title: A Study on Supported Metal Catalysts Prepared from Colloidal Precursors

authors: Jaine, Jacob Evan

subjects: catalyst

abstract: When metal nanoparticles are supported on the surface of an inert carrier, the resulting materials can become powerful heterogeneous catalysts capable of accelerating a diverse range of chemical reactions. Though there are a wide variety of synthetic routes by which these materials can be prepared, many offer little control over the textural properties of the resulting catalyst. Conversely, methods using pre-formed colloidal nanoparticles as a metal source offer the potential for precise control of properties like particle size and shape. This is both a topical class of syntheses, and the subject of the current body of work. Three different types of colloids were therefore prepared using different stabilising agents, and subsequently used to produce an array of different catalysts.

As support materials for the catalysts, a series of four commercially available materials were obtained, including silica, alumina, hydroxyapatite, and microcrystalline cellulose. Four novel analogues were also obtained, including halloysite, perlite, bioapatite, and macrofibrillar cellulose. In order to understand their physicochemical properties, they were characterised by a combination of Fourier transform infrared microspectroscopy, solid-state ¹H, ¹³C, ²⁷Al, ²⁹Si, and ³¹P nuclear magnetic resonance spectroscopy, x-ray diffraction, x-ray fluorescence spectroscopy, scanning and transmission electron microscopy, laser diffraction analysis, and zeta potential measurements. Additional experiments were performed to investigate the wetting properties of the materials using the Washburn capillary rise method, which was shown to be a valuable method for rationalising solvent choice for reactions involving these materials.

An initial batch of catalysts was produced by immobilising electrostatically-stabilised rhodium, palladium, and platinum colloids onto these support materials. Instrumental characterisation of the catalysts showed no major perturbation to the chemistry of the materials following the immobilisation, though some subtle surface effects were observed. These catalysts were tested in the hydrogenation of several olefins, and were found to have excellent catalytic activity, up to 64,400 hr⁻¹, under standard conditions. 
A second batch of catalysts was produced by immobilising polymer-stabilised metal colloids onto the supports. Characterisation of the materials showed the polymers and the nanoparticles they contained were associated strongly with the support materials, though the spatial distribution varied significantly between systems. Activation of the catalysts by calcination was shown to initiate their thermal decomposition and oxidation, which in turn affected their catalytic activity. The catalysts containing supported rhodium or platinum were inactive, while those containing supported palladium showed good activity, up to 41,900 hr⁻¹.
A third batch of catalysts was produced by immobilising solvent-stabilised metal colloids onto the supports. Amide-type solvents were shown to be the most effective for this purpose, though spectroscopic evidence suggested the samples contained residual solvent and related decomposition products. These catalysts displayed modest activities of up to 8,100 hr⁻¹.
Finally, a method was developed for quantifying the amount of metal in the catalysts using laser-induced breakdown spectroscopy. A series of matrix-matched standards were prepared, and their elemental compositions measured accurately using neutron activation analysis. The method was shown to be rapid and inexpensive to implement, with linearity up to 2.0 wt% metal and a precision of over 95%.

text: A Study on Supported Metal Catalysts Prepared from Colloidal Precursors When metal nanoparticles are supported on the surface of an inert carrier, the resulting materials can become powerful heterogeneous catalysts capable of accelerating a diverse range of chemical reactions. Though there are a wide variety of synthetic routes by which these materials can be prepared, many offer little control over the textural properties of the resulting catalyst. Conversely, methods using pre-formed colloidal nanoparticles as a metal source offer the potential for precise control of properties like particle size and shape. This is both a topical class of syntheses, and the subject of the current body of work. Three different types of colloids were therefore prepared using different stabilising agents, and subsequently used to produce an array of different catalysts.

As support materials for the catalysts, a series of four commercially available materials were obtained, including silica, alumina, hydroxyapatite, and microcrystalline cellulose. Four novel analogues were also obtained, including halloysite, perlite, bioapatite, and macrofibrillar cellulose. In order to understand their physicochemical properties, they were characterised by a combination of Fourier transform infrared microspectroscopy, solid-state ¹H, ¹³C, ²⁷Al, ²⁹Si, and ³¹P nuclear magnetic resonance spectroscopy, x-ray diffraction, x-ray fluorescence spectroscopy, scanning and transmission electron microscopy, laser diffraction analysis, and zeta potential measurements. Additional experiments were performed to investigate the wetting properties of the materials using the Washburn capillary rise method, which was shown to be a valuable method for rationalising solvent choice for reactions involving these materials.

