Catalytic conversion of bioethanol and acetaldehyde to butadiene over a tantalum oxide-supported Spherical mesoporous silica catalyst in a circulating fluidized bed

Article abstract of DOI:10.1166/jnn.2017.13404

Spherical silicas with mesopore (6 nm) supported tantalum oxide samples (Ta/SMS) were prepared with the impregnation method using different Ta loading amounts for the production of 1,3-butadiene (BD) from ethanol and acetaldehyde (ethanol to BD, ETB). To obtain the optimum Ta loading amount, the Ta/SMS catalysts were first tested in a fixed-bed reactor. The characteristics of the Ta/SMS catalyst was analyzed by scanning electron microscopy, inductively coupled plasma atomic emission spectrometry, and N₂ physisorption analysis. Before testing the catalyst in a hot-bed circulating fluidized bed (CFB) reactor, the mechanical strength and hydrodynamic properties of the Ta/SMS catalyst were examined by using the attrition test and a cold-bed CFB reactor, respectively. The catalytic results in the hot-bed CFB reactor revealed that the Ta/SMS catalyst had a different catalytic performance for production BD, which could be attribution to the feed concentration and circulation rate of catalyst. The hot-bed CFB test for ETB with the Ta/SMS catalyst was stably operated for 140 h, and an average conversion of 56.7% and BD selectivity of 70.5% were obtained.

Full text of DOI:10.1166/jnn.2017.13404

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Journal of
Nanoscience and Nanotechnology
Vol. 17, 4322–4325, 2017
Copyright © 2017 American Scientific Publishers
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Catalytic Conversion of Bioethanol and Acetaldehyde to
Butadiene Over a Tantalum Oxide-Supported Spherical
Mesoporous Silica Catalyst in a Circulating Fluidized Bed
∗
Joo-Wan Kim, Tae-Wan Kim , Ho-Jeong Chae, Chul-Ung Kim, Jeong-Rang Kim, and Soon-Yong Jeong
Center for Convergent Chemical Process, Korea Research Institute of Chemical Technology,
141, Gajeong-ro, Yuseong-gu, Daejeon 305-600, South Korea
Spherical silicas with mesopore (6 nm) supported tantalum oxide samples (Ta/SMS) were prepared
with the impregnation method using different Ta loading amounts for the production of 1,3-butadiene
(
BD) from ethanol and acetaldehyde (ethanol to BD, ETB). To obtain the optimum Ta loading
amount, the Ta/SMS catalysts were first tested in a fixed-bed reactor. The characteristics of the
Ta/SMS catalyst was analyzed by scanning electron microscopy, inductively coupled plasma atomic
emission spectrometry, and N physisorption analysis. Before testing the catalyst in a hot-bed cir-
2
culating fluidized bed (CFB) reactor, the mechanical strength and hydrodynamic properties of the
Ta/SMS catalyst were examined by using the attrition test and a cold-bed CFB reactor, respectively.
The catalytic results in the hot-bed CFB reactor revealed that the Ta/SMS catalyst had a differ-
IP: 185.89.100.214 On: Thu, 05 Apr 2018 07:24:31
ent catalytic performance for production BD, which could be attribution to the feed concentration
Copyright: American Scientific Publishers
and circulation rate of catalyst. The hot-bed CFB test for ETB with the Ta/SMS catalyst was stably
Delivered by Ingenta
operated for 140 h, and an average conversion of 56.7% and BD selectivity of 70.5% were obtained.
Keywords: Butadiene, Spherical Mesoporous Silica, Circulating Fluidized Bed, Ta Oxide.
1
. INTRODUCTION
be a promising and environmentally friendly technology
for on-purpose BD-production because ethanol is the most
plentiful bio-based feed stock.
1
,3-butadiene (BD) is a base chemical, which is used in
1
ꢀ4ꢀ5
1
producing synthetic rubbers and polymers. Among these
applications, production of automotive tires is the main use
of BD, and the global market for automotive tires is pre-
dicted to consistently increase based on the expansion of
The ETB process is mainly divided into two processes:
the Lebedev’s (one-step) and Ostromyslensky’s (two-step)
1
ꢀ3ꢀ4
process.
The two-step process consists of EtOH dehy-
2
drogenation to acetaldehyde (AA), and EtOH-AA conden-
the automotive market, especially in China and India. This
sation to BD, which uses a Ta/SiO catalyst. However,
long-term increase in the BD demand rate has attracted
many researchers to the manufacturing of BD. Tire manu-
facturing companies have great interest in BD production
from bio-based feed stocks to solve issues related to the
global environment and rubber tree crops. Presently, BD is
the most difficult component to procure in the supply chain
of synthetic polymers and rubbers because BD is produce
2
ETB processes result in the rapid deactivation of catalysts
by coking. To overcome rapid coke formation, ordered
mesoporous silica supported tantalum oxide catalysts have
5
been studied in ETB reactions in fixed-bed reactors. To
solve the coking problem in the process, circulating flu-
idized beds (CFBs) can used in ETB reactions for con-
tinuous regeneration of deactivated catalysts. From our
previous report, the optimum spherical mesoporous silica
3
as a byproduct of ethylene production by steam cracking.
However, an increase in the natural gas supply from shale-
gas would lead to an increase in the production of ethylene
from ethane by ethane cracking, which would result in the
long-term decrease in BD production. Therefore, the cat-
alytic conversion of ethanol (EtOH) to BD (ETB) would
(
SMS) support for a CFB had both moderately large meso-
pores (∼6 nm) with a particle size of 75–150 ꢁm and good
6
attrition resistance. However, we only tested the catalytic
activity of Ta/SMS catalysts in a fixed-bed reactor and
examined its hydrodynamic properties in a cold-bed CFB
6
test. In this study, the optimum Ta amount in Ta/SMS was
∗
Author to whom correspondence should be addressed.
examined using a fixed-bed reactor. The optimum Ta/SMS
4322
J. Nanosci. Nanotechnol. 2017, Vol. 17, No. 6
1533-4880/2017/17/4322/004
doi:10.1166/jnn.2017.13404

