二氧化碳和甲醇直接合成碳酸二甲酯研究进展

从均相及多相催化剂体系和反应条件等方面,综述了近年来二氧化碳和甲醇直接合成碳酸二甲酯的研究开发最新进展。介绍了均相催化剂体系包括有机金属烷氧基化合物、碱土金属烷氧基化合物、碱性催化剂和乙酸盐催化剂;多相催化剂体系包括负载型金属催化剂、负载型固体碱催化剂和氧化物催化剂。对催化剂及反应体系的设计、光催化剂、杂多酸催化剂、离子液体体系、助催化剂及吸水剂的使用、微波加热、膜反应器以及超临界二氧化碳溶剂体系进行了评述。     

稀土在我国化肥催化剂中的应用

添加稀土氧化物的转化催化剂和甲烷化催化剂是我国化肥催化剂的特色。文中概述了稀土在烃类水蒸气转化催化剂、甲烷化催化剂、中变催化剂、宽变催化剂、氨合成催化剂、二氧化硫氧化催化剂、氨氧化制硝酸催化剂及甲醇催化剂等方面的应用。     

乙苯工艺技术及催化剂的应用研究进展

综述了乙苯的主要生产工艺及应用的催化剂研究进展.乙苯生产工艺主要有液相法,气相分子筛催化法和液相分子筛催化法,采用的催化剂主要有AlCl3催化剂、ZSM-5分子筛催化剂、Y分子筛催化剂、β分子筛催化剂及MWW分子筛催化剂等.着重介绍了液相法制乙苯使用的分子筛催化剂的最新进展.     

丁烯催化裂解制取丙烯催化剂的研究进展

丁烯催化裂解制丙烯是提高丁烯利用率、提高丙烯生产工艺经济效益的新技术。分析和讨论了丁烯催化裂解制丙烯的反应机理,分别探讨了不同催化剂的优势及不足之处,包括金属氧化物催化剂、分子筛催化剂、复合分子筛催化剂和改性分子筛催化剂等。总结了分子筛酸强度、酸密度及催化剂孔道结构对催化剂转化率、丙烯选择性和稳定性的影响。提出了合成分子筛催化剂的酸性强度及酸密度是分子筛催化剂改性的主要目标,通过分子筛改性,可以提高分子筛催化剂的催化活性及目标产物丙烯的选择性,同时减少结焦,改善催化剂稳定性。最后对用于丁烯裂解制备丙烯催化剂的发展趋势和前景进行了前瞻性点评和展望。     

选择性催化还原脱硝催化剂的研究进展

选择性催化还原（SCR）是目前控制氮氧化物排放的主要技术,该技术具有选择性好、脱硝效率高、不造成二次污染等优点。本文对SCR技术及其催化剂进行了综述,重点介绍了钒钛催化剂、贵金属催化剂、金属氧化物催化剂及沸石分子筛型催化剂的研究进展,并对国内外脱硝催化剂的工业化现状及催化剂的影响因素进行了分析,最后指出我国脱硝催化剂的发展应以提高催化剂寿命、开发新型催化剂（以复合金属氧化物催化剂和新型钒基催化剂为主）及新工艺为方向进行。     

合成氨催化剂的现状和进展

综述国外新开发的合成氨催化剂及我国新近研发的合成氨催化剂,包括脱硫催化剂、烃类蒸汽转化催化剂、变换催化剂和氨合成催化剂的新进展.     

CO为还原剂的脱硝催化剂研究进展

从活性组分、助剂和载体方面综述贵金属催化剂(Ir、Pd、Rh、Ru、Ag)及非贵金属催化剂的研究进展。比较不同催化剂脱硝活性,表明贵金属催化剂及部分非贵金属催化剂均具有一定的脱硝活性。对于贵金属催化剂,中低温活性较高,但热稳定性差,易烧结,且不经济。对于非贵金属催化剂,高温活性较高,稳定性较强。助剂的引入及载体性质对催化剂脱硝活性均有不同程度的影响。     

CO_2加氢合成二甲醚催化剂的研究进展

介绍了二甲醚的性质及主要用途,对CO2加氢合成二甲醚过程的甲醇合成催化剂、甲醇脱水催化剂及复合型催化剂进行了综述,重点分析了复合型催化剂的优势及发展前景。     

多元配方乙炔氢氯化反应催化剂研究进展

对乙炔氢氯化催化剂筛选的理论基础、二元及多元配方低汞催化剂和无汞催化剂的研究进展及各组分在乙炔氢氯化催化剂中所起的作用及作用机制进行了综述,并展望了乙炔氢氯化反应催化剂发展的前景及趋势,为新一代乙炔氢氯化反应催化剂的开发提供参考。     

