Abstract: Synthesizing supercritical carbon dioxide (scCO2) soluble precursors would be helpful for many processes of material syntheses based on scCO2. Ligand (amphi-(1Z, 2Z)-N-(2-fluoro-3-(trifluoromethyl) phenyl)-N'-hydroxy-2-(hydroxyimino) were synthesized from chloro glyoxime and flourus aniline and Pd(II) complex (precursor) prepared. For scCO2 deposition method, organometallic precursor was dissolved in scCO2 and impregnated onto the SBA-15 at 90 °C and 3000 psi. Then the organometallic precursor was reduced with H2 in the CO2 mixture (150 psi H2 + 2850 psi CO2). Pd deposited support material was characterized by ICP-OES, XRD, FE-SEM, TEM and EDX analyses. The Pd loading of the prepared catalyst, measured by ICP-OES showed a value of about 1.64% mol/g Pd of catalyst. Average particle size was found 5.3 nm. The catalytic activity of prepared catalyst was investigated over Suzuki-Miyaura C-C coupling reaction in different solvent with K2CO3 at 50 oC. The conversion ratio was determined by gas chromatography.
Abstract: Biodiesel, as an alternative renewable fuel, has been
receiving increasing attention due to the limited supply of fossil fuels
and the increasing need for energy. Microalgae are promising source
for lipids, which can be converted to biodiesel. The biodiesel
production from microalgae lipids using lipase catalyzed reaction in
supercritical CO2 medium has several advantages over conventional
production processes. However, identifying the optimum microalgae
lipid extraction and transesterification conditions is still a challenge.
In this study, the quality of biodiesel produced from lipids extracted
from Scenedesmus sp. and their enzymatic transesterification using
supercritical carbon dioxide have been investigated. At the optimum
conditions, the highest biodiesel production yield was found to be
82%. The fuel properties of the produced biodiesel, without any
separation step, at optimum reaction condition, were determined and
compared to ASTM standards. The properties were found to comply
with the limits, and showed a low glycerol content, without any
separation step.
Abstract: This research studies the electroplating of zinc coating
in the zinc chloride bath mixed with supercritical CO2. The sodium
fluoride (NaF) was used as the bath additive to change the structure
and property of the coating, and therefore the roughness and corrosion
resistance of the zinc coating was investigated. The surface
characterization was performed using optical microscope (OM), X-ray
diffractometer (XRD), and α-step profilometer. Moreover, the
potentiodynamic polarization measurement in 3% NaCl solution was
employed in the corrosion resistance evaluation. Because of the
emulsification of the electrolyte mixed in Sc-CO2, the electroplated
zinc produced the coating with smoother surface, smaller grain, better
throwing power and higher corrosion resistance. The main role played
by the NaF was to reduce the coating’s roughness and grain size. In
other words, the CO2 mixed with the electrolyte under the supercritical
condition performed the similar function as brighter and leveler in zinc
electroplating to enhance the throwing power and corrosion resistance
of the coating.
Abstract: In this study, a nickel film with nano-crystalline grains,
high hardness and smooth surface was electrodeposited using a post
supercritical carbon dioxide (CO2) mixed Watts electrolyte. Although
the hardness was not as high as its Sc-CO2 counterpart, the thin coating
contained significantly less number of nano-sized pinholes. By
measuring the escape concentration of the dissolved CO2 in post
Sc-CO2 mixed electrolyte with the elapsed time, it was believed that
the residue of dissolved CO2 bubbles should closely relate to the
improvement in hardness and surface roughness over its conventional
plating counterpart. Therefore, shortening the duration of
electroplating with the raise of current density up to 0.5 A/cm2 could
effectively retain more post Sc-CO2 mixing effect. This study not only
confirms the roles of dissolved CO2 bubbles in electrolyte but also
provides a potential process to overcome most issues associated with
the cost in building high-pressure chamber for large size products and
continuous plating using supercritical method.