Promotion effect of residual K on the decomposition of N2O over cobalt–cerium mixed oxide catalyst

Abstract

A series of cobalt-cerium mixed oxide catalysts (Co 3 O 4 -CeO 2 ) with a Ce/Co molar ratio of 0.05 were prepared by co-precipitation (with K 2 CO 3 and KOH as the respective precipitant), impregnation, citrate, and direct evaporation methods and then tested for the catalytic decomposition of N 2 O. XRD, BET, XPS, O 2 -TPD and H 2 -TPR methods were used to characterize the catalysts. Catalysts with a trace amount of residual K exhibited higher catalytic activities than those without. The presence of appropriate amount of K in Co 3 O 4 -CeO 2 may improve the redox property of Co 3 O 4 , which is important for the decomposition of N 2 O. When the amount of K was constant, the surface area became the most important factor for the reaction. The co-precipitation-prepared catalyst with K 2 CO 3 as precipitant exhibited the best catalytic performance because of the presence of ca. 2 mol% residual K and the high surface area. We also discussed the rate-determining step of the N 2 O decomposition reaction over these Co 3 O 4 -CeO 2 catalysts. #

Nitrous Oxide Decomposition Over MCO3–Co3O4 (M = Ca, Sr, Ba) Catalysts

“…Ohnishi et al [19] have recently reported the role of alkali and alkaline earth metals doping in enhancing the N 2 O decomposition activity of Co 3 O 4 spinel oxide catalyst. Concurrent with this study, the positive influence of alkaline metals during N 2 O decomposition was also reported for other catalytic systems like Co 3 O 4 -CeO 2 [13], Co-Al [29], CuO [38], NiO [39], and Rh/Al 2 O 3 [10,11] catalysts. In the pervious references, it was argued that the alkali metal content plays a vital importance in enhancing the N 2 O decomposition activity.…”

“…nitrogen and oxygen. Wide variety of catalysts were tested such as metal surfaces [8], supported metals [9][10][11], metal oxides [12,13], supported oxides [14,15], ternary oxides [16], spinels [13,[17][18][19][20][21][22][23][24][25], perovskites [26] hydrotalcites [27][28][29], and zeolites [30][31][32][33][34][35][36][37]. Focusing our attention to spinel oxide catalysts, a high laugh gas decomposition activity was reported for cobalt containing spinel oxides, such as Co 3 O 4 .…”

Promotion Effects and Mechanism of Alkali Metals and Alkaline Earth Metals on Cobalt−Cerium Composite Oxide Catalysts for N2O Decomposition

“…Nitrates of cobalt, cerium and alkali, or alkaline earth metals were used in appropriate quantities. The details of the method can be seen in the Supporting Information or in our previous paper (15). The catalyst is referred to as CC-M-x (M indicates the doping alkali or alkaline earth metal; x indicates the molar ratio of M/Co, so that x ) 0 for the undoped catalyst).…”

“…Subsequently, the promotion effect of K was found to be more significant than ceria (15,16). Here, the influence of alkali metal additives on the chemistry environments of Co ions may be an important reason for their high activities.…”

The use of CeO2-Co3O4oxides as a catalyst for the reduction of N2O emission

“…It was found that the catalysts with a high efficiency during the low-temperature N2O reduction reaction contained rhodium supported on zirconia, praseodymiumdoped ceria or mixed systems incorporating titanium oxide and cerium oxide, additionally coated with rhodium [17][18][19]. However, research into the cobalt-based catalysts and promoted alkali metals: sodium and potassium shows that it is possible to achieve complete conversion at a temperature below 450°C [20,21]. Such catalysts are very active in this reaction and do not contain precious metals, which consequently further reduces their cost [22].…”