Kim et al.
Catalytic Conversion of Bioethanol and Acetaldehyde to Butadiene
catalyst was used in a hot-bed CFB reactor, and ETB reac-
tions were carried out under different operational condi-
tions of the hot-bed CFB.
3. RESULTS AND DISCUSSION
In Figure 2, the SEM image of the Ta/SMS catalyst
shows a spherical morphology with a particle size around
7
5–150 ꢁm (avg. 113 ꢁm). The narrow pore size distribu-
tion curve for the Ta/SMS clearly shows that the catalyst
has relatively uniform mesopores. The structural proper-
ties such as avg. pore size, BET surface area, total pore
volume, bulk density, and attrition resistance are 5.7 nm,
2
. EXPERIMENTAL DETAILS
2
.1. Catalyst Preparation
Commercial SMS (CARiACT Q-6) was obtained from
Fuji Silysia. Ta/SMS catalysts with different Ta loading
amounts (1.8–3.5 wt%) were prepared with the impregna-
2
2
3
22 m /g, 0.58 cm /g, 0.57 g/ml, and 1%, respectively.
To investigate the effects of the loading amounts of Ta,
tion method using EtOH as a solvent and TaCl (Aldrich)
5
the catalytic activities of Ta/SMS with different Ta loading
amounts were examined in the ETB reaction in a fixed-bed
reactor. Figure 3 shows the total conversion of EtOH and
AA and the BD selectivity of the Ta/SMS with different
Ta loading amounts. All the samples exhibited a gradual
decrease in conversion and constant BD selectivity with
the time-on-stream due to coke formation. Detailed cat-
alytic activities at 20 h are presented in Table I. The total
conversion increased with increasing Ta loading amounts
up to 3.0 wt%; however, it decreased at the highest Ta
loading amount (3.5 wt%), which might be connected to
the dispersion of Ta oxide on the SMS surface.
as a Ta precursor. After EtOH removal with a rotary evap-
ꢀ
orator, the samples were dried at 120 C and calcined at
ꢀ
5
00 C.
2
.2. Catalyst Characterization
N2 isotherms were measured with
a
Tristar3000
(
Micromeritics). The Ta amount of the catalyst was
analyzed with inductively coupled plasma atomic emis-
sion spectrometry. Scanning electron microscope (SEM)
images were obtained with a Philips XL-30S FEG SEM
(
10 kV). The attrition resistance of the SMS was deter-
mined with the ASTM D5757-11 method. Hydrodynamic
properties such as the catalyst circulation rate were exam-
ined with a cold-bed CFB test.
Before the hot-bed CFB test, the hydrodynamic proper-
ties of the Ta/SMS sample were estimated in the cold-bed
CFB (Fig. 4). In Table II, the minimum fluidization veloc-
ity (U ) of Ta/SMS is faster than that of the other catalysts
mf
2
.3. Catalytic Performance Tests
The production of BD from Et OI PH : 1a n8 d5 . A8 9A .1 w0 0i t .h 2 1T 4a / QO -n6 : Thu, 05 Apr 2018 07:24:31
Copyright: American Scientific Publishers
using different amounts of Ta was performed in a fixed-bed
−1
ꢀ
5ꢀ6
Delivered by Ingenta
reactor (LHSV = 1ꢂ0 h , 350 C). The hot-bed CFB
test was done with a pilot-scale CFB plant (riser length:
4
m, riser inner diameter: 14.6 mm). A picture of the CFB
plant used in the experiments is shown in Figure 1. The
effluent gas products were measured with a gas chromato-
graph (6100GC, Young Lin Ins. Co.).
Figure 2. (a) SEM, and (b) pore size distribution of Ta/SMS.
Figure 3. EtOH/AA total conversion (open symbol) and BD selectivity
Figure 1. Hot-bed CFB pilot plant.
(solid symbol) of the Ta/SMS catalysts with different Ta loading amounts.
J. Nanosci. Nanotechnol. 17, 4322–4325, 2017
4323

