Chemical Engineering Journal, Vol.156, No.3, 562-570, 2010
Preparation of titanium silicalite-1 catalytic films and application as catalytic membrane reactors
Titanium silicalite-1 (TS-1) films were prepared on porous alpha-Al2O3 tubes using nanosized silicalite-1 (Sil-1) particles as seeds by hydrothermal treatment and a TS-1 catalytic membrane reactors (CMR) was reasonably designed and evaluated by phenol hydroxylation with hydrogen peroxide as oxidant. Some factors on influencing TS-1 film formation and catalytic properties were investigated and the TS-1 films were characterized by scanning electron microscope (SEM), transmission electron micrograph (TEM), X-ray diffractometer (XRD), FTIR, UV-vis and X-ray fluorescence (XRF). It was indicated that TS-1 films prepared from Sil-1 and TS-1 seeds were comparable in structure, morphology and reaction behavior. The crystallization time and times of TS-1 film had a strong effect on its morphology, thickness and orientation. However, the film thickness could be easily controlled by crystallization time and times. The Ti/Si ratio in synthesis solution intensely influenced the content of the titanium atoms incorporated as framework Ti that was correlated well with the activity. The maximum Ti (IV) incorporated corresponds to a Ti/Si ratio of approximately 0.02-0.03. A constant conversion for phenol hydroxylation was obtained with the film thickness of over 7.5 mu m. It is demonstrated that most of the reaction occurred in a shallow layer near the film due to the mass transfer effects in the TS-1 films. (C) 2009 Elsevier B.V. All rights reserved.