分子筛改性研究综述

综述了国内外分子筛的主要改性方法,阐述了脱铝改性、脱硅改性和金属改性的特点。脱铝改性主要有水蒸气改性法和酸处理改性法,相比于水蒸气处理分子筛需要大量的能量且难以掌握脱铝程度,酸处理脱铝以能耗低、环保、脱铝程度易控制的优势更加适用于低硅铝比分子筛脱铝,微波处理可以大幅缩短酸处理的时间。采用碱处理脱硅制备的介孔-微孔分子筛,结合了微孔的催化性能、择形选择性和介孔的优异扩散性能,提高了分子筛的综合价值。金属改性能在不改变分子筛结构的基础上,有效的提高目的产物的收率与选择性,延长分子筛的寿命。在总结目前分子筛改性研究进展的基础上,提出随着分子筛催化剂生产的产业化,应研究更适合大规模生产的改性条件。     

乙醇制乙烯催化剂P改性ZSM-5的研究进展

介绍了P改性ZSM-5分子筛中P的来源和ZSM-5分子筛上生物乙醇制乙烯的反应机理(包括未改性ZSM-5分子筛和P改性的ZSM-5分子筛),分别从催化效果和催化剂结构2方面阐述了P改性ZSM-5分子筛的研究进展,介绍了P改性ZSM-5分子筛的微观结构的研究现状.P改性后的ZSM-5催化剂可有效地降低反应温度、提高催化剂...     

甲醇制烯烃用ZSM-5分子筛的研究进展

综述了甲醇制烯烃用ZSM-5分子筛催化剂的研究进展,包括甲醇制低碳烯烃的合成机理、ZSM-5分子筛的结构与酸性对合成低碳烯烃性能的影响以及分子筛的改性。重点探讨了ZSM-5分子筛的改性（如水热处理改性、磷改性、氟改性、硼改性、金属离子改性及其他化学改性）对催化剂表面酸性和孔径、低碳烯烃选择性和催化剂稳定性的影响,指出分子筛孔径/表面酸性的调控和MTO/MTP反应机理的研究是甲醇制低碳烯烃催化剂研究的发展方向。     

超稳Y分子筛改性的研究进展

本文从超稳Y分子筛的制备与改性两个方面综述了超稳Y分子筛(USY分子筛)的研究进展,对改性的超稳Y分子筛的二次孔体积、比表面积、水热稳定性、酸量和酸强度等方面进行总结,并对USY分子筛改性研究的重点及发展方向进行了展望.     

Zr改性Y分子筛中油型加氢裂化催化剂设计制备

采用等体积浸渍法对Y分子筛进行了Zr修饰改性,系统考察了不同用量Zr对改性Y分子筛的结构、催化剂的理化性质和加氢裂化反应性能的影响规律。通过XRD、NH₃-TPD、H₂-TPR和TEM等方法对改性分子筛和催化剂进行表征分析。结果表明：Zr改性降低了Y分子筛的酸量,随着改性Zr用量的增加,这种变化趋势不断增大。同时,Zr改性有效地削弱了分子筛催化剂中金属活性组分与载体间的作用,提高了W物种在催化剂表面的分散程度。加氢裂化反应结果表明：与Y分子筛催化剂相比,Zr改性Y分子筛催化剂的减压馏分油(VGO)转化率降低,中间馏分油选择性提高约20%,随着改性Zr用量的增加,VGO的转化率不断降低,中间馏分油选择性略有增加。     

酸处理改性Hβ分子筛催化合成乙基蒽醌

采用微波辐射法,对Hβ分子筛进行酸处理改性,并通过NH₃-TPD、XRD和吡啶－IR对分子筛进行表征,考察改性前后分子筛酸性质和晶相变化,采用改性的Hβ分子筛催化乙苯和苯酐合成乙基蒽醌。结果表明,无机酸改性分子筛时,由于酸性太强,溶解了大量分子筛的铝物种,减小了分子筛固有的酸催化中心数,使分子筛的催化活性大幅度下降,不适合作为Hβ分子筛的改性试剂。有机酸对Hβ分子筛的改性效果较好,以0.1 mol·L^-1马来酸处理后的分子筛催化效果最好,苯酐转化率为51.53%,乙基蒽醌选择性为39.10%,乙基蒽醌收率最高可达20.15%。采用马来酸和Ce(NO₃)·6H₂O复合改性分子筛,乙基蒽醌选择性为54.0%,乙基蒽醌收率最高可达23.5%,选择性比马来酸单独改性时提高约15个百分点,催化效果明显提高。     

分子筛在甲苯甲醇烷基化反应中的应用

采用分子筛催化甲苯、甲醇烷基化生产对二甲苯,可以通过一次反应直接获得高选择性的对二甲苯;另外,甲苯和甲醇价格低廉,因而具有较高的开发价值。本文简单介绍了分子筛的择形催化原理和影响分子筛择形性的因素,综合描述了Y型及其改性沸石、ZSM-5及其改性分子筛、ZSM-22及其改性分子筛等分子筛催化剂在甲苯甲醇烷基化反应中的特性。     

USY分子筛的改性研究进展

主要从超稳分子筛(USY)的制备与改性技术两个方面介绍了USY分子筛的改性研究进展.对USY分子筛进行改性,调变其结构和表面酸性,可以达到改善其催化性能的目的.常用的改性方法有:负载阳离子及氧化物、酸处理、再脱铝(生成DUSY)等,并对以后USY分子筛的改性进行了展望.     

ZSM-5分子筛的改性及应用进展

ZSM-5分子筛特殊的孔结构和优异物化性质,使得ZSM-5分子筛具有良好的热稳定性、耐酸性及择型催化性能,已经被广泛应用于多个领域。作为一种理想的多孔分子筛材料,介绍了ZSM-5分子筛的最新改性及应用进展,并对改性方法(如水热改性、酸碱改性、金属与非金属改性)做了概述。通过对各种改性方法的总结,讨论了不同改性方法对催化效果的影响与最新应用进展,以期为ZSM-5分子筛的研究提供借鉴。     

磷改性分子筛的研究进展

综述了国内外采用磷化合物改性沸石分子筛（ZSM-5、Y、β和MCM-41等）的研究进展,重点介绍了改性后沸石分子筛的结构、催化活性,水热稳定性和表面酸性以及其催化反应等方面的变化,同时对磷改性沸石分子筛的应用前景进行了展望。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

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.     

Insect antifeedant properties of anthranoids from the genusVismia

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

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.