576
P. Ferreira et al. / Catalysis Communications 12 (2011) 573–576
Table 2
out during 3 h. Fig. 3 compares the conversion of glycerol obtained
with PW2_AC and without catalyst. It was observed that the
heteropolyacid leaching from activated carbon to reaccional mixture
seem to be small.
Conversion and selectivity to the products of the esterification of glycerol with acetic
acid over PW_AC catalyst. Reaction conditions: molar ratio of glycerol to acetic
acid=1:16; Temperature=120 °C; catalyst loading=0.2 g.
Sample
Conversion1
(%)
Selectivity (%)
Monoacetin
4. Conclusions
Diacetin
Triacetin
Others
AC
15
55
86
75
42
20
25
24
54
65
63
63
3
14
11
12
1
1
1
1
The esterification of glycerol with acetic acid was carried out over a
series of PW immobilized on activated carbon. Catalysts with different
PW loading on activated carbon, which varied from 3.5 to 6.5 wt.%,
were prepared. It was observed that the PW2_AC (with 4.9 wt.%)
shows the highest catalytic activity. Good values of selectivity to
diacetin were obtained with all catalyst. Catalytic stability of the
PW2_AC was evaluated by performing consecutives batch runs. After
the third batch, a stabilization of the catalytic activity was observed.
PW1_AC
PW2_AC
PW3_AC
1Glycerol conversion after 3 h of reaction.
Table 3
Catalytic stability of the PW2_AC sample in acetylation of glycerol. Reaction conditions:
molar ratio of glycerol to acetic acid =1:16; Temperature=120 °C; catalyst
loading=0.2 g.
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Fig. 3. Esterification of glycerol with acetic acid over PW2_AC catalyst. Conversion (%)
versus time (h): ( ) PW2_AC (fresh); ( ) PW2_AC after catalyst removal.