Preferential CO oxidation (CO-PROX) catalyzed by CuO supported on nanocrystalline CeO2 prepared by a freeze-drying method

Abstract

a b s t r a c tNanocrystalline CeO 2 with a regular size of 9.5 nm was prepared by a freeze-drying method, and subsequent impregnated with a Cu(II) acetate solution, varying the loading of Cu (3, 6, 12 wt.%). The resulting CuO/CeO 2 materials were characterized by N 2 physisorption at −196 • C, HRTEM, H 2 -TPR, X-ray diffraction, Raman spectroscopy and XPS and tested as catalysts in the preferential CO oxidation in a H 2 -rich stream (CO-PROX) in the temperature range • C. In spite of their low specific surface areas the catalysts exhibited a good catalytic performance, resulting active and selective in the CO-PROX reaction at low temperatures. The inhibiting effect of the simultaneous presence of CO 2 (15 vol.%) and H 2 O (10 vol.%) in the reaction mixture on the performance of CuO-CeO 2 catalysts was also investigated. The addition of CO 2 and water in the gas stream depressed CO oxidation up to 160• C, its effect being negligible at higher temperatures. Nevertheless, despite these expected deactivation phenomena, a CO conversion value higher than 90% and a CO 2 selectivity of about 90% was achieved for all the samples at 160• C. The excellent performance, especially shown by the catalyst with 6 wt%. of copper, has been related to the wide dispersion of the copper active sites associated with the high amount of Ce 4+ species before reaction.

Tailoring the properties of BaTi0.8Cu0.2O3 catalyst selecting the synthesis method

“…The deconvolution of the normalized spectra of Cu-BTOsg reveals two bands with binding energy (BE) maxima at 933.2 eV and 935.2 eV, corresponding to Cu (II) species, which is confirmed by the appearing of a satellite peak (not shown) at 941-944 eV, due to the presence of a free 3d level [53,54]. For the Cu-BBOH catalyst, the bands BE maxima appear at 932.2 eV and 934.1 eV, being the satellite 13 peak (not shown) at 941-944 eV and, consequently, also corresponding to Cu (II) species [43,55].…”

Synthesis of Cu-Ce/KIT-6 materials for SOx removal

“…According to the literature, it can be decomposed in ten contributions [52][53][54][55]. Ce 4+ is fitted with six peaks (three doublets) with binding energies (BE) at 0 = 882.8 eV, 1 respectively as v, u and , u with splitting of 18.4 eV.…”

Catalytic Behaviour of CuO-CeO2 Systems Prepared by Different Synthetic Methodologies in the CO-PROX Reaction under CO2-H2O Feed Stream

“…The O 1s core level spectra show an asymmetric band, which can be separated into two components located at 529.2 eV, ascribed to oxide species, and another contribution at 531.3 eV, attributed to the presence of hydroxyl or carbonate species [24,25,62].…”

“…All samples were synthesised with a nominal copper loading of 6 wt %, considering that several authors have pointed that the maximum CO conversion in the CO-PROX is obtained at a Cu content of 6-7 wt % [22,62].…”