超临界甲醇法制备生物柴油技术的研究进展

主要总结了国内外利用超临界甲醇法制备生物柴油的进展,分析了影响超临界甲醇法制备生物柴油的因素,重点阐述了温度、醇油比、压力、反应时间、水含量及自由脂肪酸含量等对超临界甲醇法制备生物柴油的影响;介绍了超临界甲醇法制备生物柴油技术的强化途径,主要涉及添加共溶剂和催化剂以强化超临界酯交换过程;另外,归纳了反应机理、动力学并分析了制备工艺的新进展。     

利用乙醇制备地沟油生物柴油的应用前景

介绍了乙醇作为制备地沟油生物柴油原料醇的应用前景,综述了均相催化(碱、酸及酸碱两步催化酯交换反应)及非均相催化(固体酸、固体碱、酶及超临界法)酯交换反应制备地沟油生物柴油的研究进展,并着重分析了各自的优缺点,旨在为后续研究制备地沟油生物柴油提供参考。     

介孔材料在生物柴油合成中的应用

生物柴油是一种绿色可再生能源,一般是通过酸或碱催化酯化或酯交换反应来制备。综述了介孔金属氧化物、介孔分子筛及介孔磷酸盐等不同类型介孔材料催化剂用于制备生物柴油的研究进展,并对制备生物柴油的介孔催化剂研究方向进行展望。     

新型固体酸碱催化法生物柴油生产技术

技术简介 随着石油资源的枯竭和改善生态环境的需要,生物柴油已成为当今世界新能源研制和开发的热点,发展极为迅速。目前生物柴油普遍采用均相催化法合成工艺,制备生物柴油的酯交换过程可以在催化剂作用下进行,也可以在无催化剂作用下进行。     

酯交换反应在制备生物柴油上的应用

生物柴油因其环境友好且可再生作为矿物柴油的替代燃料而备受关注,生物柴油主要通过均相酸碱催化、脂肪酶催化、超临界法和固体酸碱催化的酯交换反应制备得到,但各种制备方法各有优劣,均相酸碱催化法反应迅速,转化率高但存在后续处理复杂,污染严重等问题;脂肪酶催化法反应条件温和,对原料中的水和游离脂肪酸不敏感,不需要过量的甲醇参与反应,后续处理工序简单,但酶的成本过高,这是制约其商业化发展的最大阻碍;超临界法是制备生物柴油的新技术,反应迅速,不需要催化剂,油脂转化率非常高,但其反应需要高温高压且能耗很大;固体酸碱催化剂腐蚀性小可以重复使用,后续分离工序简单,对环境的冲击较弱。其中负载型固体碱催化剂催化油脂酯交换反应将成为制备生物柴油的一个主要发展方向。     

碳基固体酸催化大豆油酯交换制备生物柴油

通过一步碳化-磺化法制备了碳基固体酸催化剂,采用IR、XRD以及TG对催化剂进行了表征;并将催化剂用于催化大豆油与甲醇的酯交换反应制备生物柴油中,考察了相关因素对反应的影响,用气相色谱分析生物柴油的产率。实验结果表明,碳基固体酸催化大豆油与甲醇的酯交换反应效果显著,最佳反应条件为:醇油摩尔比36∶1、反应温度130℃、反应时间4h、催化剂用量为大豆油质量的10%时,生物柴油的收率可达95.5%。催化剂重复利用6次,活性下降较小。     

固定化酶催化酯交换反应制备生物柴油的研究现状及展望

生物柴油是以动植物油脂为原料合成的可再生能源,可作为石油、柴油的替代品或部分替代燃料。脂肪酶法制备生物柴油具有反应条件温和、醇用量小、甘油易回收和无废物产生等特点。综述了脂肪酶的固定化、不同载体固定的脂肪酶催化合成及其操作条件(酰基受体、有机溶剂、含水量、温度),并对酶促酯交换反应合成生物柴油的发展前景进行了展望。     

超声波辅助潲水油直接酯交换法制备生物柴油

采用潲水油和甲醇为原料,KOH作为催化剂,通过酯交换反应制备生物柴油。综合考察了反应时间、反应温度、催化剂用量、醇油摩尔比和超声波功率5个因素对酯交换反应制备生物柴油的影响。并且采用L9(34)正交试验法对实验结果进行分析和优化,最终确定反应的最佳条件如下:醇油摩尔比为8∶1、催化剂用量为油重的1.2%、反应时间为50min、反应温度为70℃,超声波功率为400W,转化率最高可达97.53%。     

