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1.
The 12-molybdosphoric acid mixed with titania (MPA-TiO2) was found to be a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) via transesterification of dimethyl carbonate (DMC) and phenol. The X-ray diffraction (XRD) and infrared (IR) techniques were employed to characterize the prepared catalysts. The effect of the weight ratio of the 12-molybdosphoric acid to titania on the transesterification was investigated. A 13.1% yield of DPC and an 11.6% yield of methyl phenyl carbonate (MPC) were obtained over MPA-TiO2 with the weight ratio of MPA to TiO2 as 5:1.  相似文献   

2.
Dimethyl carbonate was synthesized by transesterification reaction between ethylene carbonate and methanol under supercritical conditions without any catalyst. Experimental results showed that the residence time and the molar ratio of methanol to ethylene carbonate all can affect the conversion of ethylene carbonate. When the molar ratio of methanol to ethylene carbonate was 8:1, 81.2% conversion can be achieved at 9.0 MPa and 250℃ after 8 h.  相似文献   

3.
 The catalytic performance of Al-MCM-41 containing 5?5 wt% H3PO4 was studied for the vapor phase alkylation of phenol with tert-butyl alcohol (TBA) from 383 to 493 K. 4-Tert-butyl phenol was produced as the main product with moderate selectivity. The product distribution depends on the reaction temperature, number of acid sites, and the Br鰊sted to Lewis sites ratios. A lower molar ratio of reactants (TBA/phenol = 2) and a higher space velocity facilitated the production of 4-tert-butyl phenol. The influence of various parameters such as temperature, reactant feed molar ratio, feed rate, and time on stream were investigated for conversion yield and product selectivity.  相似文献   

4.
A quaternary ammonium salt covalently linked to chitosan was first used as a catalyst for dimethyl carbonate (DMC) synthesis by the transesterification of propylene carbonate (PC) with methanol. The effects of various reaction variables like reaction time, temperature and pressure on the catalytic performance were also investigated. 54% DMC yield and 71% PC conversion were obtained under the optimal reaction conditions. Notably, the catalyst was able to be reused with retention of high catalytic activity and selectivity. Consequently, the process presented here has great potential for industrial application due to its advantages such as stability, easy preparation from renewable biopolymer, and simple separation from products.  相似文献   

5.
有机阴离子柱撑水滑石催化酯交换合成碳酸二苯酯   总被引:10,自引:0,他引:10  
 A series of organic anion-pillared hydrotalcites were synthesized by the ion exchange method and characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The hydrotalcite precursor and pillared hydrotalcites with different anions was tested as catalysts in transesterification of dimethyl carbonate (DMC) with phenol. The results show that the catalytic selectivity of this transesterification reaction over these organic anion-pillared hydrotalcites is significantly improved. The catalytic selectivities of C4H4O4-, C6H8O4-, C10H16O4-, 1,4-C8H4O4-, and C7H5O2-pillared hydrotalcites for transesterified products (diphenyl carbonate and methyl phenyl carbonate) are all greater than 90%, at least 10% higher than that of the hydrotalcite precursor. Under the conditions of n(phenol)/n(DMC)=4, catalyst amount=1.5%, and t=10 h, the C6H8O4-pillared hydrotalcite presents the best catalytic performance, and the DMC conversion and the selectivity for transesterified products reach 43.8% and 93.2%, respectively.  相似文献   

6.
Acylation of anthracene and oxalyl chloride in the presence of anhydrous AlCl3 was investigated. Pure 1,2-aceanthrylenedione, which is used as new functional macromolecule, was prepared by extraction and recrystallation. The structure of 1,2-aceanthrylenedione was identified by measure of melting point, GC/MS, FTIR and 1↑HNMR analyses. The influences of various parameters, such as solvent, dosage of catalyst, molar ratio of anthracene to oxalyl chloride, reaction temperature, and reaction time were studied. The anhydrous AlCl3 was found to catalyze the reaction with high yeild and good selectivity. When the reaction temperature is 303K, reaction time is 5h and molar ratio of anthracene to oxalyl chloride is 1:2, the yield and selectivity of 1,2-aceanthrylenedione is 83.8 % and 92.3% respectively.  相似文献   

7.
A natural polymer catalyst, sillca-supported chitosan palladium complex (abbr. asSiO_2-CS-Pd) was found to catalyze the hydrogenation of phenol and cresols to correspond-ing cyclohexanones in high yield and 100% selectivity at 70℃ and 1.01325×10~5 Pa mildconditions. N/Pd molar ratio in the complex, temperature and solvents have much infiuenceon the reaction. The reactivity order of reactants was found to be: phenol >m->p->o-cresol. The catalyst is stable during the reaction and could be repeatedly used for severaltimes without much decrease in its catalytic activity.  相似文献   

