Production of hydrogen and MWCNTs by methane decomposition over catalysts originated from LaNiO3 perovskite

LaNiO3 type perovskite was prepared by the "self-combustion" method and was used as catalyst precursor for the methane decomposition reaction at 600 and 700 degrees C. CH4 conversion reaches 80% at 700 degrees C and 65% at 600 degrees C using pure CH4. The yield of CNT and H-2 were 2.2 g(CNT) g(-1) h(-1) and 8.2 L g(-1) h(-1) at 700 degrees C respectively after 4 h of reaction. When the reaction is prolonged to 22 h the catalytic activity decreases but the catalyst is still active, the production of hydrogen reaches 63.5 L (STP) per gram of catalyst and the production of MWCNT was equal to 17 g per gram of catalyst. Multi-wall carbon nanotubes were characterized by X-ray diffraction (XRD), surface area (BET), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Raman spectroscopy. TEM micrographs showed that MWCNT longer than 20 mu m were formed with inner diameters ranging from 5 to 16 nm and outer diameters up to about 40 nm. The results obtained here clearly show that the use of the perovskite LaNiO3 as catalytic precursor is very effective for the simultaneous production of carbon nanotubes and hydrogen. (C) 2009 Elsevier B.V. All rights reserved.