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A series of Ce-M(Cu, Co and Fe) catalysts were synthesized via sol–gel methods. In situ DRIFTS was introduced to explored the process of toluene degradation, confirming oxygen vacancies played an important role. [Display omitted] • Ce-Cu sample exhibited best catalytic activity and stability for toluene oxidation. • Superb activity was attributed to high Ce3+/ Ce4+ and high O ads /O latt. • The oxygen vacancies were modulated by different metal doping. • Benzoic acid was key intermediates in toluene catalysis by in situ DRIFT analysis. A series of CeO 2 samples modified with various metals M (M = Cu, Co and Fe) were synthesized via a simple sol–gel approach. The experimental results showed that there were significant differences in the catalytic activities between different metal-doped Ce-based catalysts. The Ce-Cu sample possessed excellent catalytic activity at low temperatures, and 90 % conversion of toluene was at 255 ℃, which was due to the presence of ample oxygen vacancies (O v). Three degradation pathways for toluene oxidation were inferred based on the in situ DRIFTS. The Ce-Cu catalysts possessed abundant O v , which improved the conversion between O ads → O latt and the breakage of aromatic rings, thus reducing the production of intermediates. The Ce-Co and Ce-Fe catalysts owned few amounts of O v species, leading to an extensive amount of by-products. Furthermore, the loss of active sites inhibited the reaction rate, causing the inferior catalytic performance of the Ce-Co and Ce-Fe samples. [ABSTRACT FROM AUTHOR]

The development of ultrathin two-dimensional metal–organic framework nanosheets (2D MONs) has recently attracted increasing interest due to their extensive application potential originating from their ultrathin thickness, large surface area, and innumerable accessible surface-active sites. In this frontier article, we highlight the recent developments of 2D MONs for highly efficient heterogeneous catalysts; they can be grouped into three sections in terms of their functions: (i) as catalysts capable of showing outstanding intrinsic reactivity, (ii) as support materials for prevalent catalysts, and (iii) as catalysts with multifunctional catalytic activity for diverse organic transformations. In addition, the present challenges and future opportunities in this field are also discussed. [ABSTRACT FROM AUTHOR]

• The formation of Fe3+-O-Mn3+ over FeMnO x affected catalytic activity, stability and reaction rate. • Oxygen vacancies are altered by Fe and Mn interactions. • Oxygen adsorbed on the surface of FeMnO x was the active species. • The possible reaction mechanism of toluene was proposed by DRIFT analysis. To examine the influence of Fe-Mn interactions on the catalytic removal to toluene, FeO x , MnO x and FeMnO x catalysts were manufactured via co-precipitation approach. FeMnO x catalysts presented the optimal low-temperature catalytic toluene activity which attained 100 % removal of toluene (T 100) at 270 ℃. The physical and chemical characterization of the material confirmed an increased ratio of Mn3+/Mn4+ and O ads /O lat bonds caused by to the formation of Fe3+-O-Mn3+ bonds. Concurrently, the low-temperature catalytic activity for toluene increased with the increased density of oxygen vacancies, the changed properties in oxygen vacancies and the enhanced oxidation capacity of surface activated oxygen species. In situ DRIFTS experiments were performed to infer different toluene degradation pathways on three catalysts. The catalytic routes for toluene over FeMnO x catalyst was different at 150 ℃ and 260 ℃. At 150 ℃, as the surface oxygen vacancies were not fully activated, the reaction pathway was toluene → benzyl alcohol → benzaldehyde → phenol. The path of toluene over FeMnO x catalyst at 260 ℃ was toluene → benzyl alcohol → benzoaldehyde → benzoate → maleic anhydride and carbonate → H 2 O and CO 2. As compared with MnO x and FeO x catalysts, FeMnO x catalyst could oxidize benzyl alcohol to benzaldehyde and phenol at 150 ℃. This decreased the energy required to open the ring of benzene and accelerated the catalytic oxidation rate. FeO x , MnO x and FeMnO x catalysts were prepared by co-precipitation method and the high-velocity active sites and catalytic mechanism on FeMnO x catalysts were investigated. The degradation pathway of toluene oxidation on the FeMnO x was speculated: toluene → benzyl alcohol → benzaldehyde → benzoic acid → maleic anhydride → CO 2 and H 2 O. [Display omitted] [ABSTRACT FROM AUTHOR]

Dehydrogenation of long chain paraffins over commercial Pt-Sn-K-Mg/Al 2 O 3 and Pt-Sn-Na-Co/Al 2 O 3 catalysts were investigated using a temperature programmed reaction/single-photon ionization time-of-flight mass spectrometry (TPRn/SPI-TOF-MS) system under realistic reaction conditions using model compound C 12 0 and in the industrial PACOL dehydrogenation plant using n-C 10 0 -C 13 0 mixture. The catalysts were characterized by BET, mercury intrusion porosimetry, CO-chemisorption and NH 3 -TPD. Catalytic activity, selectivity to various components and stability were compared between TPRn/SPI-TOF-MS measurement and industrial plant run data to explore the reliability, predictability and application of TPRn/SPI-TOF-MS for rapid catalyst testing and screening. Characteristics of the catalysts, such as Pt dispersion and acidity, affected paraffin dehydrogenation conversion and mono-olefin selectivity. This was reflected in the catalyst performance data obtained on TPRn/SPI-TOF-MS system, which was in good agreement with the data from industrial runs. It is shown that use of TPRn/SPI-TOF-MS measurements allows to identify the reaction temperature range for maximum mono-olefin yield. Further it is possible to judge onset temperature for all the products and help identify operation temperature for industrial plant operation. Investigation of aromatics formation over the catalysts establishes the consecutive reaction pathways of long chain paraffin dehydrogenation over modified Pt-Sn/Al 2 O 3 catalyst. [ABSTRACT FROM AUTHOR]