8.
Mg-Al mixed oxides with different Mg/Al molar ratio were prepared by thermal decomposition of hydrotalcitelike precursors at 500℃ for 5.0 h and used as catalysts for the transesterification of diphenyl carbonate with 1,4-butanediol to synthesize high-molecular-weight poly(butylene carbonate)(PBC). The structure-activity correlations of these catalysts in this transesterification process were discussed by means of various characterization techniques. It was found that the chain growth for the formation of PBC can only be obtained through connecting ―OH and ―OC(C)OC_6H_5 end-group upon removing the generated phenol, and the sample with Mg/Al molar ratio of 4.0 exhibited the best catalytic performance, giving PBC with M_w of 1.64 × 10~5 g/mol at 210 ℃ for 3.0 h. This excellent activity depended mainly on the specific surface area and basicity rather than pore structure or crystallite size of MgO.  相似文献   

9.
锗钨酸催化合成水杨酸异戊酯   总被引:15,自引:0,他引:15  
Isoamyl salicylate was synthesized by using germanotungtic acid as catalyst.The effects of the amaunt of catalyst,the molar ratio of salicycic acid of isoamy l alcohol,the reaction temperature and the reaction time on the yield of ester w ere studied.The optimum reaction conditions were 1.3∶100 (mass ratio) of cataly st to reactants,1∶2.5 (molar ratio) of acid to alcohol,135~153℃ being satisfa ctary reaction temperature and reaction time suitable being 3h.Under such condit ion,the yield of ester was up to 94%.Germanotungtic acid catalyst can be used re peatedly.  相似文献   

10.
PdCl2/ O-MCM-41催化剂制备及其在苯酚氧化羰化反应中的应用   总被引:1,自引:0,他引:1  
Hybrid mesoporous silica MCM-41 (O-MCM-41) was prepared using γ-aminopropyltriethoxysilane (APTES) as spacer, tetraethoxysilane as precursor and 2-acetylpyridine as organic moiety. The heterogeneous palladium catalyst (PdCl2/ O-MCM-41) was then prepared by reaction of the hybrid MCM-41 with PdCl2(PhCN)2. The products were characterized by means of IR, XRD, XPS and N2 adsorption-desorption isotherms. The catalytic properties of the supported catalyst in the oxidative carbonylation of phenol to diphenyl carbonate (DPC) were investigated. The yield of DPC and turnover number (TON) reached 5.8% and 29 mol DPC·mol Pd-1, and Pd loss was only 2.7% at 110 ℃, 4.4 MPa for catalytic reaction of 5 h with 4.2wt% Pd loading, and molar ratio of phenol to Pd being 1000 in the presence of Cu2O and terahydrofuran (THF).  相似文献   

11.
 利用碳酸二甲酯和碳酸二乙酯进行酯交换反应制备了碳酸甲乙酯,并考察了Ti(OBu)4,Ti(OPh)4,Bu2SnO和BuSnCl3在这一反应中的催化性能. 结果表明,这些催化剂对该反应都有较好的催化性能. 其中,Bu2SnO的催化性能最好,在103 ℃下反应3 h时,碳酸甲乙酯的收率可达45.6%. 提出了Bu2SnO催化剂对碳酸二甲酯与碳酯二乙酯酯交换反应的可能机理.  相似文献   

12.
A method of modifying silicate and carbonate fillers with titanate coupling agents and proadhesive agents was worked out. The modification aimed at hydrophobization of filler surface by introduction to the surface of functional groups with chemical affinity to polymers. Optimum amounts of modifying substances and appropriate conditions for performing the modification process were established. The obtained fillers showed a high degree of hydrophobicity.The modified fillers were applied in rubber mixtures based on butadienestyrene or natural rubber, in polyurethanes, in PVC, and as pigments in oil dyes of high corossive resistance.  相似文献   

13.
Sol-Gel Processing of Some Electroceramic Powders   总被引:1,自引:0,他引:1  
This review deals with the solution-sol-gel processing (SSG) of powders such as BaTiO3, MgTiO3, PbTiO3, Bi4Ti3O12, La2Ti2O7, Pb(Zr0.52Ti0.48)O3, Pb(Mg1/3Nb2/3)O3 and Ba(Mg1/3Ta2/3)O3. Fine powders of good sinterability can be easily obtained at low temperatures although the process can be expensive and time consuming. We propose a nanocomposite route which utilizes nanophases of different components as a cost-effective alternative to sol-gel process for powder preparation.  相似文献   