Catalytic Conversion of Bioethanol and Acetaldehyde to Butadiene
Kim et al.
Table I. ETB results from Ta/SMS with different Ta loading amounts
at 20 h.
Selectivity (C mol%)
a
=
b
c
Ta (wt%)
Total conv. (%)
BD
C2
DEE
HV
1.8
2.0
2.8
3.0
3.5
31.3
34.0
36.6
37.3
35.7
74.8
74.1
73.2
75.0
74.4
3.4
4.1
6.1
4.6
6.0
5.7
6.0
8.5
6.6
7.9
16.1
15.8
12.2
13.8
11.7
Notes: aC2 , ethylene; bDEE, diethyl ether; cHV, heaviers.
=
Figure 5. Catalytic results in the hot-bed CFB with different feed con-
centrations (left), and CCRs (right).
Table II. Physical and fluidization properties of Ta/SMS and other CFB
catalysts.
Table III. ETB results for different operating conditions in a hot-bed
CFB.
Mean Apparent
Bed
particle density Umf
size (ꢁm) (kg/m ) (cm/s) (cm/s) (Pa) (Lf-Lm/Lm) (m/s)
Umb ꢃPUmb expansion
Ut
Feed
Conc.
Circulation
rate
Total
conv.
Selectivity (C mol%)
3
Catal.
(
%)
(kg/h)
(%)
BD
C2
C
C
4=
DEE
=
3=
Ta/SMS
FCC
113
53
2225
1921
1.45 1.53 1215
0.26 0.64 1006
0.66 1.01 1026
1.11 1.27 1055
0.19 0.48 991
0.15
0.15
0.14
0.12
0.17
0.53
0.18
0.47
0.86
0.18
5
1
1
26.4
50.4
45.4
57.1
53.7
46.9
42.8
63.8
64.9
55.8
62.9
66.9
64.7
26.6
22.4
25.9
17.5
15.5
17.5
3.9
4.0
3.7
3.1
3.2
3.5
0.9
2.2
4.8
3.3
1.5
1.0
4.8
0.8
8.6
9.6
9.2
7.7
90
0
0
141
10.9
SAPO-34
60
1497
26.4
28.0
30.3
because it has a relatively high particle density. Similar
tendencies were observed in the minimum bubbling veloc-
ity (U ) and pressure drop (ꢃP). Based on the fluidization
the conversion at the same feed concentration. The con-
version is relative to the residence time of the catalyst
in the riser of the hot-bed CFB. As the CCR increases,
mb
properties of Ta/SMS, to circulate Ta/SMS, the minimum
gas velocity should be larger than 0.53 m/s, and the con-
IP: 185.89.100.214 On: Thu, 05 Apr 2018 07:24:31
the residence time decreases, which subsequently lowers
tact time would be shorter than 7.5 s .C To hp ey roi gp thi mt : uA mm eE rTi cB an Scientific Publishers
catalyst, 3.0 wt% Ta/SMS, was loaded into theD he ol it v- be er de d by Ingenta
the conversion. From these results, the optimum operating
condition for the ETB reaction with the highest BD selec-
tivity in a CFB is a feed concentration of 10% and a CCR
of 28.0 kg/h.
Finally, to verify the availability of the Ta/SMS cat-
alyst in the ETB reaction using a hot-bed CFB reactor,
a longevity test was done using the optimum operating
conditions for 160 h (Fig. 6). After an initial reaction sta-
bilization time (<20 h), the conversion and BD selectivity
only showed slightly fluctuations, and the CFB reactor sta-
bly operated for 20–160 h without catalyst deactivation.
CFB. To evaluate the reaction conditions, we performed
a hot-bed CFB test with different feed concentrations and
catalyst circulation rates (CCRs) for the Ta/SMS catalyst
ꢀ
at 350 C. In Figure 5, the conversion decreased with an
increase in the feed concentration and C olefin (BD, C )
4
4=
selectivity slightly increased (Table III). A lower feed con-
centration indicates a lower weight hourly space velocity
(
WHSV), which would increase the conversion. In addi-
tion, a high feed concentration may facilitate the formation
of C olefins due to the increased possibility of EtOH-AA
4
condensation. An increase in the CCR led to a decrease in
1
00
8
6
4
2
0
0
0
0
0
BD Selec.
Total Conv.
0
20
40
60
80
100 120 140 160
Time-on-stream (h)
Figure 4. Pressure drop of Ta/SMS with superficial gas velocity (U ).
Figure 6. ETB hot-bed CFB results with the Ta/SMS catalyst for 160 h.
J. Nanosci. Nanotechnol. 17, 4322–4325, 2017
o
4324

