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In this work, two‐dimensional (2D) Co(OH)2 nanosheets, with large surface areas and wrinkles are obtained, and used to support Pd nanoparticles (NPs) by simple impregnation method as an efficient catalyst for the oxidation of benzyl alcohol under solvent‐free conditions. The resulting 1 wt.% Pd/Co(OH)2 catalyst exhibits a high turnover frequency value of 57999 h−1. The catalysts were characterized by SEM, TEM, AFM, XRD, BET, XPS and CO‐pulse chemisorption. The results of characterizations reveal that the Pd NPs are highly dispersed on the Co(OH)2 nanosheets. The abundant hydroxyl groups on the surface of Co(OH)2 nanosheets promote the reduction of Pd species, resulting in a higher proportion of Pd0 than that of Pd/AC catalyst, which further facilitates the catalytic performances. [ABSTRACT FROM AUTHOR]

Two types of apatite supports including hydroxyapatite (HAP) and fluorapatite (FAP) were prepared by the co-precipitation method. Supported Co catalysts with the above carriers were synthesized from Co(NO3)2·6H2O via the impregnation method. The catalytic activity for N2O decomposition was investigated using a continuous flowing microreactor system. The catalytic results demonstrated that the Co/HAP exhibited more excellent catalytic activity as well as the impurity gas (H2O, O2, and NO) resistance capability than the Co/FAP in the temperature range of 300–600 °C. Furthermore, the physicochemical properties of Co/HAP and Co/FAP were determined by several relevant characterization methods. The obtained experimental results revealed that Co/HAP possessed larger specific surface area, more ion-exchanged Co2+ and stronger oxygen desorption capacity than Co/FAP, which are the key factors for high N2O decomposition activity. Moreover, compared with Co/FAP, Co/HAP has not only more basic content, but also higher basic site density, which may be also conducive to enhance the electron donating ability of Co2+, thereby promoting the N2O catalytic decomposition. [ABSTRACT FROM AUTHOR]

Co 3 O 4 , Y 2 O 3 -Co 3 O 4 and NiO-Y 2 O 3 -Co 3 O 4 samples were prepared by the simple co-precipitation method, and their N 2 O catalytic decomposition performance was evaluated. Experimental results disclose that the order of catalytic activity among the three catalysts is NiO-Y 2 O 3 -Co 3 O 4 > Y 2 O 3 -Co 3 O 4 >> Co 3 O 4. N 2 O conversion over NiO-Y 2 O 3 -Co 3 O 4 catalyst reached 100 % at 360 °C, which was 20 °C and 60 °C lower than those over Y 2 O 3 -Co 3 O 4 and Co 3 O 4 , respectively. In addition, NiO-Y 2 O 3 -Co 3 O 4 catalyst shows better water resistance compared with Co 3 O 4 and Y 2 O 3 -Co 3 O 4. Systems-based characterization techniques, it is confirm that Y and Ni were successfully doped into Co 3 O 4 , where Y was on the surface and Ni was mainly in the bulk phase. Due to the co-doping of Y and Ni, NiO-Y 2 O 3 -Co 3 O 4 catalyst has smaller average particle size and reinforced surface alkalinity. Furthermore, the surface modification of Y enhances the electron-donating capacity of Co2+ and oxygen desorption ability, while bulk phase doping of Ni facilitates the reduction of Co3+ to Co2+ and weakens Co-O bond in Co 3 O 4 , which endow NiO-Y 2 O 3 -Co 3 O 4 sample with lower E a for N 2 O decomposition. Therefore, NiO-Y 2 O 3 -Co 3 O 4 catalyst exhibits the best N 2 O catalytic decomposition performance. [Display omitted] • NiO-Y 2 O 3 -Co 3 O 4 catalyst exhibits better catalytic performance for deN 2 O. • Y was dispersed on the surface and Ni was mainly in the bulk phase of Co 3 O 4. • Y enhances the electron-donating ability of Co2+ and O 2 desorption ability. • Ni promotes the reduction of Co3+ to Co2+ and weakens the strength of Co-O bond. [ABSTRACT FROM AUTHOR]