14.
钛酸钴;钛酸镓;水热合成;钛酸盐(钴、镓)沸石分子筛的合成与表征  相似文献   

15.
Synergistic effect of CdS decorated sodium titanate nanostructures showed enhanced H2 production abilities. The confinement effect and synergistic effect of decorated CdS inside the sodium titanate nanotubes are investigated.  相似文献   

16.
几种钛酸钾纤维的合成及其相关性研究   总被引:1,自引:0,他引:1  
本文以K_2CO_3和TiO_2为主要原料,采用混练-干燥-煅烧三步法合成出了K_2Ti_2O_5、K_2Ti_4O_9、K_2Ti_6O_13三种形式的钛酸钾纤维物质。测定了它们的XRD、DTA-TG、SEM、ICP、激光拉曼等有关特征数据和谱图,并对它们之间的相互关系进行了研究。  相似文献   

17.
The study presents results of examination on Na0.5Bi0.5TiO3 (NBT) ferroelectric synthesis through intermediate binary compound Bi4Ti3O12 (BIT). The first stage of the study related to obtaining BIT from oxide precursors, i.e. Bi2O3 and TiO2. The second stage included obtaining NBT from Bi4Ti3O12, Na2CO3 and TiO2. Two polymorphic modifications of TiO2 (anatase, rutile) and diversified initial homogenization of raw material batches were applied during examination.  相似文献   

18.
在固定床反应器上,评价了不同温度下钙钛矿型复合氧化物SrTiO3和CaTiO3的组成变化对甲烷氧化偶联反应的影响.同时,利用XPS和CO2-TPD对催化剂的结构及其氧物种的反应特性进行了表征.结果表明:SrTiO3和少量Ca掺杂的CaxSrl-xTiO3有利于在较低温度(923K)下催化反应的活性和选择性,而CaTiO3体系则在高温(1073K)下表现出较好的活性和选择性.钙钛矿型复合氧化物SrTiO3和CaTiO3组成变化对不同温度下反应活性的影响与CO2-TPD的脱附谱图有很好的平行关系.  相似文献   

19.
《印度化学会志》2023,100(2):100901
The novel calcium titanate-lithium lanthanum titanate doped with zinc oxide (0.10, 0.30, and 0.50 mol. %) ceramic samples were prepared by solid-state reaction route. The phase formation, microstructure, densification, and microwave dielectric properties were investigated. It was found that the doping with zinc oxide led to a decrease in sintering temperature by 25 oC as compared with pure calcium titanate lithium lanthanum titanate due to the liquid phase effect. Also, the calcium titanate lithium lanthanum titanate (10ZCTLLT&30ZCTLLT)) doped with lower zinc oxide (0.10 and 0.30 mol. %) led to higher densification parameter. This was followed by increasing the zinc oxide doping up to (0.50 mol. %) which resulted in a decrease in densification and microwave dielectric properties which may be attributed to increase in porosity and grain growth upon the evaporation of zinc and oxygen vacancy. This led to the increase in dielectric loss (≈10 × 10?4) value with 50ZCTLLT. Hence, the best result of microwave dielectric characteristics was obtained for 0.5CaTiO3–0.5(Li0.5La0.5)TiO3 with (0.10 and 0.30 mol. % ZnO) 10ZCTLLT and 30ZCTLLT ceramic samples sintered at 1175 oC/2h, with low dielectric constant (εr) = 4.4–10.5, very low dielectric loss = 1.07-2.23 × 10?4 and high quality factor (Q x ?) ≈59-55 × 104 at 8 GHz. Consequently, they can be used not only in wireless satellite communications technology but also can be used in the fifth-generation telecommunication 5G technology construction.  相似文献   

20.
TiO2与浓NaOH溶液反应可制得组成是Na2-xHxTi2O4(OH)2,0≤X≤2的纳米管。X随后处理时溶液的pH值的不同而不同,当X=2时即为钛酸纳米管。本文在考察热处理温度对钛酸纳米管和钛酸纳米薄片相变的影响时,发现它们的相变规律几乎完全相同。本文通过TEM、XRD、Raman及FT-IR光谱等技术对合成的钛酸纳米管和钛酸纳米薄片随焙烧温度的相变规律、晶粒形状及结晶程度等性质进行了比较和讨论。  相似文献   

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