n-decane dehydrogenation on bimetallic PtSn and PtGe catalysts prepared by dip-coating

Abstract

The catalytic performance of Pt, PtSn and PtGe supported on γ Al 2 O 3 (γ A) deposited by dip coating of spheres of α Al 2 O 3 (α A) is studied in the n decane dehydrogenation. The effect of Sn and Ge addition to Pt on the activity and selectivity was analyzed. The catalytic characterization was carried out by using cyclohexane dehydrogenation (CHD), cyclopentane hydrogenolysis (CPH), temperature pro grammed reduction (TPR), hydrogen chemisorption, X ray photoelectron spectroscopy (XPS), thermo gravimetric analysis (TGA) and scanning electronic microscopy (SEM). Pt(0.5)Sn/γ A/α A catalyst had the best catalytic performance and showed a low electronic interaction between the metals, with a surface segre gation of Sn and the presence of oxidized Sn stabilized on the support. PtGe catalysts presented strong inter actions with probable alloy formation. The catalytic performance of these catalysts is comparable to that reported in the patents.

Catalytic Dehydrogenation of Light Alkanes on Metals and Metal Oxides

“…130−133 Another alloy that has been investigated is Pt−Ge, which is believed to function in a way analogous to that of Pt−Sn, although the electronic effect is believed to be weaker. 134 An overview of the Pt-based dehydrogenation catalysts discussed above, including relevant reaction parameters, such as conversion, selectivity, temperature, space velocity, and feed composition, is given in Table 3. The activity of the catalysts is compared using their calculated "specific activity", which is defined as the moles of olefin formed per mol of Pt per second at the start of the dehydrogenation reaction.…”

Promoter-poison partnership protects platinum performance in coked cluster catalysts

“…This change in selectivity has been attributed to carbon blocking the most reactive and least selective sites, which can catalyze side-reactions leading to coke formation. [18][19][20][21][22][23] An additional explanation is that the presence of carbon can modify olefin adsorption strength on a surface, and increase the energy barrier for C-H activation. 17 Coke may therefore deactivate Pt catalysts via an electronic interaction, in addition to steric blocking.…”

“…Sn is the most widely-used dopant for Pt, though Ge has been found to produce similar improvements in stability against cok-ing. [20][21][22][23] XPS of subnano PtSn clusters shows a shift to lower binding energies, implying that Sn tends to donate electrons to Pt. 3 However, there have been reports that PtSn catalysts build up more coke than their pure Pt analogues, 24 suggesting that they are not simply resistant to the build-up of coke, but that their activity persists despite partial coking.…”

Synthesis of spherical structured catalysts by dip‐coating: Application to n‐butane dehydrogenation

“…However, a deep study of the deposition conditions of thin layers of bohemite on a substrate with spherical geometry has not been reported yet. Besides, few papers investigate the catalytic performance of bimetallic catalysts supported on γ‐Al 2 O 3 deposited on α‐Al 2 O 3 spheres …”

“…Besides, few papers investigate the catalytic performance of bimetallic catalysts supported on g-Al 2 O 3 deposited on a-Al 2 O 3 spheres. [21][22][23][24] Hence, in this paper a technique to deposit thin layers of g-Al 2 O 3 on an inert substrate of a-Al 2 O 3 spheres with very low porosity is developed. In this case, bohemite was used as a precursor of the g-Al 2 O 3 layer, which has high surface area, low acidity, and good interaction with metals.…”