Performance of a Ni/ZrO_2 catalyst in the steam reforming of the volatiles derived from biomass pyrolysis

摘要

The activity and stability of a Ni/ZrO2 catalyst have been studied in a continuous bench scale plant, in which biomass has been pyrolysed at 500 degrees C in a conical spouted bed reactor and the outlet volatile stream has been subjected to catalytic steam reforming at 600 degrees C in a fluidized bed reactor. The influence of space time has been analyzed, and both the fresh and the deactivated catalysts have been characterized by means of different techniques: N-2 adsorption-desorption, X-ray fluorescence (XRF), X-ray powder diffraction (XRD), temperature programmed oxidation (TPO), and transmission electron microscopy (TEM). The aim of this characterization is to relate catalyst performance to the evolution of the properties from the fresh to the deactivated catalysts. Thus, an increase in space time leads to an improvement in the stability of the catalyst extending its operation period from 20 to 100 min on stream, with a maximum H-2 yield of 92.4% (referred to the maximum allowed by stoichiometry) when a space time of 20 g(cat) min g(volatiles)(-1) has been used. Although the ZrO2 support has suitable properties, coke deposition is the main cause of catalyst deactivation.