Carbon-supported Pt-M catalysts for the selective direct dehydrogenation of n-decane

In this work, monometallic Pt and bimetallic PtM catalysts (M = In, Ge, or Sn) supported on purified multiwalled carbon nanotubes (CNP) and Vulcan carbon (CV) were evaluated in the non-oxidative dehydrogenation of n-decane to α-decene. Catalytic behavior was correlated with the defect structure of the supports and with structural and electronic descriptors established by Raman spectroscopy, TPR, XPS, HRTEM, and test reactions. Although Pt/CV exhibited a slightly higher overall conversion, it also showed a greater tendency toward the formation of light, branched, and cyclic products. In contrast, Pt/CNP directed a larger fraction of the converted n-decane toward olefinic products, particularly 1-decene. This behavior is consistent with the more electron-rich Pt environment which may suppress C-C bond cleavage and facilitate olefin desorption, although it may also limit n-decane conversion. Promoter addition suppressed secondary transformations and improved α-olefin yield and stability without producing substantial changes in mean particle size. The PtGe/CNP and PtIn/CNP catalysts showed the highest yields to α-monoolefins, averaging 40% higher than the corresponding monometallic catalyst. These results demonstrate that support-controlled Pt electronic properties and promoter-induced ensemble modification jointly determine the balance between primary dehydrogenation and secondary C₁₀ reaction pathways, providing a structure-performance basis for the development of catalysts for long-chain paraffin direct dehydrogenation.