固体酸催化剂在制备生物柴油中的进展

生物柴油是环境友好的替代燃油,由天然油脂与低级醇通过酯交换反应制备。采用固体酸催化剂制备生物柴油较为简单,同样适用于低等级、高度酸性以及含有水的油的酯化和酯交换反应,且不形成皂化物,还可以有效避免传统均相酸碱催化酯交换工艺中存在的产品分离困难和废催化剂的二次污染问题。研究非均相固体酸催化剂在生物柴油生产中的应用,对于正在兴起的中国生物柴油产业具有重要的意义。详细介绍了各种固体酸,包括硫酸化的金属氧化物、磺酸离子交换树脂、磺酸改性的介孔二氧化硅材料、磺化碳基催化剂、杂多酸和酸性离子液体作为酯化和酯交换反应中的非均相催化剂的研究进展。     

K2CO3/γ-Al2O3催化玉米油制备生物柴油成分的定性分析

采用等体积浸渍法制备了负载型固体碱催化剂K2CO3/γ-Al2O3,并将其用于催化玉米油与甲醇酯交换反应制备生物柴油。采用气相色谱质谱联用仪对其成分进行了定性分析。通过分析质谱图的分子离子峰和特征离子峰,确定所制备的生物柴油主要由四种脂肪酸甲酯组成,分别为棕榈酸甲酯、亚油酸甲酯、油酸甲酯和硬脂酸甲酯。     

Recent advances in ion exchange materials and processes for pollution prevention

 Even though ion exchange technology is mature and widely employed in industry, new applications, approaches, and materials are emerging at a rapid pace. This article summarizes recent advances in ion exchange technology abstracted from presentations made at the Trends in Metal Adsorption Workshop held on May 5–6, 1998 in Cincinnati, OH co-sponsored by the United States Environmental Protection Agency (U.S. EPA), the American Institute of Chemical Engineers (AIChE), the Council for Chemical Research, and the United States Department of Energy (U.S. DOE). Additional information was obtained from reviews of U.S. EPA sponsored pollution prevention projects, panel discussions and workshops, user surveys, and the authors' discussions with practitioners in industry. The objectives of this article in the context of ion exchange applications were: (1) to review advances and applications of ion exchange; (2) to present an overview of commercially available ion exchange technology; and (3) to highlight areas for further research. Many of the advances discussed achieve improvement in ion exchange performance through the use of alternate support matrices or through the combination of technologies such as membranes or electric fields with ion exchange. Received: 8 October 1998 / Accepted: 15 Januar 1999     

Current hurdles in the commercial development of inorganic membrane reactors

This article is a summary of a presentation which was given at the 4th International Conference on Catalysis in Membrane Reactors (ICCMR 2000), which was held 3–5 July 2000 in Zaragoza, Spain. At an earlier ICCMR meeting which was held during 1994 in Lyon, France there was some optimism that by now we would see some commercial implementations of catalytic membrane reactors. In the event this optimism has proved to be unfounded. Not only are there no immediate commercial prospects for catalytic membrane reactors, but we have yet to see any ceramic gas separation membranes in industrial use. This article will examine why this should be the case. It will also look at the underlying reasons, the progress made so far, and the problems which still need to be resolved.     

CO2 mitigation potential from biodiesel of castor seed oil in Indian context

Biodiesel has become an interesting alternative to be used in diesel engine, because it has similar properties to the traditional fossil diesel fuel and may, thus, substitute conventional fuel with none or very minor engine modification. This article deals with alkaline transesterfication of castor oil and their properties for engine application. The purpose of the transesterfication process is to lower the viscosity of the oil from 226.82 cS to 8.50 cS ‘at’ 38°C. The flash point values of castor methyl esters are lower than that of castor oil. The density and gross calorific value of castor methyl ester are much closer to those of diesel. If 10% of total production of castor seed oil is transesterfied into biodiesel, then about 79,782 tones of CO₂ emission can be saved on annual basis. The CO₂ released during combustion of biodiesel can be recycled through next crop production, therefore, no additional burden on environment.     

