Hydroisomerization of n-hexadecane over a Pd-Ni2P/SAPO-31 bifunctional catalyst: synergistic effects of bimetallic active sitesElectronic supplementary information (ESI) available: 27Al and 31P MAS NMR spectra; SEM and HR-TEM images; XRD, EDS, XPS and Py-IR spectra; N2 adsorption, H2 chemisorption, ICP, and TG-DTG results; and an estimation of nas. See DOI: 10.1039/c7cy02106b

• Main Authors: Zhang, Yang, Wang, Wei, Jiang, Xin, Su, Xiaofang, Kikhtyanin, O. V, Wu, Wei
• Format: Journal Article
• Published: 05.02.2018
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c7cy02106b

A series of bifunctional catalysts are prepared by loading Pd, Ni 2 P and bimetallic Pd-Ni 2 P on di- n -butylamine(DBA)-templated SAPO-31 molecular sieves through either impregnation or impregnation combined with temperature-programmed reduction methods. All bifunctional catalysts are characterized using XRD, N 2 adsorption, 27 Al and 31 P MAS NMR, SEM, TEM, IR spectroscopy of adsorbed pyridine, XPS, H 2 chemisorption, ICP, and TG-DTG measurements. The catalytic performance over all prepared bifunctional catalysts is compared for n -hexadecane hydroisomerization. The obtained results demonstrate that the 0.05Pd-4Ni 2 P/S31 catalyst produces a higher iso-C 16 yield of 72.7% with n -C 16 conversion of 83.1% compared with the other two catalysts. This result is attributed to two reasons: i) the bimetallic Pd-Ni 2 P component possesses stronger (de)hydrogenation functionality than Ni 2 P does, and ii) the bimetallic bifunctional catalyst has a better balance between metal and acid functionality than the monometallic catalysts do. Moreover, the 0.05Pd-4Ni 2 P/S31 catalyst also shows the best catalytic stability among all catalysts, since the n -C 16 conversion and iso-C 16 selectivity are still above 80% and 90%, respectively, even after 100 h of long-term testing. Therefore, the present study has provided a novel idea for the design of bimetallic bifunctional catalysts for long-chain n -alkane hydroisomerization. The Pd-Ni2P/SAPO-31 catalyst shows excellent performance in n -hexadecane hydroisomerization due to the synergistic effects of Pd-Ni2P and improved metal/acid balance.