An initial batch of catalysts was produced by immobilising electrostatically-stabilised rhodium, palladium, and platinum colloids onto these support materials. Instrumental characterisation of the catalysts showed no major perturbation to the chemistry of the materials following the immobilisation, though some subtle surface effects were observed. These catalysts were tested in the hydrogenation of several olefins, and were found to have excellent catalytic activity, up to 64,400 hr⁻¹, under standard conditions. 
A second batch of catalysts was produced by immobilising polymer-stabilised metal colloids onto the supports. Characterisation of the materials showed the polymers and the nanoparticles they contained were associated strongly with the support materials, though the spatial distribution varied significantly between systems. Activation of the catalysts by calcination was shown to initiate their thermal decomposition and oxidation, which in turn affected their catalytic activity. The catalysts containing supported rhodium or platinum were inactive, while those containing supported palladium showed good activity, up to 41,900 hr⁻¹.
A third batch of catalysts was produced by immobilising solvent-stabilised metal colloids onto the supports. Amide-type solvents were shown to be the most effective for this purpose, though spectroscopic evidence suggested the samples contained residual solvent and related decomposition products. These catalysts displayed modest activities of up to 8,100 hr⁻¹.
Finally, a method was developed for quantifying the amount of metal in the catalysts using laser-induced breakdown spectroscopy. A series of matrix-matched standards were prepared, and their elemental compositions measured accurately using neutron activation analysis. The method was shown to be rapid and inexpensive to implement, with linearity up to 2.0 wt% metal and a precision of over 95%.

year: 2016

title: Does investor sentiment predict the near-term returns of the Chinese stock market?

authors: Cheema, Muhammad A.

abstract: Recent evidence on the relationship between investor sentiment and subsequent monthly market returns in China shows that investor sentiment is a reliable momentum predictor since an increase (decrease) in investor sentiment leads to higher (lower) future returns. However, we suggest that momentum predictability of investor sentiment originates from the boom and bust period of 2006-2008 (the bubble period hereafter). The bubble period is characterized by several months of sustained optimism followed by several months of sustained pessimism, with the market consequently earning high (low) returns following high (low) sentiment months. Therefore, we find a strong positive association between investor sentiment and subsequent market returns during the bubble period. However, investor sentiment has a negligible impact on subsequent monthly market returns once we exclude the bubble period.

text: Does investor sentiment predict the near-term returns of the Chinese stock market? Recent evidence on the relationship between investor sentiment and subsequent monthly market returns in China shows that investor sentiment is a reliable momentum predictor since an increase (decrease) in investor sentiment leads to higher (lower) future returns. However, we suggest that momentum predictability of investor sentiment originates from the boom and bust period of 2006-2008 (the bubble period hereafter). The bubble period is characterized by several months of sustained optimism followed by several months of sustained pessimism, with the market consequently earning high (low) returns following high (low) sentiment months. Therefore, we find a strong positive association between investor sentiment and subsequent market returns during the bubble period. However, investor sentiment has a negligible impact on subsequent monthly market returns once we exclude the bubble period.

year: 2018

title: Toi tu te whenua, toi tu te tangata: A holistic Māori approach to flood management in Pawarenga

