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1.
研究了以固体超强酸SO4^2-/TiO2/La^3+为催化剂,丁酸和无水乙醇为原料合成丁酸乙酯,并考察了影响反应的因素。结果表明,醇酸摩尔比为2.0:1,催化剂用量的0.5g(丁酸为0.2mol的情况下),带水剂苯为15mL,反应时间为2.0h,是最适宜的反应条件,酯化率达95.6%。 相似文献
2.
稀土固体超强酸SO42-/TiO2/La3+催化合成马来酸二戊酯 总被引:3,自引:0,他引:3
研究了以固体超强酸SO4^2-/TiO2/La^3+为催化剂,马来酸和正戊醇为原料合成马来酸二戊酯并考察了影响反应的因素。结果表明,醇酸摩尔比为4.0:1,催化剂用量为1.0g,带水剂甲苯为15mL,反应时间为3.0h是最适宜的反应条件,酯化率达98.8%。 相似文献
3.
稀土固体超强酸SO^2—4/TiO2/La^3+催化合成异丁酸丁酯 总被引:5,自引:0,他引:5
研究了以稀土固体超强酸SO^2-4/TiO2/La^3+为催化剂,异丁酸和正丁醇为原料合成异丁酸丁酯,并考察了影响反应的因素。结果表明,醇酸比为1.81:1,催化剂用量为0.5g,带水剂甲苯为15ml,反应时间为2.0h是最适宜的反应条件,酯化率达97.2%。 相似文献
4.
稀土固体超强酸SO^2—4/TiO2/La^3+催化合成马来酸二丁酯 总被引:18,自引:3,他引:15
以固体超强酸SO^2-4/TiO2/La^3+为催化剂,马来酸和正丁醇为原料合成马来酸二丁酯,考察了影响反应的因素,结果表明:n(醇):n(酸)=4.0:1,催化剂用量为1.0g;带水剂甲苯为15mL;反应时间为3.0h是最的反应条件,酯化率达97.4%。 相似文献
5.
稀土固体超强酸SO4^2—/TiO2/La^3+催化合成丁酸丁酯 总被引:4,自引:0,他引:4
研究了以稀土固体超强酸SO4^2-/TiO2/La^3+为催化剂,丁酸和正丁醇为原料合成丁酸丁酯,并考察了影响反应4 因素。结果表明,醇酸物质的量比为1.8:1,催化剂用量为0.5g(本酸为0.2mol的情况下),带水剂甲苯为15mL,反应时间为2.0h是合成丁酸丁酯的较适宜的反应条件,酯化率达98.6%。 相似文献
6.
固体超强酸SO4^2—/ZrO2—TiO2催化剂的研制及其催化合成草莓酸酯的 … 总被引:10,自引:2,他引:8
选用SO4^2-/MxOy型固体超强酸催化草莓酸的酯化反应,筛选出催化剂SO4^2-/ZrO2-TiO2,制备该催化剂的最优条件为:钛锆物质的量比为4:1,氨水调节pH值8~9,用浓度为0.5mol/L硫酸浸渍,马弗炉550℃焙烧3h;使用该仙化剂合成草莓酸酯的最优酯化条件为:催化剂用量3g/mol,酯化时间3h,其催化合成草莓酯戊酯产率可达90.8%。 相似文献
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稀土改性SO^2—4/TiO2催化合成尼泊金酯 总被引:8,自引:0,他引:8
以稀土改性的固体超强酸SO^2-4/TiO2为催化剂,无水MgSO4作脱水剂,合成了尼泊金丁酯。考察了影响收率的诸因素,其最佳条件为:醇酸摩尔比为3:1,催化剂用量20g/mol酸,回流温度下反应3.0h,收率达到90.4%。 相似文献
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固体超强酸SO4^2—/ZrO2催化合成对羟基苯甲酸乙酯 总被引:6,自引:0,他引:6
以固体超强酸SO4^2-/ZrO2为催化剂合成了对羟基苯甲酸乙酯,并研究了催化剂等条件对反应的影响,在最佳反应条件下,酯收率达到80.1%。 相似文献
11.
In glasses with the compositions (100 ? x)(2Na2O·16K2O·8Al2O3·74SiO2)xBaF2 (with x = 0 to 6), the glass transition temperature decreases with increasing BaF2-concentration. Samples with x = 6 were thermally treated at temperatures in the range from 500 to 600 °C for 5–160 h. This leads to the crystallisation of BaF2. The quantity of crystalline BaF2 increases with increasing time of thermal treatment, while the mean crystallite size remains constant within the limits of error. The glass transformation temperature of partially crystallised samples increases with increasing crystallisation time and approaches a value equal to the temperature, at which the samples were treated. This is explained by the formation of a highly viscous layer enriched in SiO2 which is formed during crystallisation. This layer acts as a diffusion barrier and hinders further crystal growth. 相似文献
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复合固体超强酸SO42-/ZrO2-Al2O3催化合成乳酸正丁酯的研究 总被引:12,自引:0,他引:12
《化学试剂》2001,23(5):269-270
合成了几种不同Zr、Al原子比的SO42-/ZrO2-Al2O3复合固体超强酸,将其用于催化乳酸与正丁醇的酯化反应,均有较好的催化活性,尤以ZrAl=12的催化效果最好,经济性优于ZrO2超强酸催化剂.其最佳反应条件为酸醇摩尔比为13,催化剂用量为乳酸质量的10%,反应时间2~2.5h,酯化率达96.9%.该催化剂具有制备容易、催化活性高、不污染环境、可重复使用的优点. 相似文献
14.
