Monodimensional tubular medium pore molecular sieves for selective hydroisomerisation of long chain alkanes: n-octane reaction on ZSM and SAPO type catalysts

n-octane has been hydroisomerised at 523 K on ZSM-12, 48 and 32, SAPO-5, 11 , 31 and 41 containing Pt-Pd metal function. The materials were prepared wi th hydrothermal methods, and characterized. Selectivities to Cs isomers ran ged from 99 to 50% maximum yield around 80% being reached on SAPO-11, 31 an d 41, ZSM-22 and 48. Among the various Cs isomers 2-MeC7 was preferentially formed. Such selectivity was interpreted in terms of transition state shap e selectivity at the pore mouths. To further corroborate these interpretati ons the reaction of 2-MeC7, 3-MeC7. 4-MeC7. 2,5-diMeC(6), 2.2,4-TMP on the previous catalysts was also investigated. Determination of the respective r eaction rates of these molecules, as well the product distribution analysis allowed to reinforce the concept of transition state shape selectivity at the pore mouths.