Modulating isomers distribution of n-dodecane hydroisomerization by mordenite-ZSM-22 composite zeolite

Abstract

Mordenite-ZSM-22 composite zeolite is prepared by the physical mixing. The structure, pore properties, acid properties and diffusion properties of samples are characterized by the means of XRD, N2 physical adsorption-desorption, SEM, TEM, NH3-TPD, Py-IR, and ZLC. The pore properties and acid properties of mordenite-ZSM-22 composite zeolite can be efficiently modulated by changing mass ratio of mordenite and ZSM-22. In n-C12 hydroisomerization reaction, Pt/HMZ-x displays great capacity in modulate n-dodecane isomers distribution (mono-branched i-C12, multi-branched i-C12, terminal branched i-C12 and central branched i-C12), these results are ascribed to that these composite zeolite catalysts combined the topology structure advantage of mordenite and ZSM-22. When reaction temperature is 280 °C, the ratio of mono-branched i-C12 selectivity to multi-branched i-C12 selectivity (SMB/SMTB) of Pt/HZSM-22, Pt/HMZ-1, Pt/HMZ-3, Pt/HMZ-5 and Pt/HMOR were 37.64, 15.04, 5.48, 5.20 and 1.47, respectively. The ZLC diffusion experiment results indicate that low isomer selectivity of Pt/HMOR is due to its poor diffusivity. On the contrary, Pt/HZSM-22 favors the diffusion of reactants and has better catalytic performance.

Keywords

• Mordenite
• ZSM-22
• Composite zeolite
• Hydroisomerization
• Isomer distribution