Aspen Plus Simulation of a Sorption-Enhanced Steam Methane Reforming Process in a Fluidized Bed Reactor Using CaO as a Sorbent for CO2 Capture

In this work, Aspen Plus was used to simulate a sorption-enhanced steam methane reforming (SE-SMR) process in a fluidized bed reformer using a Ni-based catalyst and CaO as a sorbent for CO2 removal from the reaction environment. The performances of the process in terms of the outlet gas hydrogen purity (yH2), methane conversion (XCH4), and hydrogen yield (ηH2) were investigated. The process was simulated by varying the following different reformer operating parameters: pressure, temperature, steam/methane (S/C) feed ratio, and CaO/CH4 feed ratio. A clear sorption-enhanced effect occurred, where CaO was fed to the reformer, compared with traditional SMR, resulting in improvements of yH2, XCH4, and ηH2. This effect, in percentage terms, was more relevant, as expected, in conditions where the traditional process was unfavorable at higher pressures. The presence of CaO could only partially balance the negative effect of a pressure increase. This partial compensation of the negative pressure effect demonstrated that the intensification process has the potential to produce blue hydrogen while allowing for less severe operating conditions. Indeed, when moving traditional SMR from 1 to 10 bar, an average decrease of yH2, X, and η by −16%, −44%, and −41%, respectively, was recorded, while when moving from 1 bar SMR to 10 bar SE-SMR, yH2 showed an increase of +20%, while XCH4 and ηH2 still showed a decrease of −14% and −4%.