HC-SCR of NOx_x emissions over Ag-AL2_2O3_3 catalysts using diesel fuel as a reductant

Hydrocarbon selective catalytic reduction (HC-SCR) of nitrogen oxides (NO$_x$) over silver-alumina (Ag-Al$_2$O$_3$) catalysts, in diesel exhaust gas, has been investigated and presented in this research thesis. The work involved the use of H$_2$ to activate diesel-type HC reductants. Numerous HC-SCR studies have been conducted (to date) by various authors and research groups in an effort to improve the low temperature (< 350 $^\circ$C) NO$_x$ reduction activity of the catalyst, but mainly at laboratory scale, using simulated diesel exhaust gases and the pelletized form of the catalyst. Conversely, the work presented and discussed herein is based on Ag-Al$_2$O$_3$ coated monolith substrates for the examination of the NO$_x$ reduction efficiency when utilizing the full diesel exhaust gas. The activity of the pelletized form of the catalyst and that of a coated monolith substrate could vary according to various characteristics, such as, the chemical (reaction kinetics) and physical (mass transfer, species filtration) processes. These effects were examined under ‘passive’ and ‘active’ operation of the respective catalysts. Diesel oxidation catalysts (DOCs) and unique prototype catalysts were also utilized in order to reduce possible poisoning species, which can lead to the deactivation of the Ag-based catalyst. Furthermore, variations in exhaust gas temperature and composition, by continually changing engine load and speed, were explored and the effects on catalyst activity presented. It was suspected that the fluctuating temperature profiles of the exhaust gas could limit the amount of poison species accumulation onto the catalyst active surface and, as a result, could slow down the deactivation mechanisms. Finally, fuel reforming of conventional diesel, RME and GTL fuels was conducted for the production of hydrogen (H$_2$). The produced H$_2$ could then be utilized in the combustion process itself or in a HC-SCR reactor, for reduced engine out or tailpipe emissions

Towards a theological synthesis of Christian and Shona views of death and the dead: implications for pastoral care in the Anglican diocese of Harare, Zimbabwe

In this contextual study I investigate why and how the traditional approach to mission, engaged by Anglican missionaries, gave rise to a dual observance of ritual among Shona Anglican Christians. I begin by establishing the significance and essence of Shona views of death and the dead, then investigate the missionaries' historical background. I highlight that Christian arrogance, in the guise of racial superiority, underlies the confrontational and condemnatory approach. Traditional views were considered evil, in their place, Shona converts were forced to adopt western Christian views as the only acceptable and valid way of coping with this eschatological reality. These views did not usually fit the Shona worldviews and religious outlook, hence the adoption of dual observance. For some, life continues to be classified as either Christian or traditional and never both. However, some present Shona Anglican practices reflect a desire to integrate the two. Unless there is this integration, the Church remains other and irrelevant to the Shona people. The ultimate aim of this thesis is to advocate for a theological synthesis of Christian and Shona traditional views. I argue that such a synthesis, patterned on the interactive dialogical model, could lead to the cessation of confrontation and condemnation and its attendant dual observance, and enhance the development of a Shona Christian theology of death and the dead which provides for relevant and sensitive pastoral care