Insights into Adsorption of Linear, Monobranched, and Dibranched Alkanes on Pure Silica STW Zeolite as a Promising Material for Their Separation

The adsorption of linear, monobranched and dibranched saturated hydrocarbons in the gasoline range has been studied on pure silica STW zeolite (Si-STW) by using pentane, hexane, and heptane isomers as model adsorbates. Experimental single-component adsorption isotherms and kinetic measurements together with configurational bias Monte Carlo (CBMC) and molecular dynamics (MD) simulations were carried out. Significant differences in both the equilibrium adsorption and especially the adsorption kinetics were found, which suggests that the separation of the quaternary-carbon dibranched isomer is feasible. The adsorption capacities and selectivities surpass those of pure silica MFI (Si-MFI), considered as reference. Altogether, Si-STW is presented as a promising adsorbent for increasing the octane number (ON) of the hydroisomerization product by selectively excluding quaternary-carbon dibranched hydrocarbons.