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Piroliza biomasy jako źródło energii

Retajczyk M., Wróblewska A.

Wiadomości Chemiczne

2018

[Z] 72, 3-4

127--146

The use of fossil fuels for energy purposes results in the emission of large amounts of carbon dioxide into the atmosphere, which in turn contributes to global warming, which is one of the civilization threats to the environment, and thus to modern civilization. The use of waste of plant origin to obtain energy reduces the amount of greenhouse gas (carbon dioxide) in the atmosphere, which results from the fact that plants take CO2 in the process of photosynthesis. Plants are a carbon reservoir, which in turn allows the use of biomass to obtain biofuels. In addition, the use of waste to obtain energy, solves the problem of storage, which is particularly problematic in the case of tires and plastics, which pose a potential threat to the natural environment. The article describes the composition of waste used for thermal processes and explains why waste is a good source of energy. In addition, it presents the division of thermal processes into three types: combustion, gasification and pyrolysis. In the further part of the article, the division of pyrolysis can be found due to its speed and related differences in the content of individual products and the division of this type of thermal processes, due to the type of reactors used. In addition, the article presents the conditions for conducting thermal processes and their impact on the content of solid, gaseous and liquid products. The work presents the construction of reactors, the principle of their operation, as well as the advantages and disadvantages resulting from their use. In the further part of the article, microalgae are described as an efficient source of fuel in combination with other widely used products of plant origin. In the last part of this work, the composition of products obtained after pyrolysis of waste of various origins was compared.

Katalizatory metatezy olefin, modyfikacje liganda NHC

Retajczyk M., Wróblewska A.

Wiadomości Chemiczne

2017

[Z] 71, 5-6

323--347

Olefin metathesis is one of the most important synthetic tools, both in organic and olefin chemistry. Olefin metathesis allows to shorten production time of organic compounds and it is characterized by a smaller amount of by-products and waste in comparison with the classical ways of the synthesis of these compounds. Simultaneously, the conditions at which metathesis is performed are environmentally friendly. This method allows obtaining very valuable compounds, such as: anti-inflammatory agents, fungicides and many others. This causes that olefin metathesis has an important place in the organic synthesis and develops constantly. The first catalysts had undefined structure, therefore, it was difficult to predict the mechanism of their action. Big development metathesis came with the synthesis of catalysts with a clearly defined structure. This article explains what olefin metathesis is and shows applications of olefin metathesis. This work presents catalysts, which possess transition metal in the structure, such as: ruthenium, molybdenum or tungsten. It also shows the comparison of catalysts possess ruthenium (Grubbs catalyst first and second generation and Hoveyda-Grubbs catalyst) taking into account their structure and properties. This work describe carbenes, which improve thermal stability of catalysts compare with complexes containing phosphine. Researchers receive new compounds through modifications on the NHC ligand. In this work are presented modifications of the NHC ligand complexes of ruthenium described in the literature and their influence on such catalytic properties as: activity, selectivity, and efficiency. Modifications concern: heteroatoms, bulky groups and groups, which change electron density. Despite many studies and receiving large amounts of catalysts for this reaction, still a problem is the obtaining of an universal catalyst for all types transitions, that would have a high activity, high efficiency and which could be easily recovered after the reaction.