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Enhanced recovery and recycling of catalyst by post‐impregnation of γ‐Al 2 O 3 with 12‐tungstophosphoric acid for esterification reaction
Author(s) -
Nazari Pegah,
Setayesh Shahrbanoo Rahman
Publication year - 2018
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23052
Subject(s) - catalysis , keggin structure , polyoxometalate , activation energy , leaching (pedology) , reaction rate constant , chemistry , kinetics , nuclear chemistry , fourier transform infrared spectroscopy , inorganic chemistry , reaction rate , chemical kinetics , materials science , chemical engineering , organic chemistry , physics , environmental science , quantum mechanics , soil science , engineering , soil water
12‐tungstophosphoric acid, polyoxometalate with Keggin structure, and γ‐Al 2 O 3 were synthesized. Loading of 12‐tungstophosphoric acid (HPW) on γ‐Al 2 O 3 was performed by the post‐impregnation method. The catalysts were characterized by XRD, SEM, FTIR, BET, and DRS techniques. According to the pertinent observation, using the post‐impregnation method promises the stability of polyoxometalate Keggin structure after loading on γ‐Al 2 O 3 support. The stability of 20 %HPW/Al 2 O 3 was also confirmed by a leaching test. Textural characterization demonstrates that HPW on the γ‐Al 2 O 3 had a much larger surface area as compared with the pure HPW. The 20 %HPW/Al 2 O 3 exhibited roughly high activity toward an esterification reaction. The influence of various reaction parameters (% loading HPW on support, reaction temperature, reaction time, catalyst weight, and acid/alcohol molar ratio) on the catalytic performance was studied. The efficiency of catalytic activity for six cycles remains approximately constant, which confirms the enhanced recovery and recycling of the catalyst. The kinetics of the esterification reaction and the kinetic parameters such as rate constants and activation energy were determined (25.37 kJ/mol).