Mechanism of Propane Adsorption and the Following NO x Reduction over an In/BEA Catalyst: A Computational Study

To expand the knowledge on hydrocarbon selective catalytic reduction (SCR) and follow the research steps of methane-SCR and propane-SCR in our previous work, we studied the characteristics of propane adsorption on In/BEA zeolite, explored the NO and NO₂ activation process on a propane adsorbed catalyst, and calculated the reaction enthalpy of two reaction pathways. Results showed that O site in the L-model (the [InO]⁺/BEA structure) was the main active site in the adsorption process, and any of the carbon atoms in the propane molecule could react with it, with a lower adsorption energy than methane (-3.20 vs -2.98 eV). Also, NO or NO₂ could not be directly activated on the propane adsorbed catalyst, indicating that the process may be complicated. In addition, propane reduces the NO or NO₂ molecule with two different pathways and the final products were less stable than those of methane (-5.6 vs -20 eV). These results could explain the fact that propane and methane had different reaction temperatures and would further deepen our understanding of the propane-SCR process.

An efficient strategy to screen an effective catalyst for NOx-SCR by deducing surface species using DRIFTS

HYPOTHESIS

Transition metal supported TiO₂ is one of the hottest catalysts in the field of selective catalytic reduction (SCR) of nitrogen oxides. Various formulas have been put forward for an enhanced activity. However, seldom work emphasizes on easy and fast screening of an effective catalyst.

EXPERIMENTS

In this work, Diffuse Reflection Fourier Transform Infrared (DRIFTS) screened catalyst by analyzing intermediates during SCR.

FINDINGS

TiO₂ provided main adsorption sites for NH₃ and the "Eley-Rideal" mechanism dominated the catalysis. The transition metals served as the bridge of electron transport. Moreover, the area reduction rate of adsorbed NH₃ and NH₄⁺ species in DRIFTS represented the electron-transfer rate as well as catalytic activity. In other words, a faster area reduction indicated a better SCR activity. Therefore, this work supplied a fast strategy to screen the most effective catalyst among different materials even without using a nitrogen oxides detector. At the same time, less ammonia and nitrogen oxides were used or discharged.

Effects of different exposed crystal surfaces of CeO2 loaded on an MnO2/X catalyst for the NH3-SCR reaction

To study the effects of the loading of different exposed crystal surfaces of CeO2 on an MnO2/X catalyst for the NH3-selective catalytic reduction (SCR) reaction, Mn/X, Mn–CeNP/X, Mn–CeNC/X and Mn–CeNR/X catalysts were synthesized via a solid-state diffusion method.

Highly improved acetone oxidation performance over mesostructured CuxCe1−xO2 hollow nanospheres

Mesostructured CuxCe1−xO2 hollow nanospheres with porous shells and controllable Cu/Ce molar ratios exhibit highly improved catalytic acetone oxidation performance.

Recent advances and perspectives in the resistance of SO2 and H2O of cerium-based catalysts for NOx selective catalytic reduction with ammonia

This review emphasizes the aspects related to cerium-based catalysts at different levels: metal modification, preparation methods, structures, and reaction mechanisms.

Promoting the effects of CuSO4 on N2 selectivity in selective catalytic oxidation of ammonia over Pt/TiO2 catalysts

The NH3-SCO reaction mechanism over a Pt/TiO2 catalyst was transferred into the i-SCR mechanism after adding CuSO4, and thus the formation of N2 was promoted.

Selective catalytic reduction of NO over W–Zr-Ox/TiO2: performance study of hierarchical pore structure

A series of W–Zr-Ox/TiO2 catalysts with hierarchical pore structure were prepared and used for selective catalytic reduction of NO by NH3.

Characterization of WMnCeTiOx catalysts prepared by different methods for the selective reduction of NO with NH3

WMnCeTiOx(CP) catalysts showed excellent NH3-SCR activity and better SO2 tolerance.