Methanol steam reforming for hydrogen generation: A comparative modeling study between silica and Pd-based membrane reactors by CFD method

Abstract

Pd-based membranes are the most studied in applications of membrane reactors in the field of high grade hydrogen production. The main issues of Pd-membranes such as high cost and relatively low hydrogen permeability limit their wide development at larger scale, favoring other inorganic materials such as silica to be used as membrane for hydrogen generation/purification. Therefore, this theoretical study aims to evaluate the performance of silica (4 mm of thickness and 5 cm of active length) and PdAg (50 μm thick and 5 cm of active length) membrane reactors exercised at the same operating conditions and using the same reaction kinetics to produce hydrogen from methanol steam reforming reaction. Furthermore, an equivalent traditional reactor is studied for comparison. A computational fluid dynamics model was developed, firstly validating the former with experimental literature data. The effects of reaction pressure and temperature on the reactors performance in terms of hydrogen yield, methanol conversion and CO selectivity were hence studied and discussed. The simulations via CFD method indicated that the silica membrane reactor results to be the best solution over the PdAg MR and the TR as well, presenting the best simulation results at 513 K, 10 bar, sweep-factor = 6, GHSV = 6000 h−1 and feed molar ratio = 3/1 with CO selectivity equal to 0.04%, methanol conversion and hydrogen yield >90%.