Introducing atmosphere in transmission electron microscope enables to directly observe the structural features of catalyst under working conditions. It offers the possibility to study the microstructural evolution and correlate real structures with catalytic properties at nano‐ or atomic‐scale during catalysis. However, the damages to catalyst derived from the high energy electron‐beam irradiation cannot be ignored and may lead to ambiguous conclusions, as the interaction between reactive gas molecules and active structures is only desired. Herein, the α‐Ga2O3 supported Pd catalyst was selected as a model to evaluate the potential effect of electron‐beam on the surface and interface structures, which directly affect the catalytic performance, at varied atmospheres, elevated temperatures and increased electron dose rate in ambient pressure. The results indicate that the supported Pd nanoparticles could be encapsulated by GaOx layer when the imaging electron dose rate is higher than 100 e/Å2s under reduction and oxidizing atmosphere. Either increasing the electron dose rate or elevating the temperature exacerbates the irradiation damage to α‐Ga2O3 support. This work was expected to evaluate the effect of electron dose rate to supported catalysts under chemical environments, and provide guidance for the investigation of in‐situ transmission electron microscopy under ambient pressure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Y 2 O 3 promoted Co 3 O 4 catalyst was synthesized using co-precipitation method. • Y 2 O 3 -Co 3 O 4 exhibits excellent catalytic activity and stability than Co 3 O 4. • The surface basic property is increased due to the addition of Y 2 O 3. • The catalytic performance is correlated with the electron donating ability of Co2+ and the O 2 desorption capacity. Co 3 O 4 and the Y 2 O 3 -Co 3 O 4 catalysts were synthesized via the precipitation method and the co-precipitation method. Y 2 O 3 -Co 3 O 4 exhibits excellent activity and stability for catalytic decomposition of N 2 O in comparison with Co 3 O 4. The characterization results show that Y 2 O 3 -Co 3 O 4 catalyst possesses larger S BET , smaller particle size and the enhanced surface basic property than Co 3 O 4 resulting from the interactions between Y and Co oxides. Furthermore, the promoted electron-donating ability of Co2+ and the facilitated O 2 desorption capacity endow the Y 2 O 3 -Co 3 O 4 catalyst a lower activation energy for N 2 O decomposition. Moreover, the Y 2 O 3 -Co 3 O 4 catalyst shows better catalytic performance in the presence of O 2 or H 2 O than Co 3 O 4. [ABSTRACT FROM AUTHOR]

Pd-Cu/APT catalysts were prepared by an impregnation method (PC-IM) and an evaporation ammonia method (PC-AE), respectively. Their catalytic activities for low-temperature CO oxidation were studied. It is found that PC-AE shows much higher catalytic activity. Characterizations results suggest that Cu species exist as the Cu(OH)Cl phase with nanoplatelet morphology in PC-AE. In addition, PC-AE possesses high specific surface area and enhanced reducibility, which may contribute to the excellent catalytic ability. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

• Co 3 O 4 /g-CN is clearly more active than bare Co 3 O 4 , Co 3 O 4 /AC, and Co 3 O 4 /γ-Al 2 O 3 for deN 2 O. • Co 3 O 4 /g-CN exhibits much higher specific activity than bare Co 3 O 4. • Co species may be bonded to the g-CN matrix through coordination bonds with forming Co-N. • The g-CN facilitates Co 3 O 4 /g-CN with high surface Co2+ content, massive surface oxygen species, and facile electrons transfer. A material of graphitic carbon nitride-supported cobalt oxides (Co 3 O 4 /g-CN) was synthesized via a facile and cost-effective impregnation route as a high-performance catalyst for decomposition of N 2 O. For comparison, bare Co 3 O 4 and other Co 3 O 4 catalysts supported on activated carbon (AC) and γ-Al 2 O 3 (Co 3 O 4 -A, Co 3 O 4 /AC, and Co 3 O 4 /γ-Al 2 O 3 , respectively) were also prepared. While g-CN was found to be active in the decomposition of N 2 O, AC and γ-Al 2 O 3 were inert to this reaction. Co 3 O 4 /g-CN showed superior catalytic activity than the other catalysts, and concurrently exhibited much higher specific activity compared to Co 3 O 4 -A. The experimental results revealed that all examined catalysts had the spinel structure. The Co species could incorporate into the g-CN matrix/layers and bond to the g-CN matrix through Co-N coordination bonds. The excellent performance of Co 3 O 4 /g-CN was attributed to the high surface Co2+ content, massive surface oxygen species, facile electrons transfer from the catalyst to N 2 O domains, and the synergistic coupling effects among active species such as Co3+/Co2+ redox couple, Co-N, and nitrogen sites. The active Co 3 O 4 /g-CN catalyst additional activity tests were conducted with N 2 O gas contaminated with H 2 O, O 2 , or NO. [ABSTRACT FROM AUTHOR]

