scholarly journals Enhanced Performance of the OMS-2-Supported CuOx Catalysts for Carbon Monoxide, Ethyl Acetate, and Toluene Oxidation

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 713
Author(s):  
Zhidan Fu ◽  
Mengyue Chen ◽  
Qing Ye ◽  
Ning Dong ◽  
Hongxing Dai
Keyword(s):  
Ethyl Acetate ◽  
Active Oxygen Species ◽  
Oxygen Mobility ◽  
Oxidation Of Co ◽  
Toluene Oxidation ◽  
In Situ Drifts ◽  
Redox Couples ◽  
Ft Ir ◽  
Incorporation Method

Different Cu contents (x wt%) were supported on the cryptomelane-type manganese oxide octahedral molecular sieve (OMS-2) (xCu/OMS-2; x = 1, 5, 15, and 20) via a pre-incorporation method. Physicochemical properties of the OMS-2 and xCu/OMS-2 samples were characterized by means of the XRD, FT-IR, SEM, TG/DTG, ICP-OES, XPS, O2-TPD, H2-TPR, and in situ DRIFTS techniques, and their catalytic activities were measured for the oxidation of CO, ethyl acetate, and toluene. The results show that the Cu species were homogeneously dispersed in the tunnel and framework structure of OMS-2. Among all of the samples, 15Cu/OMS-2 sample exhibited the best activities with the T50% of 65, 165, and 240 °C as well as the T90% of 85, 215, and 290 °C for CO, ethyl acetate and toluene oxidation, respectively, which was due to the existence of the Cu species and Mn3+/Mn4+ redox couples, rich oxygen vacancies, good oxygen mobility, low-temperature reducibility, and strong interaction between the Cu species and the OMS-2 support. The reaction mechanisms were also deduced by analyzing the in situ DRIFTS spectra of the 15Cu/OMS-2 sample. The excellent oxygen mobility associated with the electron transfer between Cu species and Mn3+/Mn4+ redox couples might be conducive to the continuous replenishment of active oxygen species and the constantly generated reactant intermediates, thereby increasing the reactant reaction rate.

scholarly journals Catalytic Elimination of Carbon Monoxide, Ethyl Acetate, and Toluene over the Ni/OMS-2 Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 581
Author(s):  
Ning Dong ◽  
Mengyue Chen ◽  
Qing Ye ◽  
Dan Zhang ◽  
Hongxing Dai
Keyword(s):  
Ethyl Acetate ◽  
Molecular Sieve ◽  
Space Velocity ◽  
Oxidation Of Co ◽  
Toluene Oxidation ◽  
Catalytic Activities ◽  
Catalytic Mechanisms ◽  
Ni Species ◽  
Synthesized Materials ◽  
Incorporation Method

The Ni-loaded cryptomelane-type manganese oxide octahedral molecular sieve (OMS-2) catalysts (xNi/OMS-2: x = 1, 3, 5, and 10 wt%) were prepared by a pre-incorporation method. Physicochemical properties of the as-synthesized materials were characterized by means of various techniques, and their catalytic activities for CO, ethyl acetate, and toluene oxidation were evaluated.The loading of Ni played an important role in improving physicochemical propertiesof OMS-2. Among all of the samples, 5Ni/OMS-2 exhibited the best catalytic activity, with the T90 being 155 °C for CO oxidation at a space velocity (SV) of 60,000 mL/(g·h), 225°C for ethyl acetate oxidation at an SV of 240,000 mL/(g·h), and 300 °C for toluene oxidation at an SV of 240,000 mL/(g·h), which was due to its high Mn3+ content and Oads concentration, good low-temperature reducibility and lattice oxygen mobility, and strong interaction between the Ni species and the OMS-2 support. In addition, catalytic mechanisms of the oxidation of three pollutants over 5Ni/OMS-2 were also studied. The oxidation of CO, ethyl acetate, and toluene over the catalysts took place first via the activated adsorption, then intermediates formation, and finally complete conversion of the formed intermediates to CO2 and H2O.

scholarly journals Experimental and Theoretical Studies of Sonically Prepared Cu–Y, Cu–USY and Cu–ZSM-5 Catalysts for SCR deNOx

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 824
Author(s):  
Przemysław J. Jodłowski ◽  
Izabela Czekaj ◽  
Patrycja Stachurska ◽  
Łukasz Kuterasiński ◽  
Lucjan Chmielarz ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Ultrasonic Irradiation ◽  
Active Phase ◽  
Spectroscopic Studies ◽  
In Situ Drifts ◽  
Ft Ir ◽  
Diffuse Reflectance Infrared ◽  
Experimental And Theoretical Studies

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNOx reaction. The faujasite-based catalysts were fully active at 200–400 °C, whereas the ZSM-5-based catalysts reached 100% activity at 400–500 °C. Our in situ DRIFTS experiments revealed that Cu–O(NO) and Cu–NH3 were intermediates, also indicating the role of Brønsted sites in the formation of NH4NO3. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNOx reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation).