A new approach to gas sensing with nanotechnology

Nanosized gas sensor elements are potentially faster, require lower power, come with a lower limit of detection, operate at lower temperatures, obviate the need for expensive catalysts, are more heat shock resistant and might even come at a lower cost than their macro-counterparts. In the last two decades, there have been important developments in two key areas that might make this promise a reality. First is the development of a variety of very good performing nanostructured metal oxide semiconductors (MOSs), the most commonly used materials for gas sensing; and second are advances in very low power loss miniaturized heater elements. Advanced nano- or micro-nanogas sensors have attracted much attention owing to a variety of possible applications. In this article, we first discuss the mechanism underlying MOS-based gas sensor devices, then we describe the advances that have been made towards MOS nanostructured materials and the progress towards low-power nano- and microheaters. Finally, we attempt to design an ideal nanogas sensor by combining the best nanomaterial strategy with the best heater implementation. In this regard, we end with a discussion of a suspended carbon nanowire-based gas sensor design and the advantages it might offer compared with other more conventional gas sensor devices.     

分布式虚拟现实系统InteVR1.0的研究及实现

分布式虚拟现实系统向位于不同地理位置的人们提供了一种通过网络共享资源、互通信息、或对特定问题进行讨论、协作的手段。笔者对分布式虚拟现实系统的体系结构及分布式虚拟现实系统中的若干关键技术——图形平台、数据库系统及分布式环境等,进行了深入的研究,提出了相应的实现方法,并初步实现了一个桌面型分布式虚拟现实原型系统InteVR1.0。     

Polar liquids: A survey of purification,conduction mechanisms,and interfacial effects

Interest is reviving in the dielectric properties of liquids. The present paper is concerned with a specific group of polar liquids having electrical conductivities which lie in the intermediate range between those of insulating oils and those of liquids such as electrolytic solutions.It has been found recently that ion exchange techniques provide a powerful means of purifying polar liquids. In this way, liquids have been deionised so effectively that their resistivities have been increased by three orders of magnitude as compared with previously published values.Published work on this subject is summarised. Removal of trace impurities from liquids may help to clarify mechanisms of electrical conduction, charge injection, and charge exchange phenomena in polar liquids.Preliminary results of investigations made by the authors are included in the article.     

TiO2光催化剂的非金属离子修饰改性及其在水盐体系中的应用

金属离子掺杂、非金属离子掺杂、离子注入以及染料光敏化等方法都可不同程度地实现TiO2可见光化,其中非金属掺杂TiO2可见光催化剂其可见光活性是不以损失UV光激发效率而可以独立存在的.本文重点介绍了近年来非金属掺杂修饰改性TiO2光催化剂及本课题组在染料敏化半导体光催化制氢研究方面所取得的一些研究成果,对非金属离子改性TiO2光催化剂的效能进行了整理分类.构建以天然海水和盐湖卤水为应用背景的无电子给体的无机水盐廉价制氢反应体系,是光催化走向实用化的一个新探索.本文回顾了无机水盐制氢反应体系构建方面的研究成果,并对未来光催化分解水的研究工作进行了展望.     

国内外扭矩测试方法综述

本文回顾了扭矩测试的研究进展，对几种典型的测试方法进行了分析的总结，并分析了扭矩测试方法今后的发展趋势。     

Nanoparticles for improving cancer diagnosis

Despite the progress in developing new therapeutic modalities, cancer remains one of the leading diseases causing human mortality. This is mainly attributed to the inability to diagnose tumors in their early stage. By the time the tumor is confirmed, the cancer may have already metastasized, thereby making therapies challenging or even impossible. It is therefore crucial to develop new or to improve existing diagnostic tools to enable diagnosis of cancer in its early or even pre-syndrome stage. The emergence of nanotechnology has provided such a possibility. Unique physical and physiochemical properties allow nanoparticles to be utilized as tags with excellent sensitivity. When coupled with the appropriate targeting molecules, nanoparticle-based probes can interact with a biological system and sense biological changes on the molecular level with unprecedented accuracy. In the past several years, much progress has been made in applying nanotechnology to clinical imaging and diagnostics, and interdisciplinary efforts have made an impact on clinical cancer management. This article aims to review the progress in this exciting area with emphases on the preparation and engineering techniques that have been developed to assemble “smart” nanoprobes.     

Some advances in the casting of metals

Casting is one of the oldest metal shaping methods used by engineers who, therefore, sometimes do not maintain their awareness of progress in the technology. This article provides a rapid update of progress made in the last fifteen years in moulding and casting procedures and the treatment of metal itself.