Superior activity and isomerization selectivity in n-dodecane hydroisomerization over Ni clusters on ZSM-22 zeolite with structural defects

Abstract

Developing nonnoble catalysts with high performance for the selective hydroisomerization of long-chain n-alkanes to isoalkanes that are comparable to commercial Pt catalysts is important but challenging. We report a low-loading nickel catalyst on structure-defective nanosized ZSM-22 zeolite (Ni/SD-HZSM-22, 1.0 wt%) with superior activity and isomerization selectivity for n-dodecane hydroisomerization than a commercial Pt catalyst (Pt, 0.5 wt%). The developed Ni/SD-HZSM-22 catalyst achieves 86.0–88.6 % n-dodecane conversion and 80.0–81.3 % C12-isomer yield, outperforming the conventional ZSM-22–supported Ni catalyst (Ni/HZSM-22; 50.4 % and 41.1 %, respectively) and the commercial Pt catalyst (56.8 % and 52.4 %, respectively) under the same reaction conditions, with high durability for 120 h. This is because SD-HZSM-22 with abundant surface structural defects increased available 10-membered ring openings, anchoring the small-sized Ni species and enhancing the isomerization activity and selectivity, endowing Ni/SD-HZSM-22 with good synergy between metal and acid functions.