Document Type : Research Paper


1 Chemical Engineering Department, University of Technology-Iraq

2 Chemical Engineering Department, University of Technology - Iraq


The synthesis of NaY-zeolite was performed hydrothermally. The preparation of the bifunctional catalysts was achieved by loading NH4Y-zeolite with a cheap Zr metal, as a second loading metal, with tiny amounts of Pt to compose a Pt-Zr/Y-zeolite catalyst. Different characterization methods (i.e., XRD, SEM, EDX, BET, and AFM) were used to investigate the catalyst properties. The catalytic performance was studied by performing the hydroisomerization of n-heptane in a gas phase at a temperature of 275°C and atmospheric pressure in a fixed-bed reactor. The GC-FID results of the products confirmed the positive role of Zr in enhancing the catalytic features, as reflected by the increase in the isomerized products and the decrease in the unwanted by-products. Incorporating 1.0wt%Zr with 1.0wt% of Pt significantly improved the activity and selectivity and increased the yield of branched alkanes. This was achieved because the addition of zirconium provided an extraordinary Lewis acidity to the zeolite-framework structure and simultaneously took advantage of the electronic and catalytic properties of Zr and Pt metals to enhance its novel catalytic features. This reduced the amount of Pt metal and halved the cost of the catalyst. In addition, the bimetallic catalyst (HY-zeolite loaded with 1wt%Pt & 1wt%Zr) achieved values of 74.2, 78.8, and 58.5mol% for conversion, selectivity, and yield, respectively. The conversion was improved to a level close to 2wt% Pt/HY-zeolite catalyst, while selectivity was not significantly decreased from that of 2wt% Zr/HY-zeolite catalyst, reaching a yield level of isomers close to that of 2wt% Pt/HY-zeolite catalysts.

Graphical Abstract


  • The synthesis of NaY-zeolite by the hydrothermal method.
  • Modification of NaY to form NH4Y, HY, and Metal-Loaded-HY-Zeolites by incipient wetness impregnation method
  • The preparation of the bimetallic catalyst depends on the two metals Zr and Pt.
  • Performing the hydroisomerization of n-heptane and proving the novel catalyst (1wt% Pt with 1wt% Zr)/ HY-Zeolite is an active and selective catalyst.
  • The amount of the costly Pt metal in the catalyst depends on the cheap Zr Metal was decreased.


