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Mechanism of CaO catalyst deactivation with unconventional monitoring method for glycerol carbonate production via transesterification of glycerol with dimethyl carbonate
Author(s) -
Praikaew Wanichaya,
Kiatkittipong Worapon,
Aiouache Farid,
NajdanovicVisak Vesna,
Termtanun Mutsee,
Lim Jun Wei,
Lam Su Shiung,
Kiatkittipong Kunlanan,
Laosiripojavadol,
Boonyasuwat Sunya,
Assabumrungrat Suttichai
Publication year - 2022
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.7281
Subject(s) - transesterification , dimethyl carbonate , glycerol , chemistry , catalysis , methanol , carbonate , yield (engineering) , calcium carbonate , selectivity , inorganic chemistry , nuclear chemistry , organic chemistry , materials science , metallurgy
Summary Glycerol carbonate (GC) was synthesized by transesterification of glycerol with dimethyl carbonate (DMC) using calcium oxide (CaO) derived from eggshell as a catalyst. The best results of 96% glycerol conversion and 94% GC yield were achieved under the following reaction conditions: 0.08 mole ratio of CaO to glycerol, 1:2.5 mole ratio of glycerol to DMC, 60°C reaction temperature, and 3 hours reaction time. As expected, CaO showed deteriorated catalytic performance when recycling as observed by a rapid decrease in GC yield. This research showed that the active CaO phase first was converted to calcium methoxide (Ca[OCH 3 ] 2 ) and calcium diglyceroxide (Ca[C 3 H 7 O 3 ] 2 ) and finally to carbonate phase (CaCO 3 ) which can be confirmed by XRD patterns. According to the phase transformation, the basicity decreased from 0.482 mmol/g to 0.023 mmol/g, and basic strength altered from strong basic strength (15.0 < H_ < 18.4) to weak basic strength (7.2 < H_ < 9.8), resulting in the lower catalytic activity of the consecutive runs. Despite the fact that the GC selectivity was almost 100%, the reaction products (methanol and GC) were not obtained in their stoichiometric ratio and their extents corresponded with that of the catalyst phase transformation to CaCO 3 . The mechanism of CaO catalyzed transesterification based on the condensation reaction of glycerol and catalyst was proposed, and in situ formation of water‐derivative species was hypothesized as a cause of CaO transformation. CaO could react with DMC and water, generating methanol and CaCO 3 . This enabled unconventional monitoring of catalyst deactivation by checking if the mole ratio of methanol to GC was higher than 2:1 of its reaction stoichiometric ratio. It was also demonstrated that calcination of post‐run catalyst at 900°C to CaO exhibited almost constant catalytic activity, and the mole ratio of methanol to GC was constant at its reaction stoichiometry (2:1) for at least 4 times use.