ranking four different commercial catalysts and parameter screening under conditions relevant to industrial applications (temperature, pressure, and water concentration) also achieved successful outcomes. High throughput technology The most advanced 16-fold high throughput system designed for operation at high temperature combined with elevated pressures was used for this study. High-temperature metal alloy reactors were equipped with ceramic inlay tubes of 3-5 mm inner diameter to ensure the inert behaviour of the reactor material, which becomes relevant at >550°C. A similar test unit was validated and used for a reverse water-gas shift study published recently (Mutz, et al., 2022) and was further modified for processing NH₃. Figure 1 shows a simplified scheme of the high throughput testing equipment. The feed components H₂, N₂, and Ar were dosed individually using mass flow controllers, whereas NH₃ and H2 O were dosed as liquids using two separate high-precision syringe pumps. The feed mixture was equally distributed over the 16 parallel reactors. The catalysts were tested as particles in a size fraction of 125-160 µm and diluted in inert material of a similar size to minimise temperature gradients in the catalyst bed. The reactor pressure was controlled downstream by feeding additional N₂. The reactor effluent gas was analysed using a multi- detector gas chromatograph (GC) configured in-house and equipped with different thermal conductivity detectors (TCDs) for permanent gas, NH₃, and H₂O quantification. hte process control software enabled fully automated and continuous operation and monitoring of the high throughput system. Data evaluation and charting were performed with the myhte software solution, which was specifically developed for processing large amounts of data produced by such a high throughput setup (Hauber & Sauer, 2022). Validation A flexible hte 16-fold parallel testing unit was upgraded to process NH₃ and subsequently validated using a Fe-based catalyst prepared in-house to further optimise the equipment and
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Figure 1 Simplified scheme of the 16-fold parallel high throughput testing unit by hte
demanding industrially applicable investigation, establishing long-term viability, and conducting accelerated ageing experiments. Enhancing the NH₃ cracking process is necessary to achieve equilibrium NH₃ conversion, particularly when dealing with decentralised plant operations at lower temperatures. The purity of H₂ obtained from NH₃ is contingent upon its intended use; even NH₃ traces can act as a poison in applications such as fuel cells (Guo & Chen, 2017). The optimisation of NH₃ cracking, particularly at elevated pressures, is essential for downstream H₂ usage (such as syngas conversion) in industrial applications. While low-pressure conditions are thermodynamically favoured and commonly studied, industrial needs, such as efficient H₂ use, necessitate re-evaluating NH₃ cracking at higher pressures. This article introduces the most advanced high throughput approach to accelerate catalyst screening and optimise the NH 3 cracking process, thereby addressing the significant research gap in studies combining high temperature and pressure. A versatile 16-fold parallel fixed-bed reactor set-up operated in hte’s laboratories in Heidelberg was used, featuring high-temperature reactor technology designed for elevated pressures. Validation of the high throughput unit for the NH₃ cracking process was carried out using a Fe-based catalyst prepared in-house while screening a wide range of parameters. Subsequent customer projects aimed at
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