Experimental and exergy evaluation of ethanol catalytic steam reforming in a membrane reactor

Abstract

The application of exergy analysis in the evaluation of the ethanol steam reforming (ESR) process in a catalytic membrane reactor (CMR) was presented. ESR experiments were performed at T=873–923K and P=4–12bar in a CMR containing Pd–Ag membranes sandwiched by Pd–Rh/CeO2 catalyst, aiming to produce fuel cell grade pure hydrogen. The effect of the operating conditions on the pure hydrogen production rate, hydrogen yield and recovery, exergy efficiency, and thermodynamic losses was investigated. Total hydrogen yield of 3.5mol H2 permeated per mol ethanol in feed with maximum hydrogen recuperation of 90% was measured at 923K and 12bar. The highest amount of exergy was destructed via heat losses and the retentate gas stream. Exergy efficiency up to around 50% was reached in the case of the insulated reactor at 12bar and 923K. Exergy efficiency placed between 70–90% in the case of recovery of the retentate gas in an insulated reactor. It was concluded that operating at the highest pressure, the lowest S/C ratio, and 923K gives the best exergy efficiency.