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991.
本文提出一种能快速灵敏地检测地面水和污水中苯胺类化合物的试剂盒。该方法是以 N-氯代丁二酰亚胺氧化苯胺 ,在 p H9- 1 1的碱性介质中 〔1〕,以 1 -萘酚偶联显色。显色反应所得的蓝色化合物的最大吸收波长为 61 0 nm,在苯胺浓度为 0 .2~ 8mg/L的浓度范围内符合比尔定律 ,最低检出限为 0 .0 2 mg/L ,测定的重现性在± 5 %以内。该试剂盒用于合成水样和环境水样的分析 ,回收率在 94.9~ 98.2之间。这种试剂盒可以成功地用于合成水样和环境水样的分析 相似文献
992.
The nano-CeO2/ZnO catalysts were prepared using a novel combination of homogeneous precipitation with micro-emulsion for oxidative coupling of methane with CO2 as an oxidant. The prepared catalysts were compared with those prepared using the conventional impregnation. The catalysts prepared in two ways were characterized with FTIR, TEM, XRD and CO2-TPD. The effects of the reaction temperature, the amount of ZnO doped in the catalysts and the average size were investigated. The experimental investigation demonstrated that methane conversion over the nano-CeO2/ZnO catalysts prepared by the combined technique was higher than that obtained over catalysts prepared by the conventional impregnation. A better low-temperature activity has also been achieved over the nanocatalysts. There was no clear trend between the average size of nano-CeO2/ZnO catalysts and their catalytic performance but methane conversion increased with increasing fractal dimension of nanocatalysts. 相似文献
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995.
A kind of novel superabsorbent hydrogel with high swelling ratio property that could be used for the development of water absorbing resin, soil water retention agent, and chemical sand‐fixing material was synthesized in this study. The hydrogels were prepared by the crosslinking reaction of polysuccinimide (PSI). The relationships between swelling ratio and volume of solvent as well as the concentration of crosslinking agent were investigated in detail. Several composites, such as starch, carrageenan, and polyacrylamide, were added into hydrogels to enhance the swelling ratio. It was found that the swelling ratio was significantly increased, which the maximum water absorbency was enhanced 2.46 times when the composite polyacrylamide (PAM) was added compared to the control. The effects of ionic strength and sensitivity of pH on hydrogels were also studied. The modified hydrogels products with swelling ratio less sensitivity to the salinity as well as relative high swelling ration in salinity system were also obtained by adding PAM. Through the Fourier transform infrared spectroscopy (FTIR) characterizations, the crosslinking reaction mechanism and the structure of composite were proposed. In addition, the transmission electron microscopy (TEM) examinations showed that some composite materials elevated the physical crosslinked and connected channels density substantially. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 550–557, 2006 相似文献
996.
Pt, Ir, Pt-Ir and Pt-Ni bimetallic catalysts supported on NaY- and HY-zeolite were examined as a catalyst for producing gasoline
from n-decane via simultaneous reforming and cracking. The catalysts were prepared by calcining and reducing metal-ion-exchanged
Y-zeolite with O2 and H2 at 300°C., respectively. Thus prepared catalysts were characterized by hydrogen chemisorption and temperature programmed
desorption of ammonia. Pt-Ni/NaY and Pt-Ir/NaY bimetallic catalysts offered the improved activity maintenance compared to
Pt/NaY monometallic catalyst. The catalysts supported on HY-zeolite showed higher selectivity toward C5–C7 and skeletal isomers of C5–C7- and C8–C10 than those of the catalysts supported on NaY-zeolite, which is a desired characteristic for increasing octane value of gasoline
these days. However, deactivation with reaction time was much more pronounced on HY-zeolite-supported catalyst. When the catalyst
was prcsulfided with H,S, the stability with time on stream was enhanced and the selectivity was quite different from that
of the catalyst before presulfiding. The acidity of Y-zeolite and presulfiding of catalyst greatly influenced the activny,
selectivity and stability of Pt, Ir, Pt-Ir and Pt-Ni bimetallic catalysts supported on Y-zeolite in n-decane reforming reaction. 相似文献
997.
Systems of Pd supported on various La2O3-modified -Al2O3 and CeO2–Al2O3 catalysts were tested for catalytic methanol decomposition and characterized by means of XRD, BET, TPR, H2-chemisorption and CO–FTIR. The addition of lanthanum significantly improved the selectivity of CO and H2 for all the catalysts but showed a different influence on the catalytic activity in two systems. Methanol conversion decreased on La2O3-modified Pd/-Al2O3 catalysts, in line with the reduction of Pd dispersion, while the addition of La2O3 improved the dispersion of Pd and reinforced Pd–CeO2 interaction for La2O3-modified Pd/CeO2–Al2O3 catalysts, which resulted in a high production rate of CO and H2. Thus, a synergistic effect between CeO2 and La2O3 was observed on -Al2O3-supported Pd catalyst for methanol decomposition. 相似文献
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1000.
Hai‐Xia Yang Yan‐Feng Li Jin‐Gang Liu Shi‐Yong Yang Da‐Xue Yin Lincheng Zhou Lin Fan 《应用聚合物科学杂志》2004,91(6):3981-3990
A series of new polymerized monomer reactants (PMR) matrix resins of poly(pyrrolone‐benzimidazole)s containing a pyridine unit (PPBP) were synthesized by polycondensation of monoethyl ester of cis‐5‐norbornene‐endo‐2,3‐dicarboxylic acid, 2,6‐diphenyl ester pyridinedicarboxylic acid or 3,5‐diphenyl ester pyridinedicarboxylic acid, and diethyl ester of 4,4′‐oxydiphthalic acid with 3,3′‐diaminobenzidine in a mixing solution of anhydrous ethyl alcohol and N‐methylpyrrolidone under given temperature and pressure conditions. The resulting resin solutions showed good solubility in polar organic solvents and stability at room temperature. The corresponding PPBP matrix resin, molded powder, and molded plate were prepared by undergoing amidation, imidization, cyclization, and crosslinking reactions when the reaction temperature was increased from 80 to 350°C, successively; the crosslinking structure was formed by the reverse Diels–Alder reaction at 270–290°C under 50 MPa pressure (2.5–3.5 MPa displayed by the pressure meter). The chemical reactions and properties of the resulting PPBP were studied by means of FTIR, TGA, and DMA methods, and the results indicated that the kinds of PPBP materials retain excellent thermal stability and processability; when the initial decomposition temperature was above 620°C the Tg was at 413.5°C for 3,5‐PPBP‐20 molded plate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3981–3990, 2004 相似文献