共查询到20条相似文献,搜索用时 218 毫秒
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《离子交换与吸附》2017,(2)
以裙带菜孢子叶残渣为原料进行水热液化制备乙醇酸,并采用响应面法优化了该工艺。首先,通过单因素实验分析了甲胺浓度、温度、固液比、时间4个关键因素对乙醇酸产率的影响,得到单因素条件下乙醇酸的最高产率为34.64g/L。进一步利用中心组合设计原则对4个关键因素进行实验设计,以乙醇酸产率为响应值,采用响应面法对实验结果进行方程回归,得到4个因素与响应值的回归模型。响应面法优化后的水热液化条件为甲胺浓度4.86mol/L、温度216.73℃、固液比1:6.25、时间37.49min,该条件下乙醇酸的产率达到36.46g/L,比单因素实验的最高产率高出1.82g/L。最后通过方差分析和平行实验,证明该模型准确可用,且平行实验的实际值与预测值的误差仅为0.84%。 相似文献
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利用响应面法研究了翻白草总黄酮的微波辅助提取工艺.在单因素试验的基础上,以乙醇体积分数、液固比、提取温度、微波时间为自变量,总黄酮的得率为响应值,研究各因素及其交互作用对黄酮得率的影响.结果表明其最佳提取条件是:乙醇体积分数55%、液固比32 m L/g、温度82℃、微波时间10 min.此条件下,翻白草中黄酮的提取率为6.96 mg/g,与理论预测值基本吻合. 相似文献
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采用沉淀-浸渍法制备了不同金属配比的S2O82-/TiO2-Al2O3固体超强酸催化剂,并研究了其在催化水解花生壳制备乙酰丙酸反应中的作用。实验发现n(Al)∶n(Ti)=1∶2时催化效果最佳,并进一步考察了其水解温度,水解时间,固体酸用量和液固比对乙酰丙酸得率的影响。采用响应面法对水解工艺进行了优化,并建立二次回归模型。结果表明,当水解温度为235℃、水解时间为30min、固体酸用量为4.6%和液固比18∶1(mL/g)时为较优的制备工艺,在该工艺条件下,乙酰丙酸得率为26.43%。 相似文献
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以白云鄂博稀土精矿-钙化焙烧-HCl浸磷后的矿物为原料,用HCl-柠檬酸混合溶液浸出稀土并对浸渣进行了场发射扫描电镜和能谱分析。考察了HCl-柠檬酸混合溶液浸出过程中HCl用量、柠檬酸用量、反应温度、反应时间、搅拌速度及液固比对稀土、氟浸出率的影响,并采用五因素正交回归试验对工艺参数进行了优化。结果表明:在HCl浓度3.0 mol·L~(-1),柠檬酸浓度0.3mol·L~(-1),反应温度40℃,液固比9∶1,反应时间40 min,搅拌速度300 r·min~(-1)时,稀土的浸出率大于92.0%,氟的浸出率小于5.0%,实现了稀土与氟的分离。 相似文献
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《高分子学报》2015,(7)
以4-甲酰基苯并15-冠-5(FB15C5)和聚乙烯醇(PVA)为原料,通过缩醛化反应制备苯并15-冠-5接枝聚乙烯醇(PVA-g-FB15C5),采用单因素实验考察了其冠醚用量、催化剂用量及PVA浓度等对冠醚固载量的影响规律,并利用响应面分析法对合成条件进行了优化.结果表明,在冠醚用量为0.79 g、催化剂用量为0.51 g、PVA浓度为3.7×104mg/L条件下,冠醚固载量达到2.11 mmol/g.在固-液萃取锂同位素分离过程中,当萃取温度为20℃,锂盐为Li Br时,其分离因子高达1.039.此外,重同位素7Li富集于固相,轻同位素6Li富集于液相. 相似文献
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《Arabian Journal of Chemistry》2021,14(12):103450
A new process of leaching zinc oxide dust by ozone oxidation in a sulfuric acid system was studied. The main factors affecting the leaching rate, such as ozone time, leaching temperature, initial acidity, leaching time, and liquid/solid mass ratio, were comprehensively investigated. The results show that leaching efficiency depends on all the above factors. The optimum conditions for leaching Zn and Ge from zinc oxide dust are as follows: ozone time 10 min, leaching temperature 90 ℃, initial acidity 160 g/L, leaching time 60 min, and liquid/solid mass ratio 7:1. Under the optimum conditions, the leaching rates of Zn and Ge are 95.79% and 93.65%, respectively. The leaching rates of zinc and germanium in the ozone leaching are 4.05% and 10.49% higher than those of the atmospheric leaching, respectively. Therefore, it is determined that ozone in solution plays a key role in rapidly oxidizing sulfide and releasing encapsulated germanium. Sulfuric acid-ozone media can efficiently extract Zn and Ge from zinc oxide dust. 相似文献
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以聚苯乙烯-二乙烯苯接枝磷钨酸季铵盐为三相相转移催化剂,以H2O2为氧化剂,KCl为助催化剂,研究了环戊烯(CPE)合成环氧环戊烷(CPEO)的无溶剂工艺。 讨论了催化剂和助催化剂用量、反应温度、反应时间、环戊烯与H2O2摩尔比对反应的影响。 确定了无溶剂环氧环戊烷合成反应的条件为(以0.056 mol H2O2计):催化剂1.0 g、助催化剂0.025 g、反应温度40 ℃、反应时间5 h、n(CPE)∶n(H2O2)=2.1∶1.0。 CPEO的平均收率约为96%。 催化剂回收重复使用6次活性无明显降低。 相似文献
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从氧化锌矿制备高纯超细ZnO粉体 总被引:7,自引:0,他引:7
超细ZnO具有表面效应、体积效应、久保效应以及优良的光活性、电活性、烧结活性和催化活性 ,可用来制造气体传感器、荧光体、紫外线遮蔽材料、变阻器、图像记录材料、压电材料、压敏电阻、高效催化剂、磁性材料、陶瓷材料、化妆品及医药材料。在橡胶工业、染料油墨等领域也有应用前景[1~ 5] 。目前 ,国内外对制备超细ZnO粉体的研究文章较多 ,但以氧化锌矿为原料直接研制的文章还很少。湿化学法是近二十年来超细ZnO产品应用开发的主要活跃点之一 ,直接沉淀法是制备超细ZnO的一种重要湿化学方法 ,它是在含有一种或多种粒子的可溶… 相似文献
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B. Kweto D. R. Groot E. Stassen J. Suthiram J. R. Zeevaart 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):131-137
