

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Please cite this article in press as: L. Torrente-Murciano, et al., Ammonia decomposition over cobalt/carbon catalysts-Effect of carbon support and electron donating promoter on activity, Catal. Today (2016), http://dx. a b s t r a c tThis paper sets the new design parameters for the development of low temperature ammonia decomposition catalysts based on readily available cobalt as an alternative to scarce but highly active ruthenium-based catalysts. By using a variety of carbon materials as catalytic supports, we systematically demonstrate that microporous supports capable of stabilising small cobalt crystallites (∼2 nm) lead to high catalytic activities compared to bigger nanoparticles. Additionally, the degree of graphitisation of the carbon support has a detrimental effect on the activity of the cobalt (0) active sites, likely due to their potential as an electron donator. Consequently, the addition of electron donating promoters such as cesium substantially decreases the activity of the cobalt catalysts. This relationship deviates from the trends observed for ruthenium-based catalysts with an optimum 3-5 nm size where an increase of the graphitisation degree of the support and the addition of electron donating promoters increases the ammonia decomposition activity.

reactor and heat transfer into a single step. Moving toward renewable electricity as the source of heat for chemical reactions will enable the decarbonization of the chemical process industries as around 60% of process heating at present comes from fossil fuels. [3] Direct RF heating elevates the catalyst temperature above the bulk reactor temperature. This reduces the impact of noncatalytic hot-spots and has been shown to enhance yields for a variety of organic synthesis and pyrolysis reactions. [4][5][6] Lower coke formation is also reported in pyrolysis, [5,7] caused by a rapid quenching of side reactions as products quickly diffuse from the heated catalyst surface to the cooler bulk fluid. [8] RF heating uses lower frequencies than microwave heating, resulting in different advantages and challenges between the two methods. Lab-scale microwave reactions typically operate at 2.45 GHz and are heated through microwave absorption within a high dielectric solvent. [9] Larger microwave systems suffer from non-uniform heating due high absorption and low penetration of microwaves in the reactor solvent and hot-spots caused by constructive interference on the scale of the microwave wavelength, 12 cm for 2.45 GHz. [9] Higher frequencies are used to achieve greater heating power when scaling up microwave heating systems, which lead to lower heating efficiencies of 30% or less. [10] RF heated systems can achieve theoretical efficiencies greater than 80%, and efficiency increases with scale. [11] Finally, the absorption of microwaves in the human body leads to increased Radiofrequency heating of magnetic particles promises highly efficient and direct heating of catalytic reactors for coupling of low carbon electricity with energy intensive chemical transformations. In this work, a novel real-time and in situ magnetometry method is developed to measure minor and major hysteresis loops of soft magnetic nanopowders. It is applied to measure the magnetic properties and hysteresis power absorption of magnetite and maghemite powders up to 500 °C. An arctangent model for saturation magnetization is adapted for minor hysteresis loops. It produces an excellent fit for hysteresis loop power across field strengths up to 18.5 kA m −1 and allows prediction of heating power, remanence, and susceptibility. Samples of magnetite and maghemite are shown to heat rapidly from room temperature at more than 25 °C s −1 , with maghemite giving the strongest heating response. The peak heating power occurs at the transition beyond the ellipsoidal Rayleigh law region. These findings suggest that the properties of magnetic powders, coupled with variable magnetic field strengths and frequencies, can be tuned to optimize the heating power for a variety of applications.

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A method has been developed to reliably quantify the isotopic composition of liquid water, requiring only immersion of a “ReactIR” probe in the sample under test. The accuracy and robustness of this method has been extensively tested using a deuterium/protium system, and substantial improvements in sensitivity were obtained using highly novel chemical signal amplification methods demonstrating a standard deviation of 247 ppb D (a δD of 1.6 ‰). This compares favorably with other more costly and time-consuming techniques and is over 20 times more sensitive than any previously published FTIR study. Computational simulations of a model system match the experimental data and show how these methods can be adapted to a tritium/protium system.