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Natural Gas Dehydroaromatization
Published in Jianli Hu, Dushyant Shekhawat, Direct Natural Gas Conversion to Value-Added Chemicals, 2020
Rekha Yadav, Sreedevi Upadhyayula
Rahman et al. (2019) studied the various species formed during induction period with different pretreatment. The four types of treatment were performed and studied using temperature-programmed reduction and carburization profiles: (1) heating the catalyst in a reducing gas, H2, up to reaction temperature and switching to CH4; (2) heating the catalyst in a reducing gas, H2, mixed with dilute CH4; (3) heating the catalyst in CH4 up to reaction temperature; and (4) heating the catalyst in an inert gas (commonly He) up to reaction temperature and then switching to CH4 or to H2 followed by CH4 or to H2/CH4 mixture. All the pretreated samples (with CH4) showed the presence of Mo2C species on H-ZSM-5 (see Table 10.5). The mechanism involved in Mo2C varied with pretreatment conditions. However, catalyst treated with H2 followed by CH4, or in a dilute mixture of CH4/H2 showed higher stability, which might be due to higher Mo dispersion.
Structural characterizations of copper incorporated manganese oxide OMS-2 material and its efficiencies on toluene oxidation
Published in Chemical Engineering Communications, 2022
C. Kaewbuddee, P. Chirawatkul, K. Kamonsuangkasem, N. Chanlek, K. Wantala
The crystalline phase of the samples was analyzed by XRD (PANalytical, EMPYREAN (Netherlands)) using Cu Kα radiation with wavelength λ = 0.1514 nm at 40 mA and 45 kV and Bruker D8 Advance using Cu Kα with wavelength λ = 0.1514 nm at 30 mA and 40 kV. The specific surface area was analyzed using a N2 adsorption-desorption analyzer (ASAP2460, Micromeritics, USA) and calculated using the BET equation. The redox ability of the catalyst was studied by H2 temperature-programmed reduction (H2-TPR) by using AMI-300IR (Altamira Instruments, USA) chemisorption analyzers model with a thermal conductivity detector (TCD). About 9.5 mg of samples was treated at 105 °C with flowrate 30 mL/min of N2 gas for 1 h. Then, the temperature was decreased to 30 °C and keep for 10 min under Ar gas at the same flow rate. The samples were continuously heated from 30 °C to 550 °C with an increasing rate 10 °C/min under 10%H2/Ar gas at flowrate 30 mL/min. The oxidation states of manganese, copper, and oxygen were determined by XPS and XANES techniques (BL5.3 and BL1.1W, respectively), Synchrotron Light Research Institute (Public Organization), Thailand. The neighboring atoms and absorber-neighbor distances were analyzed via the EXAFS technique (BL1.1W). The stand-alone XPS with a Kratos AXIS Ultra model was operated using monochromatic Al Kα hν = 1486.71 eV, 5 mA, and 15 kV as X-ray source.
Effect of preparation method on the catalytic performance of formaldehyde oxidation over octahedral Fe3O4 microcrystals supported Pt catalysts
Published in Journal of Dispersion Science and Technology, 2020
Weiyi Cui, Ling Liu, Jiajun Yang, Naidi Tan
The materials were characterized by powder X-ray diffraction (XRD) using a Rigaku X-ray diffractometer equipped with Cu Ka radiation. The Pt loadings in the catalysts were determined by inductively coupled plasma optical emission spectroscopy (ICP-AES, Optima 2000DV). 57Fe Mössbauer spectra were obtained using an OIMS-500 Mössbauer spectrometer with 57Co(Pd) g-ray radioactive source. Transmission electron microscopy (TEM) images and energy-dispersive X-ray spectra (EDX) images were obtained using a FEI Tecnai F20 EM operated at an accelerating voltage of 200 kV and equipped with an energy-dispersive spectroscopy analyzer. Brunauer-Emmett-Teller (BET) surface areas were acquired from nitrogen adsorption at 77 K using an ASAP 2010. X-ray photoelectron spectroscopy (XPS) analyses were performed with an ESCALAB250 X-ray photoelectron spectrometer with Al Kα radiation; the elemental binding energies were calibrated with C 1 s (284.6 eV) as standard. H2-O2 titration experiments were carried out on a Builder PCA-1200 Pulse Chemisorption System. Temperature-programmed reduction (TPR) was carried out using a Builder PCA-1200 adsorption analyzer equipped with a thermal conductivity detector (TCD).
Ordered mesoporous La–Co–Ce–O3 through nanocasting: an effective catalyst for the photodegradation of phenol
Published in Journal of Experimental Nanoscience, 2020
Menggentuya Bao, Yang Guiping, Jia Meilin, Wang Jiang
The composition and crystal phase of samples were characterised by powder X-ray diffraction meter with Cu Ka radiation. Nitrogen adsorption–desorption measurements were determined using an ASAP 2020 M analyser utilising the Brunauer–Emmett–Teller (BET) model and Barrett–Joyner–Halenda (BJH) method for the calculation of specific surface areas and pore size distribution. Before measurement, the samples of 0.1–0.15 g were degassed in vacuum at 100 °C for 5 h. Hydrogen temperature programmed reduction (H2-TPR) measurements were carried out on a self-assembled apparatus with thermal conductivity detector (TCD) as detector under a flow rate of 50 mL·min−1 (5% H2/Ar). Approximately 50 mg of sample was pre-treated with Ar at 100 °C for 2 h, prior to running the H2-TPR experiments, and the temperature was raised from room temperature to 800 °C at a rate of 10 °C·min−1. X-ray photoelectron spectroscopy (XPS) also has been registered using ESCALAB 250xi Electron Spectrometer.