共查询到19条相似文献,搜索用时 65 毫秒
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乳酸甲酯(MLA)是重要的生物质基平台化合物。Snβ分子筛催化生物质糖醇解制备MLA技术具有重要的工业化应用前景。针对Snβ分子筛催化剂制备工艺对其活性和重复使用性能影响的研究非常不系统、不全面等问题,详细考察了Snβ分子筛催化剂制备过程中脱铝、浸渍和焙烧等3步的工艺参数对其结构及催化果糖转化生成MLA性能的影响。结果表明,Snβ分子筛制备过程中市售Hβ分子筛脱铝步骤需要强酸,其中硝酸较佳;Hβ分子筛的硅铝比(物质的量比(n(Si):n(Al))、酸处理过程中酸浓度、浸渍液中SnCl2浓度和焙烧温度都存在较佳条件,具体为:以n(Si):n(Al)=60的Hβ分子筛为原料、经质量分数为47%的HNO3脱铝、再在浓度为0.1 mol·L-1的SnCl2乙醇溶液中浸渍、最后在550℃下焙烧得到的催化剂具有较佳的反应活性,用该催化剂180℃下催化果糖反应6 h时MLA收率最高可达53.6%;此外,该催化剂还具有良好的重复使用性能;表征结果显示,采用上述工艺制备的催化剂,Sn可以进入β分子筛骨架。本研究可为生... 相似文献
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采用浸渍法以稀土元素(Y、Nd、Ce、La)对NaY分子筛进行改性,并以改性后的分子筛为催化剂,考察催化乳酸脱水制丙烯酸反应活性。通过NH3-TPD、CO2-TPD和XRD等对催化剂进行表征,结果表明,稀土元素进入NaY分子筛骨架,其中,La对分子筛晶体结构影响最小;随着负载稀土元素离子半径的增大(Y3+<Nd3+<Ce3+<La3+) ,总酸性位数量减少,除了重稀土元素Y,弱酸性位比例和中等强度碱性位数量增多,La改性最有利于丙烯酸的生成。稀土元素改性的NaY分子筛在一定程度上提高丙烯酸收率,抑制乙醛生成。以质量分数38%的乳酸为原料,在空速3 h-1、反应温度325 ℃和2%La/NaY分子筛为催化剂时,丙烯酸收率为54.2%,而未改性NaY分子筛上丙烯酸收率仅为34.7%。 相似文献
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分别采用FeCl3·6H2O和MnCl2·4H2O对HzsM-5分子筛进行改性,得到Fe-ZSM-5和Mn-ZsM-5催化剂,采用x射线衍射(xRD)和傅立叶红外光谱(FT-IR)对改性前后的样品进行表征,并考察了HZSM-5分子筛改性前后在乳酸乙酯脱水制丙烯酸乙酯反应中的催化性能.结果表明,与HZSM-5相比,改性后的Fe-ZSM-5和Mn-ZSM-5的结晶度下降,硅铝比降低,活性降低,选择性增加,且Mn-ZSM-5的催化性能优于Fe-ZSM-5的催化性能,在180℃下反应3 h,丙烯酸乙酯收率达到14.65%. 相似文献
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Synthesis of methyl tertiary butyl ether (MTBE) from methanol and isobutene was studied using macroporous cation exchange resin, Amberlyst 15 in the hydrogen form, as a catalyst in the temperature range of 313-328 K. The reaction was carried out in a batch reactor at a pressure of one atmosphere in the liquid phase. A high degree of agitation was maintained in order to eliminate film diffusion resistance. The effect of catalyst loading, catalyst particle size and reaction temperature on reaction rate were studied. The reaction rate increased with increase in catalyst concentration and reaction temperature. Resin particle size had virtually no effect on the rate under the experimental conditions. The reaction rate data were analysed using homogeneous kinetics and heterogeneous models based upon Langmuir-Hinshelwood rate expressions. The apparent activation energies using homogeneous and heterogeneous models were determined and found as 79.0 kJ/mol and 76.7 kJ/mol respectively. 相似文献
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This paper presents the results of an experimental investigation of the kinetics of liquid phase reaction between methanol and isobutene, catalyzed by an acidic ion-exchange resin, to form methyl tertiary butyl ether (MTBE). A one litre Parr batch reactor was used. Experiments were carried out at 70, 80, 90 and 100°C and at pressures sufficient to maintain liquid phase at those temperatures. Initial methanol/isobutene mole ratios of 1.0 and 2.0 were used. The catalyst amount was also varied. These kinetic data were used to model the reaction kinetics, by non-linear least squares regression technique. The reaction was found to follow Rideal-Eley kinetics. The values of the rate constants are reported. 相似文献
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Jana Horniakova Kenichi Komura Hisashi Osaki Yoshihiro Kubota Yoshihiro Sugi 《Catalysis Letters》2005,102(3-4):191-196
H-form zeolites, H-FAU and H-BEA have been studied as heterogeneous catalysts for the hydroamination. They catalyzed the reaction of methyl acrylate with aniline to give N-[2-(methoxycarbonyl)ethyl]aniline (1) as a main product. H-BEA and H-FAU zeolites efficiently catalyzed the hydroamination to afford anti-Markovnikov adduct as a main product. The conversion of aniline around 55–85% was achieved within 18 h over H-BEA and H-FAU zeolites with SiO2/Al2O3 molar ratio of 25–30; however, the formation of N,N-bis[2-(methoxycarbonyl)ethyl]aniline (2) as a product of double addition of methyl acrylate to aniline has also been observed as a by-product over H-BEA and H-FAU catalysts. The influences of the reaction parameters such as temperature and catalyst amount, and type of α,β-unsaturated esters and amines have been also investigated. 相似文献
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以SnCl_2·2H_2O为催化剂,对比13种不同有机碱在催化葡萄糖醇解制备乳酸甲酯过程中的助催化作用,包括1-甲基咪唑、咪唑、1-乙烯基咪唑、三苯基膦、苯胺、邻菲罗啉、喹啉、2,6-二甲基吡啶、4,4-联吡啶、吡啶、4-甲基吡啶、2,6-二溴吡啶、2-溴吡啶等有机碱,考察反应时间、反应温度、有机碱与SnCl_2物质的量比的影响。结果表明,以2-溴吡啶为助催化剂,且与SnCl_2物质的量比为1∶1时,在220℃、2 MPa的氮气气氛反应6 h,乳酸甲酯收率最高,为44.6%。 相似文献
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A. A. Lamberov Kh. Kh. Gil’manov S. R. Egorova S. V. Trifonov 《Theoretical Foundations of Chemical Engineering》2007,41(5):679-685
The effect of modification with metal salts and acids on the acid-base characteristics and the catalytic properties of active aluminum oxide in the reaction of methyl phenyl carbinol dehydration to styrene was studied using the IR spectroscopy of adsorbed base molecules. The surface treatment of γ-Al2O3 with chromium and nickel cations decreased the catalyst activity because of the occurrence of hydrogenation side reactions. The appearance of strong Bronsted and Lewis acid sites as a result of modification with sulfate, nitrate, and fluoride anions accelerated the deactivation of the catalyst. Upon modification with acetic acid solutions, additional Lewis acid sites with Q CO = 33.5?34 kJ/mol were formed on the surface of aluminum oxide, and the concentration of strong basic sites with PA = 900 kJ/mol decreased; this facilitated an increase in the catalyst activity and a decrease in the rate of catalyst deactivation. 相似文献