G Model
CATTOD-9083; No. of Pages4
ARTICLE IN PRESS
3
Table 1
the differences in surface areas and micro-pore volumes of pure
ACC and fresh SILCAs. Specific surface area and micropore volume
of the spent ZnCl2/[N(3-OH-Pr)Py][NTf2]/ACC was 915 m2/g and
0.32 cm3/g, respectively. Small specific surface areas and pore vol-
umes of the spent catalyst indicated the accumulation of reaction
compounds and organic impurities on the catalyst. This was further
confirmed by extracting a catalyst with methanol and analysing the
extractant by means of GC-analysis. The extractant from the spent
catalyst revealed that small amounts of e.g. isomerisation prod-
ucts were agglomerated on the catalyst surface. Accumulation of
reaction compounds and organic impurities is presumably one of
the primary reasons for the catalyst deactivation as in the case of
hydroformylation of propene with supported ionic liquid catalysts
[17].
Specific surface areas and micropore volumes of supported ionic liquid catalysts.
Catalyst
Surface area
(m2/g)a
Micropore volume
(cm3/g)b
Pure ACC
1720
1402
1314
1452
1270
915
0.67
0.49
0.46
0.51
0.45
0.32
SnCl2/[N(3-OH-Pr)Py][NTf2]/ACC
CrCl3/[N(3-OH-Pr)Py][NTf2]/ACC
ZnCl2/[N(3-OH-Pr)Py][NTf2]/ACC
ZnCl2/[NB4MPy][BF4]/ACC
ZnCl2/[N(3-OH-Pr)Py][NTf2]/ACC (spent)
a
Calculated by Dubinin method.
Calculated by Dollimore/Heal method.
b
2.3. ˇ-Pinene oxide isomerisation
The leaching of metal species from the catalyst was studied by
means of ICP-MS analysis. SILCAs containing zinc and tin chlorides
were applied. Results from these leaching studies indicated that no
leaching of metal species occurred during the experiments. More-
over, ionic liquids were not miscible with the bulk solvents (hexane
and toluene) used.
Isomerisation of -pinene oxide was performed in a batch reac-
tor (Parr Instrument Company, total volume 600 ml, liquid volume
250 ml) under argon atmosphere. High stirring rate (700 rpm) was
applied to achieve the kinetic regime for the reaction. Approxi-
mately 0.46 g of (+)--pinene oxide (80+%, Advanced Technology &
Industrial Company Ltd.), corresponding to a pure -pinene oxide
concentration of 0.0096 M, was dissolved in 250 ml of n-hexane
(Merck, >99%) or toluene (Merck, >99%). Four pieces of active car-
bon cloth (1.2 g) containing ionic liquid and metal chloride (1:2
ratio of ionic liquid to metal chloride) were applied as a catalyst for
the isomerisation experiment. The samples taken from the reac-
tor were analysed by means of gas chromatography with a HP wax
bonded polyethylene glycol column (30.0 m × 250 m × 0.25 m).
In addition, a gas chromatograph coupled to a mass-spectrometer
(Agilent 6980N GC with Agilent 5973 MS detector) was used to con-
firm correct identification of the products. The chemicals used for
the product calibration were (1R)-(−)-myrtenol (95+%, Safc) and
(S)-(−)-perillyl alcohol (90+%, Safc).
3.2. ˇ-Pinene oxide isomerisation
Results from -pinene oxide isomerisation experiments with
different SILCAs are compared in Table 2. Four different ionic liq-
ionic liquid to myrtanal selectivity was studied over SILCAs con-
taining tin chloride (SnCl2) as a Lewis acid. [N(3-OH-Pr)Py][NTf2]
and [NB4MPy][BF4] were the most efficient ionic liquids for the
myrtanal production (Table 2, entry 1–2). It can be observed that
ionic liquids have an effect to the product distribution. The reason
for this behaviour is that ionic liquids influence to the concentra-
tions of products and intermediates on the surface of the catalyst
[14].
3. Results and discussion
cient Lewis acid catalyst when aiming at myrtanal production.
Three different Lewis acids were applied with the ionic liquid [N(3-
OH-Pr)Py][NTf2]. The zinc chloride modified SILCA resulted in 54%
molar yield of myrtanal (Table 2, entry 6).
Pr)Py][NTf2]/ACC and ZnCl2/[NB4MPy][BF4]/ACC catalysts. The
effect of temperature in the isomerisation of -pinene oxide over
ZnCl2/[N(3-OH-Pr)Py][NTf2]/ACC and ZnCl2/[NB4MPy][BF4]/ACC
3.1. Catalyst characterization
The results of nitrogen physisorption measurements of the
selected catalysts are listed in Table 1. The specific surface area
of pure ACC was found to be 1720 m2/g and the micro-pore vol-
ume 0.67 cm3/g, whereas the micropore volume of the catalyst
ZnCl2/[N(3-OH-Pr)Py][NTf2]/ACC was 0.51 cm3/g. The amount of
ACC support used for a catalyst was approximately 1.5 g whereas
the amount of ionic liquid was 150 mg. The densities of the ionic
liquids [NB4MPy][BF4] and [N(3-OH-Pr)Py][NTf2], at ambient con-
ditions, were 1.18 g/cm3 and 1.55 g/cm3, respectively [16]. Thus, it
can be estimated that 10–20 vol% of the pore volumes were filled
with an ionic liquid layer. Similar deductions can be made from
catalysts are illustrated in Figs.
3
and 4, respectively.
The reaction rates were higher at higher temperatures as
expected. The highest molar yields of myrtanal, obtained
with
the
catalysts
ZnCl2/[N(3-OH-Pr)Py][NTf2]/ACC
and
Table 2
Molar yields of products from -pinene oxide isomerisation reactions (after 4 hours). Reaction conditions were T = 70 ◦C, p(Ar) = 5 bar and Vhexane = 250 ml. IL1 = [N(3-OH-
Pr)Py][NTf2], IL2 = [NB4MPy][BF4], IL3 = [MO3A][TFA] and IL4 = [NB3MPy][OTf].
Entry
Catalyst
Conversion [%]
Myrtanal [%]
Perillyl alcohol [%]
Myrtenol [%]
Other products [%]
1
2
3
4
5
6
7
SnCl2/IL1/ACC
ZnCl2/IL1/ACC
ZnCl2/IL2/ACC
ZnCl2/IL2/ACC
ZnCl2/IL1/ACC
ZnCl2/IL2/ACC
100
100
80
38
41
38
25
28
54
50
52
68
65
16
15
10
13
25
15
12
12
18
11
8
9
11
7
15
4
4
0
6
4
38
35
21
23
32
27
34
36
8
68
100
100
100
100
100
100
8a
9b
10b
20
a
Toluene as a solvent.
b
Reaction conditions were T = 120 ◦C and p(Ar) = 5. Product yields are illustrated after total conversion.
Please cite this article in press as: E. Salminen, et al., Biomass to value added chemicals: Isomerisation of -pinene oxide over supported
Salminen, Eero
