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Alcohols are a good energy source from biomass and can be converted to functional groups, such as amides, amines, carboxylic acids, esters, and imines. One of the key transformations is the dehydrogenation of alcohols. The common method is to use traditional oxidants, or use catalysts based on precious metals. However, these two methods are either not “green” or sustainable. The 3d transition metals are cheap and relatively nontoxic, and they have a high abundance and a large annual production. Catalysts based on these metals could have a good performance on the dehydrogenation. The acceptorless dehydrogenation of alcohols means that alcohol, catalyzed by metal complexes, undergoes formal oxidation to the corresponding carbonyl compound accompanied by the removal of H2 gas. The advantage of these dehydrogenative transformations is that alcohol oxidation occurs in the absence of an oxidizing agent, which leads to less waste and more environmentally friendly reaction conversions. Two catalysts based on Earth-abundant transition metals for acceptorless alcohol dehydrogenation are described in this Ph.D. thesis. Both catalysts mediate the dehydrogenative coupling of primary alcohols and amines to form imines. The first developed catalyst is chromium(III) tetraphenylporphyrin chloride (Cr(TPP)Cl). This is the first time for Cr(TPP)Cl to be applied for acceptorless alcohol dehydrogenation. The catalyst has a good performance on the dehydrogenation of alcohols with amines to form imines. The reaction mechanism has been investigated by various practical experiments, and a metal-ligand cooperative pathway has been proposed. The second developed catalyst is vanadium(IV) salen chloride. The catalyst indeed has a good performance on the dehydrogenation of alcohols, and the mechanism is believed to involve a metal-ligand cooperation pathway. The thesis begins with four short chapters regarding the aim of the project, introduction to alcohols, imines, and acceptorless alcohol dehydrogenation. Subsequently, the development of the two novel catalysts is described and discussed in two chapters, followed by a conclusion on the entire project.

C 5 f 10 O has the potential to replace SF 6 gas in medium and low voltage gas insulated switchgear because of its excellent insulation performance and low global warming potential. In the case of partial overheating or discharge in the equipment, whether C 5 f 10 O can recover itself after decomposition is one of the important factors that determine its application prospect. However, there are few researches on the recovery of decomposed C 5 f 10 O by overheating at home and abroad. In this paper, the recovery experiments of C 5 f 10 O were carried out on the existing experimental system of partial decomposition of gas insulating medium. The experimental results show that C 5 f 10 O has a certain self-recover ability after overheating decomposition in the temperature range of 400 °C - 475 °C; the molecular structure of C 5 f 10 O and its main decomposition products is optimized by the hybrid: B3LYP method in the density functional theory, and the reaction paths of CF 3 CFCOCF 3 -, CF 3 - radicals and C3F6 to produce C 5 f 10 O are studied, and compared with the main decomposition reactions of C 5 f 10 O under the same conditions, the self-recover characteristics of C 5 f 10 O were revealed preliminarily in molecular level, which laid a foundation for the industrial application of C 5 f 10 O gas.

Research on the determination of the product gas decomposed by sulfur hexafluoride (SF 6 ) in diverse discharge conditions is of considerable significance for the status evaluation of related electrical equipment. In this paper, the discharge experiment of SF 6 medium was conducted with a needle-plate electrode simulating the operating environment of gas insulated substation (GIS). The products were measured by gas chromatography, ion chromatography and other instruments, by which the appearance moment and content variation of HF, SO 2 F 2 , CF 4 , hydrolysable fluoride and other decompositions generated at 50 kV power frequency are illustrated. The formation of the product at lower energy conditions was investigated as a comparison by the discharge test at 14kV, and further experimental investigation was carried out with the electrode spacing of 0.2cm. This article also analyzed the impact of solid insulating medium (such as polyester film) on characteristic breakdown products by the discharge experiment involving solid insulating medium. The results indicated that HF was the first to be generated despite of the discharge energy, and the detected moment of SO 2 F 2 will be delayed with the decrease of discharge energy, as its concentration promoted when the discharge energy augmented. CF 4 was found in different discharge experiment, and a higher concentration of CF 4 was supposed to be related with the participating of solid insulating media. The experiment launched in this paper considered all forms of discharge fault in SF 6 electrical equipment in general and measured the consistence of breakdown gas of SF 6 correspondingly. The conclusion in this paper could contribute to the beforehand diagnosis and monitoring of sudden failures caused by discharges in SF 6 electrical equipment.

Because of its excellent insulation and arc extinguishing performance, Sulfur hexafluoride (SF 6 ) is widely used in electrical equipment such as gas insulated switchgear (GIS), circuit breakers, transformers. The detection of the components and contents of the decomposition products of SF 6 can provide an effective basis for the running state, abnormality or latent faults of SF 6 gas insulated electrical equipment in time. In order to ensure the accuracy and reliability of the results, this paper analyzed many cases in which SF 6 gas insulated electrical equipment were abnormal or broken-down in recent years, and made an in-depth study on multiple influence factors, such as sampling vessel material, sampling time, detection time, SF 6 decomposition products auto hydrolysis or be adsorbed by adsorbent and equipment structure. The results show that sampling by stainless steel bottles with fluorine coating, comprehensive investigation of the SF 6 gas decomposition products (such as SO 2 F 2 , SOF 2 ) that could characterize the fault, going to the scene as soon as possible or carrying out the inspection work through online device, fully considering the different detailed structure of electrical equipment are of important significance to improve the supervision level of SF 6 electrical equipment and achieve diagnosis and prediction when SF 6 electrical equipment gets fault.

Contact temperature of GIS is the most direct index reflecting contact thermal fault information, so it is necessary to monitor its temperature in real time. At present, it is impossible to install sensors on the contacts to monitor their temperature. So, in this paper, an inversion calculation method is presented for contact temperature of GIS using the monitoring values of multi-point shell temperature and environmental temperature and an optimal layout method of the multi-point sensors installed on the shell is proposed. First, the temperature rise test was carried out on the 500kV real size GIS to obtain the distribution characteristics of internal temperature field. Then, support vector regression machine was used to gain the corresponding relationship between multi-point shell temperature, environmental temperature and contact temperature, and the actual measurement of multi-point shell temperature and environmental temperature was used to obtain the contact temperature by inversion calculation. By comparing the calculated and measured results, the average absolute monitoring error was 0.47%. Finally, the genetic algorithm was used to optimize the layout of the shell temperature sensors, and the number of sensors was reduced from 25 to 5. After optimization, the average absolute monitoring error was 2.07%, which saved the cost and improved the speed of inversion calculation.

The influences of carbon nanotubes (CNTs) introduced in three different phases of carbon fiber/pyrolytic carbon/silicon carbide (Cf/PyC/SiC) composites on the microstructure and properties of the composites were investigated in this paper. The results showed with CNTs introduced at PyC-PyC interface, tensile strength and work of fracture (WOF) of a Cf/PyC/SiC composite had the largest increase, and significantly improved 54.9% and 130.3% respectively from those of the CNTs-free composite. Multiple interfaces (CF-PyC interface, CNT-PyC interface, PyC-PyC interface) failure and a great number of carbon fiber and carbon nanotube pull-outs were observed from tensile fracture morphology of the composite, which indicated weakening of PyC-PyC interface due to CNTs and accounted for the remarkable improvement in WOF of the composite. The increase of tensile strength of the composite was resulted from the reduction of residual stress of the composite.

Liquid hyperbranched polycarbosilanes (LHBPCSs) with different reactant molar ratios of chloropropene/chloromethyltrichlorosilane were synthesised by Grignard coupling, followed by reduction. Diffe...