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Laser Particle Size Analysis (laser + particle_size_analysis)
Selected AbstractsSynthesis and characterization of uniform-sized hollow chitosan microspheresADVANCES IN POLYMER TECHNOLOGY, Issue 1 2009Shan Wang Abstract Hollow chitosan (CS) microspheres were obtained using an inverse-emulsion crosslinking method. The temperature and viscosity of the CS emulsion affected the characteristics of the derived microspheres. The microspheres were characterized by differential scanning calorimetry, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy, optical microscopy, scanning electron microscopy (SEM), and laser particle size analysis. FT-IR indicated the sequence of transformations taking place before, during, and after the crosslinking of CS. Optical microscopy and SEM confirmed the spherical morphology of the gel. The formation of hollow microspheres with a single cavity was identified by SEM. The CS microspheres exhibited a narrow particle size distribution. Furthermore, particle size could be controlled by changing the stirring speed. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:40,47, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20145 [source] Reactivation of spent Pd/AC catalyst by supercritical CO2 fluid extractionAICHE JOURNAL, Issue 9 2009Xiaoxin Zhang Abstract In this article, we reported a nondestructive and environmentally friendly method for the reactivation of a spent Pd/AC catalyst for the hydrogenation of benzoic acid by using supercritical CO2 (scCO2) fluid extraction. The effects of reactivation conditions, such as extraction temperature, pressure, CO2 flow rate, and time, on the activity of the reactivated Pd/AC catalyst, were presented. The catalyst was characterized by N2 physisorption, laser particle size analysis, and transmission electron spectroscopy, and the liquid extract was analyzed by GC-MS. It is found that scCO2 fluid extraction was very efficient in eliminating organic substances blocking the pores of the catalyst, while did not affect noticeably the granule size of the catalyst and the particle size of Pd. The reactivated Pd/AC catalyst regained more than 70% of the activity of the fresh 5.0 wt % Pd/AC catalyst, and has been successfully used in an industrial unit for the hydrogenation of benzoic acid. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Synthesis and modification of zeolite NaA adsorbents for separation of hydrogen and methaneASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Yanna Liu Abstract To improve the adsorption capacity of zeolite A, two kinds of zeolite NaA with submicron and hierarchical structure were prepared. The XRD patterns indicated that both synthesized products were pure zeolite with LTA-type framework. The SEM images and laser particle size analysis showed that the particle size of submicron zeolite NaA was about 240 nm. The TEM and N2 adsorption/desorption isotherms proved the existence of mesopores in the hierarchical zeolite NaA. The adsorption capacities of single component CH4 or H2 on zeolite SrA adsorbents, obtained by Sr2+ ion-exchange of submicron and hierarchical zeolite NaA, and commercial zeolite 5A adsorbent were measured by the static volume method at 25 °C and pressures up to 1 MPa. The results show that both prepared zeolite SrA adsorbents have higher adsorption capacities of CH4 and ideal separation factors of CH4/H2 than commercial zeolite 5A, and the submicron zeolite SrA has the largest adsorption capacity of CH4 and ideal separation factor of CH4/H2. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Electrical transport properties of aliovalent cation-doped CeO2ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009Mark C. Pearce Abstract We report the comparative electrical properties of monovalent (Na+), divalent (Ca2+, Sr2+), trivalent (In3+, La3+) and coupled substitution of divalent and trivalent (Ca2+ + Sm3+) cation-doped CeO2. The investigated samples were prepared by solid-state reaction (ceramic) using the corresponding metal oxides and salts in the temperature range 1000,1600 °C in air. Powder X-ray diffraction (PXRD), laser particle size analysis (LPSA), scanning electron microscopy (SEM), and ac impedance spectroscopy measurements were employed for structural, morphology, and electrical characterization. PXRD studies reveal the formation of single-phase cubic fluorite-type structures for all investigated samples except those doped with In3+. The variation of lattice parameters is consistent with ionic radii (IR) of the dopant metal ions, with the exception of Na+ -doped CeO2. Our attempt to substitute In3+ for Ce4+ in CeO2 using both ceramic and wet chemical methods was unsuccessful. Furthermore, diffraction peaks attributed to CeO2 and In2O3 were observed up to sintering conditions of 1600 °C. Among the single-phase compounds investigated, Ce0.85Ca0.05Sm0.1O1.9 exhibits the highest bulk conductivity of 1.3 × 10,3 S/cm at 500 °C with activation energy of 0.64 eV in air. The electrical conductivity data obtained for Ce0.85Ca0.05Sm0.1O1.9 in air and Ar were found to be very similar over the investigated temperature range, indicating the absence of p-electronic conduction in the high oxygen partial pressure (pO2) range which is consistent with literature reported on Sm-doped CeO2. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||