The influence of palladium on the catalytic activity for ethanol conversion over heteropoly tungstate catalysts

  • Orsina Verdes
  • Viorel Sasca
  • Mariana Suba
  • Silvana Borcanescu
  • Alexandru PopaEmail author


The dehydration reaction was studied using pure and palladium doped Keggin type heteropoly compounds (H3PW12O40 and Cs2.5H0.5PW12O40) in the temperature range from 433 to 573 K. The structure and texture of catalysts were characterized by thermal analysis, FTIR, XRD, BET and SEM–EDS methods. Pd doped samples exhibit a deviation of Pd concentration value from the stoichiometric ones, while parent samples have concentration values similar to the stoichiometric ones. The catalytic activity of the compounds was tested by continuous flow reactor technique at different temperatures. The favorable effect of Pd doped on the catalysts for dehydration reaction to ethylene results from the examination of apparent activation energies Ea and reaction rate values. Evidence of a decreasing Ea was obtained for ethylene formation in the case of PdCs2.5PW (83.4 kJ/mol) comparatively with pure Cs2.5PW (160.7 kJ/mol). For all reaction temperatures, the reaction rates of ethylene formation are higher for palladium-doped samples than undoped ones.


Heteropoly compound Ethanol dehydration Palladium Activation energy 



These investigations were partially financed by Romanian Academy Project No. 4.3.


