“PdO vs. PtO”—The Influence of PGM Oxide Promotion of Co3O4 Spinel on Direct NO Decomposition Activity

Abstract

Direct decomposition of NO into N2 and O2 (2NO→N2 + O2) is recognized as the “ideal” reaction for NOx removal because it needs no reductant. It was reported that the spinel Co3O4 is one of the most active single-element oxide catalysts for NO decomposition at higher reaction temperatures, however, activity remains low below 650 °C. The present study aims to investigate new promoters for Co3O4, specifically PdO vs. PtO. Interestingly, the PdO promoter effect on Co3O4 was much greater than the PtO effect, yielding a 4 times higher activity for direct NO decomposition at 650 °C. Also, Co3O4 catalysts with the PdO promoter exhibit higher selectivity to N2 compared to PtO/Co3O4 catalysts. Several characterization measurements, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and in situ FT-IR, were performed to understand the effect of PdO vs. PtO on the properties of Co3O4. Structural and surface analysis measurements show that impregnation of PdO on Co3O4 leads to a greater ease of reduction of the catalysts and an increased thermal stability of surface adsorbed NOx species, which contribute to promotion of direct NO decomposition activity. In contrast, rather than remaining solely as a surface species, PtO enters the Co3O4 structure, and it promotes neither redox properties nor NO adsorption properties of Co3O4, resulting in a diminished promotional effect compared to PdO.

Emissions Control Catalysis

“…The direct NO decomposition activity on PdO or PtO supported on Co 3 O 4 spinel was studied by Reddy et al [26] in an attempt to discover means of enhancing the activity of Co 3 O 4 spinel, one of the most active single-element oxide catalysts for NO decomposition at high temperatures (typically > 650 • C). In fact, the authors demonstrated a four-fold higher promotion on the NO decomposition activity of PdO-rather than of PtO-modified Co 3 O 4 at 650 • C, accompanied by superior selectivity towards N 2 as well.…”

Emissions Control Catalysis

“…In respect to the poisoning effect of phosphorous on the SCR of NO x it was revealed that the formations of N 2 and N 2 O were decreased in favor of NH 3 production; the reaction is more influenced by the phosphorous poisoning than the ammonia formation from the stored nitrates. The direct NO decomposition activity on PdO or PtO supported on Co 3 O 4 spinel was studied by Reddy et al [26] in an attempt to discover means of enhancing the activity of Co 3 O 4 spinel, one of the most active single-element oxide catalysts for NO decomposition at high temperatures (typically > 650 • C). In fact, the authors demonstrated a four-fold higher promotion on the NO decomposition activity of PdO-rather than of PtO-modified Co 3 O 4 at 650 • C, accompanied by superior selectivity towards N 2 as well.…”

“…The review of Smirniotis P. and co-workers [18] concerns the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR of NO x ) focusing to low temperature applications that is a highly desirable perspective, and finally the review of Bogaerts A. and co-workers [19] covering a hot recent trend in emissions control implicating cyclic economy strategies, that is the conversion and utilization of CO 2 for the production of value-added chemicals. On the other hand, a major part of contributions (9/21) concerns original research on nitrogen oxides reduction processes [20][21][22][23][24][25][26][27][28], reflecting the fact that this topic still remains hot among the targets of environmental catalysis. Five out of 21 studies concern CO and hydrocarbons oxidation processes [29][30][31][32][33] while the remained 4/21 concern CO 2 capture/recycling processes under the view of cyclic economy [34][35][36][37].…”

Análisis de la microestructura de humos de soldadura de aceros de bajo y medio contenido de carbon

“…According to the peak values shown in Fig. 4; 3296, peaks in the band range of 2921 cm -1 (Ehrman et al, 1999;Jenkins et al, 2005a;Jenkins and Eagar, 2005b;Wang et al, 2006;Chen and He, 2008;Sowards et al, 2008;Sevilla and Fuertes, 2009;Gibot and Vidal, 2010;Saikia and Parthasarathy, 2010;Zheng et al, 2010;Vaculikova et al, 2011;Basu et al, 2011;Farzaneh and Najafi, 2011;Lin et al, 2012;Abdullah et al, 2014;Jamal et al, 2014;Golbabaei and Khadem, 2015;Naushad et al, 2015;Diko et al, 2016; Sahai et al, 2016;Benykhlef et al, 2016;Yi et al, 2018;Ge et al, 2019;Habtemariam et al, 2019;Bahah et al, 2019;Abinaya et al, 2019;Alias et al, 2019;Altunal et al, 2019;Boroń et al, 2019;Reddy et al, 2019;Karthik et al, 2019;Karunathilaka et al, 2019;Kono et al, 2019;Mohammadi et al, 2019;Ponmudi et al2019;Scaccia et al, 2019;Wang et al, 2019a;Wang et al, 2019b;Yang et al, 2019), indicate O-H bonding i...…”

“…Welding fumes contain very different structures by its nature. 1139, 1257, 1407, 2848 and 2921 cm -1 peaks obtained from FTIR analysis were Al-O (Jamal et al, 2014;Benykhlef et al, 2016;Yi et al, 2018) (Abdullah et al, 2014;Golbabaei and Khadem, 2015), F 2 O 3 (Oberdörster et al, 2005), Mn-O (Jamal et al, 2014;Alias et al, 2019), N-O (Boroń et al, 2019;Yang et al, 2019), P-O (Kono et al, 2019), Pd-O (Reddy et al, 2019), Si-O (Saikia and Parthasarathy, 2010;Vaculikova et al, 2011;Diko et al, 2016;Bahah et al, 2019;Mohammadi et al, 2019) functional due to the fact that stretching of bonds of functional groups has increased.…”