The role of doped Fe on the activity of alumina-supported Pt and Pd diesel exhaust catalysts

Abstract

Supported Pt and Pd are most commonly used for oxidation catalysts. They have similar and different characteristics for deactivation factors. The catalytic activity of Pt and Pd catalysts supported on c-Al 2 O 3 was studied in the presence and absence of H 2 O and SO 2 during CO oxidation under simulated conditions of diesel exhaust gas. Without the addition of H 2 O and SO 2 to the feed gas, Pd/Al 2 O 3 had a superior catalytic activity compared to Pt/Al 2 O 3 . The addition of H 2 O to the feed gas strongly and negligibly affected the activity of Pd and Pt, respectively, while the addition of SO 2 to the feed gas had a strong poisoning effect on the catalytic activity of both Pt and Pd catalysts. Although being the most active, Pd catalysts exhibited a strong sensitivity to water and sulfur-containing compounds. Fe was added to the Pt and Pd catalysts to introduce sulfur resistance. The addition of Fe enhanced the activity of the catalysts by suppressing the phase transition of Al 2 O 3 to Al 2 (SO 4 ) 3 and by hindering metal sintering.

A Review on the Impact of SO2 on the Oxidation of NO, Hydrocarbons, and CO in Diesel Emission Control Catalysis

“…80,201,210,264,270,276 Note that the dopant may work in crossing roles, which involves protecting noble metals from sulfation and hindering sintering and enriching oxygen vacancies, among other effects, at the same time. 153,277 For instance, the Ti aimed at modifying the support acidity can also enhance oxygen mobility by Ti−O−Si linkage when incorporated into the Si matrix in Pd/SBA-15 and Pd/hollow mesoporous silica (HMS) catalysts. However, the real sulfurresistance effect is associated with the distribution form of Ti.…”

SOx Tolerant Pt/TiO2 Catalysts for CO Oxidation and the Effect of TiO2 Supports on Catalytic Activity

“…Much research has been conducted into the effects of SO 2 on the activity of noble-metal catalysts. − Pd/Al 2 O 3 , a widely used combustion catalyst, has been reported to suffer from severe deactivation because Pd reacts with SO 2 to form PdSO 4 . , While the catalytic activity of Pd/Al 2 O 3 is partially recovered by the elimination of SO 3 from the Pd surface to the Al 2 O 3 during the reaction, this recovery process is inhibited by water vapor in the reaction gas. , Thus, the coexistence of SO 2 and H 2 O promotes the deactivation of Pd/Al 2 O 3 .…”

“…The tolerance of noble metals against SO 2 strongly depends on the kinds of metals. Pt-based catalysts show higher catalytic activity for CO oxidation than Pd-based catalysts in the presence of SO 2 because the SO 3 species formed on Pt are more easily removed than that on Pd . However, even Pt-based catalysts were deactivated in the presence of SO 2 , , because SO 2 was oxidized on Pt to form SO 3 , which migrated to the surface of the supports, giving rise to surface sulfates. − The amount of sulfate formed on the supports depends on the reaction temperature, and it significantly increases as the reaction temperature decreases.…”

Promoting effect of vanadium on catalytic activity of Pt/Ce–Zr–O diesel oxidation catalysts

“…The control regulations on automobile pollution are being rigorously tightened. To meet these tight regulations, various catalytic exhaust converters are installed to reduce exhaust emissions (Kim et al, 2011;Millet et al, 2009;Christensen and Rak, 2002). In a typical diesel after-treatment system, a diesel oxidation converter (DOC) system is often used in combination with a diesel particulate filtration system and NOx selective catalytic reduction (SCR) system.…”

“…Wu et al (2012) reported that adding WOx to Pt/Al 2 O 3 (Pt/WOx/Al 2 O 3 ) can improve its behavior in C 3 H 8 oxidation compared with Pt/Al 2 O 3 alone. Kim et al (2011) tried Fe doping on Pt/Al 2 O 3 , and the result showed that the sulfur resistance of the catalyst evidently increased. Zheng et al (2013) investigated the effect on the conversion of C 3 H 8 after loading Ni on the diesel oxidation catalyst Pt/Ce 0.4 Zr 0.6 O 2 , and the result suggested that catalytic activity was enhanced because of the strong interaction between Ni and Pt.…”