No abstract

Hydrodeoxygenation (HDO) of various bio oil oxygenated model compounds in low H2 pressure has been discussed in this study. Because of the high yield of aromatic mixtures in bio-oil, they carry great potential for fuel efficiency. Nevertheless, due to its high viscosity, abundance of Abstract……………………………………………………………………………………………………………………………………. 1 Keywords…………………………………………………………………………………………………………………………………... 2 1-Introduction………………………………………………………………………………………………………………………….. 2 2-Bio-oil characteristics and its upgrading techniques……………………………………………………………………….………. 5 3-Low H2 pressure HDO………………………………………………………………………………………………………………. 8 3-1 Catalysts……………………………………………………………………………………………………………………. 14 3-1-1 Molybdenum……………………………………………………………………………………………………………………... 14 3-1-2 Platinum………………………………………………………………………………………………………………………….. 15 3-1-3 Other metals……………………………………………………………………………………………………………………... 16 3-1-4 Bi-functional active sites………………………………………………………………………………………………………… 17 3 _ 1-5 Supports…………………………………………………………………………………………………………………………... 19 3-2 Deactivation……………………………………………………………………………………………………………………. 20 3-3 Reaction network and Kinetics of guaiacol HDO at atmospheric pressure…………………………………………………. 21 3-4 Overall aspects and prospects…………..……………………………………………………………………………………. 25 Conclusion………………………………………………………………………………………………………………………………….

No abstract

To achieve the requirements of rechargeable Zn–air batteries (ZABs), designing efficient, bifunctional, stable, and cost-effective electrocatalysts is vital for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which still are struggling with unsolved challenges. The present research provides a concept based on the nanoscale composites which were engineered by using MnO2@C, CoO@C, and CoO:MnO2@C bifunctional electrocatalysts for fabrication of uniform carbon cloth (CC)-based electrodes. The CoO:MnO2@C electrocatalyst represented more efficient electrochemical properties through ORR and OER processes with superior positive half-wave potential (E 1/2 = 0.78 V) and better limiting current density (i = 1.10 mA cm–2) in comparison with MnO2@C (E 1/2 = 0.71 V, i = 0.92 mA cm–2) and CoO@C (E 1/2 = 0.69 V, i = 0.86 mA cm–2) electrocatalysts. For the rechargeable ZABs fabricated by using CoO:MnO2@C–CC as an O2-breathing cathode, the specific capacity (SC), peak power density (P), open-circuit voltage (E OCV), and gap of charge/discharge voltage resulted in values of 520 mAh gZn –1, 210.0 mW cm–2, and 1.45 and 0.45 V, respectively, that afforded greater electrochemical characters than what was obtained for ZABs based on MnO2@C–CC (410 mAh gZn –1, 195.0 mW cm–2, 1.38 and 0.44 V) and CoO@C–CC (440 mAh gZn –1, 165.0 mW cm–2, 1.15 and 0.54 V). At the same time, lower E i=10 (= 1.45 V) implied a more efficient OER in alkaline electrolyte solution for CoO:MnO2@C than MnO2@C (E i=10 = 1.50 V) and CoO@C (E i=10 = 1.39 V). Based on cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and X-ray photoelectron spectroscopy (XPS) results, it could be stated that the CoO:MnO2@C catalytic surface could experience 30 and 32% lower charge transfer resistance (R ct = 13.9 Ω) than MnO2@C (R ct = 20.1 Ω) and CoO@C (R ct = 29.7 Ω), respectively, which empowers an enhancement in ORR/OER performance. Prominently, the design concept of proposed electrocatalysts could suggest clear horizon for the synthesis and development paradigms of bifunctional catalysts for energy storage materials and devices.

No abstract

No abstract

The present investigation aimed to study the physicochemical characteristics of supported catalysts comprising various percentages of zinc dispersed over SiO2. The physiochemical properties of these catalysts were surveyed by N2 physisorption (BET), thermogravimetry analysis (TGA), H2 temperature-programmed reduction, field-emission scanning electron microscopy (FESEM), inductively coupled plasma-optical emission spectrometry (ICP-OES), and NH3 temperature-programmed desorption (NH3-TPD). In addition, to examine the activity and performance of the catalysts for the hydrodeoxygenation (HDO) of the bio-oil oxygenated compounds, the experimental reaction runs, as well as stability and durability tests, were performed using 3% Zn/SiO2 as the catalyst. Characterization of silica-supported zinc catalysts revealed an even dispersion of the active site over the support in the various dopings of the zinc. The acidity of the calcinated catalysts elevated clearly up to 0.481 mmol/g. Moreover, characteristic outcomes indicate that elevating the doping of zinc metal led to interaction and substitution of proton sites on the SiO2 surface that finally resulted in an increase in the desorption temperature peak. The experiments were performed at temperature 500 °C, pressure 1 atm; weight hourly space velocity (WHSV) 0.32 (h−1); feed flow rate 0.5 (mL/min); and hydrogen flow rate 150 (mL/min). Based on the results, it was revealed that among all the prepared catalysts, that with 3% of zinc had the highest conversion efficiency up to 80%. However, the selectivity of the major products, analyzed by gas chromatography flame-ionization detection (GC-FID), was not influenced by the variation in the active site doping.

No abstract