Highly efficient oxidation of soot over RuOx/SiO2 in fluidized bed reactor

Removal of NOx and soot over Ce/Zr/K/Me (Me = Fe, Pt, Ru, Au) oxide catalysts

“…In the case of the CZKRu sample the effect of the presence of NO is less evident, due to the intrinsic high reactivity of the Me-doped CZK catalysts in soot combustion for the reasons discussed above. As a matter of facts, over the CZKRu sample, NO promotes soot oxidation at high temperatures (see TPO experiments) where the occurrence of the oxidation/recycling of NO to NO 2 is expected to favor soot combustion [22,58,65]. Moreover, the presence of ruthenium has been reported to increase the formation of surface oxygen complexes thus favoring the carbon-NO 2 O 2 oxidation [64,66,67].…”

“…(NO) band of chelating nitrites and any bands related to linear nitrites not evident, with the appearance of a false peak at 1375 cm −1 . Finally, CZKRu shows the presence of a broad band centered at about 1747 cm −1 that is assigned to ruthenium mononitrosyls [65,69].…”

An Overview on the Catalytic Materials Proposed for the Simultaneous Removal of NOx and Soot

“…Of note, it should be remembered that Ru-based catalysts have often been accused of low stability due to the possible loss of active phase (i.e., with consequent catalyst deactivation) via volatilization of Ru oxides. In particular, several recent studies [119,120] reported that at high temperatures (i.e., higher than 700 • C) RuO 2 is oxidized into volatile RuO 4 . Notably, focusing on this crucial aspect, Villani et al [121] investigated the stability of Ru/Zeolite based catalysts and found 900 • C as the upper limit temperature for practical applications of ruthenium catalysts, while Matarrese et al [118] performed repeated TPO soot oxidation cycles reporting a quite stable and reproducible behavior.…”

Three-dimensionally ordered macroporous spinel-type MCr2O4 (M = Co, Ni, Zn, Mn) catalysts with highly enhanced catalytic performance for soot combustion

“…One is the noble metal-loaded catalyst with excellent catalytic activity at low temperature. [6][7][8][9][10] But the prohibitively high cost and scarcity of precious metals have been the bottlenecks that impede their widespread use in soot combustion. The discovery of alternative inexpensive multicomponent metal oxide catalysts has become a very attractive subject for researchers to replace high-cost precious metal-supported catalysts.…”