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Improvement of catalytic performance of H-Y zeolite by dealumination procedure for the reaction of diisopropylbenzene transalkylation to cumene in supercritical carbon dioxide

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.

Informations connexes

Reported by

Consorzio Interuniversitario per la Scienza e la Tecnologia dei Materiali, INSTM
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