Acetals and ketals are among the most important perfume materials and industrial materials of organic synthesis. Up to now, there are many methods to synthesize them.Conventionally H2SO4 is used as catalyst in factories, but it causes many problems, such as the erosion of equipment, difficulty for after-treatment, low quality of the products, etc. Heteropolyacids (HPA) and their salts have been extensively studied because of their interesting catalytic properties.Significant research effort has been directed towards the entrapment of heteropolyanions in suitable polymeric matrices with the main goal of preparing a new type of polymer-supported catalyst for various applications in heterogeneous and electrocatalysis. It showed that the main catalysis of HPA occurs through Brφnsted acid. The reports pointed that the rate of dehydration and etherification is directly in proportion to total acidity of heteropolyacids, HPA and its salts showed excellent catalytic activity to the esterification and have recently attracted much attention as catalysts for various industrial processes, because that their acidic and redox properties can be controlled at atomic/molecular levels. Mizuno and Misono, Pope, Kozhevnikov and Wang Enbo have reviewed the homogeneous catalysis and fine organic synthesis catalyzed by heteropoly compounds.Polyaniline (PAn) is another example of a polymer host which can accommodate anions originating from 12-tungstophosphoric acid (PW12). The polyemeraldine base was prepared by condensation-polymerization of aniline in aqueous HCl using (NH4)2S2O8 as the oxidant.PW12/PAn can be achieved by doping the protonation of the polyemeraldine base with H3PW12O40 in a two-step procedure. However, there is no report on the synthesis of 2-methyl-2-ethyl acetoacetate-1,3-dioxolane catalyzed by PW12/PAn.In this paper, 2-methyl-2-ethyl acetoacetate-1,3-dioxolane was synthesis from ethyl acetoacetate and ethylene glycol in the presence of PW12/PAn. The factors influencing the synthesis were discussed and the best cond
In this work,a dual-phase material consisting of La0.7Ca0.3Cr0.95Zn0.05O3-δ（LCCZ,40 wt%） and Gd0.1Ce0.9O2-δ（GDC,60 wt%） was synthesized.Properties including phase structure,sintering behavior,electrical conductivity and oxygen permeability for LCCZ—GDC were evaluated.The results show that dense LCCZ-GDC dual-phase disks were obtained at the sintering temperature of 1250,1300,1350 and 1400 ℃by tape casting and high temperature sintering method.The grain sizes of both GDC and LCCZ grew up with the increasing of sintering temperature.The average grain size of GDC was about 0.5,0.8,1.4,1.8 μm while the average grain size of LCCZ was about 0.8,1.5,1.8 and 2 μm after sintering at 1 250,1 300,1350 and1400 ℃,respectively.Oxygen flux of LCCZ-GDC decreased with the increase of sintering temperature from1250 to 1400 ℃.The oxygen flux of LCCZ-GDC sintered at 1250 ℃ reached 0.079 mL/min/cm2 at 975 ℃with a membrane thickness of 800 urn.Dual-phase material of LCCZ-GDC will be a promising oxygen transport membrane material for its low sintering temperature and good microstructure.
Barium sulfate aggregates with an average size of 0.5 μm were synthesized at pH 7,directed by ethylenediaminetetraacetic acid（EDTA） anions.The particle morphology,chemical composition,and size distribution of the BaSO4 aggregates were characterized.The as-synthesized BaSO4 particles were spherical and comprised many interconnected nanoballs,of which the surface properties were affected by the EDTA anions.The adsorption of EDTA anions reversed the charge and weakened the surface polarity of BaSO4,instigating the formation of aggregates by a self-assembly and transformation process.The resulting BaSO4 particles at pH 9-10 were ellipsoidal and featured smooth surfaces.Based on the zeta potential of BaSO4,variations in the morphology induced by changes in pH were closely related to the adsorption of mono- and multi-valent anions onto the electrical double layer of BaSO4.
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