Search

[Display omitted] • The Sn(II)/Sn(IV)-doped CeZrO x catalysts were prepared by co-precipitation method. • Diethylamine combustion over CeZrSnO x -(Sn2+) had high activity and N 2 selectivity. • CeZrSnO x -(Sn2+) showed high hydrothermal stability during diethylamine combustion. • The ratio of Sn2+/Sn4+ had a significant impact on the catalytic activity. • The strong acidic sites on the catalyst were conducive to diethylamine combustion. The synthesis of CeZrSnO x by co-precipitation with different valence-state of Sn for diethylamine combustion is novel and intriguing. In this research, the Sn(II)/Sn(IV)-doped CeZrO x catalysts (CeZr(Sn)O x -(Sn2+) and CeZr(Sn)O x -(Sn4+)) were facilely prepared using the co-precipitation method, and their catalytic activities on destruction of diethylamine were evaluated. Detailed characterizations of the catalysts were conducted using X-ray photoelectron spectrometer (XPS), X-ray powder diffraction (XRD), hydrogen-temperature programmed reduction (H 2 -TPR), temperature programmed ammonia desorption (NH 3 -TPD) and so on. For diethylamine combustion, CeZr(Sn)O x -(Sn2+) showed higher activity and nitrogen selectivity than other catalysts, and a high conversion of diethylamine (>90 %) at 250 °C was obtained. After hydrothermal aging treatment, a high conversion (>90 %) and high N 2 selectivity maintained over CeZr(Sn)O x -(Sn2+)-H at 280 °C, indicating high hydrothermal stability of CeZr(Sn)O x -Sn2+. Owe to the large specific surface area (SSA), high oxygen mobility and strong redox performance, and the synergy between metal elements in CeZr(Sn)O x -Sn2+ catalysts, the catalytic properties were enhanced. Moreover, Sn2+/Sn4+ ratio in the catalyst and strong acidic sites on the surface of the catalyst both had significant impacts on the catalytic activity and N 2 selectivity of the catalyst. Finally, the mechanism of diethylamine combustion over CeZr(Sn)O x -Sn2+ was obtained by analyzing the reaction through in-situ diffuse reflection infrared Fourier-transform spectrum (in situ DRIFTS) test. [ABSTRACT FROM AUTHOR]

Layered δ-MnO2 catalysts were prepared using the one-step redox method in precursor solutions with five different pH values (pH = 7, 9, 11, 13, and 14). The effects of pH on the physical properties and catalytic activity of the catalyst were investigated through XRD, SEM, TEM, BET, XPS, H2-TPR, and HCHO degradation tests at room temperature. The results showed that the layer spacing, manganese vacancy content, Mn4+/Mn3+ ratio, and surface-reactive oxygen species content of MnO2 increased with the increase in pH value in the alkaline range. When the catalyst was prepared at pH = 13, the above characteristics of the catalyst reached the optimal value which contributed to the high catalytic activity. Combined with the related characterization results, it was proved that changing the pH can affect the degree of oxidation in the catalyst synthesis process, increase the number of active oxygen and the oxygen mobility of the catalyst, and effectively improve the catalytic activity of the manganese dioxide catalyst for HCHO. This work represents a giant step toward the preparation of an effective catalyst for practical applications of HCHO removal at room temperature at a low concentration and high velocity. [ABSTRACT FROM AUTHOR]

