8
18
R. C. Runnebaum et al.
Table 1 Products of conversion of anisole catalyzed by Pt/Al
by HY zeolite (liquid product streams)
O
2 3
and
0.7
0
0
0
0
0
0
0
.6
.5
.4
.3
.2
.1
.0
Product
Selectivity to
product in reaction
catalyzed
Selectivity to
product in reaction
catalyzed
by HY zeolite
by Pt/Al
O
2 3
Phenol
0.65
0.60
0.11
–
2
-Methylphenol
0.15
Benzene
0.044
0.033
0.024
0.0077
0.0022
0.0013
Cyclohexanone
–
2
2
4
4
,6-Dimethylphenol
-Methylanisole
-Methylphenol
-Methylanisole
0.011
0.13
0.045
0.15
0
.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18
anisole conversion
Fig. 1 Selectivity for the formation of phenol (closed circles) and 2-
methylphenol (open circles) in the conversion of anisole catalyzed by
HY zeolite at 573 K. Data for each product were fitted with a straight
line and extrapolated to zero conversion; intercepts of regression lines
significantly different from zero selectivity at zero conversion
Data were extrapolated to zero time on stream, and thus represent
approximate initial selectivities determined at a weight hourly space
velocity of 18 (g of reactant)/(g of catalyst Á h), a pressure of 140 kPa,
and a temperature of 573 K. Selectivity is defined as yield [mol
product formed/mol of organic reactant fed]/conversion [mol of
organic reactant consumed/mol of organic reactant fed]. In the
(
analyzed with 95% confidence limits) indicate primary products, in
this case phenol, and those not significantly different from zero
analyzed with 95% confidence limits) are considered non-primary, in
2 3 2
experiments with the Pt/Al O catalyst, the feed molar ratio of H to
the organic reactant was 2400
(
this case 2-methylphenol
conversions (0.14 for Pt/Al O and 0.16 for HY zeolite) are
3
reactive to be detected). The selectivity–conversion data
observed for anisole conversion catalyzed by HY zeolite
(Figs. 1, 2) indicate that phenol, 2-methylanisole, 4-meth-
ylanisole, and 2,6-dimethylphenol (data not shown) were
primary products and that 2-methylphenol and 4-methyl-
phenol (data not shown) were non-primary products.
Benzene and cyclohexanone were not observed.
2
summarized in Table 1; these data represent extrapolations
to zero time on stream and therefore initial catalyst per-
formance, prior to significant deactivation.
The most abundant products of the conversion catalyzed
by HY zeolite were phenol, methylanisoles, and methyl-
phenols; less abundant products included dimethylanisoles
and dimethylphenols. The substitution at the 2- and 4-
positions on the aromatic ring is consistent with the
kinetically determined substitution preference of aromatic
ethers and aromatic alcohols [11]. Trace products included
those with additional methyl-group substitutions on the
aromatic ring (observed with each catalyst) and hydrogen-
ation products, such as cyclohexane, which were also formed
with Pt/Al O in the presence of H .
On the basis of the data showing that methyl group
transfer (transalkylation) is the predominant class of reac-
tion and a primary reaction in the formation of phenol,
2-methylanisole, and 4-methylanisole in the conversion
catalyzed by HY zeolite, we infer the qualitative reaction
network shown in Fig. 3. For simplicity, the source of the
methyl group is not always shown in the reaction network.
The selectivity–conversion data observed for anisole
conversion catalyzed by Pt/Al O (Figs. 4, 5) in the pres-
2
3
2
The most abundant products of the reactions catalyzed
by Pt/Al O were phenol, 2-methylphenol, and benzene;
2
3
ence of H2 indicate that phenol, 2-methylphenol, and
4-methylphenol (data not shown) were primary products
and that benzene, cyclohexanone, 2- and 4-methylanisole,
and 2,6-dimethylphenol (data not shown) were non-primary
products.
2
3
less abundant products included water, methane, methanol,
-methylanisole, and 4-methylanisole. The appearance of
2
cyclohexanone, for example, indicates hydrogenation of
the aromatic ring [12].
Thus, an important class of reaction, observed for both
catalysts, is methyl group transfer. Hydrogenolysis,
hydrogenation, and hydrodeoxygenation were also
observed in the conversion catalyzed by Pt/Al O in the
Presuming that methyl group transfer, hydrodeoxygen-
ation, and hydrogenation are the important reaction classes,
and by recognizing which compounds were primary prod-
ucts, we inferred the reaction network of Fig. 6 for anisole
conversion catalyzed by Pt/Al O in the presence of H .
2
3
presence of H2.
2
3
2
Selectivity versus conversion plots (e.g., Fig. 1) were
used to identify products as primary or not [13, 14] (these
designations are empirical, falling short, for example, of
providing information about intermediates that were too
The data characterizing the conversion of anisole cata-
lyzed by Pt/Al are represented satisfactorily by first-
O
2 3
order kinetics (Fig. 7). The pseudo first-order rate constant
for the overall disappearance of anisole was found to be
1
23