Main Subjects

[1]  S. F. Perry, Isomerization, Industrial & Engineering Chemistry, ACS Publications,1948
[2] Hsu, C. Samuel, and P.  R. Robinson. Petroleum Science and Technology; Springer, Switzerland, 2019.
[3] Jones, S. J. David, and P. P. Pujadó, eds. Handbook of Petroleum Processing; Springer, Switzerland, 2015.
[4] Y. Ono, A survey of the mechanism in catalytic isomerization of alkanes. Catalysis Today 81 (2003): 3-16. doi: 10.1016/S0920-5861(03)00097-X.
[5] P. B. Weisz, Polyfunctional Heterogeneous Catalysis, Advances in Catalysis, (1962)137–190. doi: 10.1016/S0360-0564(08)60287-4.
[6] M. Saito, and T. Iwasaki. Isomerization of Pentanes on Platinum/Rare Earths-Hydrogen-Zeolite Y Catalysts. Bulletin of The Japan Petroleum Institute 18 (1976) 117-126.
[7] J. Scherzer, and A. J. Gruia. Hydrocracking science and technology. Crc Press, 1996.
[8] E. Kikuchi, M. Tsurumi, T. Kimura, and Y. Morita. Isomerization of n-Pentane over Sodium Y Zeolite Exchanged by Palladium and Platinum, Bull. Japan Pet. Inst. 15 (1973) 122-128.doi: 10.1627/jpi1959.15.122.
[9] T. F. Degnan, Applications of zeolites in petroleum refining. Topics in Catalysis 13 (2000) 349-356.doi: 10.1023/A:1009054905137.
[10] M. S.-S. Joaquin Pérez Pariente, Structure and Reactivity of Metals in Zeolite Materials. Springer, 2018.
[11] B. C. Gates, Maria Flytzani-Stephanopoulos, David A. Dixon, and Alexander Katz. Atomically dispersed supported metal catalysts: perspectives and suggestions for future research. Catalysis Science & Technology 7 (2017) 4259-4275.
[12] J. Liu, Catalysis by supported single metal atoms, Acs Catalysis 7 (2017) 34-59. doi: 10.1021/acscatal.6b01534.
[13] M. Yang, J. Liu, S. Lee, B. Zugic, J. Huang, L. F. Allard, and M. Flytzani-Stephanopoulos. "A common single-site Pt (II)–O (OH) x–species stabilized by sodium on active and “inert” supports catalyzes the water-gas shift reaction. Journal of the American Chemical Society 137 (2015) 3470-3473. doi: 10.1021/ja513292k.
[14] L. Guczi, and I. Kiricsi. Zeolite supported mono-and bimetallic systems: structure and performance as CO hydrogenation catalysts. Applied Catalysis A: General 186 (1999) 375-394.
[15] X. Li, and Enrique Iglesia. Pt/[Fe] ZSM-5 modified by Na and Cs cations: an active and selective catalyst for dehydrogenation of n-alkanes to n-alkenes. Chemical communications 5 (2008) 594-596.
[16] J. Guzman, and Bruce C. Gates. Supported molecular catalysts: metal complexes and clusters on oxides and zeolites. Dalton Transactions 17 (2003) 3303-3318.
[17] M. Moliner, and A. Corma. Advances in the synthesis of titanosilicates: from the medium pore TS-1 zeolite to highly-accessible ordered materials. Microporous and mesoporous materials 189 (2014) 31-40.
[18] A. Corma, L. T. Nemeth, M. Renz, and S. Valencia. Sn-zeolite beta as a heterogeneous chemoselective catalyst for Baeyer–Villiger oxidations. Nature 412 (2001): 423-425.
[19] A. Corma, F. X. Llabres i Xamena, C. Prestipino, M. Renz, and S. Valencia. Water resistant, catalytically active Nb and Ta isolated lewis acid sites, homogeneously distributed by direct synthesis in a beta zeolite. The Journal of Physical Chemistry C 113 (2009): 11306-11315.
[20] Y. Zhu, G. Chuah, and S. Jaenicke. Chemo-and regioselective Meerwein–Ponndorf–Verley and Oppenauer reactions catalyzed by Al-free Zr-zeolite beta. Journal of Catalysis 227 (2004):
[21] D. J. Lewis, S. V. de Vyver, and Y. Román‐Leshkov. Acid–base pairs in Lewis acidic zeolites promote direct aldol reactions by soft enolization. Angewandte Chemie 127 (2015): 9973-9976.
[22] A. Corma, S. Iborra, and A. Velty. Chemical routes for the transformation of biomass into chemicals. Chemical reviews 107(2007): 2411-2502. doi: 10.1021/cr050989d.
[23] Y. Román-Leshkov, and M. E. Davis. Activation of carbonyl-containing molecules with solid Lewis acids in aqueous media. Acs Catalysis 1 (2011): 1566-1580.doi: 10.1021/cs200411d.
