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1, all of the materials have presented activity for ethyl
levulinate formation except the
HMOR zeolite.
Among the catalysts tested, Amberlyst-15 presented the highest
conversion
(54%), followed by sulfated stania (44%) and sulfated titania
(40%). When the acidity
of SO4/SnO2 was augmented from 784 to 1341 mol g-1 by
re-sulfating the material
three times, the levulinic acid conversion increased from 40% to
52%. The stability of
Amberlyst-15 and SO4/SnO2
was investigated by re-using the materials five times
and it was observed that while the former presented the same
conversion values, the
later underwent deactivation probably due to leaching.
4. Conclusions
The activity pattern for the non zeolitic materials was
Amberlyst-15 > SO4/SnO2 >
SO4/TiO2 > SO4/ZrO2 > SO4/Nb2O5 > SnO2
, a pattern that correlates quite well with
the acidity of the materials. On the other hand, the activity of
the zeolites seems to be
related to their pore size rather than to their total acidity,
meaning that on these
materials, the reactants or products must have diffusional
limitations.
Acknowledgements
This work was performed within the DIBANET Network, a project
within the European
Communitys Seventh Framework Programme (FP7/2007-2013) under
grant
agreement no: 227248-2.
[1] R. Rinaldi, F. Schth Energy Environ. Sci.2009 2, 610.[2] F.
Yang,Q. Liu, X. Bai, Y. Du Bioresour. Technol.2011
[3] A. G. Zavozin,N. E. Kravchenko, N. V. Ignat'ev, S. G.
Zlotin
102, 3424.
Tetrahedron Lett. 2010 51, 545.
Figure 1.Esterification of levulinic acid with ethanol.
Table 1: Catalysts characteristics.
Catalyst
Sg /
m2g -1
S /
%wt
Acid it y /
molNH3 g-1SO4/SnO2 130 2.54 1167
SO4/TiO2 107 2.74 892
SO4/ZrO2 110 0.92 656
SO4/Nb2O5 67 1.16 429
SnO2 40 0.03 345
Amberlyst 35 - 2360
HMOR 433 - 2414
HMCM-22 502 - 2411
HZSM-5 355 - 2181
HBEA 664 - 1867
HUSY 756 - 747
