Supporting Information
Effects of cesium ions and cesium oxide in sidechain alkylation of toluene with methanol over
cesium modified zeolite X
He Han a, Min Liu a, Fanshu Ding a, Yiren Wang a, Xinwen Guo *a, Chunshan Song **a,b
a
State Key Laboratory of Fine Chemicals, PSU-DUT Joint Centre for Energy Research, School
of Chemical Engineering, Dalian University of Technology, Dalian, P. R. China
b
Department of Energy and Mineral Engineering, EMS Energy Institute, PSU-DUT Joint Centre
for Energy Research, Pennsylvania State University, University Park, 16802
Corresponding Author
*
E-mail address: [email protected].
**
E-mail address: [email protected].
S1
1. SEM
Fig. S1 shows the SEM images of different samples. The parent NaX had a morphology of
octahedron with smooth surface and distinct margin, approximately 2 µm of the particle size
(Fig. S1 A). Zeolite NaX ion-exchanged with different cesium precursors seemed to have similar
morphologies, however, apparent changes were observed compared with the parent (Fig.S1 B, C
and D). For all of the ion-exchanged samples, the morphologies of octahedron were destroyed
and the surfaces of the particles were etched severely. Zeolite NaX impregnated with cesium
hydroxide aqueous solution exhibited different features with parent or ion-exchanged samples
(Fig.S1 E). Many grooves and voids appeared on the particle surface of CsX-Him. Since the
SEM images of CsX-Hex and CsX-Him were totally different, this fact indicated that the
processes of ion-exchange and impregnation made apparent different effects on the NaX.
S2
Figure S1. SEM images of NaX and cesium modified zeolite X: (A) NaX, (B) CsX-Hex, (C)
CsX-Nex, (D) CsX-Cex, (E) CsX-Him.
2. Ar physical absorption/desorption
Fig. S2 shows the Ar adsorption-desorption isotherms at 87K and pore size distributions of
different samples. Table S1 lists the pore structure properties of NaX and cesium modified
zeolite X. It can be seen that the Ar adsorption-desorption isotherms of all the samples showed
similar type
isotherm proved that the porosity of all the samples were mainly composed of
micropores. In addition, the dominant pore sizes and micropore volumes decreased dramatically
by cesium modification of NaX. Among cesium modified samples, CsX-Him exhibited the
lowest micropore volume.
S3
10
NaX
dV / dD / (cm .g )
-1
600
CsX-Hex
8
3
3
-1
Adsorbed Volume / (cm .g )
800
CsX-Nex
400
CsX-Cex
CsX-Him
200
NaX
6
4
CsX-Hex
CsX-Nex
CsX-Cex
CsX-Him
2
0
0
0.0
0.2
0.4
0.6
0.8
1.0
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
Relative Pressure / (P/P0)
Pore size / nm
Figure S2. Ar adsorption-desorption isotherms at 87K and pore size distributions of different
samples.
Table S1. Pore structure properties of NaX and cesium modified zeolite X.
Catalyst
Smicro
Sexternal
SBET
Vmicrob
V intercrystal
Vtotal
NaX
673
56
729
0.33
0.09
0.42
CsX-Hex
522
42
564
0.27
0.07
0.34
CsX-Nex
516
38
554
0.27
0.06
0.33
CsX-Cex
513
34
547
0.26
0.06
0.32
CsX-Him
320
44
364
0.17
0.08
0.25
a
Sexternal = SBET - Smicro
b
Micropore volume was calculated by NLDFT method.
3. EDS
Fig. S3 shows the mapping distribution of element Al, Na and Cs of CsX-Hex and CsX-Him
obtained from EDS analysis. The EDS mapping clearly revealed that cesium were distributed
uniformly on the surface of both samples. Besides that, the EDS results showed that the molar
ratios of Cs/Al of these two samples were both 0.29 while the molar ratios of Na/Al were 0.58
for CsX-Hex and 0.74 for CsX-Him, respectively. This also indicated that the cesium amounts of
S4
these two samples were similar, however, the sodium amount of CsX-Hex was less than that of
CsX-Him due to partial ion-exchange by cesium ions which was consistent with the trends of
XRF.
Figure S3. SEM images and EDS mapping distribution of Al, Na and Cs of CsX-Hex and
CsX-Him.
4. Carbon mass balance
The average carbon mass balances of side-chain alkylation of toluene with methanol over
different catalysts are exhibited in Table S2. Since the liquid product and gas product were
analyzed off line in our experiments, it was difficult to provide enough accurate carbon mass
balances data over different catalysts. However, calculated carbon mass balances over different
catalysts were provided for reference through considering the equation S1. The distribution of
different components listed in Table S2 was consisted with Table 2. To be noted, the selectivity
of styrene and total selectivity of styrene and ethylbenzene calculated from Table S2 was higher
than that of Table 2 because methanol in liquid product was considered to calculate the mole
ratio of aromatics in Table S2.
S5
=
S1
Table S2. Carbon mass balances of side-chain alkylation of toluene with methanol over different
catalysts.
Gaseous
product
Liquid product
CO
-
CH4
Feed
a
Carbon mass balances over different catalysts (mol%)b
NaX
CsX-Hex
CsX-Nex
CsX-Him
CsX-Him
0
0.53
3.52
2.78
3.16
15.61
-
0
4.63
0.22
0.43
0.31
0.19
CO2
-
0
0.35
0.04
0.08
0.05
0.11
C2-C4
-
0
1.12
0.02
0.04
0.12
0.08
CH3OH
-
0
7.29
13.84
14.78
12.68
9.21
DME
-
0
5.86
2.32
2.59
2.35
0.65
Aromatic c
-
0
2.17
1.90
1.70
2.07
1.25
-
C6- (CH3OH) d
33.33
6.33
11.09
10.38
12.51
5.00
-
Benzene
0
0.20
0.01
0.16
0.01
0.00
-
Toluene
66.67
68.17
65.97
66.23
66.01
64.96
-
Ethylbenzene
0
0.03
0.33
0.23
0.15
2.64
-
Xylene
0
2.62
0.12
0.20
0.18
0.02
-
Ethyltoluene
0
0.00
0.02
0.04
0.02
0.05
-
Styrene
0
0.00
0.59
0.35
0.37
0.22
-
Trimethylbenzene
0
0.22
0.00
0.00
0.00
0.00
-
C9+
0
0.48
0.01
0.01
0.01
0.01
n gaseous product
-
21.95
21.86
22.40
20.74
27.10
n liquid product
-
78.05
78.14
77.60
79.26
72.90
total
100
100
100
100
100
100
Reaction condition: T = 698 K, WHSV = 2 h-1, n (toluene) / n (methanol) = 2.
a
Feed represents mixture of toluene and methanol (n (toluene) / n (methanol) = 2).
S6
b
The average carbon mass balances over cesium modified catalysts were calculated for 50 h
while data for NaX was calculated for 25 h.
c
Aromatic in gaseous product was mainly composed of toluene.
d
C6- in liquid product was mainly composed of CH3OH.
S7