The desire for precise polymer property control, minimum wastage through grade transitions, and early instrument fault detection, has led to a significant effort in the modelling and control of ethylene polymerisation world-wide. Control is difficult due to complex inter-relationships between variables and long response times from gas to solid phase. The approach in this study involves modelling using the kinetic equations. This forms the basis of a scheme for real-time kinetic parameter identification and Kalman filtering of the reactor gas composition. The scheme was constructed off-line and tested on several industrial polymer grades using historical plant data. The scheme was also converted into a form for use on the linear low-density polyethylene plant, Poly 2, at POLlFIN Limited. There proved to be no difficulty in the identification step, but the Kalman filter requires more tuning for reliable fault detection. The software has been commissioned on-line and results from the POLlFIN plant match the off-line model exactly. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2000.

Experimental vapour-liquid equilibria (VLE) data is required for the design of separation / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.

No abstract available. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.

Olefin (alkene) metathesis can be used for the redistribution of carbon bonds to produce preferred higher range carbon number olefins (C10-C16) from low value medium chain olefins such as 1-hexene. In this study, the performance of various heterogeneous, tungsten based catalysts was investigated for the gas-phase linear cross metathesis of 1-hexene. The tested catalysts included tungsten trioxide on alumina, at various specific loadings, 8wt% tungsten trioxide on silica as well as 8wt% tungsten trioxide on silica, at various specific loadings of a potassium promoter. An existing lab-scale, fixed bed metathesis reactor system was used to conduct the required experimental work under steady state conditions. The experimental plan used for conducting the investigation of the alumina-supported catalyst was a combination of the One-Variable-At-a-Time (OVAT) approach as well as the factorial design method. The domain of the range under investigation was 8-20% for the specific loading of tungsten trioxide, 420-500oC for reaction temperature and 30-80 mol% for the feed composition of 1-hexene with constant space time. A half factorial experimental design was used for the WO3/SiO2 and potassium doped WO3/SiO2 catalysts. The potassium loadings of the 8wt% WO3/SiO2 catalyst were between 0.05-0.5wt%. Reaction temperatures of between 420-460°C were used together with 1-hexene feed compositions of between 60-80mol% and space times of 200-400g.min.mol-1. The WO3/Al2O3 catalyst was found to be an inferior catalyst for the metathesis of 1-hexene at all combinations of specific loadings and operating conditions tested. The highest yields obtained for both the detergent range olefins (C10-C16) and primary metathesis product decene (C10) were less than 1.5%. Changes made to the calcination temperature, calcination time and pH of the impregnation solution during the catalyst preparation stages had no significant effect on the yields produced. The WO3/Al2O3 catalyst was found to behave more as an isomerization catalyst rather than one for the metathesis reaction. The optimum reaction conditions determined when investigating the 8wt% WO3/SiO2 catalyst were found to be a reaction temperature of 460°C, a feed gas composition of 60mol% 1-hexene and a space time of 400g.min.mol-1. The conversion of 1-hexene, the yield of the detergent range olefins and the yield of decene at the above mentioned reaction conditions were 82%, 8.30% and 5.92% respectively Doping of the WO3/SiO2 catalyst with potassium was found to be successful in reducing the amount of isomerization and increasing the yields of both the detergent range olefins and decene by approximately 1.5% and 2% respectively when doping with 0.1 and 0.5wt% potassium. The experimental runs conducted were at the optimum reaction conditions obtained using the 8wt% WO3/SiO2 catalyst. The highest selectivity of the detergent range olefins (24.64%) and decene (23.62%) was obtained when using the 0.5wt% K doped WO3/SiO2 catalyst. At the optimised reaction conditions, the 0.5wt% potassium loading on WO3/SiO2 performed the best. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2013.

