Mendeleev Commun., 2020, 30, 355–358
ꢄ00
ꢂ0
degree of oxidation from 2.59 to 9.41. A study of the conversion
of propan-2-ol on fresh CNTcon catalyst samples showed that
acetone
acetoneꢅꢊꢇ
the process occurred entirely in the pore-diffusion region
ꢁ
ꢀ
2
0
0
0
0
–1
(
54 kJ mol ) [Figure 2(a)]. In the conversion of propan-2-ol on
spent CNTcon samples at 190°C, a transition of the process from the
–1
–1
kinetic (108 kJ mol ) to the pore-diffusion region (54 kJ mol ) was
observed [Figure 2(b)].
Hydrogen regeneration of the spent samples returns the process
2
00 220 2ꢀ0 2ꢁ0 2ꢂ0 ꢃ00
–1
to the pore-diffusion region (43 kJ mol ) [Figure 3(c)]. In the
TꢈꢉC
conversion of butan-2-ol on CNTcyl, the apparent E decreases
act
–
1
from 65 to 36 kJ mol with an increase in the degree of oxidation
from 0.64 to 1.4%. Thus, the study of kinetic parameters (degree
of conversion, selectivity, and apparent activation energy) in the
catalytic transformation of the secondary alcohols allowed us not
only to evaluate the nature and composition of surface functional
groups in CNMs but also to control changes in their composition
during oxidative and reductive treatments.
Figure 2 Temperature dependence of selectivity for acetone in propan-2-ol
conversion on unoxidized CNTcon before and after treatment with hydrogen.
and oxidized (1.4% O) CNTcyl with hydrogen has little effect on
the selectivity and conversion of propan-2-ol and butan-2-ol,
whereas the reduction treatment of unoxidized CNTcon (see
Figure 2) leads to an increase in selectivity for propene from 14
to 63% and an increase in conversion at 300°C from 33 to 86%.
In the conversion of butan-2-ol on unoxidized CNTcon treated
with hydrogen, selectivity for dehydration products grows from
4 to 91%, and the conversion at 300°C increases from 41 to
00%. Apparently, the treatment of cylindrical and conical CNTs
with hydrogen not only affects the surface groups of these
catalysts but also leads to a partial destruction of the carbon
matrix, which results in the formation of new defect centers
We are grateful to F. M. Spiridonov for performing X-ray powder
diffraction analysis, K. I. Maslakov and S. V. Dvoryak for recording
the XPS spectra of CNT samples, andA.V. Egorov for performing
the microelectrophotographic analysis of the CNT samples.
The study was supported by the Russian Science Foundation
(project no. 18-13-00217).
3
1
(Lewis acid sites) in the catalysis because the selectivity for
Online Supplementary Materials
dehydration products formed at Lewis acid sites changes
drastically with increasing conversion. Conical CNTs with their
specific carbon configuration are more susceptible to destruction
than cylindrical
Supplementary data associated with this article can be found
in the online version at doi: 10.1016/j.mencom.2020.05.032.
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(
–
357 –