近几年整体式催化剂的开发与应用

介绍整体式催化剂相较于传统催化剂的优越性以及在汽车尾气与环保、强吸热/放热及耦联催化重整反应、脂交换反应、烃类燃烧或氧化反应中的研究及应用。阐述整体式催化剂结构性能及相关数学建模方面的最新研究。通过对整体式催化剂制备及应用的系统分析,提出整体式催化剂仍需解决工艺繁琐、活性成分负载困难和内部结构不明确等观点。同时,整体式催化剂可对催化剂研发提供一种切实可行的解决问题的方法和思路。     

硼酸钙对铜渣中夹杂铜沉降效果的影响

考察了添加剂CaB2O3对转炉铜渣中夹杂铜沉降效果的影响，并结合铜渣的粘度测试及红外光谱表征，研究其影响机理，采用FactSage软件计算了添加剂对铜渣液相线温度的影响。结果表明，随添加剂含量增大，铜渣中夹杂铜的沉降效果逐渐增强，添加剂含量由0增至6wt%时，底部渣含铜量由4.10wt%增至6.85wt%，这是由于添加剂可有效降低铜渣粘度。随添加剂含量增大，渣粘度降低，但降低效果随温度增大而趋于平缓。随添加剂含量增大，铜渣的硅酸盐结构趋于简化，添加剂通过破坏铜渣复杂的硅酸盐结构降低铜渣粘度。铜渣的液相线温度随添加剂含量增大而减小，添加剂通过减少渣中固体颗粒的方式降低铜渣粘度。     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.     

Charakterisierung von Suspensionen nanoskaliger Partikel mittels Ultraschallspektroskopie und elektroakustischer Methoden

Technical control over dispersions with particles in the nanometer size realm should bring about a boost in innovations for some parts of industry. Requirements for the development of these new products is the accurate characterization of the various materials systems. A characterization should always include a determination of the particle size distribution, since it is coupled to the specific effects of these systems. Ultrasound measurement techniques and electroacoustics are two if the available techniques that allow determination of the size distribution and zeta potential of particles with dimensions up to 10 nanometers. A further fundamental advantage of the method is the possibility of carrying out measurements in high‐concentration materials systems. This report describes ultrasound spectroscopy for the measurement of fine‐ and very‐fine‐dispersion particles, and the known theoretical concepts for the interpretation of spectra. In addition, experiences in the use of currently available measurement techniques are presented.     

Trapping the western pine beetle at and near a source of synthetic attractive pheromone Effects of trap size and position

Western pine beetles were caught on unbaited sticky traps placed near a source ofexo-brevicomin, frontalin, and myrcene. Size of trap, distance and direction from the source of attractant, and height from the ground were varied. Significant differences in trap catch were observed in relation to each of the variables. Traps close to the source of attractant caught more beetles than traps farther from the source. Traps downwind of the source of attractant caught more beetles than did upwind traps. More males than females were trapped close to the source of attractant.Based in part on a thesis submitted by the senior author to the University of California, Berkeley, California, in partial fulfillment of the requirements for the degree Master of Science in entomology, December 1976. These studies were supported by the U.S. Forest Service and in part by the Rockefeller Foundation and a joint grant (NSF GB-34718/BMS 75-04223) from the U.S. National Science Foundation and the U.S. Environmental Protection Agency to the University of California. The findings, opinions, and recommendations are not necessarily those of the University of California or the funding agencies.Trade names and commercial enterprises or products are mentioned solely for information and do not constitute endorsement by the U.S. Department of Agriculture or University of California.     

Mechanical Means of Enhancing Drying Rates: Effect on Drying Kinetics and Quality

The effect of various pretreatments on drying kinetics as well as quality parameters of selected vegetables and fruits was studied experimentally in a convective dryer. The pretreatments tested include application of pinholes and drilled holes of different diameters and densities, blanching and freezing. Potato, cassava, dragon fruit and red chilli were used as the sample drying materials. As expected, increase of the diameter and density of the holes under fixed drying conditions increased the drying rate. Samples with drilled holes showed better drying performance than those with pinholes. The improvement of the drying rate was found to be dependent on the physical properties and the initial moisture content of the material. Results show that the drying performance of the products that possess a skin of low moisture diffusivity, such as chilli, can be improved significantly by blanching and making perforations in the skin. Overall changes of color and volume shrinkage during drying of the samples with and without holes were similar. The effect of different modes of heat input, such as convection, conduction and radiation, on the drying performance of the treated samples was also experimentally investigated. On-off type controllers were used to regulate the power of the heaters and maintain the product temperature within a range of pre-set values. Convection combined with radiation displayed the highest drying rate.     

