Hydroisomerization of n-hexane over Pt±SAPO-11and Pt±SAPO-31 molecular sieves

Abstract

SAPO-11 and SAPO-31, two medium pore molecular sieves, were synthesized from aqueous and non-aqueous (ethylene glycol) media. Their acidities (by TPD of pyridine) and their catalytic activities in the isomerization of n-hexane are compared. Samples synthesized from non-aqueous medium possess more acidity and higher activities than those obtained from aqueous medium. 29Si MAS NMR studies suggest greater substitution of P5‡ by Si4‡ and lower concentration of silica islands in the samples synthesized from non-aqueous medium. Both SAPO-11 and -31 produce predominantly the monomethyl isomers due to their medium size pores. The activity studies were carried out over Pt loaded samples in the presence of H2.