Hydrothermal Synthesis of a Ce–Zr–Ti Mixed Oxide Catalyst with Enhanced Catalytic Performance for a NH₃-SCR Reaction

Abstract

A series of mesoporous CeZrTiO x catalysts were prepared by a facile hydrothermal method. Compared with CeTiO x catalysts synthesized under the same conditions, the catalytic activity and anti-SO2 performance of the Ce1Zr1TiO x catalyst are greatly improved, and at the gas hourly space velocity (GHSV) of 60 000 h–1, the NO x removal efficiency is maintained at 90% in the temperature range of 290–500 °C. The catalytic effect of ZrO2 on the Ce–Ti catalyst NH3-SCR activity was elucidated through a series of characterizations. The results revealed that the doping of Zr could significantly improve and optimize the structure of Ce–Ti catalysts. At the same time, due to the doping of Zr, the synergistic effect between Ce and Zr in the CeZrTiO x catalyst can effectively increase oxygen mobility, total acid content, and surface adsorbed oxygen species and lead to a larger pore volume. In addition, the introduction of ZrO2 made the transformation of Ce4+ into Ce3+ more obvious, and the 2Ce4+ + Zr2+ ↔ 2Ce3+ + Zr4+ reaction greatly improved the reducibility of Ce1Zr1TiO x . Among them, the improvement of SCR performance and H2O/SO2 tolerance is due to the electronic interaction between Zr and Ce.

Potential Risk of Significant N2O Emission without Changing NOx Conversion on Commercial V2O5/TiO2 Catalyst under Working Conditions

“…The O 1s spectra (Figure c) consisted of two overlapping peaks at 531.6 and 530.1 eV, which are assigned to chemisorbed oxygen (O α ) and lattice oxygen (O β ) . It is generally accepted that O α presents a higher reactivity than O β because it shows higher mobility. , With the Cr content in catalysts enhanced to 2 wt %, the O α proportion increased from 22.8 to 25.9% (Table ). From Figure d, the peaks at approximately 516.8 and 515.5 eV were attributed to V 5+ and V 4+ .…”

“…36 It is generally accepted that O α presents a higher reactivity than O β because it shows higher mobility. 37,38 With the Cr content in catalysts enhanced to 2 wt %, the O α proportion increased from 22.8 to 25.9% (Table 1). From Figure 2d, the peaks at approximately 516.8 and 515.5 eV were attributed to V 5+ and V 4+ .…”

An Experimental and Density Functional Theory Simulation Study of NO Reduction Mechanisms over Fe0 Supported on Graphene with and without CO

“…Catalytic reduction of NO provides an important strategy for postcombustion NO x emission control. 1,2 A commonly used method for NO catalytic reduction includes selected catalytic reduction with NH 3 , CO, and hydrocarbon. 1,3,4 Also, NO reductions by electrochemical and dielectric barrier discharge plasma are studied.…”

“…1,2 A commonly used method for NO catalytic reduction includes selected catalytic reduction with NH 3 , CO, and hydrocarbon. 1,3,4 Also, NO reductions by electrochemical and dielectric barrier discharge plasma are studied. 5−7 An alternative for NO reduction is catalytic NO reduction by various carbon materials.…”

“…Nitrogen oxides (NO x ) from fossil fuel combustion have a huge impact on the environment. Catalytic reduction of NO provides an important strategy for postcombustion NO x emission control. , A commonly used method for NO catalytic reduction includes selected catalytic reduction with NH 3 , CO, and hydrocarbon. ,, Also, NO reductions by electrochemical and dielectric barrier discharge plasma are studied. − An alternative for NO reduction is catalytic NO reduction by various carbon materials. , Rosas et al found that the addition of chromium can enhance NO reduction by activated carbon. Iron is abundant, nontoxic, and cheap and possesses strong redox ability .…”