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电位法测定加氢催化剂中的硼含量 总被引:1,自引:0,他引:1
利用氟硼酸根离子选择电极对加氢催化剂中硼含量进行了测定,详细考察了实验条件及镍、钨、铝等离子的干扰。测定结果令人满意,相对标准偏差<0.18%。 相似文献
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José M. Guil Josefa E. Herrero García Anselmo Ruiz Paniego José M. Trejo Menayo 《Topics in Catalysis》2002,19(3-4):313-321
Measurements of the heat of adsorption of hydrogen on Ir/Al2O3 catalysts of different metal particle size were made by employing adsorption microcalorimetry. The values of this quantity were different for each sample and the results also indicated the heterogeneity of the iridium surface. In contrast to this, the heat of adsorption of oxygen measured on the same samples in the same manner was practically the same for all of them. The heat of oxygen adsorption as presented in the differential calorimetric isotherms was constant up to half the monolayer coverage for all the samples. This result is unexpected and in contradiction to the presence of surface heterogeneity in the iridium crystallites, as revealed by hydrogen adsorption. To clarify these anomalies the energetics of oxygen adsorption was determined using a different method. Titration experiments with hydrogen of preadsorbed oxygen were carried out. The heat of adsorption of oxygen was calculated from these results by means of adopting a thermochemical cycle. The values of heat of adsorption obtained as a function of the amount adsorbed unveiled the heterogeneity of the iridium surface. The differences found between the samples can be correlated to both the different particle size and degree of sintering of the samples. 相似文献
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用氨水做溶剂,使对苯二甲酸溶解,并形成对苯二甲酸铵,用NaOH标准溶液滴定NH^+4,通过计算 得对苯二甲酸的含量,本方法简便,准确,重现性和于浆料中对苯二甲酸含量的测定,结果令人满意。 相似文献
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蒙脱土负载型固体酸催化剂的烷基化性能与结构研究 总被引:7,自引:0,他引:7
以酸化后蒙脱土为载体,采用浸渍蒸发法制备了环境友好的蒙脱土负载znCl2型固体酸催化剂。研究了蒙脱土酸化处理、ZnCl2负载量及活化温度对催化剂烷基化活性的影响,并初步考察了催化剂的稳定性,比较了几种不同酸催化剂的烷基化活性。利用XRD、BET、TG—DTA、吡啶吸附FTIR对催化剂的结构进行了表征和测定;结果表明,蒙脱土酸化处理后形成的孔道有利于负载ZnCl2,ZnCl2与蒙脱土的羟基之间存在着化学键合,经活化后转化成Zn(0H)C1。蒙脱土负载ZnCl2后明显地提高蒙脱土表面的总酸量,催化剂活性与其表面总酸量之间有关,催化剂表面L酸与B酸的共存有利于其烷基化活性的提高。实验条件下,蒙脱土负载ZnCl2型催化剂在苯与氯节的烷基化反应中表现出较高的催化活性,二苯甲烷的收率最高可达83.6%。与其它Lewis酸试剂及酸化蒙脱土相比,蒙脱土负载型催化剂催化活性大有提高。 相似文献
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研究了用高氯酸标准溶液对对氨基苯甲酸正丁酯含量的非水滴定,具体方法为:精确称量对氨基苯甲酸正丁酯,用约25 mL的冰醋酸微热溶解。用配制好的高氯酸进行电位滴定,应用一阶导数法得出滴定结果。此方法容易操作,回收率在98.5%~103.9%之间。 相似文献
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电导滴定法测定聚酯浆料中对苯二甲酸含量 总被引:1,自引:0,他引:1
对苯二甲酸溶解于氨水,并形成H4NOOC-()-COONH4.用NaOH标准溶液进行电导滴定,求得对苯二甲酸的含量。本方法简便、准确、重现性好。用于聚酯浆料中对苯二甲含量的测定,结果令人满意。 相似文献
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改进了林文如酸碱双点电位滴定方法,导出了不作近似的计算公式,并对该方法准确度进行了探讨。用于鱼酸价测定,其相对误差皆小于1%。. 相似文献
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O,O—二异丙基二硫代磷酸的制备及分析方法 总被引:4,自引:0,他引:4
分析了影响二烷基二硫化代磷酸的合成和提纯的主要因素,通过控制原料异丙醇的滴加温度和提纯时的碱化pH值,以P2S5和异丙醇反应制备了纯度较高的二异丙基二硫化磷酸(HDDP),探讨了溴量法分析HDDP纯度的可行性和精度。 相似文献
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Three types of supported cobalt catalysts (CoOx/SiO2, CoOx/TiO2 and CoOx/Al2O3) were prepared by incipient wetness impregnation with aqueous Co(NO3)2·6H2O solution. The phase composition and the interactions of cobalt with supports under different calcined temperatures were
investigated using thermogravimetry (TG), N2-adsorption at −196 °C, X-ray diffraction (XRD), temperature-programmed reduction (TPR) and diffuse reflectance spectroscopy
(DRS). Their catalytic activities towards the CO oxidation were further studied in a continuous flow micro-reactor. The results
showed that the interaction of cobalt oxide with supports was much stronger in the kinds of Al2O3 and TiO2, while no conclusive evidence of any interaction was found for SiO2. Besides the crystalline Co3O4 which was formed in three supported catalysts, both high-temperature phases CoAl2O4 and CoTiO3 spinel were also detected under XRD, DRS and TPR analysis. The degree of interaction between cobalt oxide and the support
not only affected the surface area and reduction behavior of the catalysts, the catalytic activity toward the CO oxidation
also affected simultaneously. As the CoAl2O4 and CoTiO3 spinel formed, both the surface area and catalytic activity decreased significantly. 相似文献
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The preparation of pseudoionones by aldol condensation reaction between citral and acetone have been carried out in the presence of acid (HY and beta zeolites), an acid–base (amorphous aluminophosphate) and basic catalysts such as an aluminophosphate oxynitride, MgO and different activated hydrotalcites. The results showed that acid or acid–base catalysts were not successful for performing in one pot the preparation of ionones. MgO and calcined hydrotalcites showed excellent activity and selectivity to pseudoionones, with calcined hydrotalcite more selective than MgO. Moreover, the rate of reaction can be improved by activating the hydrotalcite through rehydration. This activation can be successfully done by simply adding the optimum amount of water to the calcined hydrotalcite before reaction. The inhibiting effect of the concentration citral on the catalytic activity of rehydrated hydrotalcites that has been reported to occur at 273 K can be avoided by working at a reaction temperature of 333 K. 相似文献