• Co 3 O 4 / m -ZrO 2 is clearly more active than Co 3 O 4 / t -ZrO 2 for N 2 O catalytic decomposition. • Co 3 O 4 / m -ZrO 2 exhibits similar activity and much higher specific activity compared with bare Co 3 O 4. • Co 3 O 4 / m -ZrO 2 shows stronger interactions between the active component and support than Co 3 O 4 / t -ZrO 2. • The reasons contributing to the excellent N 2 O decomposition performance of Co 3 O 4 / m -ZrO 2 are proposed. Two ZrO 2 supports with either monoclinic (m -ZrO 2) or tetragonal (t -ZrO 2) crystal phases were obtained under hydrothermal reaction conditions. ZrO 2 -supported Co 3 O 4 catalysts (Co 3 O 4 / m -ZrO 2 and Co 3 O 4 / t -ZrO 2) were subsequently prepared through an impregnation-loading route. The effects of zirconia crystal phases on the catalytic decomposition of N 2 O over Co 3 O 4 /ZrO 2 catalysts were investigated in the presence or absence of contaminants (O 2 /H 2 O/NO) in the feed gas. The catalytic results indicated that Co 3 O 4 / m -ZrO 2 was more active than Co 3 O 4 / t -ZrO 2 during N 2 O decomposition. ZrO 2 supports and/or Co 3 O 4 /ZrO 2 catalysts were characterized via multitudinous techniques to explore the relationships between the structures, catalytic activities, and active sites of samples. The experimental results confirmed that there were more Co oxides dispersed on m -ZrO 2 than t -ZrO 2 , and Co 3 O 4 / m -ZrO 2 had superior textural properties than Co 3 O 4 / t -ZrO 2. Furthermore, Co 3 O 4 / m -ZrO 2 possessed a relatively higher redox Co2+/Co3+ activity, more surface Co2+, and more surface oxygen vacancies than Co 3 O 4 / t -ZrO 2 due to strong interactions between the m -ZrO 2 support and active Co oxides. m -ZrO 2 also contributed to the formation of stable Co2+. Moreover, the Co 3 O 4 / m -ZrO 2 surface contained abundant basic sites that helped improve the electron-donating ability of Co2+ which further decreased the activation energy for N 2 O decomposition. [ABSTRACT FROM AUTHOR]

The effect of acid treatment on the catalytic performance of CuO/Cryptomelane (CuO/CR) for CO preferential oxidation (CO-PROX) in H 2 -rich streams has been investigated. The CR supports are synthesized via the sol-gel approach. The hydrochloric acid or water is used to treat the CR support, and the corresponding CuO/CR catalysts are prepared by an initial wet impregnation method. Compared with the pristine CuO/CR and water-treated CuO/CR W catalysts, the acid-treated CuO/CR H exhibits the best catalytic activity with almost 100% of CO conversion at 110 °C, which can be maintained at least 100 h. The characterization results show that acid treatment decreases the K+ content in the CuO/CR H catalyst, which is conducive to the formation of more oxygen vacancies, thereby promoting the reducibility of CuO/CR H. This is the main reason for the high catalytic activity of the acid-treated CuO/CR H catalyst. Moreover, the abundant Brönsted acid sites on CuO/CR H are favorable for the desorption of acidic product CO 2 , which also could result in the significant promotion of the catalytic activity for CO-PROX. This study sheds a light on the importance of acid treatment for cryptomelane and provides an efficient catalyst for hydrogen purification. [Display omitted] • CuO/CR H exhibits better catalytic performance than CuO/CR W and CuO/CR. • The acid treatment is helpful for the generation of oxygen vacancy over CuO/CR H. • More oxygen vacancies promoted the improvement of the reducibility of CuO/CR H. • The improved reducibility of the CuO/CR H enhanced the CO-PROX reaction. • The enhanced Brönsted acid property favours the desorption of acidic product CO 2. [ABSTRACT FROM AUTHOR]

