Catalytic decomposition of methane on Raney-type catalysts
The catalytic decomposition of methane into COx-free hydrogen and filamentous carbon was investigated on Raney-type catalysts. Catalysts performance was assessed by comparing the measured conversions with the equilibrium values and with selected results reported recently. The activity, selectivity and stability were dependent on the alloy composition and preparation method (conventional or quenched alloy types), as well as the operating conditions. Textural properties, chemical compositions and catalyst performances were determined, and the carbon deposits were characterized by different techniques. Ni and Co catalysts obtained from Raney-type alloys prepared by quenching showed better performance for methane decomposition than conventional systems, with conversions approaching equilibrium. The stability of the catalysts could be extended by increasing the contact time and by hydrogen pre-treatment of the catalysts. The carbon deposits consist mostly of carbon nanofibres and carbon nanotubes. In addition to the high activity and stability for methane decomposition, there was no generation of carbon oxides, which makes these catalysts suitable for the production of pure hydrogen for fuel cells.
Graphical abstractRaney-type catalysts promote the decomposition of methane into COx-free hydrogen and filamentous carbon (CNF or MWCNT). Nickel and cobalt catalysts perform better than iron. Catalysts obtained from alloys prepared by quenching lead to better results than conventional systems, which was interpreted on the basis of the respective microstructures. Higher temperatures increase activity and higher contact times favour stability. Figure optionsDownload full-size imageDownload as PowerPoint slide
Journal: Applied Catalysis A: General - Volume 348, Issue 1, 30 September 2008, Pages 103–112