[24] M. Moliner, State of the art of Lewis acid-containing zeolites: lessons from fine chemistry to new biomass transformation processes. Dalton transactions 43 (2014): 4197-4208.
[25] Y. H. Luo, J. D. Lewis, and Y. Román-Leshkov. Lewis acid zeolites for biomass conversion: Perspectives and challenges on reactivity, synthesis, and stability. Annual review of chemical and biomolecular engineering 7 (2016):
[26] G. X. Yan, A. Wang, I. E. Wachs, and J. Baltrusaitis. Critical review on the active site structure of sulfated zirconia catalysts and prospects in fuel production.Applied Catalysis A: General 572 (2019): 210-225. doi: 10.1016/j.apcata.2018.12.012.
[27] H. Li, J. Wang, D. Zhou, D. Tian, C. Shi, U. Mueller, M. Feyen et al. Structural stability and Lewis acidity of tetravalent Ti, Sn, or Zr-linked interlayer-expanded zeolite COE-4: A DFT study. Microporous and Mesoporous Materials 218 (2015): 160-166. doi: 10.1016/j.micromeso.2015.07.020.
[28] W.  Jian, W. Zhang, Y. Suo, and Y. Wang. Synthesis of Ni/H-Zr-MCM-48 and their isomerization activity of n-heptane." Journal of Porous Materials 25(2018): 1317-1324. doi: 10.1007/s10934-017-0542-7.
[29] A. S. Karakoulia, E. Heracleous, and A. A. Lappas. Mild hydroisomerization of heavy naphtha on mono-and bi-metallic Pt and Ni catalysts supported on Beta zeolite. Catalysis Today 355 (2020): 746-756.doi: 10.1016/j.cattod.2019.04.072.
[30] L. E. Kitaev, Z. M. Bukina, V. V. Yushchenko, N. S. Nesterenko, and L. N. Alekseenko. Acidic and catalytic properties of dealuminated zeolite Y treated with zirconyl nitrate solution. Petroleum Chemistry 46 (2006): 246-256.doi: 10.1134/S0965544106040049.
[31] L. Yang, Z. Song, Y. Yu, L. Zhu, and D. Xia. Bimetallic Bifunctional Pt-NiP/Hβ as a Novel and Highly Efficient Catalyst for n-Hexane Isomerization. Catalysis Surveys from Asia 24 (2020): 104-114. doi: 10.1007/s10563-020-09295-4.
[32] B. Y. S. Al-Zaidi, The effect of modification techniques on the performance of zeolite-Y catalysts in hydrocarbon cracking reactions, Ph.D. Thesis, The University of Manchester, (United Kingdom), 2011.
[33] H. Robson, Verified synthesis of zeolitic materials. Gulf Professional Publishing, 2001.
[34] S. Colin Cundy and P. A. Cox. The hydrothermal synthesis of zeolites: Precursors, intermediates and reaction mechanism. Microporous and mesoporous materials 82 (2005): 1-78. doi: 10.1016/j.micromeso.2005.02.016.
[35] W. Arthur Chester and E. G. Derouane. Zeolite characterization and catalysis.  360. New York, EUA: Springer, 2009.
[36] A. Sayari, Recent advances and new horizons in zeolite science and technology. Studies in Surface Science and Cataysis 102 (1996): 1-46.
[37] V. Meynen, P. Cool, and E. F. Vansant. Verified syntheses of mesoporous materials. Microporous and mesoporous materials 125 (2009): 170-223.
[38] H. Ma, J. Zhang, M. Wang, and S. Sun. Modification of Y‐Zeolite with Zirconium for Enhancing the Active Component Loading: Preparation and Sulfate Adsorption Performance of ZrO (OH) 2/Y‐Zeolite. ChemistrySelect 4 (2019): 7981-7990.doi: 10.1002/slct.201901519.
[39] M. J. Ramos, J. P. Gomez, F.  Dorado, P. Sánchez, and J. L. Valverde. Hydroisomerization of a refinery naphtha stream over platinum zeolite-based catalysts. Chemical Engineering Journal 126 (2007): 13-21. doi: 10.1016/j.cej.2006.08.026.
[40] Z. B. Wang, A. Kamo, T. Yoneda, T. Komatsu, and T. Yashima. Isomerization of n-heptane over Pt-loaded zeolite β catalysts. Applied Catalysis A: General 159 (1997): 119-132. doi: 10.1016/S0926-860X(97)00059-8.
[41] L. Ping, Y. A. O. Yue, X. Zhang, and W. A. N. G. Jun. Rare earth metals ion-exchanged β-zeolites as supports of platinum catalysts for hydroisomerization of n-heptane. Chinese Journal of Chemical Engineering 19 (2011): 278-284. doi: 10.1016/S1004-9541(11)60166-3.