Enhanced ammonia decomposition in a structured membrane reactor using a Ru-coated SiC open-cell foam and a Pd-based membrane
J. Zúñiga, Gaetano Anello, J.J. Aragon, María del Mar Díaz de Guereñu, A. Arratibel, Gabriel Marino, Cristina Italiano, Antonio Vita, Fausto Gallucci
Abstract
Ammonia decomposition into nitrogen and hydrogen was carried in a structured membrane reactor in this work. The performance of the structured catalyst and the effect of hydrogen permeation through a Pd-based membrane were evaluated. The structured catalyst is based on a commercial silicon carbide open cell foam (40 PPI). The catalyst (3 wt% Ru/CeO 2 ) was coated by in situ-solution combustion deposition method with sequential cycles to reach the desired catalyst loading (0.31 g cm −3 ). TEM, SEM, XRD, TPR analysis and adhesion tests were used to characterize the prepared sample. A double-skinned Pd-based membrane has been prepared depositing a selective layer by electroless plating onto porous asymmetric α-Al 2 O 3 support. The results proved a successful integration of structured catalyst and membrane. The beneficial effects of the proposed structured membrane reactor configuration enabled an increase in conversion up to 29 % compared with the structured catalyst system. The reaction system allowed an ammonia conversion of 98.4 % and hydrogen purity of 99.2 % at 450 °C and 4 bar. Furthermore, at fixed flow rate, the structured membrane reactor can achieve comparable conversion at operating temperatures about 55 °C lower than in the case of the structured reactor. Moreover, the proposed configuration enabled a conversion higher than the thermodynamic value at 4 and 5.5 bar at fixed temperature (480 °C) and fixed feed flow rate (62 ml min −1 ). To the best of our knowledge, this work is the first study combining a structured catalyst and a Pd-based membrane for ammonia decomposition.