Simultaneous naphthalene and thiophene hydrogenation over Ni(X)–Pt/HMOR catalysts

• For the thiophene hydrogenation, the Ni(0.5)–Pt/HMOR catalyst is the most active.
• Ni(X)–Pt/HMOR samples exhibit thio-resistance and thio-tolerance on thiophene HYD.
• Ni(X)–Pt/HMOR catalysts show hydrogenation activity in the presence of 500 ppm S.
• Ni(X)–Pt/HMOR catalysts is less prone to deactivation.
• Hydrogen spillover plays a key role in keeping HYD activity in the presence of sulfur.

A series of Ni(X)–Pt/HMOR catalysts (X = 0, 0.5, 1.0, 1.5 and 2.0 wt% of Ni and a fixed quantity of Pt = 1 wt%) were prepared and tested in the hydrogenation (HYD) of naphthalene with and without thiophene and also in the hydroconversion of thiophene. The catalysts were characterized using N2 physisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM) and TEM-EDS elemental analysis. The TPR and TEM results indicate that Pt is mainly located inside the pore system of the mordenite, whereas Ni is located on both the external surface and inside the pore system of the mordenite zeolite. Naphthalene hydrogenation exhibited a high conversion for all the catalysts. In the presence of a sulfur compound and for naphthalene hydrogenation, all the tested catalysts present a fast deactivation. Ni/HMOR catalyst was less active and presents complete deactivation. However, the Ni(0.5)–Pt/HMOR and Pt/HMOR catalysts are able to convert thiophene and produce mainly tetrahydrothiophene. This hydrogenation activity was stable, at least for 12 h, showing that the catalytic system can preserve some of the hydrogenating capability. The values of thiophene hydroconversion and the selectivity to tetrahydrothiophene are much higher than the reported for similar systems. The hydrogenation activity is most likely due to the hydrogen spillover.

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