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1.
Reza Shokrani Hossein Ajamein Mozaffar Abdollahifar 《Particulate Science and Technology》2018,36(2):217-225
Fuel cell-grade hydrogen production has been studied via steam reforming of methanol (SRM) over a series of CuO/ZnO/Al2O3 nanocatalysts fabricated by the combustion method. The effect of sonication and urea/nitrate ratio on the characteristics and catalytic properties of the prepared catalysts has been investigated. The synthesized catalysts were characterized by x-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Particle Size Distribution (PSD), energy dispersive x-ray (EDX), Brunauer-Emmett-Teller (BET) and FTIR analyses XRD patterns showed positive influence of urea/nitrate ratio on CuO and ZnO crystallite sizes. The ultrasonic mixing of primary gel compared with conventional mixing led to lower crystallite size. FESEM images showed that the sample mixed by sonication with a urea/nitrate ratio of 1 had more homogeneous morphology with narrow particle size distribution. EDX results proved the presence of all metals on the surface of the nanocatalysts and better consistence between the gel and surface composition of elements in samples prepared by sonication. Catalytic performance showed that sonication during the mixing of primary gel dramatically increased the methanol conversion. It was also proved that increasing the amount of urea led to lower catalytic activity. The ultrasound-treated nanocatalyst with urea/nitrate?=?1 was the best sample in terms of activity and selectivity. It was stable in the SRM for 1200?min without considerable change in methanol conversion and product selectivity. 相似文献
2.
A. Abdollahifar A.R. Shafiei A. Mohyeddin M. Bozorg 《Engineering Analysis with Boundary Elements》2010,34(8):721-726
One of the popular methods for solving ordinary differential equations is the state-space approach. In this paper, the use of the state-space method to analyze elastodynamic problems, discretized by the MLPG method, is proposed. Two methods commonly used in solving such problems, namely, the central difference method and the Newmark method, are compared with the proposed method. To examine the accuracy and the computational time of the new method, an example is studied. The results of the implementation of these methods are compared with a finite element solution. The results show that the state-space method saves substantial computational time for a given accuracy. 相似文献
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Recombinant Aspergillus oryzae expressing a dye-decolorizing peroxidase gene (dyp) was cultivated for repeated-batch production of recombinant dye-decolorizing peroxidase (rDyP) using maltose as a carbon source. High-level rDyP activity in limitation of carbon and nitrogen sources was maintained stably for 26 cycles of repeated 1-d batches of A. oryzae pellets without any additional pH control. Cultures maintained at 4 degrees C for 20 d resumed rDyP production following a single day of incubation. One liter filtrated crude rDyP containing 4600 U rDyP decolorized 5.07 g RBBR at the apparent decolorization rate of 17.7 mg l(-1) min(-1). 相似文献
4.
We examined production levels of dye-decolorizing peroxidase (rDyP) by recombinant Aspergillus oryzae using wheat bran and rice bran powders in repeated-batch and fed-batch cultures. Similar average rDyP productivities were observed in repeated-batch cultures using wheat bran powder and rice bran powder. Average rDyP productivities in fed-batch cultures were slightly lower than those in repeated-batch cultures. The rDyP production was affected by the addition of K(2)HPO(4) in the repeated-batch and fed-batch cultures using wheat bran powder. All average rDyP productivities in this study were significantly higher than those for any other peroxidases previously reported. 相似文献
5.
The activity of an extracellular lipase from the fungusPythium ultimum was studied as a function of emulsion properties, and the amount and type of surfactants used in preparing the emulsions.
The highest emulsified globule surface area as a function of surfactant concentration and emulsion stability were in the order
taurocholic acid >Triton X-100>3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). Lipase activity was dependent
on both the type and the concentration of surfactant, with taurocholic acid and CHAPS giving tenfold stimulation over the
control at 0.1 and 0.8 mM, respectively. The evidence suggests that the influence of surfactant is related more to interaction
with the enzyme at the oil-water interface than to providing greater interfacial surface area. 相似文献
6.
The nanoparticles of Fe3O4 as well as the binary nanoparticles of ionic liquid and Fe3O4 (IL-Fe3O4) were synthesized for removal of reactive red 120 (RR-120) and 4-(2-pyridylazo) resorcinol (PAR) as model azo dyes from aqueous solutions. The mean size and the surface morphology of the nanoparticles were characterized by TEM, DLS, XRD, FTIR and TGA techniques. Adsorption of RR-120 and PAR was studied in a batch reactor at different experimental conditions such as nanoparticle dosage, dye concentration, pH of the solution, ionic strength, and contact time. Experimental results indicated that the IL-Fe3O4 nanoparticles had removed more than 98% of both dyes under the optimum operational conditions of a dosage of 60 mg, a pH of 2.5, and a contact time of 2 min when initial dyes concentrations of 10-200 mg L−1 were used. The maximum adsorption capacity of IL-Fe3O4 was 166.67 and 49.26 mg g−1 for RR-120 and PAR, respectively. The isotherm experiments revealed that the Langmuir model attained better fits to the equilibrium data than the Freundlich model. The Langmuir adsorption constants were 5.99 and 3.62 L mg−1 for adsorptions of RR-120 and PAR, respectively. Both adsorption processes were endothermic and dyes could be desorbed from IL-Fe3O4 by using a mixed NaCl-acetone solution and adsorbent was reusable. 相似文献
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The online version of the original article can be found at 相似文献
8.
An extracellular triacylglycerol lipase (EC 3.1.1.3) fromPythium ultimum strain No. 144 was purified by ammonium sulfate precipitation, and by diethylaminoethyl Sepharose CL-6B and Sephacryl S−200
chromatography. The purified enzyme preparation showed a prominent polypeptide band in polyacrylamide gel electrophoresis,
associated with esterase activity according to activity staining. Molecular weight of the protein was estimated at 270 kD
using gel filtration on Sephacryl S−200, and 68 kD by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicating
that the enzyme may be a tetramer. The optimum pH and temperature for activity of the enzyme were 8.0 and 30°C, respectively.
Activity was reduced by Co2+, Fe2+, Sn2+ and Mn2+ and stimulated by Ca2+, Mg2+, Na+, K+ and surfactants such as taurocholic acid, Triton X−100,n-octyl glucoside,n-dodecyl-β-D-maltoside, 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate(CHAPS), and 3-[-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate.
The apparent maximum specific activity was 42 μmole/min/mg in the absence of CHAPS and 77 μmole/min/mg in its presence. The
reaction rate was progressively higher with increasing number of double bonds in the substrate, and the enzyme showed a preference
for triacylglycerols containing fatty acids having thecis double bond configuration.
AAES publication No. 6-933419. 相似文献
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