Effects of Support Material and Sulfation on Propane Oxidation Activity over Platinum

Sulfur promoted low-temperature oxidation of methane over ceria supported platinum catalysts

“…Figure 4 and 5), the methane conversion starts to decrease when SO 2 is removed from the feed but not to the initial conversion of the experiment, indicating that the role of the support is not only to provide an alternative route for SO x removal from Pt. It has been reported that sulfation of alumina increases the surface acidity [15,16]. However, Hubbard et al [15] did not find any correlation between surface acidity and catalytic activity for sulfated Pt/SiO 2 , Pt/ZrO 2 and Pt/Al 2 O 3 .…”

“…Hubbard et al [15], Burch et al [16] and Skoglundh et al [17] have reported a promotional e↵ect on propane oxidation over Pt/Al 2 O 3 but not over Pt/SiO 2 when SO 2 was introduced. It is well known that sulfur oxides interact di↵erently with these support materials, while rapidly forming surface sulfates on Al 2 O 3 such species are not formed in the same extent on the SiO 2 surface [17,30].…”

“…For supported catalysts this mechanism is likely of less importance keeping in mind that the degree of promotion has been shown to significantly depend on the type of support material. For example, promotional e↵ects on oxidation of methane and/or propane have been seen for Pt/Al 2 O 3 [14][15][16][17][18][19][20][21] and Pt/Ce 0.67 Zr 0.33 O 2 [22] but not for Pt/SiO 2 [15][16][17]. The ability of the support to form sulfates is most likely of importance, which explains the di↵er-ence between SiO 2 and the former two support materials.…”

“…It is also important which support sites that undergo sulfation. For example, Burch et al [16] and Hubbard et al [15] showed that the increase in surface acidity of the support upon SO 2 exposure correlates poorly with the changes in activity for propane oxidation.…”

“…Corro et al [13] reported a decreased light-o↵ temperature for methane oxidation over presulfated Pt/Al 2 O 3 by the addition of C 2 -C 4 n-alkanes. Several authors have also reported on an increased activity for oxidation of short saturated hydrocarbons over Pt/Al 2 O 3 catalysts in the presence of sulfur, either through presulfation of the catalyst or by inclusion of low amounts of SO 2 in the feed gas [14][15][16][17][18][19][20]. The mechanism for the promotional e↵ect of sulfur on the activity for hydrocarbon oxidation is not fully understood.…”