Electron spin resonance and optical spectroscopy of tubular aluminophosphate materials containing framework vanadium

Zhaohua Luan;东元 赵;Larry Kevan

University of Houston;China Association for Science and Technology

发表时间:1998-2

期 刊:Microporous and Mesoporous Materials

语 言:English

U R L: http://www.scopus.com/inward/record.url?scp=0031995993&partnerID=8YFLogxK

摘要

A series of aluminophosphate materials without (UHM-1) and with variable amounts of vanadium (VUHM-1) have been synthesized in the presence of a cationic surfactant cetyltrimethylammonium chloride and an organic base tetramethylammonium hydroxide. Powder X-ray diffraction and electron probe microanalysis show that both UHM-1 and VUHM-1 with V/A1 ratios up to 0.05 possess disordered arrays of tubular channels which mimic the hexagonal MCM-41 structure. The overall P/A1 ratio is about half of the initial unity ratio in the gel mixture, especially for VUHM-1. This indicates incomplete condensation of phosphorus oxide and a non-ideal aluminophosphate framework; this seems associated with poorer thermal stability than microporous aluminophosphate and mesoporous aluminosilicatc MCM-41. Electron spin resonance and diffuse reflectance ultraviolet-visible spectroscopies reveal that in as-synthesized VUHM-1 the vanadium exists as monoatomically dispersed square pyramidal VO2+ ions and as tetrahedral V5+ ions which are consistent with a framework location for the vanadium.

关键词

Electronic spin resonance
Mesoporous aluminophosphate
Molecular sieve
Vanadium

相关科学

化学
工程
材料力学
材料科学
物理学和天文学
凝聚态物理学

期刊度量

Scopus度量

年份 CiteScore SJR SNIP
1996
1997
1998
1999 0.591 1.06
2000 0.983 1.367
2001 1.493 1.378
2002 1.869 1.338
2003 1.607 1.511
2004 1.344 1.632
2005 1.408 1.766
2006 1.51 1.32
2007 1.392 1.235
2008 1.373 1.444
2009 1.25 1.331
2010 1.551 1.404
2011 6.6 1.524 1.464
2012 5.8 1.496 1.554
2013 5.4 1.234 1.349
2014 5.8 1.25 1.277
2015 6.6 1.184 1.167
2016 6.1 1.093 1.209
2017 6.4 1.08 1.107
2018 7 1.066 1.224
2019 7.7 0.999 1.256
2020 7.1

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