lyst’s lifetime. Grades range from the highest activity shape mini QuadraLobe (MQ) to the low pressure drop extra-large QuadraLobe (XQ) catalyst, allowing a tailored selection to optimise between activity and pressure drop. The water gas shift section of the hydrogen plant typically contributes around 15% of the hydrogen pro- duced. High temperature shift catalyst with a higher activity, better thermal stability, and improved poison - ing resistance can also enable an increase in hydrogen production. Premium catalysts such as Katalco 71-6 have enhanced activity, improved in-service strength, and more wetting resistance. The water gas shift reaction is an exothermic and equilibrium reaction. A higher activity catalyst allows operation at lower opti- mal temperatures and thus a more favourable equi- librium position for higher conversion. The improved strength ensures a consistently low pressure drop throughout the operating life, and simple StreamLine technology can be installed to reduce further the pres- sure drop across a water gas shift vessel. In summary, many factors limit the production rate of a hydrogen plant. To maximise the production rate, a good understanding of the plant limits is needed, and selection of the right catalyst is required to enable maximum production capacity whilst maintaining reliability and efficiency. A Rainer Rakoczy, Technology Advisor Fuel, and Maximilian Dochnahl, Head of Modelling & On-site Technology, Clariant Catalysts Technip Energies and Clariant recently made a break- through in the productivity, efficiency, and sustain - ability of steam reforming. EARTH, an acronym for “enhanced annular reforming tube for hydrogen,” is a technology patented by Technip Energies that consists of an innovative, concentric tubular struc- ture as a drop-in insert for the steam reformer tubes and contains tailor-made structured catalysts jointly developed with Clariant. This unique setup results in superior heat recovery, higher throughput, and signifi - cantly lower pressure drop than a conventional cata- lyst and catalytic tube layout. The outstanding internal heat recovery of the EARTH technology presents several major advantages for hydrogen and syngas producers. Firstly, it signifi - cantly reduces external heat flux demand through fir - ing. Hence, producers can increase plant throughput and capacity by up to 20% while maintaining their current costs and process conditions. Alternatively, producers can choose to significantly lower their oper - ating costs at equal yield while reducing CO 2 emis- sions by up to 10% per unit of syngas produced. Our EARTH technology is designed as a drop-in solution compatible with new or existing steam reformers tubes with inlet and outlet sections at opposing ends of the furnace. Its installation requires no additional plot space and is comparable to a typical catalyst changeout. In addition, the tubes can be deliv- ered preloaded with catalysts on request.
transfer from the burners to the catalyst are important for maximising production. The formulation and the manufacturing process determine the intrinsic activity of the catalyst. Katalco 57-6 series has a patented man- ufacturing technique that makes the active metal on the pellet more accessible to the gas and enables per- formance deeper into the operating cycle. The size and shape of the catalyst will impact the tube-side lami- nar film layer and, therefore, the overall heat trans - fer coefficient. Catalysts such as Johnson Matthey’s QuadraLobe catalysts can provide better packing characteristics, more tube wall contact points, and radial gas mixing, thereby improving the heat transfer properties. Uniformity of the catalyst loading, reliable tube wall temperature monitoring, and balancing for better utilisation of firing capacity are also important controls for easing limits caused by tube temperature limits or other furnace constraints, such as limited combustion airflow or flue gas temperature limits. Due to the temperatures at which steam reform- ers operate, carbon is constantly being formed from the hydrocarbon feed. However, carbon gasification reactions simultaneously occur that remove the car- A higher activity catalyst allows operation at lower optimal bon laid down, meaning there is no net accumulation of carbon in a well-run plant. The rate of carbon lay- down depends on a number of conditions, such as the catalyst activity, degree of sulphur poisoning, and heat input to the tubes. As the steam reformer cata- lyst ages, the gradual deactivation of the catalyst can increase the tube wall temperatures and the potential for carbon formation. High activity, good thermal stability, and alkali promotion can ensure the carbon removal rate is faster than the carbon formation rate. Promoted catalysts, such as Katalco 25-series and Katalco 46-series, maximise protection against carbon formation and allow higher production rates to be maintained through the life of the catalyst. For higher production rates, the catalyst should allow for the lowest possible pressure drop, as this will enable the highest possible plant throughput before compressor limits are reached. The catalyst breakage characteristics are important for the steam reforming catalysts as all pelleted steam reforming catalysts will break due to the forces exerted on them when reformer tubes expand in operation and then contract during plant shutdowns. QuadraLobe shaped catalyst pellets are specifically designed to avoid generating small pellet fractions when breaking and hence minimise pressure drop increase over the cata- temperatures and thus a more favourable equilibrium position for higher conversion
20 Catalysis 2022
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