Reformage catalytique à la vapeur des hydrocarbures aromatiques lourds. Conversion du méthyl-1-naphtalène en présence de vapeur d'eau sur Rh, Ni et Pt Catalytic steam reforming of heavy aromatic hydrocarbons. I. Steam reforming of 1-methylnaphthalene on rhodium, nickel, and platinum catalysts
Résumé
The steam reforming of methylnaphthalene (I) was performed at 440°C on Al2O3 supported Rh, Ni and Pt catalysts. Three main reactions may occur, i.e. dealkylation (DA), selective ring opening (OCN) yielding C2H6 and PhMe, and degrdn. of the naphthalene ring (DCN). The relative activity order is the following: Rh >> Ni > Pt. As regards initial selectivities, the metals may be ranked as follows: DA:Pt 84 > Rh 55 > Ni 36, OCN:Rh 30 .apprx. Ni 29 > Pt 11, and for DCN:Ni 35 > Rh 14 > Pt 5. Although PhMe was more reactive than I in steam reforming, the behavior of alkylbenzenes and of alkylnaphthalenes are relatively similar. Only Ni and Ph are able to open arom. rings so that Pt appears essentially to be active in dealkylation. The same support effect is obsd. both in PhMe and in I conversion: Rh is a very support-sensitive metal (Rh/Al2O3 > Rh/SiO2) whereas Ni is not. The mechanism of steam reforming is discussed in the light of these observations.