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Dramatic innovation of propene epoxidation efficiency derived from a forced flow membrane reactor
Author(s) -
Kobayashi Masayoshi,
Togawa Junya,
Kanno Tohru,
Horiuchi Junichi,
Tada Kiyosi
Publication year - 2003
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.775
Subject(s) - propene , catalysis , selectivity , membrane reactor , chemistry , propylene oxide , membrane , chemical engineering , diffusion , inorganic chemistry , organic chemistry , ethylene oxide , thermodynamics , biochemistry , polymer , physics , engineering , copolymer
It is possible to develop a selective epoxidation process for propene using heterogeneous catalysis in a forced‐flow membrane reactor. The most innovative processes required two catalysts, Cs–Ag and Re–Ag, which were immobilized in the membrane pores of a micro‐porous glassy (MPG) substance, and three different reactor systems for reaction gas flows in the membrane pores. The systems included a convection‐flow reactor (CFR), a diffusion‐flow reactor (DFR), and a packed‐bed‐flow reactor (PFR). The three types were examined over temperatures ranges from 420 to 525 K, while keeping the total conversion of propene to less than 10%. The membrane reactor systems followed two common Langmuir‐type equations of reaction rates for CO 2 and propylene oxide (PO) formation under steady state operations at atmospheric pressure. The amount of the intermediate for CO 2 formation, whose structure retained the CCC bond of a propene molecule, was sensitively controlled by the types of catalysts and reactor systems used. Comparing the three immobilized catalysts, Cs–Ag, Re–Ag, and Ag 2 O, the larger the amount of intermediate formed on the catalysts the higher was the propylene oxide (PO) selectivity and thus the PO selectivity followed the order of Re–Ag > Cs–Ag > Ag 2 O. The CFR with Re–Ag/MPG clearly demonstrated hysteresis kinetics depending on the increase (C‐up) or decrease (C‐down) in the propene concentration. The PO selectivity was separately evaluated as 73–35% for the C‐up and 35–21% for the C‐down. The convection flow rate of reactants in the pores effectively contributed to an enhancement of the PO production rate from 18 to 41% of PO selectivity, for the reactant flow rate of 70–130 cm 3 min −1 at 483 K. © 2003 Society of Chemical Industry