Dynamic simulation of pure hydrogen production via ethanol steam reforming in a catalytic membrane reactor

Abstract

Ethanol steam reforming (ESR) was performed over Pd-Rh/CeO2 catalyst in a catalytic membrane reactor (CMR) as a reformer unit for production of fuel cell grade pure hydrogen. Experiments were performed at 923 K, 6–10 bar, and fuel flow rates of 50–200 µl/min using a mixture of ethanol and distilled water with steam to carbon ratio of 3. A static model for the catalytic zone was derived from the Arrhenius law to calculate the total molar production rates of ESR products, i.e. CO, CO2, CH4, H2, and H2O in the catalytic zone of the CMR (coefficient of determination R2 = 0.993). The pure hydrogen production rate at steady state conditions was modeled by means of a static model based on the Sieverts' law. Finally, a dynamic model was developed under ideal gas law assumptions to simulate the dynamics of pure hydrogen production rate in the case of the fuel flow rate or the operating pressure set point adjustment (transient state) at isothermal conditions. The simulation of fuel flow rate change dynamics was more essential compared to the pressure change one, as the system responded much faster to such an adjustment. The results of the dynamic simulation fitted very well to the experimental values at P = 7–10 bar, which proved the robustness of the simulation based on the Sieverts' law. The simulation presented in this work is similar to the hydrogen flow rate adjustments needed to set the electrical load of a fuel cell, when fed online by the pure hydrogen generating reformer studied.Peer ReviewedPostprint (author's final draft

Preliminary Equipment Design for On-Board Hydrogen Production by Steam Reforming in Palladium Membrane Reactors

“…Considering other aspects related to the mechanical stability of the membrane, a total pressure of 10 bar for the retentate side was selected as the most appropriate operating condition to be used in the membrane reactor, both for ethanol and methane intakes. The stability of H 2 -selective membranes at this operating pressure was demonstrated in previous works at lab scale, avoiding cracks generation or delamination of the selective film [36,40].…”

“…Under this perspective, and considering that temperatures above 650 • C do not increase the hydrogen productivity remarkably, this value was selected as the most appropriate operating temperature to perform the process when feeding both ethanol and methane. was demonstrated in previous works at lab scale, avoiding cracks generation or delamination of the selective film [36,40]. Influence of main operating conditions for the membrane reactor when feeding ethanol or methane: (a) temperature, (b) steam to feed hydrocarbon ratio and (c) total retentate pressure.…”

“…Pd-based membranes are prepared onto supporting materials and experimentally they are used in the typical range of 400-550 • C to prevent possible damages on the composite structure, although it is expected to resist slightly higher temperatures [33,34]. In this manner, it is also possible to find several works in which these membranes operate at temperatures up to 650 • C with satisfactory results in terms of mechanical stability [35][36][37][38]. Under this perspective, and considering that temperatures above 650 • C do not increase the hydrogen productivity remarkably, this value was selected as the most appropriate operating temperature to perform the process when feeding both ethanol and methane.…”

Coke formation and deactivation during catalytic reforming of biomass and waste pyrolysis products: A review

“…To enhance these attributes even further, some other new technologies include microreactors, some of which use foam-like porous catalysts, in the steam reforming of ethanol [128,129], dimethyl ether [130,131] or phenol [132]; and membrane reactors, for the steam reforming of methanol [133], ethanol [134] or glycerol [135]. However, in general terms these approaches are not as efficient as traditional systems, in terms of conversion, H2 yield and future scaling-up [136].…”

Process Modeling, Optimization, and Heat Integration of Ethanol Reforming Process for Syngas Production with High H2/CO Ratio

“…Rossetti et al [10] calculated the equilibrium compositions of the ethanol steam reforming at different conditions and estimated their kinetic model parameters. Hedayati et al [11] conducted dynamic simulation of ethanol steam reforming for hydrogen production in a catalytic membrane reactor. Serra et al [12] developed a nonlinear dynamic model and conducted a static-dynamic analysis for the ethanol steam reforming with membrane separation process.…”