In:
Pure and Applied Chemistry, Walter de Gruyter GmbH, Vol. 84, No. 3 ( 2011-11-23), p. 561-578
Abstract:
Direct epoxidation of propylene to propylene oxide (PO) with H 2 and O 2 has been performed on bifunctional catalysts, Au nanoparticles supported on novel Ti-MWW titanosilicate (Au/Ti-MWW). In comparison to conventional Au/TS-1 catalysts, Au/Ti-MWW exhibited a similar phenomenon with respect to PO formation, that is, the PO selectivity increased with increasing Si/Ti ratio of titanosilicate. However, at optimized Ti contents corresponding to Si/Ti ratio & gt;140, the PO selectivity of Au/Ti-MWW catalysts was lower than 60 % in comparison to ca. 90 % achieved on Au/TS-1. A large number of boron species and defect-site-related hydroxyl groups contained in Ti-MWW were assumed to retard the desorption of PO from the channels or crystallite surface of zeolite, which favors side reactions such as over-oxidation and decomposition of PO. Poststructural rearrangement was then carried out on Ti-MWW with piperidine (PI) solution to improve effectively its hydrophobicity, leading to defect-less Re-Ti-MWW. This enhanced significantly the PO selectivity of Au/Re-Ti-MWW thus prepared, which reached as high as 92 % at Si/Ti ratio of 135. Au/Re-Ti-MWW(135) then gave the highest PO formation rate of 22.0 g PO kg –1 h –1 .
Type of Medium:
Online Resource
ISSN:
1365-3075
,
0033-4545
DOI:
10.1351/PAC-CON-11-07-10
Language:
Unknown
Publisher:
Walter de Gruyter GmbH
Publication Date:
2011
detail.hit.zdb_id:
2022101-0
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