Browsing by Author "Clark, James H."
Now showing 1 - 8 of 8
Results Per Page
Sort Options
Item Catalysis of the Knoevenagel reaction by γ-aminopropylsilica(1997-12) Macquarrie, Duncan J.; Clark, James H.; Lambert, Arnold; Mdoe, James; Priest, AndrewThe Knoevenagel reaction can be catalysed by γ-aminopropylsilica. Reactions are rapid and essentially quantitative with small amounts of catalyst. A range of aldehydes and ketones can be reacted successfully, the only exceptions being very bulky ketones. The reaction is very dependent on the efficient removal of water, which leads to faster reaction rates and to much higher conversions. The choice of solvent is also extremely important, with nonpolar solvents such as cyclohexane being optimal. Less polar, higher boiling solvents are significantly less effective, even at much higher reaction temperatures. Catalyst poisoning is slow and appears to be due to amide formation on the surface.Item Current and Future Trends In Food Waste Valorization for the Production of Chemicals, Materials and Fuels: A Global Perspective(Wiley, 2014) Lin, Carol S. K.; Koutinas, Apostolis A.; Stamatelatou, Katerina; Mubofu, Egid B.; Matharu, Avtar S.; Kopsahelis, Nikolaos; Pfaltzgraff, Lucie A.; Clark, James H.; Papanikolaou, Seraphim; Kwan, Tsz H.; Luque, RafaelFood waste is currently generated in significant quantities worldwide. While most of this has generally few uses different from landfilling or composting, advanced valorization alternatives should be developed to maximize the value derived from such an important waste source. This contribution aims to illustrate a series of examples and current valorization strategies proposed in different countries in order to tackle the food waste issue. Proposed processing schemes involve biorefinery approaches based on both chemical and biological technologies. Important legislation aspects in different countries are also presented.Item Food Waste as a Valuable Resource for the Production of Chemicals, Materials and Fuels. Current Situation and Perspective(2013) Lin, Carol S. K.; Pfaltzgraff, Lucie A.; Herrero-Davila, Lorenzo; Mubofu, Egid B.; Solhy, Abderrahim; Clark, James H.; Koutinas, Apostolis A.; Kopsahelis, Nikolaos; Stamatelatou, Katerina; Dickson, Fiona; Thankappan, Samarthia; Zahouily, Mohamed; Brocklesby, Robert; Luquek, RafaelIncreasing demand for fuels and chemicals, driven by factors including over population, the threat of global warming and the scarcity of fossil resources, strain our resource system and make necessary the development of sustainable and innovative strategies for the chemical industry. The strain upon which our resource system is under drives industry to increase its overall efficiency by improving existing processes or finding new uses for waste. Food supply chain waste emerged as a resource with a significant potential to be employed as raw material for the production of fuels and chemicals given the abundant volumes globally generated, its contained diversity of functionalised chemical components and the opportunity to be utilised for higher value applications. The present manuscript is aimed to provide a general overview of current and most innovative uses of food supply chain waste, providing a range of worldwide case studies from around the globe. These studies will focus on examples illustrating the use of citrus peel, waste cooking oil and cashew shell nut liquid in countries such as China, UK, Tanzania, Spain, Greece or Morocco. This work emphasises 2nd generation food waste valorisation and re-use strategies for the production of higher value and marketable products rather than conventional food waste processing (incineration for energy recovery, feed or composting) while highlighting issues linked to the use of food waste as a sustainable raw material. Influence of food regulations on food supply chain waste valorisation will also be addressed as well as our society’s behavior towards food supply chain wasteItem Michael Additions Catalyzed by N,N-Dimethyl-3-aminopropyl — Derivatized Amorphous Silica and Hexagonal Mesoporous Silica (HMS)(1998-06) Mdoe, James; Clark, James H.; Macquarrie, Duncan J.Solid bases prepared by derivatisation of amorphous silica and hexagonal mesoporous silica with dimethylaminopropyl groups are good catalysts for Michael addition reactions. Of the prepared catalysts, those based on hexagonal mesoporous silica show particularly high activities. The sol-gel method used in preparing the catalysts based on hexagonal mesoporous silica enables loading to be increased to more than twice that of those based on amorphous silica which are prepared by the post-modification method.Item Novel Supported Heterogeneous Palladium Catalysts for Carbon—Carbon Forming Reactions(Elsevier, 2000) Mubofu, Egid B.; Clark, James H.; Macquarrie, Duncan J.A novel palladium catalyst has been supported on chemically modified silica and tested for activity. The catalyst has high activity towards the Heck reaction of aryl iodides with olefins in acetonitrile solvent and has been reused several times without signicant loss of activity.Item A Novel Suzuki Reaction System Based on a Supported Palladium Catalyst(2001) Mubofu, Egid B.; Clark, James H.; Macquarrie, Duncan J.A range of supported palladium complex-catalysed Suzuki reactions is described with notable features including fast and efficient reactions, excellent catalyst recyclability, and total catalyst stability under the reaction conditions. We have achieved turnover numbers of several thousand based on ten re-use experiments from batch reactions in air. Our system not only solves the basic problems of catalyst separation and recovery but also avoids the use of phosphine ligands.Item Organomodified hexagonal mesoporous silicates(1999-01) Macquarrie, Duncan J.; Jackson, Dominic B.; Mdoe, James; Clark, James H.A neutral templating route to organically modified silicates with tightly controlled porosity is described. The materials prepared are characterised and compared to the corresponding organofunctionalised silicaItem Preparation of a Novel Silica-Supported Palladium Catalyst and Its Use in the Heck Reaction(2000) Clark, James H.; Macquarrie, Duncan J.; Mubofu, Egid B.A novel palladium catalyst supported on a chemically modified mesoporous silica gel has been prepared and exhibits high activity and stability in the Heck reaction of aryl iodides with olefins. The catalysts has been reused several times in reactions without significant loss of activity and selectivity.