n-Butane dehydrogenation over Pt/Mg(In)(Al)O

The thermal dehydrogenation of butane to butene and hydrogen was investigated over Pt nanoparticles supported on calcined hydrotalcite containing indium, Mg(In)(Al)O. Prior work has shown that upon reduction in H-2 at temperatures above 673 K, bimetallic Pt-In particles of are formed, as evidenced by XANES and EXAFS. The performance of Pt/Mg(In)(Al)O for butane dehydrogenation was found to be highly dependent on the bulk In/Pt ratio. The optimal ratio was found to be between 0.33 and 0.88, yielding >95% selectivity to butenes. Hydrogen co-fed with butane was shown to suppress coke formation and catalyst deactivation, a ratio of H-2/C4H10 = 2.5 providing the best catalytic performance. Regeneration of catalysts after removal of accumulated carbon and reduction in H-2 restored the original catalyst activity and selectivity. Butane dehydrogenation above 803 K resulted in higher formation of butadiene, a known precursor to coke. No evidence for butane cracking was found to occur on Pt/Mg(In)(Al)O due to moderately basic nature of the support. The present study shows that Pt/Mg(In)(Al)O exhibits superior performance for butane dehydrogenation compared to supported Pt catalysts promoted with Sn, Ge, Pb, and In prepared by successive incipient wetness impregnation of the Pt and promoter precursors. (C) 2013 Elsevier B.V. All rights reserved.