Applied Catalysis A: General, Vol.557, 25-38, 2018
Catalytic activities and resistance to HCl poisoning of Ni-based catalysts during steam reforming of naphthalene
Hydrogen chloride is commonly present in syngas produced from municipal solid waste and biomass gasification. The influence of HCl on the activity of nickel-based catalysts during catalytic naphthalene reforming was investigated. Two synthesized and two commercial catalysts were tested for steam reforming at 790 degrees C and SV 24,000 h(-1). In the absence of HCl, nickel supported on limestone (Ni/Limestone) demonstrated lower naphthalene conversion (similar to 80%) compared to nickel supported on alumina (Ni/Alumina) and two commercial alumina supported catalysts (similar to 100%). In the presence of 2000 ppmv HCl, the naphthalene conversion of Ni/Limestone rapidly decreased due to the reaction with HCl and, probably, formation of molten CaCl2 deactivating the supported Ni nanoparticles. These data demonstrate limited applicability of calcium-based nickel catalysts for naphthalene reforming at the studied temperature. The efficiencies of Ni/Alumina and two commercial catalysts were maintained at similar to 100% naphthalene conversion. However, HCl concentrations of 500-2000 ppmv had detrimental effect on water-gas shift activity of alumina supported catalysts during naphthalene reforming. The spent alumina supported catalysts were characterized by N-2 adsorption, FESEM/EDS, XRD, XPS, TPR and TEM after the reforming in the absence and presence of HCl, and the results suggested that HCl increased nickel sintering in the catalysts causing the loss of water-gas shift activity. The losses of catalytic activity varied among the catalysts and were the lowest for Ni/Alumina, which contained nanosized porous alumina support and had the strongest Ni nanoparticle-support interactions.