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Document Details
Document Type
Document Title
: Article In Conference
: Influence of reducing atmosphere on nanostructure and activity of Mo-V-Te-Nb-O
catalysts for propane selective oxidation
Influence of reducing atmosphere on nanostructure and activity of Mo-V-Te-Nb-O
catalysts for propane selective oxidation
Subject
Document
Language
Abstract
: ‫ءك يم يا‬
: English
: Due to the abundance and low cost, the light
alkanes are widely used as starting materials for
the industrial production of many oxygenates
by oxidation processes. Recently discovered
Mo-V-Te-Nb-O has received a great attention
because of high activity and selectivity in the
selective oxidation to acrylic acid. And it is
well known that two phases, so-called
orthorhombic M1 and hexagonal M2 phases,
are indispensable for a highly effective catalyst.
However, there are ongoing debates about the
origin of the high catalytic performance of MoV-Te-Nb-O catalysts. For this reason, in this
study, the reductant, namely ammonium
chloride, was added to the solution containing
Mo-V-Te-Nb-O to adjust the proportion
between M1 and M2 phase. Further, catalysts
with different reductant concentrations were
characterized by XRD, XPS, XRF, H2-TPR,
SEM and BET and their catalytic behavior for
propane selective oxidation to acrylic acid were
investigated. Our findings indicate that only the
M1 phase was observed for the catalyst without
reductant; with an increase in reductant/Mo
ratio to 0.05, the M2 phase began to appear and
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especially Mo8O23 was also observed when
the ratio was further increased to 0.2,
supporting the conclusion that the existence of
the reductant is responsible for the
transformation of phase structure of the
catalysts. It was found that, with the addition of
the reductant, M1 phase would be transformed
into M2 phase during calcination by reacted
with α-TeVO4，which could be formed in the
precursor by adding NH4Cl to the solution. In
addition, results of XPS and XRF showed that
the addition of reductant has no obvious
influence on the composition of elements in the
bulk of catalysts, but the slight enrichment of
surface Nb element was observed. Especially, it
was found that the existence of reductant led to
the sharp decrease in the ratio of surface
V5+/V4+, which has been confirmed to have
an important influence on the catalytic activity
of propane oxidation. Furthermore, H2-TPR
results revealed that, upon the addition of the
reductant, consumption peaks of H2 raised
from 892K to 936K, showing the obvious
weaken on the reactivity of lattice oxygen
Finally, according to our results obtained from
the propane oxidation to acrylic acid, it can
concluded that M1 phase content has direct
relation with activity of catalysts, the more is
the M1 phase content, the more active are the
catalysts. And the ratio of V5+/V4+ on the
surface and reactivity of lattice oxygen are also
found to be important factors that can affect the
activity of catalysts.
: Tenth International Symposium on
Heterogeneous Catalysis
: From : 22/8/1429 AH - To : 26/8/1429 AH
From : 23/8/2008 AD - To : 27/8/2008 AD
: 1429 AH
2008 AD
: Article
: Sunday, February 22, 2009
Researchers
Researcher Name Researcher Name Researcher
Dr
Email
(Arabic)
(English)
Type
Grade
Zhonghua Deng
Zhonghua Deng
Researcher Doctorate
Wenling Chu
Wenling Chu
Researcher Doctorate
Weishen Yang
Weishen Yang
Researcher Doctorate
Files
File Name
18556.pdf
Type
pdf
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