The purpose of this study was to determine the kinetics of the dissolution of a uranium residue in ammonium carbonate media. The residue is generated in the production of medical isotopes. The effects of parameters, such as varying peroxide and carbonate concentrations, dissolution time as well as temperature on the extraction rate have been separately studied. Results indicate complete dissolution of the residue at 60 °C, after 30 min, in ammonium carbonate solution enriched with hydrogen peroxide. The yield and rate of uranium extraction were found to increase as a function of both temperature, in the range of 25–60 °C, and hydrogen peroxide concentration. The extraction process was governed by chemical reaction as the activation energy was found to be 45.5 kJ/mol. The order of reaction with respect to uranium concentration was found to be approximately first order. 相似文献
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Yu. A. Grankina V. N. Shubina V. A. Elizarova V. V. Donskikh 《Russian Journal of Applied Chemistry》2016,89(1):40-44
Carbon dioxide absorber based on hydrated zirconium oxide was synthesized with ammonium carbonate and hydrogen peroxide. The effect of the molar ratio between ammonium carbonate and hydrogen peroxide on the sorption characteristics of the absorber was examined. The structural-sorption properties of the absorber were analyzed. It was shown tat the absorber has a high absorption capacity for CO2. 相似文献
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相转移催化应用于催化裂化汽油氧化脱硫的研究 总被引:11,自引:0,他引:11
随着人们环境保护意识的增强及原油硫含量的增大, 生产满足环境保护要求的清洁燃料是全球炼油工业的发展趋势, 燃料油脱硫显得越来越重要. 在众多的脱硫方法中, 选择性氧化脱硫技术以其工艺条件温和, 脱硫效果明显等特点, 受到了炼油行业的极大关注[1~3], 但脱硫率偏低(30%), 其关键是水相氧化剂与含硫化合物的有效混合. 本文将相转移催化应用于催化裂化(FCC)汽油的氧化脱硫中, 并对脱硫的工艺和机理进行了研究. 相似文献
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由正己醇合成正己酸不仅可以提高附加值,还能生产己酸类香料以及多种医药产品.利用杂多过氧磷钨季铵盐催化剂,以对环境友好的H2O2 为氧化剂催化十八醇氧化成十八酸的研究已有报道[1,2],但合成负载型相转移催化剂并用于本课题的研究还未见报道.由于过氧磷钨十八烷基季铰盐催化剂(POWP)通常只有很小的比表面积,而SiO2不仅有大的比表面积,同时它所具有的表面羟基是杂多化合物的良好载体[2],POWP负载后的催化剂(POWPS)与未负载的POWP相比,将正己醇氧化为正已酸的收率提高了10多个百分点. 相似文献
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模拟轻质油品的氧化脱硫 总被引:6,自引:10,他引:6
以正庚烷为溶剂,苯并噻吩(BT)、二苯并噻吩(DBT)、4,6-二甲基二苯并噻吩(4,6-DMDBT)作为模型含硫化合物组成模拟轻质油品,在H2O2-HCOOH氧化体系中对模拟轻质油品氧化脱硫进行了研究。考察了氧化剂用量、氧化温度、氧化时间及芳烃、烯烃、含氮化合物的存在等因素对BT、DBT脱除的影响。实验结果表明:在反应温度60 ℃,H2O2∶S=7∶1(mol/mol),H2O2∶HCOOH=1∶1(v/v),反应时间在40 min的条件下,4,6-DMDBT能全部脱除, DBT、BT的脱除率分别为96% 、58%。向油品中添加芳烃、烯烃、含氮化合物等对BT、DBT的脱除均有不同程度的影响。 相似文献
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G. L. Grigoryan P. S. Gukasyan A. I. Martiryan A. A. Beglaryan G. S. Grigoryan 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(8):1212-1216
The properties of the intermediate compound formed on the surface of zinc oxide and partially transferred into the gas phase in the reaction between zinc oxide and hydrogen peroxide vapor were studied. An analysis of the experimental data showed that intermediate compounds could be zinc peroxide and zinc peroxide peroxosolvate. 相似文献
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Polymer-supported zinc catalysts were prepared by the reaction of di-ethylzinc with polymers containing carboxyl groups. The catalysts were employed in the alternating copolymerization of carbon dioxide and propylene oxide to give poly(propylene carbonate) of high molecular weight. Copolymers of styrene and acrylic acid were shown to be better catalyst supports than poly(acrylic acid) and some other polymers. Maximum activity was achieved when the molar ratio of Zn/COOH was around unity. The yield and molecular weight of the polycarbonate rose with increasing reaction time. Higher reaction rates but lower molecular weights of the product were observed at elevated reaction temperatures 相似文献