ABSTRACT
Carbonyl sulfur (COS) is a prominent organic sulfur pollutant commonly found in the by-product gas generated by the steel industry. A series of Sm-doped CeOx@ZrO2 catalysts were prepared for the hydrolysis catalytic removal of COS. The results showed that the addition of Sm resulted in the most significant enhancement of hydrolysis catalytic activity. The 3% Sm2O3-Ce-Ox@ZrO2 catalyst exhibited the highest activity, achieving a hydrolysis catalytic efficiency of 100% and H2S selectivity of 100% within the temperature range of 90-180 °C. The inclusion of Sm had the effect of reducing the acidity of the catalyst while increasing weak basic sites, which facilitated the adsorption and activation of COS molecules at low temperatures. Appropriate doping of Sm proved beneficial in converting active surface chemisorbed oxygen into lattice oxygen, thereby decreasing the oxidation of intermediate products and maintaining the stability of the hydrolysis reaction.
ABSTRACT
Steam reforming for hydrogen production is one of the important research directions for clean energy. NiTiO3 catalysts with a hierarchical porous structure are prepared and applied to methanol steam reforming for hydrogen production. The results show that the optimum catalyst (10% Ni-Ti-Ox) not only has a hierarchical porous structure, but it also involves the coexistence of NiTiO3, anatase TiO2 and rutile TiO2. The formation of NiTiO3 is beneficial to the adsorption and activation of methanol molecules on the surface of the Ni-Ti-Ox catalyst, and the main intermediate species of the methanol molecular reaction are hydroxyl groups, methoxy species and formic acid species. Furthermore, the methanol steam reforming reaction is mainly dominated by methanol decomposition at low temperature (350-500 °C), while it is mainly dominated by methanol and water molecular reactions at high temperature (500-600 °C).
ABSTRACT
Sulfur dioxide is one of the main causes of air pollution such as acid rain and photochemical smog, and its pollution control and resource utilization have become important research directions. La2O3 was incorporated into CeO2 to enhance the surface basicity of La-Ce-Ox catalyst and increase the concentration of chemisorbed oxygen, thereby promoting the improvement of catalytic performance of SO2 reduction by CO. Results have showed that the incorporation of La2O3 would not only increase the concentration of chemisorbed oxygen and hydroxyl on the catalyst surface, but also increase the basicity of the catalyst, thereby facilitating the adsorption of SO2 on the catalyst surface. The 12%La-Ce-Ox was the optimal catalyst, and its SO2 conversion at 350-400 â reached close to 100%, and the sulfur yield at this temperature range was higher than 93%. Finally, according to the in situ infrared diffuse reflectance spectrum, it was found that the main reaction intermediates of 12%La-Ce-Ox in the catalytic reduction of SO2 were weakly adsorbed sulfate, SO32-, non-coordinating CO32-, monodentate carbonate, and CO, so the catalytic reaction followed the L-H and E-R mechanisms simultaneously.
Subject(s)
Ammonia , Cerium , Oxidation-Reduction , Oxides , Sulfur Dioxide , Catalysis , OxygenABSTRACT
Nitrogen oxides, mercury and chlorobenzene are important air pollutants emitted by waste incineration and other industries. Coordinated control of multiple pollutants has become an important technology for air pollution control. Through solid-phase structure control, the catalytic performance of the WCeMnOx/TiO2-ZrO2 catalyst for simultaneous catalytic removal of NO, mercury and simultaneous removal of NO and chlorobenzene were improved. MnWO4 improved the solid acidity of the catalyst and improved the catalytic activity at high temperature. The formation of Ce0·75Zr0·25O2, Ce2WO6, Ce2Zr2O7 and Ce2Ti2O7 improved the catalytic activity at low temperature. The presence of TiOSO4 would affect the valence of metal ions and the reduction of chemisorbed oxygen, thereby reducing the catalytic activity at low temperature. Within the same size range of nanoparticles, cyclic nanoparticles exposed more active sites due to their hollow structure, and their catalytic performance was better than spherical nanoparticles. The thickness of the circular nanoparticles of WCM/TZ-14 catalyst was about 14 nm, and the diameter was about 40 nm Ce0.75Zr0.25O2 and MnWO4 were also present in the phase composition. Therefore, it exhibited the best performance for simultaneous catalytic removal of NO, mercury and simultaneous removal of NO and chlorobenzene. The coincidence temperature window was 347-516 °C. Finally, WCM/TZ-14 catalyst followed both E-R and L-H mechanisms in the NH3-SCR reaction.
Subject(s)
Mercury , Catalysis , Chlorobenzenes/chemistry , Mercury/chemistry , Oxidation-Reduction , Titanium , Zirconium/chemistryABSTRACT
A series of W-Zr-O x /TiO2 catalysts with hierarchical pore structure were prepared and used for selective catalytic reduction of NO by NH3. Results showed that the 5C-WZ/T had a hierarchical pore structure, and exhibited high catalytic activity and good resistance to water and sulfur poisoning. The activity of the 5C-WZ/T catalyst was close to 100% in the range of 350-500 °C. The hierarchical pore structure not only improved the specific surface area, redox performance, and acid quantity, but also enabled the catalyst to expose more active sites and improved the catalytic performance. Although the reducing atmosphere caused by citric acid monohydrate reduced the chemical adsorption oxygen concentration, it increased the oxygen mobility and Ti3+ ion concentration, which was more conducive to the improvement of catalytic activity. Finally, the NH3-SCR reaction over 5C-WZ/T catalyst followed L-H and E-R mechanisms. The monodentate nitrite, bidentate nitrate, gas-phase NO2, coordinated NH3 and NH4 + were the main reaction intermediates.
ABSTRACT
Deferasirox (DFX) is an iron chelator approved for the treatment of iron overload diseases. However, the role of DFX in oxidative stress-induced cell apoptosis and the exact molecular mechanisms underlying these processes remain poorly understood and require further investigation. In this study, we found that DFX rendered resistant to H2O2-induced apoptosis in HEK293T cells, reduced the intracellular levels of the labile iron pool (LIP) and oxidative stress induced by H2O2. Furthermore, DFX inhibited the ubiquitination and degradation of the cyclin-dependent kinase inhibitor p21WAF1/CIP1 (p21) via modulation of the interaction of p21 with SCF-Skp2. DFX also showed the inhibition effect on the activation of c-Jun N-terminal kinase (JNK), pro-caspase-3 and related mitochondrial apoptosis pathway induced by H2O2. These results provide novel insights into the molecular mechanism underpinning iron-mediated oxidative stress and apoptosis, and they may represent a promising target for therapeutic interventions in related pathological conditions.