改性偶氮二甲酰胺/水复合发泡在硬质聚氨酯发泡中的应用研究

目的 通过偶氮二甲酰胺(AC)热分解反应释放出发泡用气体,用改性偶氮二甲酰胺/水复合发泡制备无卤素硬质聚氨酯泡沫(RPUF)。探讨改性偶氮二甲酰胺在聚氨酯发泡中的可行性。方法 通过改变体系中改性偶氮二甲酰胺的用量,探讨改性偶氮二甲酰胺对聚醚发泡体系黏度、聚氨酯泡沫力学性能和导热系数的影响。结果 发泡剂的加入能显著降低聚醚体系的黏度,提高发泡物料的流动性,随着改性AC用量的增加,体系黏度逐渐增加,当改性AC的添加量为0.3 g时,体系黏度最低为2 080 mPa.s。当改性AC用量为0.75 g时,聚氨酯泡沫的表观密度为78.65 kg/m³,压缩强度为539.35 kPa,改性AC的加入使得聚氨酯泡沫的导热系数增高,导热系数为0.023 51 W/mK。结论 改性AC的加入能显著提高硬质聚氨酯泡沫的压缩强度,相比纯水发泡,二者复合发泡性能更优异,可以作为无卤素发泡剂应用于聚氨酯发泡。     

Blended Learning – ein innovatives Weiterbildungskonzept für die Technische Chemie

The ever‐increasing and ever‐changing challenges of the job market require professionals to constantly attend extra occupational education programs. Professionals furthermore express their desire for a compatibility of family and work. Therefore, a general concept for extended vocational training in the field of natural science and technology was developed based on blended learning. As an example, the concept was implemented and tested on the basis of the extended vocational training course “tc‐compact^BL” in Chemical Technology.     

Quaternäre Metall/Metalloxid‐Katalysatoren als Wandkatalysatoren in Mikroreaktoren für Power‐to‐Gas‐Applikationen mittels kombinatorischer Hochdurchsatzmethoden

Catalysts of quaternary composition have been prepared and tested for the Sabatier process. For catalyst syntheses the following techniques have been used: sol‐gel methods, wet impregnation and incipient wetness impregnation. The Sabatier reaction was carried out at temperatures between 520 K and 670 K, pressures of 15 bar and 30 bar using a mixture H₂:CO₂ of 4:1. Activity screening of the microscale wall catalysts was performed by a custom‐built 10‐fold parallel gas‐flow microreactor setup in sequential operating mode. To analyze the gas phase compositions GC‐FID was used.     

Techniken der Vermittlung

  Techniques of Mediation. Chemistry as a Combination of Work, Teaching and Research: the Case of J. F. A. G?ttling A typical career of a chemist in Germany around 1800 consisted of being trained as an apothecary, followed by an occupation as a professor at a university or another institution of higher education. These conditions deeply influenced the concept and the practice of chemistry as a science. Johann Friedrich August G?ttling is an intriguing example for merging education and daily duties of teaching with the self-image of a scientific chemist. He linked chemical teaching, work, and research by using different hybrid media, such as the Almanach oder Taschenbuch für Scheidekünstler und Apotheker, a stove specifically designed for the narrow student’s room, portable laboratories, a pharmaceutical boarding school and textbooks. This allowed him to practice three different forms of chemistry as a science. A “socio-epistemological diagram” of German chemistry around 1800 shows that these forms neatly corresponded to the then predominant three-level epistemology. In particular, the concept of a chemical fact served to link pharmaceutical practice with teaching practice, while granting only the chemistry done by professors the status of a science.

     

哈依煤气的运行现状分析与评价

通过对煤的热力学分析,探索出利用鲁奇气化技术对劣质煤进行气化生产城市煤气并联产甲醇的可行经验。     

Solid-state polymerization of derivatives of 2,4,6-octatriyne: 9. Topochemical reactions of monomers with conjugated triple bonds

The solid-state polymerization of monomers with three conjugated triple bonds gives rise to polymer single crystals. The lattice parameters of the polymers from 2,4,6-octatriyne-1,8-diol and 2,4,6-octatriyne-1,8-diol-bis(phenyl urethane) were determined. Based on these data and considering the mechanical properties and dichroism of the polymer crystals, it is concluded that polymerization proceeds according to a 1,4-addition to the triple bond system of the monomers. Only two of the three triple bonds of the monomers are affected by polymerization to form the polymer backbone of regularly alternating double, single and triple bonds. The residual triple bond is regularly arranged in the all-trans position as part of the substituents. The kinetics of the thermal and photopolymerization of these monomers are quite similar to those of the corresponding diynes. The activation energy of thermal polymerization was found to be 23 kcal/mol as compared to 19 kcal/mol for comparable diynes. The long wavelength limit of photosensitivity was found to be at about 380 nm as compared to 330 nm for diynes.     

Dehydrocyclization of n-hexane on a bifunctional catalyst

Dehydrocyclization of n-hexane was investigated in the temperature range 400–500 °C, pressure range 3–20 atm, and at space velocities 10–150 (g feed/g cat × hr) on a commercial $\text{Pt}\text{Al}{}_2\text{O}{}_3$ catalyst in a fixed bed reactor. From product distributions of the individual conversions of n-hexane, 1-hexene, 2-methylpentane, 2-methyl-1-pentene, 1,5-hexadiene, and methylcyclopentane at the same reaction conditions and from experiments with variation of residence time at constant temperature and pressure, a reaction mechanism for the dehydrocyclization of n-hexane is proposed, in which at least four different reaction paths for the aromatization are possible: 5- and 6-membered ring closure and cyclization of cis-2-hexene and 1,5-hexadiene.