Plausibility of potassium ion-exchanged ZSM-5 as soot combustion catalysts

Abstract

Potassium (K) ion-exchanged ZSM-5 zeolites were investigated for catalytic soot combustion. X-ray absorption fine-structure (XAFS), Raman, in situ IR and NH3-temperature programmed desorption (NH3-TPD) confirmed the location of K+ at the ion-exchanged sites. Temperature-programmed oxidation (TPO) reactions showed that K-ZSM-5 decreased ignition tempeatures of soot combustion and increased selectivity to CO2. The improved activity for soot combustion by increasing K+-exchanged amounts via decreasing the Si/Al ratio reinforced the K+ ions participating in soot combustion. 18O2 isotopic isothermal reactions suggested the activation of gaseous oxygen by the K+ ions. This demonstrated a new appliction of alkali metal exchanged zeolites and the strategy for enhancement of catalytic soot combustion activity.

Catalytic Combustion of Diesel Soot on Ce/Zr Series Catalysts Prepared by Sol-Gel Method

“…Clearly, when Co 3 O 4 , ZrO 2 , and K 2 CeO 3 phases coexist with Ce x Zr 1−x O 2 solid solution, the ignition temperature of soot decreases and the catalytic performance of the catalyst gets improved as presented in Figure 4a-d. Among the catalysts, K/ZC exhibited an excellent effect and the ignition temperature was 351 • C, thus indicating that the oxidation of soot was promoted by increasing the catalyst contact with the high mobility alkali metals [15][16][17][18][19]. Figure 4e-f present the different between Cobalt-doped ZC (Co/CZ) and CZ.…”

“…Figure 5a shows the Ce 3d XPS spectra of cat-K/ZC, cat-CZ, and cat-ZC, which demonstrate the presence of eight components, as reported in several relevant studies [34][35][36][37][38][39][40][41]. The Ce 3d spectrum consists of two series of spin-orbit lines u and v. Figure 5a displays that Ce 3d 3/2 spin-obit components of cat-ZC which correspond to u lines include three characteristic peaks labeled as u (901.7 eV), u" (908.9 eV), and u Catalysts 2019, 9, x FOR PEER REVIEW phases coexist with CexZr1−xO2 solid solution, the ignition temperature o catalytic performance of the catalyst gets improved as presented in Figure 4a K/ZC exhibited an excellent effect and the ignition temperature was 351 C oxidation of soot was promoted by increasing the catalyst contact with the hi [15][16][17][18][19]. Figure 4e-f present the different between Cobalt-doped ZC (Co/C doped ZC reduces the ignition temperature of the soot particles by 153 C, a to cat-CZ.…”

“…For this reason, properties of the Ce 4+ /Ce 3+ couple and the capacity of CeO 2 to exchange oxygen with the gas phase make CeO 2 -based materials one of the most promising catalysts for soot combustion [13,14]. They are widely known to favor the oxidation of soot by increasing the catalyst/soot contact with the high mobility of alkali metals or alkaline-earth metals [15][16][17][18][19][20]. Fan et al studied the effect of Ba loading on Cu-Ce catalysts, and it was shown that Ba restrains the sintering of (Cu, Ce)O x , resulting in relatively more favorable redox properties and thus higher activity for NO oxidation [20].…”

Síntesis De Zeolita ZSM-5 Utilizando Diatomita Como Precursor; Su Aplicación en El Proceso De Metanol a Hidrocarburos (Mth)

“…[15,18]. In addition, the second de-convoluted signal can have a contribution of NH 3 desorbed from week Lewis acid sites [19][20][21]. This week Lewis acid site can be originated by Na + which remains in the final ZSM-5 zeolite (see ICP results, Section 2.1.1.…”

Catalytic Combustion of Dimethyl Disulfide on Bimetallic Supported Catalysts Prepared by the Wet-Impregnation Method

“…At present, there are many studies on catalysts for catalytic combustion of DMDS, but problems such as poor activity, sulfur poisoning, and poor selectivity of SO2 are common. In the process of catalytic combustion of DMDS, sulfur compounds bond tightly to the active site of the catalyst forming stable surface metal sulfides, which prevent adsorption of reactants on the surface [31]. Sulfur can also concentrate on the oxide support forming sulfates such as aluminum sulfates and cerium oxy-sulfates, which can have an impact on the metal-support interaction.…”