The effect of FeCl 3 addition on the catalytic property of Pd–Cu/hydroxyapatite (Pd–Cu/HAP) for low-temperature CO preferential oxidation (CO-PROX) under H 2 -rich condition has been investigated. It can be found that CO conversion of Pd–Cu/HAP rapidly decreases from 56% to 21% within 2 h at 30 °C in the presence of water, however, the Pd–Cu–Fe/HAP with the Fe/Cu atomic ratio of 1:1 presents a stable CO conversion of 40% and CO 2 selectivity of 100% under the same reaction conditions. The characterization results display that the addition of FeCl 3 to Pd–Cu/HAP causes the formation of Fe 2 O 3 species, and the strong interaction presents between Fe 2 O 3 species and Pd–Cu/HAP. Thus, the Pd0 species generated during CO-PROX over Pd–Cu–Fe/HAP can be more easily oxidized than that over Pd–Cu/HAP, which could avoid H 2 adsorption on Pd0 species and maintain CO adsorption and activation. [Display omitted] • Pd–Cu–Fe/HAP exhibits the better catalytic performance than Pd–Cu/HAP for CO-PROX. • The addition of FeCl 3 to Pd–Cu/HAP causes the formation of Fe 2 O 3 species. • There is a strong interaction between Fe 2 O 3 species and Pd–Cu/HAP. • The Pd0 generated during CO-PROX over Pd–Cu–Fe/HAP can be more easily oxidized. • Pd–Cu–Fe/HAP avoids H 2 adsorption on Pd0 and keeps CO adsorption and activation. [ABSTRACT FROM AUTHOR]

• Eggshell is an effective support to prepare Co 3 O 4 -based catalyst for N 2 O removal. • Co 3 O 4 /eggshell-DP exhibits much higher specific activity than Co 3 O 4. • Co 3 O 4 /eggshell-DP displays outstanding stability and anti-poisoning property. • Co 3 O 4 /eggshell-DP shows a close incorporation between CaCO 3 and Co 3 O 4. Co 3 O 4 shows excellent catalytic activity for N 2 O decomposition, in which it is urgently needed to develop novel efficient catalysts/supports with cheap and environmentally-friendly properties. Herein, Co 3 O 4 nanoparticles decorated eggshell catalysts (Co 3 O 4 /eggshell-GR, Co 3 O 4 /eggshell-IM, and Co 3 O 4 /eggshell-DP) were prepared using simple grinding, impregnation, and deposition-precipitation methods, where waste eggshells were used as an effective support and reaction-promoter. The results indicated that the preparation methods significantly influenced the catalytic activity of Co 3 O 4 /eggshell catalysts; the highest activity was obtained over the Co 3 O 4 /eggshell-DP. The activity of Co 3 O 4 /eggshell-DP was comparable to that of pure Co 3 O 4. More importantly, its specific activity was about 7.3 times that of Co 3 O 4 at 400 °C. The examined Co 3 O 4 /eggshell-DP also displayed outstanding stability and anti-poisoning property in NO, O 2 , and/or H 2 O-containing atmospheres. It was also verified that the excellent activity of Co 3 O 4 /eggshell-DP correlated with the unique structure of the eggshell and the close incorporation between CaCO 3 and Co 3 O 4. The Co 3 O 4 /eggshell-DP catalyst owned abundant Co 3 O 4 nanoparticles, more Co3+ species, and excellent redox performance, promoting the conversion of N 2 O at a lower temperature. The presence of abundant surface basic sites and a larger amount of oxygen vacancies also facilitated the catalytic efficiency of Co 3 O 4 /eggshell-DP. [Display omitted] [ABSTRACT FROM AUTHOR]