氮气幕对瓦斯爆炸进行阻爆实验

为阻断瓦斯爆炸在管道方向上的传播，保护管道后方区域，本文采用氮气幕来进行阻爆，所设计的实验装置在爆炸发生后能自动喷出氮气。主要研究了氮气的喷气压力和喷气时刻对阻爆功能的影响。结果表明，在喷气压力为0.1MPa时，氮气幕仅起到抑制作用，爆炸火焰能穿过整个实验管道。在喷气压力为0.2MPa时，仅部分实验能够阻爆，氮气幕产生不稳定的阻爆效果。在喷气压力为0.3MPa时，阻爆位置均稳定在左喷头和右喷头之间区域，氮气幕产生稳定地阻爆效果。喷气压力超过0.4MPa后，阻爆位置稳定在右喷头附近。在较低氮气压力0.2MPa下，喷气时刻对阻爆效果产生显著影响。随着喷气时刻延迟，氮气喷出量减小，氮气幕由不稳定阻爆变为不阻爆。喷气时刻延迟到198ms后，氮气幕便丧失阻爆功能。在喷气压力超过0.3MPa后，氮气幕阻爆效果便不受喷气时刻的影响，喷气压力对能否阻爆起决定作用。     

水平及竖直基底上微小固着液滴的蒸发特性分析

为揭示非水平表面上微小蒸发液滴的传热传质特性,本文在准稳态模型的假设下构造三维液滴模型,综合考虑了蒸气扩散、蒸发冷却以及气相域中的自然对流这3种传输机理,对水平以及竖直基底上液滴的蒸发过程进行数值研究。通过分析气液界面上温度分布、蒸发通量分布及总蒸发率的变化,重点探究了基底过热度以及重力的改变对液滴蒸发特性的影响。结果表明：与水平基底上温度的对称分布不同,竖直基底上气液界面温度分布表现出明显的非对称性,且非对称性随基底过热度的升高而增强,最低温度点不再位于液滴顶点,而向一侧偏移。此外,水平基底上气液界面局部蒸发通量呈对称分布,各截面分布相似,而竖直基底上局部蒸发通量分布则呈现出显著的非对称性以及各截面异性,非对称性随着基底过热度的升高而增强,这是重力改变后气相域自然对流发生改变的结果。与水平基底相比,竖直基底上蒸发率更高,总蒸发时间更少。最后,基底由水平变为竖直时,液滴内部流场由对称双涡转变为非对称单涡,单涡流速显著大于双涡流速,液滴内流速随基底过热度的上升而增大,单涡环流造成了气液界面温度分布的改变以及最低温度点的偏移。     

Kinetics of base-catalyzed transesterification of triglycerides from Pongamia oil

The kinetics of transesterification of Pongamia oil using methanol at 60°C were studied. The forward as well as the reverse rate constants of all three steps involved in the transesterification of Pongamia oil are reported for the first time. Among the forward rate constants, the one governing the conversion of TG to DG was the highest and the one for DG to MG was the lowest. A distinct feature of the present work is the direct estimation of the equilibrium constants of all three steps by measuring the concentrations of TG, DG, and MG at very long reaction times. This reduced the number of parameters to be, determined from the kinetic data by one-half, thereby leading to more accurate estimation of the rate constants. The equilibrium constant of the final step involving the conversion of MG to methyl ester and glycerol was at least an order of magnitude greater than that of the first two reaction steps. A detailed comparison was made with kinetic parameters reported in literature. The trend in the relative magnitudes of the rate constants appears to be unique to Pongamia oil.     

Breakage patterns of agglomerates

The experimental information available in the literature regarding the patterns of breakage of agglomerate materials is scarce, particularly in dynamic loading. The primary objective of this paper is to present our findings on the breakage patterns of the agglomerates and the interparticle bond. A high-speed digital video imaging technique is used here to gain an insight into the impact behaviour of individual agglomerates against a target plate. Several breakage patterns are observed. Agglomerates may suffer localised damage only, with the disintegration of the damaged zone into very fine debris, or localised damage combined with fracture. The frequency of occurrence of these patterns depends on the impact velocity and agglomerate structure. The pattern of breakage affects significantly the size distribution of the impact product. An investigation of the breakage of individual interparticle bonds is also presented. Two forms of failure are observed, internal (cohesive) and interfacial (adhesive) failure. The morphology of the fractured surface depends greatly on the type of breakage. Internal breakage shows irregular surfaces due to crack jumping, whereas interfacial failure produces clean, smooth fracture surfaces. These observations should provide the necessary foundation for the development of a fundamental model of agglomerate breakage.     

Functional properties of proteins in foods

The measurement of functionality of protein food ingredients has developed somewhat haphazardly, probably due to the wide range of proteins used as ingredients and the diversity of foods. Studies of the physiochemical properties of proteins should enable prediction of a proteins response to process environments and prove more fruitful than many of the empirical measurements of functionality. The effects of pH, salt type and concentration on the phase behaviour of the oilseed globulin and arachin, demonstrates the complexity of protein solubility and the inadequacies of simple tests that have arisen. Studies of the effects of salts and conditioning on meat fibres, coupled with measurement of the location of water in pellets from water holding tests enable the latter to be applied with increased confidence. Comparison of the endothermic transitions observed on heating with the development of storage and loss moduli allow the contributions of domains of skeletal muscle myosin to gel structure to be investigated.