Diffuse Reflectance FT-IR Characterization of Active Sites under Reaction Conditions: The Production of Oxygenates in the CO/H2 Reaction

1994 ◽  
Vol 48 (10) ◽  
pp. 1208-1212 ◽  
Author(s):  
J. J. Benítez ◽  
I. Carrizosa ◽  
J. A. Odriozola
Keyword(s):  
Infrared Spectra ◽  
Active Sites ◽  
Diffuse Reflectance ◽  
Reaction Conditions ◽  
In Situ Drifts ◽  
Ft Ir

The reactivity of a Lu2O3-promoted Rh/Al2O3 catalyst in the CO/H2 reaction is reported. Methane, heavier hydrocarbons, methanol, and ethanol are obtained. In situ DRIFTS has been employed to record the infrared spectra under the actual reaction conditions. The structure of the observed COads DRIFTS bands has been resolved into its components. The production of oxygenates (methanol and ethanol) has been correlated with the results of the deconvolution calculation. Specific sites for the production of methanol and ethanol in the CO/H2 reaction over a Rh,Lu2O3/Al2O3 catalyst are proposed.

Toluene oxidation over Co3+-rich spinel Co3O4: Evaluation of chemical and by-product species identified by in situ DRIFTS combined with PTR-TOF-MS

2020 ◽  
Vol 386 ◽  
pp. 121957 ◽  
Author(s):  
Jinping Zhong ◽  
Yikui Zeng ◽  
Dongdong Chen ◽  
Shengpeng Mo ◽  
Mingyuan Zhang ◽  
...  
Keyword(s):  
Toluene Oxidation ◽  
In Situ Drifts ◽  
Product Species ◽  
Tof Ms

Oxygen Mobility in Pre-Reduced Nano- and Macro-Ceria with Co Loading: An AP-XPS, In-Situ DRIFTS and TPR Study

2017 ◽  
Vol 147 (11) ◽  
pp. 2863-2876 ◽  
Author(s):  
Hyuntae Sohn ◽  
Gokhan Celik ◽  
Seval Gunduz ◽  
Doruk Dogu ◽  
Shiran Zhang ◽  
...  
Keyword(s):  
Oxygen Mobility ◽  
In Situ Drifts

A comparative study of CO adsorption and oxidation on Au/Fe2O3 catalysts by FT-IR and in situ DRIFTS spectroscopies

2006 ◽  
Vol 252 (1-2) ◽  
pp. 163-170 ◽  
Author(s):  
Goran Šmit ◽  
Neven Strukan ◽  
Menno W.J. Crajé ◽  
Károly Lázár
Keyword(s):  
Comparative Study ◽  
Co Adsorption ◽  
In Situ Drifts ◽  
Ft Ir

scholarly journals The Influence of Residual Sodium on the Catalytic Oxidation of Propane and Toluene over Co3O4 Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 867
Author(s):  
Guangtao Chai ◽  
Weidong Zhang ◽  
Yanglong Guo ◽  
Jose Luis Valverde ◽  
Anne Giroir-Fendler
Keyword(s):  
Specific Surface ◽  
Catalytic Oxidation ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Oxygen Species ◽  
Precipitation Method ◽  
Oxygen Mobility ◽  
Toluene Oxidation ◽  
Defective Structure ◽  
Practical Applications

A series of Co3O4 catalysts with different contents of residual sodium were prepared using a precipitation method with sodium carbonate as a precipitant and tested for the catalytic oxidation of 1000 ppm propane and toluene at a weight hourly space velocity of 40,000 mL g−1 h−1, respectively. Several techniques were used to characterize the physicochemical properties of the catalysts. Results showed that residual sodium could be partially inserted into the Co3O4 spinel lattice, inducing distortions and helping to increase the specific surface area of the Co3O4 catalysts. Meanwhile, it could negatively affect the reducibility and the oxygen mobility of the catalysts. Moreover, residual sodium had a significant influence on the catalytic activity of propane and toluene oxidation over the synthesized Co3O4 catalysts. The catalyst derived from the precursor washed three times presented the best activity for the catalytic oxidation of propane. The origin was traced to its better reducibility and higher oxygen mobility, which were responsible for the formation of active oxygen species. On the other hand, the catalyst obtained from the precursor washed two times exhibited better performance in toluene oxidation, benefitting from its more defective structure and larger specific surface area. Furthermore, the most active catalysts maintained constant performance in cycling and long-term stability tests of propane and toluene oxidation, being potentially applicable for practical applications.

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