No abstract

Cu-ZSM-5 zeolites exhibit promising NH3-SCR activity in a wide temperature window. The current challenges in preparing Cu-ZSM-5 are reducing the cost and simplifying the preparation process. The one-pot method using the Cu-amine complex as the template is an excellent strategy for solving the above problems. However, the above method is still lacking in preparing Cu-ZSM-5. In this work, a one-pot method using the Cu-(EDA)2 complex as the template is developed to prepare the Cu-ZSM-5-O catalyst. According to the fundamental measurements, the high dispersion of copper­(II) species, appropriate acidity, and Cu+ species are in favor of the NH3-SCR reaction. Among one-pot catalysts, Cu1.8-ZSM-5-O shows excellent NH3-SCR performance at low temperatures (NO conversion of about 87.5% at 150 °C and N2 selectivity above 95% over the entire temperature window). The boosting activity at low temperatures of one-pot catalysts is probably assigned to abundant [Cu­(OH)]+ species and appropriate amounts of Cu+ species in Cu-ZSM-5-O. Moreover, the variable-temperature EPR and subsequent computer simulation are used first to quantify the content of [Cu­(OH)]+ species in Cu-ZSM-5-O. The NH3-SCR mechanism at low temperatures (150 °C) on [Cu­(OH)]+ species is also investigated by in situ DRIFT spectra and DFT calculations, which mainly follow the Eley–Rideal route. A complete catalytic cycle of the SCR reaction was proposed based on the [Cu­(OH)]+ species by DFT calculations. Our results suggest that [Cu­(OH)]+ species contribute to the adsorption and activation of NH3, thus boosting the catalytic performance.

In this work, three-dimensionally ordered macroporous-mesoporous Ti0.7Si0.2W0.1Oy (3DOM-m TiSiWO) supported MnxCo1-xOδ catalysts with different x values were prepared using the colloidal crystal template method and incipient wetness impregnation method. The...

Many transition metal oxides supported on TiO2 have been studied for selective catalytic reduction (SCR) of NO with NH3. However, the trade-off exists between the low-temperature activity and N2 selectivity....

As an efficient and durable engine, a diesel engine has a broad application. However, soot particles (PM) and nitrogen oxides (NOx) coming from diesel engines are the main causes of air pollution, so it is necessary to design and prepare an effective catalyst for the simultaneous elimination of PM and NOx. In this work, a novel 3DOM ZrTiO4 support and a series of WxCeMnOδ/3DOM ZrTiO4 catalysts (where x indicates the wt% of W) were designed and fabricated by the colloidal crystal template technique. Among the as-prepared catalysts, the W1CeMnOδ/3DOM ZrTiO4 catalyst exhibits the highest NO conversion rate (52%) at the temperature of maximum CO2 concentration (474°C) and achieves 90% NO conversion in the temperature range of 250–396°C. The excellent catalytic performance is associated with the macroporous structure, abundant oxygen vacancies, sufficient acid sites, and the synergistic effect among the active components. The possible reaction mechanisms of WxCeMnOδ/3DOM ZrTiO4 catalysts were also discussed based on the characterization results.