首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
以蒙脱土(MMT)为载体,采用共沉淀法和浸润法负载金属卤化物和无机酸制备一种新型固体酸催化剂SO■/SnO_2-MMT,其含有双酸位点可以高效催化木糖溶液制备糠醛。在单一水相催化体系中使用该新型固体酸催化剂,190℃反应5 min,从玉米芯水解产物中催化得到的糠醛产率最高为56.2%,木糖转化率为95.3%。相比于新鲜的蒙脱土,该固体酸催化剂具有合适的路易斯酸位点、布朗斯特酸位点和更大的比表面积、孔体积,促进了木糖的异构化和脱水反应。此外,该催化剂在循环3次后也表现出较好的的催化性能和较高的稳定性。  相似文献   

2.
通过对膨润土酸化处理得到活性白土,以活性白土为载体浸渍硫酸铁,可得到Fe2(SO4)3/膨润土固体酸催化剂:以Fe2(SO4)3/膨润土为催化剂,通过正交试验对萘的异丙基化反应工艺条件进行了考察,得到适宜的反应条件为:n(萘)/n(异丙醇):1.8,n(萘)/n(十氢萘)=7.5,反应温度为260℃,反应时间为6h,催化剂用量为萘质量的12.5%,并各因素影响萘异丙基化反应结果进行了系统分析。此外,还对催化剂的酸强度、酸度和酸的类型进行了表征。  相似文献   

3.
用SO2-4-TiO2固体超酸为催化剂合成了二异丙基萘,生产过程简单、无污染、无腐蚀.SO2-4-TiO2固体超酸催化剂较为适宜的制备条件是:浸酸浓度为0.50mol/L、焙烧温度为500℃.在催化剂用量为10%、反应温度为160℃、反应时间为2.5 h的条件下连续两次使用SO2-4-TiO2超酸催化萘对丙烯的烷基化反应,产品中一异丙基萘、二异丙基萘、三异丙基萘的总含量大于98%.  相似文献   

4.
李正青  慎炼  任杰 《化工时刊》2010,24(1):23-25
研究了蒙脱土(MMT)负载硝酸铁制备的固体酸催化剂(Fe2O3/H-MMT)在四氢呋喃(THF)开环聚合中的催化性能。考察了催化剂的制备条件和乙酸酐用量对催化活性和聚四氢呋喃(PTHF)粘均相对分子质量的影响。结果表明,在酸化处理用酸浓度为3.00 mo.lL-1,Fe2O3负载量为18%(质量分数),焙烧温度为400℃下制备的催化剂,反应5 h,催化活性为1.17 g.g-1Cat.h-1。催化活性随乙酸酐用量的增加而增大。催化剂的制备条件对PTHF的相对分子质量影响不大,受乙酸酐用量的影响。  相似文献   

5.
用SO2 - 4 TiO2 固体超酸为催化剂合成了二异丙基萘 ,生产过程简单、无污染、无腐蚀。SO2 - 4 TiO2 固体超酸催化剂较为适宜的制备条件是 :浸酸浓度为 0 5 0mol/L、焙烧温度为 5 0 0℃。在催化剂用量为 10 %、反应温度为 160℃、反应时间为 2 5h的条件下连续两次使用SO2 - 4 TiO2 超酸催化萘对丙烯的烷基化反应 ,产品中一异丙基萘、二异丙基萘、三异丙基萘的总含量大于 98%。  相似文献   

6.
SO~(2-)_4 改性交联蒙脱土固体酸催化合成水杨酸正丁酯   总被引:7,自引:1,他引:7  
秦国平  郭锡坤  谌宁 《精细化工》2003,20(6):352-354
制备了SO2-4改性硅锆双组分交联蒙脱土固体酸催化剂(SO2-4/SiZrM),用于水杨酸(C7H6O3)和正丁醇(C4H10O)的酯化反应,与传统酯化反应催化剂浓硫酸、磷钨酸、硫酸铁铵以及其他单组分交联剂交联的蒙脱土做酯化反应的催化剂相比,SO2-4/SiZrM有更好的催化活性。考察了带水剂的选择、酸醇量比〔n(C7H6O3)∶n(C4H10O)〕、催化剂用量〔w(SO2-4/SiZrM)〕、反应时间(t)、反应温度(θ)对催化合成水杨酸正丁酯(C11H14O3)的影响,并对合成的产物进行了折光率、红外光谱分析。酯化反应的最佳条件为:C4H10O为带水剂、n(C7H6O3)∶n(C4H10O)=1∶1 65、催化剂占酸投料质量的百分比为w(SO2-4/SiZrM)=6 5%、t=6h、θ=120~135℃,水杨酸的转化率可达88 22%,产物中w(C11H14O3)>99 9%。  相似文献   

7.
蒙脱土固体超强酸催化合成异丙基萘   总被引:2,自引:1,他引:2  
以蒙脱土固体超强酸为催化剂,用工业精萘和工业精丙烯合成了异丙基萘,改变蒙脱土固体超强酸用量或反应温度可控制产物的主要成分;减压精馏分离出纯度大于99 9%的一异丙基萘、二异丙基萘和三异丙基萘馏分,色谱 质谱联用仪对一异丙基萘馏分的定性分析表明产物成分合理可靠。  相似文献   

8.
以廉价易得的蒙脱土为载体,采用浸渍法制备了固载型氯化铝固体酸催化剂,利用XRD、FT-IR、SEM对其结构进行了表征,并将其应用于催化油酸与甲醇的酯化反应,考察其催化性能。结果表明:氯化铝成功地被引入蒙脱土的层状结构中,既保持了氯化铝优良的催化活性,又防止其溶于反应体系。当催化剂用量为5%(质量分数)、甲醇与油酸物质的量比为10∶1、反应温度为70℃、反应3 h时,酯化反应转化率达89.9%,且该固载催化剂重复使用5次仍可保持相当高的活性。  相似文献   

9.
用SO4^2--TiO2固体超酸为催化剂合成了二异丙基萘,生产过程简单、无污染、无腐蚀。SO4^2--TiO2固体超酸催化剂较为适宜的制备条件是:浸酸浓度为0.5mol/L、焙烧温度为500℃。在催化剂用量为10%、反应温度为10℃、反应时间为2.5h的条件下连续两次使用SO4^2--TiO2超酸催化萘对丙烯的烷基化反应,产品中一异丙基萘、二异丙基萘、三并丙基萘的总含量大于98%。  相似文献   

10.
采用MgO、Zr(SO4 ) 2·4H2 O和Ce(SO4 ) 2·4H2 O等几种固体酸碱以及它们的混合物催化马来松香与甘油酯化反应 ,并与传统固体酸催化剂ZnO比较 ,探讨不同固体酸碱的催化酯化效果、催化剂对反应温度的影响、固体碱MgO用量与酯化反应的速度以及不同加料方式对催化反应的影响等。研究结果在工业生产上有应用价值  相似文献   

11.
12.
Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.  相似文献   

13.
14.
Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.  相似文献   

15.
16.
17.
In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.  相似文献   

18.
Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.  相似文献   

19.
收集了2007年7月~2008年6月世界塑料工业的相关资料,介绍了2007~2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.  相似文献   

20.
收集了2005年7月~2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、通用热固性树脂(酚醛、聚氨酯、不饱和树脂、环氧树脂)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号