Os reservatórios de águas, tais como rios e lagos são de extrema importância a manutenção da vida através do fornecimento de água para as necessidades básicas dos seres humanos. Além disso, também servem como destino final dos subprodutos das atividades humanas através dos efluentes domésticos e industriais. Em razão de possuírem duas funções opostas é necessário o desenvolvimento de tecnologias capazes de minimizar o impacto poluidor dos subprodutos das atividades humanas. O tratamento por processos convencionais nem sempre é eficiente, por isso os processos oxidativos avançados tem sido o foco de vários estudos. Dentre esses processos a fotocatálise heterogênea tem se destacado. Esta dissertação de mestrado descreve a avaliação do Ag3PO4 como catalisador no processo de fotocatálise heterogênea visando à degradação do poluente modelo fenol. O trabalho avaliou primeiramente o material na degradação do fenol em presença de uma fonte de irradiação artificial de xenônio. Na ausência de oxigenação do sistema, houve uma melhora na taxa média de degradação utilizando o catalisador Ag3PO4 comparado ao TiO2 P25. Com 120 minutos de reação pode ser observada a degradação total do fenol utilizando o catalisador Ag3PO4, enquanto, utilizando o TiO2 P25, foi possível observar menos de 30% de degradação no mesmo tempo. Além dos testes com luz artificial, foram feitos testes utilizando um reator solar do tipo CPC para comparar os resultados. Considerando algumas dificuldades encontradas foi possível obter resultados satisfatórios em relação à utilização do Ag3PO4 em fotorreatores solares. Para obter melhores resultados comparativos seria necessário modificações no sistema utilizado, como o aumento na vazão, para tentar utilizar efetivamente toda a massa de catalisador, pois no sistema utilizado ocorre sedimentação de parte da massa utilizada. Os resultados foram positivos indicando a possibilidade de ativar o catalisador Ag3PO4 com radiação solar, o que indica um caminho importante no desenvolvimento de tecnologia para processos de fotodegradação catalítica em reatores solares. / Water reservoirs, such as rivers and lakes are extremely important to maintain life through the provision of water for basic needs of human beings. Moreover, they also serve as the final destination of the byproducts of human activities such as domestic and industrial effluents. Since they have opposite functions it is necessary to develop technologies capable of minimizing the pollution impacts of the byproducts of human activities. Since the treatment of waste waters by conventional processes is not always effective, advanced oxidation processes have been the focus of several studies. Among these processes, heterogeneous photocatalysis has found an outstanding rule. This study aims at an evaluation of Ag3PO4 as a catalyst in the heterogeneous photocatalysis to degrade phenol dissolved in water. Phenol-in-water solutions has been adopted as a model contaminant in this study. The performance of the catalyst was evaluated using a xenon lamp as the source of artificial irradiation. In the absence of oxygenation, total degradation of phenol was observed in 120 minutes of reaction using the Ag3PO4 catalyst, while only 30% of the initially contained phenol was degraded when the conventional TiO2 P25 catalyst was used. Tests were also carried out in a solar reactor with CPC type collectors. These tests indicated that the Ag3PO4 catalyst can be a feasible alternative to conventional catalysts. The tests also indicated the need for further development of the catalyst production process, in order to generate smaller particles, with less tendency to settle down, and with larger specific surface area, The results were positive indicating the possibility of activating the catalyst Ag3PO4 with solar radiation, which indicates an important pathway in the development of technology for catalytic photodegradation in solar reactors.

Thesis. 1977. Sc.D. cn--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 222-228. / Sc.D.cn

Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / M̲i̲c̲ṟo̲f̲i̲c̲ẖe̲ c̲o̲p̲y̲ a̲v̲a̲i̲ḻa̲ḇḻe̲ i̲ṉ A̲ṟc̲ẖi̲v̲e̲s̲ a̲ṉḏ S̲c̲i̲e̲ṉc̲e̲.̲ / Vita. / Bibliography : leaves 378-385. / by John A. Wilkens. / Ph.D.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 483-489. / by George Albert Huff, Jr. / Sc.D.

Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 159-161. / Ph.D.

Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 64-67).