H 2 production via green NH 3 decomposition is a key process in the value chain of renewable energy storage and distribution, but reactor engineering studies are at an early stage due to the still open research on catalyst formulation and reaction kinetics. In this work, the kinetics of NH 3 decomposition are studied over Ru/MgAl 2 O 4 , Ru/γ-Al 2 O 3 and Ru/MgO catalysts, that combine the best-known active metal, Ru, and supports suitable for industrial applications. For all the formulations, NH 3 concentration and H 2 -cofeed are found to negatively affect the conversion, in line with the literature; however, original experiments at varying NH 3 concentration with large H 2 -cofeed unambiguously show that, in the presence of H 2 -rich streams representative of the catalyst application, the intrinsic kinetics have a linear dependence on NH 3 partial pressure and a negative order (−1.5) with respect to H 2 partial pressure, consistent with the hypothesis that ammonia dehydrogenation is rate determining and H* is the most abundant surface intermediate. The same kinetic dependences were obtained over a commercial Ru-based catalyst. The kinetic relevance of hydrogen coverage and the intrinsic first order dependence on NH 3 have two important implications: on a methodological plane, the performance and kinetics of the catalyst under industrially relevant conditions (e.g. pure ammonia) can be captured even under highly diluted NH 3 feeds (which guarantee the rigorous isothermal conditions) provided that the large H 2 contents are experienced; on a more applicative plane, both kinetic and thermodynamic factors play negatively at increasing concentration and pressure, thus large sizing (with GHSV values as low as 2500 Nl/kg/h) is needed to obtain complete ammonia conversion below 500 °C. • The following scale of intrinsic activity is found: Ru/MgAl 2 O 4 > Ru/MgO ≈ Ru/Al 2 O 3 . • Independently from the nature of the support, reactions orders are 1 and − 1.5 for NH 3 and H 2 . • The kinetic dependences cause a dramatic decline of reaction rate with increasing extent of conversion. • High conversion of a pure NH 3 feed can be obtained below 500 °C at GHSV as low as 2500 NL/kgcat/h.

Historically, catalytic advances often occurred during events such as wars or embargoes. However, research efforts are focused on better understanding catalytic processes, minimising feedstock and process costs, developing new catalytic materials, and addressing environmental concerns. This study provides an overview of the global energy system, which forms the basis for the need for alternative energy sources as a panacea for reducing greenhouse gas emissions and providing clean and affordable energy sources through heterogeneous catalysis. It also discusses the development of numerous heterogeneous catalytic materials and processes, focusing on the catalytic conversion of biomass and its derivatives, particularly into fuel blendstocks and petrochemicals. In this context, the analysis of the techno-economic and environmental impact of the different biomass conversion technologies was emphasised. Despite the numerous catalysts and technologies developed and documented over the last century, catalytic processes still have some drawbacks. This study further examined the challenges and offered technological opportunities for developing catalytic materials and processes. It also provided a framework for advancing clean and affordable energy in the renewable energy sector using catalytic materials.

Enhancing energy release and safety performance of energetic materials has garnered significant attention in composite solid propellants. Boron nitride (BN), known for its high thermal conductivity and lubricating properties, is a promising additive. To explore its application in propellants, Al@AP core-shell structure particles were prepared using an in situ deposition method. Structural characterisation, thermal decomposition properties, combustion characteristics, and safety of BN-doped Al@AP samples were evaluated using SEM, BET, XRD, DSC-TG-FTIR, closed bomb, laser ignition, and BAM standards. The results confirmed that AP effectively coated Al to form a typical core-shell structure, and BN was successfully incorporated into the Al@AP framework. BN promoted the thermal decomposition of Al@AP; at 0.5 wt% and 1.0 wt% BN, the low-temperature decomposition temperature of AP decreased by 28.01 °C and 26.85 °C, while the high-temperature decomposition temperature dropped by 6.41 °C and 5.25 °C, respectively. Closed bomb and laser ignition experiments indicated that with increasing BN content, the pressure rise rate and combustion intensity initially increased and then decreased. At 0.5 wt% and 1.0 wt% BN, the maximum pressure reached 127.93 kPa and 155.97 kPa, with corresponding pressure rise rates of 19.12 kPa/ms and 11.80 kPa/ms. The addition of BN significantly improves the safety performance of Al@AP, considerably reducing its impact and friction sensitivities. These findings demonstrated that when the BN content was 0.5 wt% and 1.0 wt%, both the combustion characteristics and safety of Al@AP were improved, achieving a practical balance and providing design guidance for the application of BN-doped Al@AP in solid propellants. • Dual-functional BN boosts Al@AP combustion & safety. • BN lowers AP's decomposition temps, accelerates energy release. • 1 % BN: 155.97 kPa peak pressure, 11.80 kPa/ms rate. • BN's lubricity reduces friction sensitivity. • Provides insights into high-energy, safer next-generation composite propellants.

Ammonia (NH3) cofiring provides a promising solution to carbon reduction of coal-fired boilers, but it may lead to increased NOx emissions. However, many experiments observed that the NOx emissions exhibited an increase-then-decrease trend with the increase of NH3 cofiring ratio (RNH3), indicating that NOx could be controlled under high RNH3. To reveal the underlying mechanism, the experiments of NH3 cofiring with coal volatile were first conducted in a one-dimensional flow reactor to reveal that this trend is primarily attributed to the gaseous reactions of volatile and NH3. A chemical reactor network model was then constructed to investigate the influences of RNH3 on the NO reaction pathways of NH3. The predicted results replicated the increase and then decrease trend of NOx emissions as RNH3 increased beyond 25 %. It was found that NO formation is primarily controlled by the reactions between HNO/N and OH/H radicals. Under lower RNH3, the concentrations of HNO/N increase with the increase of RNH3 leading to increased NO formation. Under higher RNH3, however, much of the OH/H radicals are consumed by the dehydrogenation reactions of NH3 which consequently inhibits the NO formation reactions. Therefore, the root mechanism of the increase-then-decrease trend of NOx emissions is attributed to the competition for the OH/H radicals between the initial and final steps of the NO formation reaction pathway.