Addressing the problems of easy collapse, Ni sintering and low catalytic activity over the nanotubular nickel phyllosilicate catalyst, the Mg species was doped via a simple hydrothermal method to construct the nanotubular Ni-Mg bimetallic phyllosilicate solid solution. The high thermal stability, nonreducible property and strong basicity of magnesium species led to the enhancement of anti-collapse, Ni-sintering resistance and basicity. As a result, the fine Ni particles and enhanced H 2 and CO 2 chemisorption and activation properties resulted in boosting the catalytic activity of both CO 2 methanation and CH 4 -CO 2 reforming reactions. The Ni/Mg ratios and the reduction temperatures were detailed optimized, and the 600oC-reduced Ni 8 Mg 2 -NT catalyst with the Ni/Mg ratio of 8:2 was the optimal, which also exhibited high long-term stability. In short, the formed Ni-Mg-phyllosilicate solid solution structure and the special interactions of different species brought about high catalytic performance of the nanotubular Ni-Mg phyllosilicate catalyst. [Display omitted] • The nanotubular Ni-Mg bimetallic phyllosilicate solid solution was synthesized. • Nanotubular Ni-Mg phyllosilicate obtained high anti-collapse and Ni-sintering resistance properties. • The Ni/Mg ratio of 8:2 and the reduction temperature of 600 oC were the optimum. • This catalyst was versatile for both CO 2 methanation and CH 4 -CO 2 reforming reactions. [ABSTRACT FROM AUTHOR]

In this work, Mn(CeZr)O x was synthesized by using chelation-induced synergistic self-assembly strategy for the combustion of toluene. The physicochemical properties of the synthesized catalysts were characterized by XRD, ICP-MS, SEM, TEM, XPS and N 2 sorption. The Mn(CeZr)O x catalyst with T 90 = 225 °C exhibited improved catalytic performance than the original MnO x catalyst (T 90 = 260 °C) and had significant low-temperature activity. The relationship between catalyst activity and structure was analyzed. By substituting Ce and Zr elements into the hollow microspheres of MnO 2 , oxygen vacancies were produced. The main factors affecting the catalytic activity of the catalyst and the reason why it remained high catalytic activity after a long period of hydrothermal treatment were discussed. After hydrothermal aging, the original pore structure of Mn(CeZr)O x catalyst collapsed and the specific surface area decreased, but the overall crystallinity of the catalyst increased and the content of oxygen species in the lattice increased. The distribution of Mn and oxygen species on the catalyst surface changed significantly after hydrothermal treatment. The appropriate ratio of Mn4+ to Mn3+ and the ratio of lattice oxygen to adsorbed oxygen species are beneficial to the redox reaction cycle. [Display omitted] • A novel Mn(CeZr)O x was prepared by a chelation-induced self-assembly strategy. • The hydrothermal aging resistance of Mn(CeZr)O x was studied. • Synergistic effect of metal species significantly improved the toluene combustion. • The superior redox and structural properties made catalysts have high activity. [ABSTRACT FROM AUTHOR]

In this work, a series of Pt–Ce 0.63 Zr 0·37 O 2 –Y catalysts were prepared by unique simple mechanical mixing method. The catalytic activity of these catalysts for toluene oxidation was investigated. The physicochemical properties of the catalysts were characterized by XRD, ICP-MS, SEM, TEM, XPS and N 2 sorption. Pore size distribution was analyzed according nitrogen adsorption and desorption isotherms. The catalytic results showed that using NaY as support for Pt–Ce 0.63 Zr 0·37 O 2 –Y could enhance the conversion of toluene during the oxidation process in comparison with HY. Further mixing cerium zirconium solid solution with Pt–NaY can improve the oxidation catalytic property of these catalysts. The conversion of toluene over Pt–Ce 0.63 Zr 0·37 O 2 –NaY reached more than 90% at 200 °C. High catalytic stability was obtained for toluene oxidation over Pt–Ce 0.63 Zr 0·37 O 2 –NaY. Platinum, cerium and zirconium can be uniformly dispersed on Y zeolite with small particle size by simple mechanical synthesis. The effect of drying methods on catalytic activity and hydrothermal stability of catalysts were also investigated in this research. [Display omitted] • Pt–Ce 0.63 Zr 0·37 O 2 –Y was synthesized by a unique simple mechanical mixing method. • High catalytic activity of Pt–Ce 0.63 Zr 0·37 O 2 –NaY was shown for toluene oxidation. • The hydrothermal stability of Pt–Ce 0.63 Zr 0·37 O 2 –Y was investigated. • Drying methods had no effect on the catalytic activity of the catalysts. • The addition of Pt and CeZrO can improve the oxidation performance of catalyst. [ABSTRACT FROM AUTHOR]