Performance and operating limits of a sorbent-catalyst system for sorption-enhanced reforming (SER) in a fluidized bed reactor

摘要

The combined performance of a synthetic CaO-Ca12Al14O33 sorbent and an Ni-MgAl2O4 reforming catalyst was tested in a fluidized bed reactor under relevant operating conditions for the sorption-enhanced reforming (SER) process. The effect of CH4 space velocity (i.e. kg(CH4)/h.kg(cat)), steam-to-carbon (S/C) ratio and superficial gas velocity on product gas composition was assessed, as well as the effect of regeneration conditions on material performance. Moreover, a bi-functional material prepared by mechanical mixing of the separate materials was also tested in the reactor under consecutive SER/regeneration cycles. H-2 contents as high as 96 vol% (N-2 free, dry basis) were achieved under SER operation, using the separate materials working with an Ni content of 3.75 wt% in the solid bed at 650 degrees C with S/C ratios of 3 and 4. This solid system is able to process up to 0.63 kg(CH4)/h.kg(cat) at 0.1 m/s superficial gas velocity and with an S/C ratio of 4, although the CH4 input has to be reduced to 0.33 kg(CH4)/h.kg(cat) when working with a lower S/C ratio. Similar H-2 contents to those found with the separate materials were obtained with the combined sorbent-catalyst material working with 0.33 kg(CH4)/h.kg(cat) at 0.1 m/s superficial gas velocity and S/C ratios of 3 and 4. The CO2 sorption capacity of the combined material produced the same as that of the separate sorbent particles (i.e. around 0.25 g(CO2)/g calcined sorbent), while remaining stable throughout the SER/regeneration cycles. (C) 2019 Elsevier Ltd. All rights reserved.