In order to preserve the environment and due to the fact that there is a limited amount of fossil fuels available, renewable energy sources, such as transgenic plants, wood residues and other plant waste, are becoming the focus of considerable attention.
Chemical processes, such as pyrolysis (thermal decomposition) or liquefaction (liquefaction) allow the conversion of biomass (the total weight of all organisms in a given unit of area) into bio-oil - a very promising renewable energy source. A team of German and Chinese scientists led by Johannes A. Lercher from the University of Munich in Germany has now developed an innovative catalytic process to convert components of bio-oil directly into the important substances alkanes and methanol. As reported in the scientific journal Angewandte Chemie, the process is based on a reaction in one vessel catalyzed by a precious metal anchored to a carbon substrate in combination with an inorganic acid.
Bio-oil is a watery, acidic and highly oxidizing mixture. However, its high oxygen content and its chemical instability have negative consequences: bio-oil cannot be used directly as a liquid fuel. However, this material may be of great interest as a source of basic raw materials if it can be converted to alkanes. Alkanes, also called paraffins, are saturated hydrocarbons; They are among the most important basic raw materials for the chemical industry, and in particular, as starting materials for the production of plastics. In addition, they are used as a major fuel in global industry.
Bio-oil contains a phenolic part consisting of compounds with a main skeleton of an aromatic ring consisting of six carbon atoms and several hydroxyl groups attached to it. Using the new process, the phenolic part of the bio-oil is converted in a highly selective manner into cycloalkanes (cyclic alkanes) and methanol. The researchers were able to demonstrate their new method for a variety of model materials. As a catalyst, they used palladium metal on a carbon substrate and phosphoric acid as the hydrogen source for the reaction.
The reaction is carried out in one vessel, that is, a one-step reaction in which the partial reactions (hydrogenation, hydrolysis and dehydration) occur in the same vessel without treatment and processing of the intermediates in the process. The secret lies in the catalyst that acts on all three of these separate reactions. The final result is a mixture of a variety of alkanes that separate independently into an organic layer, so that they can be easily removed from the aqueous layer of the starting material. The innovative process is a practical approach to the direct use of bio-oil for the production of alkanes.
to the notice of the researchers
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