title: Glycerol upgrading over zeolites by batch-reactor liquid-phase oligomerization: heterogeneous versus homogeneous reaction.
abstract: Glycerol upgrading to diglycerols in the presence of basic (Na+ or Cs+) ion-exchanged (FAU or BEA) zeolite catalysts was studied in a liquid-phase batch rector at 260 degrees C under normal pressure. Homogeneous NaHCO3 and CsHCO3 catalysts were studied for comparison. All the catalysts, including NaHCO3 and CsHCO3, displayed the same conversion-selectivity relationship. The selectivity to linear diglycerols decreased at higher conversions/reaction times owing to the consecutive formation of higher oligomers, with preferential further conversion of alpha,alpha'-diglycerol. The maximum yield of linear diglycerols was limited to about 30 %. The activities of the zeolites followed the order X>Y>Beta, independent of the alkali ion present. Catalysis by the zeolites starts with an induction period attributed to a slow leaching of alkaline cations from the zeolite. Thereafter, the reaction is characterized by a progressive loss of the microporous structure of the zeolite and increasing overlap of heterogeneous and homogeneous catalysis, where, primarily, the activity depends on the cation content of the zeolite.
authors.affiliation: Departemen Kimia, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Indonesia, Depok 16124, Indonesia.
authors.forename: Yuni K
authors.initials: YK
authors.lastname: Krisnandi
authors.forename: Reinhard
authors.initials: R
authors.lastname: Eckelt
authors.forename: Matthias
authors.initials: M
authors.lastname: Schneider
authors.forename: Andreas
authors.initials: A
authors.lastname: Martin
authors.forename: Manfred
authors.initials: M
authors.lastname: Richter
mesh_terms: D005990:Glycerol / Q000138:chemical synthesis / Q000737:chemistry; D007474:Ion Exchange; D008855:Microscopy, Electron, Scanning; D015394:Molecular Structure; D055601:Organic Chemistry Phenomena; D044367:Phase Transition; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D016062:Porosity; D013499:Surface Properties; D017641:Zeolites / Q000737:chemistry*
chemical_list: D011108:Polymers; D017641:Zeolites; C043941:polyglycerol; D005990:Glycerol