Kim et al.
Catalytic Conversion of Bioethanol and Acetaldehyde to Butadiene
The avg. conversion and BD selectivity were 56.7% and
Acknowledgments: This work was supported by fund-
ing from the R&D Convergence Program of MSIP (Min-
istry of Science, ICT and Future Planning) and NST
(National Research Council of Science and Technology)
of the Republic of Korea (CRC-14-1-KRICT), and the
R&D Convergence Program of MSIP and ISTK (Korea
Research Council for Industrial Science and Technology)
of the Republic of Korea (CMP-3-6-KIER).
7
0.5%, respectively. After the longevity test, the spent and
regenerated Ta/SMS catalysts were obtained from the CFB
reactor. The morphology and particle size of the catalyst
from the reactor was the same as those from fresh cat-
alyst in the SEM analysis (data not shown). In addition,
TGA analysis of the spent catalyst showed 0% coke. These
results indicate that Ta/SMS regenerated well without par-
ticle breakdown during CFB operations.
References and Notes
4
. CONCLUSION
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fixed-bed reactor, and the 3.0 wt% Ta/SMS catalyst had the
highest catalytic activity for the ETB reaction. This opti-
mum catalyst was loaded into a hot-bed CFB reactor and
examined under different operating conditions. The opti-
mum operating conditions were a feed of 10% and a CCR
of 28.0 kg/h. Stable performance for the ETB reaction was
achieved in the hot-bed CFB test using the optimum oper-
ating conditions. We observed an average conversion of
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6.7% and BD selectivity of 70.5% for 140 h.
Received: 30 December 2015. Accepted: 2 May 2016.
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Copyright: American Scientific Publishers
Delivered by Ingenta
J. Nanosci. Nanotechnol. 17, 4322–4325, 2017
4325