▎ 摘　　要

NOVELTY - A single-atom iridium-based nano-diamond/graphene composite catalyst comprises iridium as active material and nano-diamond/graphene composite material as carrier. The iridium is uniformly dispersed on the surface of nano-diamond/graphene carrier in the form of a single atom. USE - The single-atom iridium-based nano-diamond/graphene composite catalyst is used for direct dehydrogenation of n-butane to produce butene, preferably 1-butene, 2-butene and/or butadiene (all claimed). ADVANTAGE - The composite material catalyst can achieve efficient conversion of butane to butene under low temperature conditions and has no environmental pollution compared with the traditional platinum-tin bimetallic catalyst and chromium oxide catalyst. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) preparation of the composite catalyst comprising preparing nano-diamond/graphene composite material, loading iridium by dipping to obtain catalyst precursor, adding to quartz tube, and subjecting to reduction treatment under mixture of hydrogen and nitrogen atmosphere; and (2) direct dehydrogenation method of n-butane to butene comprising adding composite catalyst to 1-5 wt.% n-butane, and catalytically reacting at 400-450 degrees C and at space velocity of 1000-90000 mL/g.hour under n-butane and hydrogen mixed gas and helium gas as equilibrium gas. The molar ratio of n-butane and hydrogen is 1:0.5-5.