title: Metal-oxide-doped silica nanoparticles for the catalytic glycolysis of polyethylene terephthalate.
abstract: Polyethylene terephthalate (PET) was depolymerized to monomer bis(2-hydroxyethyl) terephthalate (BHET) using excess ethylene glycol (EG) in the presence of metal oxides that were impregnated on different forms of silica support [silica nanoparticles (SNPs) or silica microparticles (SMPs)] as glycolysis catalysts. The reactions were carried out at 300 degrees C and 1.1 MPa at an EG-to-PET molar ratio of 11:1 and a catalyst-to-PET-weight ratio of 1.0% for 40-80 min. Among the four prepared catalysts (Mn3O4/SNPs, ZnO/SNPs, Mn3O4/SMPs, and ZnO/SMPs), the Mn3O4/SNPs nanocomposite had the highest monomer yield (> 90%). This high yield may be explained by the high surface area, amorphous and porous structure, and existence of numerous active sites on the nanocomposite catalyst. The BHET yield increased with time and reached the highest level where equilibrium was established between BHET and its dimer. The catalysts were characterized by their SEM, TEM, and BET surface areas, and via XRD, whereas the monomer BHET was characterized by HPLC and FT-IR. The glycolysis with the Mn3O4/SNPs nanocomposite as the glycolysis catalyst produced a maximum BHET in a short reaction time.
authors: Department of Chemical and Biomolecular Engineering and Center for Ultramicrochemical Process Systems, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Gusong-dong, Yuseong-gu, Daejeon 305-701, Korea.
authors: Muhammad
authors: M
authors: Imran
authors: Kyoung G
authors: KG
authors: Lee
authors: Qasim
authors: Q
authors: Imtiaz
authors: Bo-Kyung
authors: BK
authors: Kim
authors: Myungwan
authors: M
authors: Han
authors: Bong Gyoo
authors: BG
authors: Cho
authors: Do Hyun
authors: DH
authors: Kim
mesh_terms: D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D019855:Ethylene Glycol / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D011093:Polyethylene Terephthalates / Q000737:chemistry*; D012822:Silicon Dioxide; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D017895:Manganese Compounds; D010087:Oxides; D011093:Polyethylene Terephthalates; C027424:manganese oxide; D012822:Silicon Dioxide; D019855:Ethylene Glycol; D015034:Zinc Oxide