IHEP OpenIR
Local structure analysis around the Nd center in a ternary catalyst comprising Nd(vers)(3), Al(Bu-i)(3) and Al(Bu-i)(2)Cl by XAFS
Guo HL(郭慧龙); Guo, HL; Wang JY(王佳怡); Bi, JF; Wang, JY; Zhang, XQ; Jiang, SC; Wu, ZH; Wu ZH(吴忠华)
2015
Source PublicationDALTON TRANSACTIONS
ISSN1477-9226
EISSN1477-9234
Volume44Issue:19Pages:9130-9139
Corresponding Author吴忠华
SubtypeArticle
AbstractLanthanide-based catalysts are highly active for isoprene polymerization in hexane. In this paper, a ternary catalyst consisting of neodymium neodecanoate {Nd(vers)(3)}, Al(Bu-i)(3) and Al(Bu-i)(2)Cl was studied by using X-ray-absorption fine-structure (XAFS) technique. A sealed and moisture-proof liquid sample cell with adjustable thickness was designed for Nd L-III-edge XAFS measurements. Based on the XAFS data analysis, detailed structure changes around the Nd center were obtained. It was found that the Nd(vers) 3 molecules formed an oligomer structure in hexane solution with two Nd-O subshells (5O @ 2.39 angstrom and 5O @ 2.54 angstrom) around the Nd center. The alkylation process by adding Al(Bu-i)(3) to the hexane solution of Nd (vers) 3 partially destroyed the aggregation degree of Nd(vers)(3) molecules in hexane solution. Al(Bu-i)(3) ligands were bonded to the Nd center by Nd-C bonding. With the Nd : Al ratio increasing from 1:2.5 to 1:10, the O neighbors around Nd decreased from 4 to 2 but with an unchanged Nd-O bond length of 2.38 angstrom, and the C neighbors around Nd were kept at ca. 4 with Nd-C bond lengths in the range of 2.57-2.58 angstrom. The Nd-O bonds can be further replaced by Nd-C bonds during the aging process. The chlorination process by adding Al(Bu-i)(2)Cl to the mixture solution of Nd(vers) 3 and Al(Bu-i)(3) restrained intensively the agglomeration of Nd(vers) 3 molecules in hexane solution. Al(Bu-i)(2)Cl ligands were bonded to the Nd center by Nd-Cl bonds. There were about 3-4 C neighbors at 2.58 angstrom, 2 Cl neighbors at 2.87 angstrom, and 2 Al next-neighbors at 3.14 around the Nd center. After allowing the ternary catalyst to stand for 5 days, the coordination numbers of Nd-C and Nd-Cl were all stabilized to 3 without bond length changes, and partial single Cl- anions were also bonded to the Nd center. All these structural details and their change tendency demonstrate that the decrease of aggregation degree of Nd(vers)(3) molecules in hexane solution can improve the catalytic activity of the ternary lanthanide-based catalyst system.
Subject AreaChemistry
DOI10.1039/c5dt01064k
Indexed BySCI ; EI
Language英语
WOS Research AreaChemistry, Inorganic & Nuclear
WOS SubjectChemistry
WOS IDWOS:000354203400044
Citation statistics
Document Type期刊论文
Identifierhttp://ir.ihep.ac.cn/handle/311005/228559
Collection中国科学院高能物理研究所
Recommended Citation
GB/T 7714
Guo HL,Guo, HL,Wang JY,et al. Local structure analysis around the Nd center in a ternary catalyst comprising Nd(vers)(3), Al(Bu-i)(3) and Al(Bu-i)(2)Cl by XAFS[J]. DALTON TRANSACTIONS,2015,44(19):9130-9139.
APA 郭慧龙.,Guo, HL.,王佳怡.,Bi, JF.,Wang, JY.,...&吴忠华.(2015).Local structure analysis around the Nd center in a ternary catalyst comprising Nd(vers)(3), Al(Bu-i)(3) and Al(Bu-i)(2)Cl by XAFS.DALTON TRANSACTIONS,44(19),9130-9139.
MLA 郭慧龙,et al."Local structure analysis around the Nd center in a ternary catalyst comprising Nd(vers)(3), Al(Bu-i)(3) and Al(Bu-i)(2)Cl by XAFS".DALTON TRANSACTIONS 44.19(2015):9130-9139.
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