Effect of CO2, H2O and SO2 in the ceria-catalyzed combustion of soot under simulated diesel exhaust conditions

Abstract

9The effect of CO 2 Attention must be paid to the soot-catalyst contact, and it is usually 53 accepted that "loose contact" mixtures of soot and powder catalysts (soot and 54 catalyst are mixed with a spatula, for instance) simulate the poor contact 55 attained in a real diesel particulate filter. 56Thermal stability of catalysts is also a major issue to pay attention to in 57 laboratory studies. Usually, the exhaust temperature in a diesel vehicle is lower 58 than 500 ºC, but hot spots are formed during the regeneration of the diesel 59 particulate filters where the temperature can increase out of control. 60The presence of NOx in the gas mixture also plays a key role in the formation, but the effect SO 2 on the ceria behavior was not discussed. 75The effect of H 2 O and SO 2 on the stability of Ba,K/CeO 2 catalysts during 76 diesel soot combustion was also studied [14], and it was concluded that these 77 catalysts had good tolerance to water at low temperatures (e.g., 400 ºC) while MnOx-CeO 2 mixed oxides were also tested for the low-temperature 82 oxidation of diesel soot in a O 2 + H 2 O + NO + N 2 gas stream, and the effect of 83 SO 2 was also studied [15]. The poisoning effect of SO 2 was also reported in this 84 case, but a detailed analysis of its effect on ceria was not provided apart from [18] were used in these experiments (and also an empty reactor).

Tuning the structural and catalytic properties of ceria by doping with Zr4+, La3+ and Eu3+ cations

“…The model soot used is Printex-U provided by Degussa. 10 This soot has proven to be an appropriate model for the soot oxidation reaction. Figure 1a presents the XRD patterns of CZ, CL, and CE samples along with pure ceria calcined at 773 K. As can be noted from the figure, all diffraction patterns could be indexed to ceria fluorite structure.…”

“…Different catalysts have been investigated for this purpose, which include noble metals, alkali metals, * For correspondence alkali earth metals, transition metals, and rare earth metals. Based on the laboratory results obtained by several research groups, [8][9][10] ceria-based catalysts have been proposed as promising materials because of their high oxygen storage and release capacity (OSC) which is represented in the following equation:…”

FTIR and density functional study of NO interaction with reduced ceria: Identification of N3− and NO2− as new intermediates in NO conversion

“…Important peculiarities of CeO 2 are its high oxygen storage capacity and easy reducibility [05]. There are many studies of the nature of the species formed during interaction of NO x with ceria [05, 17,[19][20][21][22][23][24][25][26][27][28][29][30][31] and ceria-containing systems [05, 16,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49], and the proposed structures are summarized in Table 1. Based on the paper of Niwa et al [21] and a more recent work of Martinez-Arias et al [20], several authors reported formation of various species, such as NO - [16,19,20,[32][33][34]48], cis-and trans-hyponitrites [16,19,20,…”

Catalytic regeneration of Diesel Particulate Filters: Comparison of Pt and CePr active phases

“…Finally, the effect of H 2 O + CO 2 in the DPFs regeneration has been studied, because it is known from experiments performed with powder catalysts that both H 2 O and CO 2 can affect the catalytic combustion of soot [3]. …”

“…Important progresses have been done at laboratory scale in the optimization of such ceria active phases. The effect of reaction conditions in the ceria-catalyzed combustion of soot, like gas composition or temperature windows for optimum operation, have been studied [2,3] and the soot combustion mechanisms have been also properly investigated the most relevant reaction steps being understood [4,5]. Even, some experiments at pilot plant level have been carried out in order to demonstrate that ceria-based formulations are able to accelerate soot combustion under real conditions [6][7][8].…”