authors: Proctor, Elizabeth-Mary

subjects: flood management

abstract: This thesis is a study of how tikanga Māori principles could be used in practice in the management of natural hazards and in particular flooding in a rural area, Pawarenga. The aim was to investigate and document Te Uri O Tai Hapū preferred strategies for reducing flood risk in Pawarenga and to consider opportunities to use tikanga Māori principles and values in emergency response. The identification of key concepts and principles of tikanga Māori customs and their connections to whānau and hapū of Te Uri O Tai is key to this study. I used kaupapa Māori research methodologies as a guiding framework since researching in my own community required me to manage accountability both to its members and to the university. In particular it was important to obtain permission from the community before beginning, to ensure my research processes were acceptable, and to return my findings to the community. Qualitative data was gathered from a series of hui and interviews with local community members. Data was analysed inductively and organised into thematic networks. Two major organising themes were identified: resilience and vulnerability. Participants described a broad range of strengths inherent in the community that enabled them to respond to crises such as flood events. A number of cultural, social, physical, economic and political vulnerabilities were also identified; most of these were fundamental aspects of people‘s daily lives and did not prevent them from responding positively when floods occurred, but may have limited the scope of their responses. Tikanga was not a subject that participants felt comfortable talking about, but from the descriptions of how people actually responded during floods I was able to see examples of how tikanga was used. The resilience of the Pawarenga community is taken for granted by residents. When disasters such as floods occur, their resiliencies and strengths are brought into play to ensure the safety of all in the community. Tikanga Māori is an inherent part of this resiliency, and marae structures and protocols already in place provide a vital framework for flood response. I conclude that tikanga already has enormous value in flood response, and for Māori communities is an obvious choice as a foundation for a flood emergency management strategy. Furthermore, the value of tikanga as a flood emergency management strategy should be more explicitly recognised and supported by all authorities involved in disaster response and management. It was also clear that multiple dimensions of vulnerability (physical, cultural, social, economic and political) affect the Pawarenga community, and to some extent limit their capacity to respond. In particular political processes that exclude them from participating in decision-making and planning around environmental management generally have left people feeling marginalised, since they are unable to fulfil their kaitiaki role. With civil defence emergency management policies explicitly focused around resilience, participation of Te Uri O Tai Hapū in planning for emergency management should allow for their existing resilience, which stems from the upholding of tikanga, to be recognised and strengthened. However, this will only happen if relationships with the various authorities involved in emergency and natural hazard response are fostered, full participation in decision-making and in responding to natural hazard events is facilitated, and resources are available to support the community with their endeavours.

text: Toi tu te whenua, toi tu te tangata: A holistic Māori approach to flood management in Pawarenga This thesis is a study of how tikanga Māori principles could be used in practice in the management of natural hazards and in particular flooding in a rural area, Pawarenga. The aim was to investigate and document Te Uri O Tai Hapū preferred strategies for reducing flood risk in Pawarenga and to consider opportunities to use tikanga Māori principles and values in emergency response. The identification of key concepts and principles of tikanga Māori customs and their connections to whānau and hapū of Te Uri O Tai is key to this study. I used kaupapa Māori research methodologies as a guiding framework since researching in my own community required me to manage accountability both to its members and to the university. In particular it was important to obtain permission from the community before beginning, to ensure my research processes were acceptable, and to return my findings to the community. Qualitative data was gathered from a series of hui and interviews with local community members. Data was analysed inductively and organised into thematic networks. Two major organising themes were identified: resilience and vulnerability. Participants described a broad range of strengths inherent in the community that enabled them to respond to crises such as flood events. A number of cultural, social, physical, economic and political vulnerabilities were also identified; most of these were fundamental aspects of people‘s daily lives and did not prevent them from responding positively when floods occurred, but may have limited the scope of their responses. Tikanga was not a subject that participants felt comfortable talking about, but from the descriptions of how people actually responded during floods I was able to see examples of how tikanga was used. The resilience of the Pawarenga community is taken for granted by residents. When disasters such as floods occur, their resiliencies and strengths are brought into play to ensure the safety of all in the community. Tikanga Māori is an inherent part of this resiliency, and marae structures and protocols already in place provide a vital framework for flood response. I conclude that tikanga already has enormous value in flood response, and for Māori communities is an obvious choice as a foundation for a flood emergency management strategy. Furthermore, the value of tikanga as a flood emergency management strategy should be more explicitly recognised and supported by all authorities involved in disaster response and management. It was also clear that multiple dimensions of vulnerability (physical, cultural, social, economic and political) affect the Pawarenga community, and to some extent limit their capacity to respond. In particular political processes that exclude them from participating in decision-making and planning around environmental management generally have left people feeling marginalised, since they are unable to fulfil their kaitiaki role. With civil defence emergency management policies explicitly focused around resilience, participation of Te Uri O Tai Hapū in planning for emergency management should allow for their existing resilience, which stems from the upholding of tikanga, to be recognised and strengthened. However, this will only happen if relationships with the various authorities involved in emergency and natural hazard response are fostered, full participation in decision-making and in responding to natural hazard events is facilitated, and resources are available to support the community with their endeavours.

year: 2010