Carbon Dioxide Reforming of Methane To Produce Synthesis Gas over Metal-Supported Catalysts: State of the Art Shaobin Wang and G. Q. (Max) Lu* Department of Chemical Engineering, The University of Queensland, St. Lucia, QLD 4072, Australia Graeme J. Millar Department of Chemistry, The University of Queensland, St. Lucia, QLD 4072, Australia Received November 14, 1995 X Carbon dioxide reforming of methane produces synthesis gas with a low hydrogen to carbon monoxide ratio, which is desirable for many industrial synthesis processes. This reaction also has very important environmental implications since both methane and carbon dioxide contribute to the greenhouse effect. Converting these gases into a valuable feedstock may significantly reduce the atmospheric emissions of CO 2 and CH 4 . In this paper, we present a comprehensive review on the thermodynamics, catalyst selection and activity, reaction mechanism, and kinetics of this important reaction. Recently, research has centered on the development of catalysts and the feasible applications of this reaction in industry. Group VIII metals supported on oxides are found to be effective for this reason. However, carbon deposition causing catalyst deactivation is the major problem inhibiting the industrial application of the CO 2 /CH 4 reaction. Ni-based catalysts impregnated on certain supports show carbon-free operation and thus attract much attention. To develop an effective catalyst for CO 2 reforming of CH 4 and accelerate the commercial application of the reaction, the following are identified to be the most important areas for future work: (1) selection of metal and support and studying the effect of their interaction on catalyst activity; (2) the effect of different promoter on catalyst activity; (3) the reaction mechanism and kinetics; and (4) pilot reactor performance and scale-up operation. Introduction In recent years, considerable attention has been paid to global warming due to the greenhouse effect. The reduction and utilization of greenhouse gases such as carbon dioxide and methane is therefore becoming more and more important. Catalytic reforming of methane with carbon dioxide to synthesis gas has been proposed as one of the most promising technologies for utilization of these two greenhouse gases as carbon-containing materials. 1 The synthesis gas, produced by the reaction, has a high CO content which is effective for the synthesis of valuable oxygenated chemicals. 2,3 Unfortunately, there is no established industrial technology for carbon dioxide reforming of methane, in spite of potentially attractive incentives with economical and environmental benefits. The principal reason for this is the carbon-forming reaction, which quickly deactivates conventional reforming catalysts if used without the presence of steam. No effective commercial catalyst to date exists which operates without carbon formation. In the past decade, efforts have focused on the development of catalysts which show high activity and stability for methane partial oxidation 4-11 and methane dry reforming with carbon dioxide 12-21 to syngas. Nickel- based catalysts 4,5,11-17 and noble metal-supported cata- lysts (Rh, Ru, Pd, Pt, Ir) 6-11,18-21 were found to have * Author to whom all correspondence should be addressed. Phone: 61 7 33653708. Fax: 61 7 33654199. Email: maxlu@cheque.uq.edu.au. X Abstract published in Advance ACS Abstracts, May 1, 1996. (1) Wang, S.; Lu, G. Q.; Tang, H. S. Proc. 23rd Austr. Chem. Eng. Conf. 1995, 2, 42-47. (2) Alyea, E. C.; He, D.; Wang, J. Appl. Catal. 1993, 104, 77-85. (3) Burch, R.; Petch, M. I. Appl. Catal. 1992, 88, 39-60. (4) Dissanayake, D.; Rosynek, M. P.; Kharas, K. C. C.; Lunsford, J. H. J. Catal. 1991, 132, 117-160. (5) Choudhary, V. R.; Samsare, S. D.; Mammam, A. S. Appl. Catal. 1992, 90, L1-L5. (6) Ashcroft, A. T.; Cheethan, A. K.; Foord, J. S.; Green, M. L. H.; Grey, C. P.; Murrell, A. J.; Vernom, P. D. F. Nature 1990, 344, 319- 321. (7) Jones, R. H.; Ashcroft, A. T.; Waller, D.; Cheetham, A. K.; Thomas, J. M. Catal. Lett. 1991, 8, 169-171. (8) Hochmuth, J. K. Appl. Catal. B: Environ. 1992, 1, 89-100. (9) Vernon, P. D. F.; Green, M. L. H.; Cheetham, A. K.; Ashcroft, A. T. Catal. Lett. 1990, 6, 181-186. (10) Poirier, M. G.; Trudel, J.; Guay, D. Catal. Lett. 1993, 21, 99- 111. (11) Torniainen, P. M.; Chu, X.; Schmidt, L. D. J. Catal. 1994, 146, 1-10. (12) Gadalla, A. M.; Bower, B. Chem. Eng. Sci. 1988, 42, 3049- 3062. (13) Gadalla, A. M.; Sommer, M. E. Chem. Eng. Sci. 1989, 44, 2815- 2829. (14) Kim, G. J.; Cho, D. S.; Kim, K. H.; Kim, J. H. Catal. Lett. 1994, 28, 41-52. (15) Swaan, H. M.; Kroll, V. C. H.; Martin, G. A.; Mirodatos, C. Catal. Today 1994, 21, 571-578. (16) Chang, J. S.; Park, S. E.; Lee, K. W. Stud. Surf. Sci. Catal. 1994, 84, 1587-1594. (17) Zhang, Z.; Verykios, X. E. J. Chem. Soc., Chem. Commun. 1995, 71-72. (18) Ashcroft, A. T.; Cheethan, A. K.; Green, M. L. H.; Vernom, P. D. F. Science 1991, 352, 225-226. (19) Rostrup-Nielsen, J. R.; Hansen, J. H. B. J. Catal. 1993, 144, 38-49. (20) Qin, D.; Lapszewicz, J. Catal. Today 1994, 21, 551-560. 896 Energy & Fuels 1996, 10, 896-904 S0887-0624(95)00227-1 CCC: $12.00 © 1996 American Chemical Society