Document Type : Regular Article


Catalyst Research Group, Petrochemical Research and Technology Company, National Petrochemical Company, Tehran, Iran


The impregnation of the alumina support with the PdCl2 solution was investigated in batch and semi-batch operation modes using a recycle packed-bed reactor. The UV-visible analysis was used to evaluate the kinetics of the adsorption of Pd on the alumina support. The adsorption data related to transient palladium showed that the adsorption of Pd was very rapid and completed within few minutes. Bi-metallic Pd-Ag/Al2O3 catalysts were synthesized by the sequential impregnation method. CO-chemisorption, CO-TPD and FE-SEM tests were used to characterize the synthesized bi-metallic samples. The catalytic performance of the samples was evaluated for the tail-end acetylene selective hydrogenation process in a fixed-bed reactor. Moreover, the deactivation of the catalysts was evaluated mathematically by the integral method of analysis, considering reaction kinetics as power laws in terms of nth orders in H2 and C2H2 partial pressures. It was observed that by the batch-wise addition of the Pd precursor solution, a sample, with the lowest amount of Pd dimmers that had the highest ethylene selectivity and lowest hydrogenation reaction rate, was obtained.


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  • References

    • Takht Ravanchi, M., Sahebdelfar, S. and Komeili, S., “Acetylene selective hydrogenation: A technical review on catalytic aspects”, Rev. Chem. Eng., 34, 215 (2018).
    • Komhom, S., Mekasuwandumrong, O., Praserthdam, P. and Panpranot, J., “Improvement of Pd/Al2O3 catalyst performance in selective acetylene hydrogenation using mixed phases Al2O3 support”, Catal. Commun., 10, 86 (2008).
    • Kim W. J. and Moon S. H., “Modified Pd catalysts for the selective hydrogenation of acetylene”, Catal. Today, 185, 2 (2012).
    • Panpranot, J., Aungkapipattanachai, S., Sangvanich, T., Boonyaporn, P. and Praserthdam,, “Effect of N2O pretreatment on fresh and regenerated Pd-Ag/α-Al2O3 catalysts duringselective hydrogenation of acetylene”, React. Kinet. Catal. Lett., 91, 195 (2007).
    • Gao, J., Zhu, Q., Wen, L. and Chen, J., “TiO2-modified nano-egg-shell Pd catalyst forselective hydrogenation of acetylene”, Particuology, 8, 251 (2010).
    • Pachulski, A., Schödel, R. and Claus, P., “Performance and regeneration studies of Pd-Ag/Al2O3 catalysts for the selective hydrogenation of acetylene”, Appl. Catal. A: Gen., 400,14 (2011).
    • Tyurina, L. A., Nikolaev, S. A., Gurevich, S. A., Kozhevin, V. M., Smirnov, V. V. and Zanaveskin, K. L., “Selective hydrogenation of acetylene on nanosized catalysts”, Catal. Ind., 1, 179 (2009).
    • Balint, I., Miyazaki, A. and Aika, K., “Alumina dissolution during impregnation with PdCl42- in the acid pH range”, Chem. Mater., 13, 932 (2001).
    • Takht Ravanchi, , Abedini, A., Sahebdelfar, S., Mehrazma, Sh. and Seyyed Shahabi, S., “Mathematical modeling of platinum and chlorine distributions within Pt-Sn/Al2O3 catalystprepared by impregnation”, Sci. Iran. C, 22, 981 (2015).
    • Anderson, J. R. and Pratt, K. C., Introduction to characterization and testing of catalyst, 2nd, Academic Press, Australia, (1985).
    • Takht Ravanchi, M., Sahebdelfar, S., Rahimi Fard, M., Fadaeerayeni, S. and Bigdeli P., “An experimental and modeling investigation on catalyst deactivation for Pd-Ag/α-Al2O3 for acetylene selective hydrogenation”, Chem. Eng. Tech., 39, 301 (2016).
    • Bos, A. N. R. and Westerterp, K. R., “Mechanism and kinetics of the selective hydrogenation of ethyne and ethane”, Chem. Eng. Proc. Proc. Int., 32, l (1993).
    • Ludwig, W., Savara, A., Madix, R. J., Schauermann, S. and Freund, H. -J., “Subsurface hydrogen diffusion into Pd nanoparticles: Role of low-coordinated surface sites and facilitation by carbon”, J. Phys. Chem. C, 116, 3539 (2012).
    • Borodziński, A. and Bond, G. C., “Selective hydrogenation of ethyne in ethene‐rich streams on palladium catalysts, Part 2: Steady‐state kinetics and effects of palladium particle size, carbon monoxide, and promoters”, Catal. Rev. Sci. Eng., 50, 379 (2008).
    • Ahn, Y., Lee, J. H., Kim, S. K. and Moon, S. H., “Three-stage deactivation of Pd/SiO2 and Pd-Ag/SiO2 catalysts during the selective hydrogenation of acetylene, Appl. Catal. A:Gen., 360, 38 (2009).
    • Sangkham, , Mekasuwandumrong, O., Praserthdam, P. and Panpranot, J., “Effect of Fe-modified α-Al2O3 on the properties of Pd/α-Al2O3 catalysts in selective acetylenehydrogenation”, React. Kinet. Catal. Lett., 97, 115 (2009).
    • Woo, K. J. and Sang, M. H., “Modified Pd catalysts for the selective hydrogenation of acetylene", Catal. Today, 185, 2 (2012).