VOX supported on TiO2–Ce0.9Zr0.1O2 core–shell structure catalyst for NH3-SCR of NO

DeNO x performance enhancement of Cu-based oxides via employing a TiO2 phase to modify LDH precursors

CuAl-LDO, CuAl-LDO/TiO₂ and CuAl-LDO/TiO₂NTs catalysts were obtained from TiO₂ modified LDHs precursor which were prepared by in situ assembly method. Then catalysts were evaluated in the selective catalytic reduction of NO_x with NH₃(NH₃-SCR), and the results showed that the CuAl-LDO/TiO₂NTs catalyst exhibited preferable deNO_x performance (more than 80% NO_x conversion and higher than 90% N₂ selectivity at a temperature range of 210–330 °C) as well as good SO₂ resistance. With the aid of series of characterizations such as XRD, N₂ adsorption/desorption, XPS, NH₃-TPD, H₂-TPR, and in situ DRIFTS, it could be concluded that, doping TiO₂NTs afforded the catalyst larger specific surface area, more abundant surface chemisorption oxygen species and more excellent redox performance. Meanwhile, In situ DRIFTS evidenced that CuAl-LDO/TiO₂NTs catalyst has a strong adsorption capacity for the reaction gas, which is more conducive to the progress of the SCR reaction.

The CuAl-LDO/TiO₂NTs catalyst derived from TiO₂NTs modified CuAl-LDHs was innovatively prepared with excellent deNOx performance.

Tar steam reforming for synthesis gas production over Ni-based on ceria/zirconia and La0.3Sr0.7Co0.7Fe0.3O3 in a packed-bed reactor

In this work, NiO level was varied from 5 to 40% whereas Ce_xZr_1-xO₂ (x = 0.5, 0.7 and 0.9) (CZO) and La_0.3Sr_0.7Co_0.7Fe_0.3O₃ (LSCF) were chosen as two different kinds of support. Regardless the type of support, the surface NiO (at 40%) was completely reduced at 600 °C, giving the amount of activated Ni at 8950 μmol/g_cat. The reducibility of the updoped LSCF was found to be much better than that of the undoped CZO, evidenced by the H₂-TPR of the both materials at 600 °C where the oxygen storage capacity (OSC) of LSCF and CZO was determined at 4273 and 307 μmol/g_cat, respectively. In contrast, the OSC of 40%Ni-CZO (where x = 0.7, 0.9) was found to be higher than that of the LSCF, implying that the addition of Ni more enhanced both electronic defect and oxygen mobility in CZO than in LSCF, according to the H₂-TPR results. Coke resistant of CZO is presumable more satisfying than that of LSCF, thus, the longer lifespan of the CZO catalyst system is expected. The catalytic performance of 40%Ni-CZO (x = 0.9) was however comparable with 40%Ni-LSCF as they accommodate the same number of active sites. The slightly better catalytic performance of the 40%Ni-CZO (x = 0.9) could be due to its smaller crystallite size (CZO = 26.83, LSCF = 35.73), rendering more access for the relative gaseous reactants. The best catalyst amongst all was 5%Ni-CZO (x = 0.9), giving 89% toluene conversion, 46% H₂ yield, 71% CO selectivity, and 25% CO₂ selectivity at optimum reaction temperature of 700 °C.

Synthesis, characterization and utilization of oxygen vacancy contained metal oxide semiconductors for energy and environmental catalysis

Developing novel functional materials with promising desired properties in enhancing energy conversion and lowering the catalytic reaction barriers is essential for the demand to solve the increasingly severe energy and environmental crisis nowadays. Metal oxide semiconductors (MOS) are widely used in the field of catalysis because of its excellent catalytic characteristics. Introduction of defects, in addition to the adjustment of composition and atomic arrangement in the materials can effectively improve the materials' catalytic performance. Especially, introducing oxygen vacancies (OVs) into the lattice structure of MOS has been developed as a facile route to improve MOS's optical and electronic transmission characteristics. And a large number of metal oxides with rich OVs have been served in oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), carbon dioxide reduction reaction (CO₂-RR) photo-degradation of organic pollutants, etc. This small review briefly outlines some preparation techniques to introduce OVs into MOS, and the characterization techniques to identify and quantify the OVs in MOS. The applications of OVs contained MOS especially in energy and environmental catalysis areas are also discussed. The effects of OVs types and concentrations on the catalytic performances are deliberated. Finally, the defective structure-catalytic property relationship is highlighted, and the future status and opportunities of MOS containing OVs in the catalytic field are suggested.

Enhanced activity and alkali metal resistance in vanadium SCR catalyst via co-modification with Mo and Sb

Enhanced surface acidity contributed significantly to the catalytic activity and alkali metal resistance of the optimum catalysts.