K atalco 65-3XR conversion
CRG-LHR conversion
Temperature
Figure 4 SEM of whisker carbon (left) and TEM of nickel crystallite in polymeric gum (right) between feedstock types, as operation with an exothermic feedstock accelerates the ageing of the catalyst beyond that expected for an endothermic feed. Under these circumstances, it becomes necessary to balance the potential benefits of low-cost feed availability against any potential reduction in catalyst life. Other deactivation mechanisms Carbon laydown is a major deactivation mechanism for pre-reforming catalysts, particularly when processing heavier feedstocks, such as naphtha, or when running at low steam-to-carbon ratios. “ Carbon laydown is a major deactivation mechanism for pre-reforming catalysts, particularly when processing heavier feedstocks Carbon laydown can be an issue both directly in the catalyst bed and also occur in the upstream preheat coils, which then deposits on the bed. When carbon laydown occurs in the catalyst, it can be in the form of polymeric gum or whisker carbon (see Figure 4 ). Polymeric gum occurs when the pre-reformer temperature is too low, whereas whisker carbon occurs via hydrocarbon cracking when the temperature is too high. The pre-reformer must therefore be run in a specific temperature window to remain carbon-free, with the position of the window depending on factors such as feedstock composition, the amount of steam used, system pressure, and catalyst selectivity. or when running at low steam-to-carbon ratios ”
Time
Figure 5 Activity of stressed Katalco 65-3XR and CRG-LHR at varying temperatures Oxidation of the catalyst can also lead to poor activity of a pre-reformer. Pre-reforming catalysts are typically supplied and charged into the pre-reformer in a reduced and passivated (surface-oxidised) form to enable easy in situ activation and handling under air. Conditions during normal operation ensure the catalyst remains in the reduced phase. However, in the event of excessive steam purge, such as during a plant drip, or due to accidental air increase, such as during a start-up, the nickel-based pre-reforming catalysts can be deactivated by oxidation. If oxidation does occur, re-reduction may not lead to full recovery of activity, as oxidation-reduction cycles promote catalyst sintering. Full re-reduction can also be difficult to achieve for some plants if they are unable to achieve the required activation temperatures. Enhancing pre-reforming performance with Katalco 65-3XR Johnson Matthey (JM) has been a leader in pre-reforming catalysis, initially in partnership with British Gas. The company has a long history of manufacturing and servicing CRG catalysts, dating back to the early 1960s when CRG catalysts were first produced. Environmental regulations and the need for improved performance have continued to drive developments in pre-reforming catalysts. Katalco 65-3XR, JM’s latest pre-reforming catalyst, is nickel-based and chromium-free. It provides robust and high activity at a relatively low cost. Containing 45% w/w nickel and utilising layered structured minerals during the production process to enhance nickel dispersion,
Refining India
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