Paul Wencil Brown 《Journal of the American Ceramic Society》1990,73(11):3457-3461
A portion of the quaternary phase diagram for Na2 O-CaO-SiO2 -H2 O has been constructed. Plotting concentrations as their 10th roots allows compounds having solubilities which differ by several orders of magnitude to be represented on a single diagram. The compositional relationships among sodium-substituted calcium silicate hydrate, calcium-substituted sodium silicate hydrate, calcium bydroxide, a quaternary compound of approximate composition 0.25Na2 O · CaO · SiO2 · 3H2 O, sodium hydroxide monohydrate, and miscellaneous sodium silicate hydrates are presented. The quaternary diagram constructed shows the quaternary compound to exist in equilibrium with sodium-substituted calcium silicate hydrate and calcium hydroxide. Conditions in concrete pore solutions which favor the formation of this quaternary compound may also favor the occurrence of the alkali-silica reaction. 相似文献
15.
In earlier work, a prediction method of the immiscibility boundary of a ternary silicate glass system was developed involving two known binary immiscibility boundaries and a measured immiscibility temperature of one ternary glass composition. In the present work, the method is extended to the case where one of the two binary immiscibility boundaries is not known and is applied as an example to ternary silicate systems containing K2 O. First, the immiscibility boundary of the system K2 O-SiO2 is estimated by measuring the immiscibility temperatures of three glasses in the system K2 O-Li2 O (or Na2 O)-SiO2 . Using this result the immiscibility boundaries of the systems K2 O-Li2 O-SiO2 , K2 O-Na2 O-SiO2 , and K2 O-BaO-SiO2 are estimated. The results agree reasonably well with the experimentally determined immiscibility temperatures at selected compositions. 相似文献
16.
BURNHAM W. KING 《Journal of the American Ceramic Society》1954,37(5):238-242
It was first shown that the enamel slips which have the best suspnding characteristics contain equal amounts of Na2 O and B2 O3 and at least a moderate amount of NaF. The solubilities of mixtures of Na2 O, NaF, and B2 O3 were then investigated. The pH of these solutions and the primary crystalline phases separating on evaporation also were determined. The solubility data obtained at room temperature were summarized. When the solutions were evaporated, NaF was the first crystalline phase to separate from a large proportion of the mixtures investigated. It was concluded that the desirable handling characteristics of enamels whose mill liquors contain the proper proportion of Na2 O, NaF, and B2 O3 are not due to the formation of complex salts but to the following combination of properties: (1) the presence of salts with a moderate solubility which changes very slightly with temperature, (2) a moderate pH of about 10 in a probably well-buffered solution, (3) a relatively stable crystalline material, NaF, as a primary phase, and (4) a secondary phase which crystallizes slowly with relatively little shrinkage. 相似文献
17.
固体超强酸SO^2—4/TiO2催化合成尿囊素的研究 总被引:11,自引:0,他引:11
《日用化学工业》2000,30(6):10-12
用固体超强酸SO42/TiO2为催化剂,以尿素和乙醛酸为原料合成了尿囊素。得到最佳条件为TiO2在1mo1·L-1H2SO4溶液中浸渍12h,再在600℃焙烧3h;尿素与乙醛酸摩尔比3.51,催化剂9%,时间3h,温度72℃~75℃,产率达57.4%。 相似文献
18.
Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu2O, Bi2O3 and ZnMn2O4 are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu2O/TiO2 and Bi2O3/TiO2 by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed. 相似文献
19.
Equilibrium phase diagrams for the systems MgCl2 -MgF2 , CaCl2 -MgF2 and NaCl-MgF2 were determined by differential thermal analysis, thermal analysis, and temperature-composition equilibrium techniques. Simple eutectics were observed at 78.0±0.5 mol% MgCl2 and 628°±2°C in the MgCl2 -MgF2 system, at 87.5±0.5 mol% CaCl2 and 694°±2°C in the CaCl2 -MgF2 system, and at 95.5±0.5 mol% NaCl and 786°±3°C in the NaCl-MgF2 system. The phase diagrams determined for these systems were compared with phase diagrams that were computed using Temkin's model. The phase diagrams of the CaCl2 -MgF2 and NaCl-MgF2 systems were also compared with diagrams that were computed using the expression suggested by Flood et al. for reciprocal systems. The experimentally determined and computed phase diagrams agreed for the MgCl2 -MgF2 system but not for the CaCl2 -MgF2 and NaCl-MgF2 systems. 相似文献
20.
Yong Sig Ko 《Powder Technology》2004,145(1):10-19
Zeolite L powder was prepared from the substrate mixture of Na2O-K2O-Al2O3-SiO2-H2O system at temperatures of 373-443 K. In order to investigate the factors which influence the synthesis outcome, a reference system which yields zeolite L in a reproducible manner was chosen and subjected to controlled changes in synthesis parameters. The crystalline zeolite L samples obtained were characterized by elemental chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). It was established that phase purity, morphology, and the size of crystals of crystalline product were affected by molar ratios of the substrate, such as SiO2/Al2O3, (K2O+Na2O)/SiO2, Na2O/(K2O+Na2O), and H2O/(K2O+Na2O). Amorphous silica powder (Zeosil) was the preferred silica source, and the crystallization rate was promoted by introducing gel aging, seeding, and rapid heating rate. 相似文献