CORDIS provides links to public deliverables and publications of HORIZON projects.
Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Deliverables
A new catalytic system has been developed which is based on Co ion as the active component, dispersed within a matrix made of magnesium-aluminum oxides. This system is particularly suitable for the oxidation of toluene under supercritical conditions by the use of carbon dioxide as the SC solvent. This catalyst type has never been previously described in literature.
Under Supercritical reaction conditions, this catalyst releases Co ions, which then represent the true active sites for the reaction. So, the solid represents a reservoir for the active components. A specific novelty of the system is that it is prepared starting from a hydrotalcite-like precursor; the transformation of the hydrotalcite to the catalyst is achieved by thermal treatment, with development of the system in which Co is dispersed in the magnesia-alumina matrix. This catalyst, while being almost inactive under non-SC conditions, reaches conversion at best of 35% in toluene oxidation with oxygen in SC carbon dioxide, while under comparable temperature, but under non-SC conditions, conversion achieved is far lower than 10%.
The performances are better than literature data of toluene oxidation in SC conditions, although performances should be further improved.
Process and reaction conditions are a determining factor to achieve good conversion and selectivity to benzoic acid in toluene oxidation, or in m-toluic acid starting from m-xylene, with co-production of isophthalic acid.
A novel method for determination of the state of advancement of a reaction under supercritical conditions has been developed.
The method is based on the direct sampling of the products of reaction during the catalytic run in a batch-type reactor under pressure. The innovation is related to the design of the interface system between the high-pressure reaction vessel and a gas chromatograph.
The method allows a much better precision of the data and to follow the change of the products with the time of reaction.
Catalysts suitable for operation in transalkylation of disopropylbenzene to cumene under supercritical conditions must reach conversion of the reactant above 80% and selectivity to cumene above 80%, in order to reach yields, which are acceptable.
Zeolite having the faujasite structure, and specifically H-Y zeolite having a Si/Al ratio equal to 2.7, as widely available on the market, do not fit this requirement, since the yield to cumene achieved in the transalkylation of diisopropylbezene using SC carbon dioxide as the reaction solvent, at the temperature of 200°C and at the pressure of 130 atm, is equal to 61%, with a selectivity to the same product equal to 72%.
However, it has been found that if a dealumination procedure is applied by treatment with oxalic acid at defined conditions, so to increase the Si/Al ratio from 2.7 to approx. 20, while maintaining a good degree of crystallinity, a catalyst is obtained which, at the same conditions as above, gives yield to cumene 77% with a selectivity of 92%. The treatment also improves the performance of the same catalyst when the latter is used under non-supercritical conditions.
Catalyst lifetime under supercritical conditions however has not been investigated. This remains one of the major issues to be investigated, since a true advantage with respect to non-supercritical, traditional conditions for transalkylation would be a longer catalyst lifetime.
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