  1. 1.
    Okuhara T, Watanabe H, Nishimura T, Inumaru K, Misono M (2000) Microstructure of cesium hydrogen salts of 12-tungstophosphoric acid relevant to novel acid. Catal Chem Mater 12:2230–2238CrossRefGoogle Scholar
  2. 2.
    Misono M, Mizuno N, Katamura K, Kasai A, Konishi Y, Sakata K, Okuhara T, Yoneda Y (1982) Catalysis by heteropoly compounds III. The structure and properties of 12-heteropolyacids of molybdenum and tungsten (H3PMo12-xWxO40) and their salts pertinent to heterogeneous catalysis. Bull Chem Soc Jpn 55:400–406CrossRefGoogle Scholar
  3. 3.
    Narasimharao K, Brown DR, Lee AF, Newman AD, Siril PF, Tavener SJ, Wilson K (2007) Structure-activity relations in Cs-doped heteropolyacids catalyst for biodiesel production. J Catal 248:226–234CrossRefGoogle Scholar
  4. 4.
    Rafiee E, Eavani S (2016) Heterogenization of heteropoly compounds: a review of their structure and synthesis. RSC Adv 6(52):46433–46466CrossRefGoogle Scholar
  5. 5.
    Heravi MM, Sadjadi S (2009) Recent developments in use of heteropolyacids, their salts and polyoxometalates in organic synthesis. J Iran Chem Soc 6:1–54CrossRefGoogle Scholar
  6. 6.
    Zong Y, Zhao Y, Luo W, Yu XH, Wang JK, Pan Y (2010) Highly efficient synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by heteropoly acids in water. Chin Chem Lett 21:778–781CrossRefGoogle Scholar
  7. 7.
    Firouzabadi H, Jafari AA (2005) Heteropoly acids, their salts and polyoxometalates as heterogenous, efficient and eco-friendly catalysts in organic reactions: some recent advances. J Iran Chem Soc 2:85–114CrossRefGoogle Scholar
  8. 8.
    Heravi MM, Fard MV, Faghihi Z (2013) Heteropoly acids-catalyzed organic reactions in water: doubly green reactions. Green Chem Lett Rev 6:282–300CrossRefGoogle Scholar
  9. 9.
    Holclajtner-Antunović I, Uskoković-Marković S, Popa A, Jevremović A, Vasiljević BN, Milojević-Rakić B, Bajuk-Bogdanović D (2019) Ethanol dehydration over Keggin type tungstophosphoric acid and its potassium salts supported on carbon. React Kinet Mech Cat. Google Scholar
  10. 10.
    Okuhara T, Nakato T (1998) Catalysis by porous heteropoly compounds. Catal Surv Japan 2:31–44CrossRefGoogle Scholar
  11. 11.
    Sasca V, Verdeş O, Avram L, Popa A, Erdöhelyi A, Oszko A (2013) The CsxH3-xPW12O40 catalysts microstructure model. Appl Catal A 451:50–57CrossRefGoogle Scholar
  12. 12.
    Sasca V, Verdeş O, Avram L, Popa A (2013) Thermal decomposition of Pd doped 12-tungstophosphoric acid and some of its cesium salt. Rev Roum Chim 58:451–461Google Scholar
  13. 13.
    Varisli D, Dogu T, Dogu G (2007) Ethylene and diethyl-ether production by dehydration reaction of ethanol over different heteropolyacid catalysts. Chem Eng Sci 62:5349–5352CrossRefGoogle Scholar
  14. 14.
    Saito Y, Cook PN, Niiyama H, Echigoya E (1985) Dehydration of alcohols on/in heteropoly compounds. J Catal 95:49–89CrossRefGoogle Scholar
  15. 15.
    Said AEAA, El-Wahab MMA, Abdelhak MM (2017) The role of Brønsted acid site strength on the catalytic performance of phosphotungstic acid supported on nano γ-alumina catalysts for the dehydration of ethanol to diethyl ether. React Kinet Mech Cat 122(1):433–449CrossRefGoogle Scholar
  16. 16.
    Popa A, Sasca V, Verdes O, Holclajtner-Antunovic I (2015) Adsorption–desorption and catalytic properties of SBA-15 supported cesium salts of 12 molybdophosphoric acid for for the dehydration of ethanol. Reac Kinet Mech Cat 115(1):355–375CrossRefGoogle Scholar
  17. 17.
    Popa A, Sasca V (2016) The influence of surface coverage on the catalytic activity of silica-supported heteropolyacids. Reac Kinet Mech Cat 117(1):205–221CrossRefGoogle Scholar
  18. 18.
    Siddiqui MRH, Holmes S, He H, Smith W, Coker EN, Atkins MP, Kozhevnikov IV (2000) Coking and regeneration of palladium-doped H3PW12O40/SiO2 catalysts. Catal Lett 66:53–57CrossRefGoogle Scholar
  19. 19.
    Sasca V, Verdeş O, Avram L, Popa A, Barvinschi P, Mracec M (2011) Non-isothermal kinetic study of the constitutional water loss from 12-tungstophosphoric acid and some of its acidic cesium salts. Rev Roum Chim 56(5):501–516Google Scholar
  20. 20.
    Bailar JC (1939) Phosphotungstic acid. Inorg Synth 1:132–133Google Scholar
  21. 21.
    Essayem N, Holmqvist A, Gayraud PY, Vedrine JC, Taarit YB (2001) In situ FTIR studies of the protonic sites of H3PW12O40 and its acidic cesium salts MxH3-XPW12O40. J Catal 197:273–280CrossRefGoogle Scholar
  22. 22.
    Bielański A, Lubańska A (2004) FTIR investigation on Wells-Dawson and Keggin type heteropolyacids: dehydration and ethanol sorption. J Mol Catal A 224:179–187CrossRefGoogle Scholar
  23. 23.
    Brown GM, Noe-Spirlet MR, Busing WR, Levy HA (1977) Dodecatungstophosphoric acid hexahydrate, (H5O2 +)3(PW12O40 3−). The true structure of Keggin, s pentahydrate from single-crystal X-ray and neutron diffraction data. Acta Cryst B33:1038–1046CrossRefGoogle Scholar
  24. 24.
    Matachowski L, Zieba A, Zembala M, Drelinkiewicz A (2009) A comparison of catalytic properties of CsxH3-XPW12O40 salts of various cesium contents in gas phase and liquid phase reactions. Catal Lett 133:49–62CrossRefGoogle Scholar
  25. 25.
    Thommes M, Kaneko K, Neimark AV, Olivier JP, Reinoso FR, Rouquerol J, Sing KSW (2015) Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report). Pure Appl Chem 87:1051–1069CrossRefGoogle Scholar

Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2019

Authors and Affiliations

  1. 1.“Coriolan Dragulescu” Institute of Chemistry TimişoaraTimisoaraRomania

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