Kinetic and Mechanisms of the Aqueous-Biphasic Hydroformylation of Olefins Contained in Naphtha Cuts Catalyzed by RhH(CO)(TPPTS)3 [TPPTS: Tri(sodium m-sulfonated-phenyl)phosphine

Abstract

A kinetic study of the individual olefins present in naphtha, their mixture (synthetic naphtha) and the olefins present in a real naphtha was carried out using RhH(CO)(TPPTS)3 [TPPTS: tri(sodium m-sulfonated-phenyl)phosphine] as the catalyst precursor in aqueous-biphasic medium (toluene/water or naphtha/water), under mild reaction conditions: 80 °C, 800 psi (55.4 atm) and 600 rpm. The study consisted in the characterization of real naphtha, the selection of the model olefins, the preparation of synthetic naphtha, followed by hydroformylation of the individual olefins, of the olefin mixture and of a real naphtha cut. For 1-hexene aqueous-biphasic reaction, a kinetic study based on initial rate method showed a first order dependence on catalyst, substrate and dissolved hydrogen concentrations, whereas a fractional order was observed for carbon monoxide concentration. This kinetic results are in accord with the traditional hydroformylation mechanism, the hydrogenolysis of rhodium-acyl species being the rate-determining step of the cycle. From all the reaction profiles, it was corroborated by using the integral method that the dependence with respect to the olefin concentration was of first order for the aqueous-biphasic hydroformylation of individual olefins and their mixture, as well as for the olefins present in real naphtha cut. These results are important because of knowing the kinetics and mechanisms of the hydroformylation of the olefins present in naphtha, it is possible to improve the activity of the precatalyst and/or to design new ones for this type of application, i.e. the improving of the fuel quality through the green technology of aqueous-biphasic catalysis. A kinetic study of the individual olefins present in naphthas, their mixture (synthetic naphtha) and the olefins present in a real naphtha was carried out in aqueous-biphasic medium using RhH(CO)(TPPTS)3 [TPPTS = tri(sodium m-sulfonated-phenyl)phosphine] as the catalyst precursor in a aqueous-biphasic media, under mild reaction conditions: 80 °C, 800 psi (55.4 atm) and 600 rpm. The kinetic results are in accord with the traditional hydroformylation mechanism.