Carbonylation of dimethyl ether over Co-HMOR

Article abstract of DOI:10.1039/c8cy00407b

Incorporation of Co²⁺ into the framework of HMOR significantly enhanced the activity for the carbonylation of dimethyl ether to methyl acetate. About 68% of the Co²⁺ cations are located at site A in the 8-membered ring (8-MR) pores, while 32% of the metal cations are incorporated at site E of the 12-MR pores. Although the amount of the Br?nsted acid sites in the 8-MR pores that are intrinsically active for DME carbonylation decreased considerably upon Co-doping, the conversion of DME increased remarkably, almost doubled. The promotional role of Co²⁺ in the 8-MR channels was to facilitate the adsorption/activation of both CO and DME molecules. Meanwhile, the Co²⁺ cations located in the 12-MR channels effectively suppressed coke deposition and thus improved the stability of the Co-HMOR catalyst.

Full text of DOI:10.1039/c8cy00407b

View Article Online
View Journal
Catalysis
Science &
Technology
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: M. Ma, E. Zhan, X.
Huang, N. Ta, Z. Xiong, L. Bai and W. Shen, Catal. Sci. Technol., 2018, DOI: 10.1039/C8CY00407B.
This is an Accepted Manuscript, which has been through the
Volume 6 Number 1 7 January 2016 Pages 1–308
Royal Society of Chemistry peer review process and has been
accepted for publication.
Catalysis
Science &
Technology
Accepted Manuscripts are published online shortly after
www.rsc.org/catalysis
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
ISSN 2044-4753
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
PAPER
Qingzhu Zhang et al.
Catalytic mechanism of C–F bond cleavage: insights from QM/MM
analysis of fluoroacetate dehalogenase
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
rsc.li/catalysis

Please do not adjust margins
Catalysis Science & Technology
Page 1 of 8
View Article Online
DOI: 10.1039/C8CY00407B
Journal Name
ARTICLE
Carbonylation of dimethyl ether over Co-HMOR
Meng Ma,a,b Ensheng Zhan,a* Xiumin Huang,a Na Ta,a Zhiping Xiong,a,b Luyi Baia and Wenjie Shena*
haoReceived 00th January 20xx,
Accepted 00th January 20xx
Incorporation of Co2+ into the framework of HMOR significantly enhanced the activity for carbonylation of dimethyl ether
to methyl acetate. About 68% of the Co2+ located at site A in the 8-member ring (8-MR) pores, while 32% of the metal
cations incorporated at site E of the 12-MR pores. Although the amount of the Brønsted acid site in the 8-MR pores that
are intrinscially active for DME carbonylation decreased considerably upon Co-doping, the conversion of DME increased
remarkably, almost doubled. The promotional role of Co2+ in the 8-MR channels was ascribed to facilitate the adsorption
/activation of both CO and DME molecules. Meachwhile, the Co2+ located in the 12-MR channels effectively suppressed
coke deposition and thus improved the stability of the Co-HMOR catalyst.
DOI: 10.1039/x0xx00000x
www.rsc.org/
the strong ability of the metal site, located near the acid site
that the methyl group is adsorbed, to effectively adsorb and
activate CO. Combination of mordenites with transition metals
Introduction
Carbonylation of dimethyl ether (DME) to methyl acetate (MA)
over zeolites has been viewed as a new reaction in syngas
chemistry, as the formation of C-C bond could be achieved
inside the micropores of zeolites.1-6 This avoids the use of
expensive noble metals (rhodium or iridium) and toxic methyl
iodide promoter, which are industrially adapted in the large-
scale methanol carbonylation to acetic acid.7 Moreover, the
product, MA, could be easily hydrogenated into ethanol which
acts as a potential fuel alternative or additive. Mechanistic
studies on DME carbonylation over zeolites have identified
that the reaction initiated with the dissociative adsorption of
DME molecule on the Brønsted acid sites in the micropores,
forming CH3* species, followed by CO insertion to produce the
acetyl group (CH3CO*) that subsequently reacted with another
DME molecule to generate MA.8-10 Zeolites with 8-MR pores,
typically mordenite (MOR), were reported to be highly active
and selective for this reaction, presumably because the 8-MR
pores, with a size of 0.26 × 0.57 nm, could effectively confine
the transition state during CO insertion. A proportional
relationship between DME carbonylation rate and the number
of the Brønsted acid sites inside the 8-MR channels of MOR
was proposed.2,3,11 Theoretical calculations further suggested
that the T3-O33 position in the 8-MR channels of mordenite
favors the unusual orientation of the adsorbed methyl group,
which facilitates the insertion of CO.4
was extensively investigated for DME carbonylation in recent
years.12-19 Cu was proposed as the most promising promotor; it
not only enhanced the activity for DME carbonylation but also
improved the stability of the catalysts by suppressing coke
deposition during reaction.12,13,15 Further addition of Zn to the
Cu-HMOR systems prevented the sintering of copper and
inhibited the formation of coke.19 Spectroscopic study on Cu-
HMOR proposed that Cu+ not only activated CO but also
promoted the adsorption of DME, and the reaction process
involved a multi-site active center consisting of a bridged
hydroxy and a neighboring Cu+.12 However, examination of DME
carbonylation over a series of Cu/HMOR catalysts showed a
negative correlation with the amount of Cu+ but a positive
correlation with the content of Cu0, which implies that Cu0,
rather than Cu+, was responsible for the promotional effect.18
It seems that the incorporation of copper into mordenites
could promote the catalytic efficiency for DME carbonylation,
but the chemical mechanism remains inconclusive.
Cobalt was also experimentally observed to enhance the
catalytic activity of mordenite for DME carbonylation.13 It is
gnerally acknowledged that the acidic sites in the 8-MR pore of
mordenite is responsible for CO insertion, and the exchanged
metal site adjacent to this acidic site facilitates this rate-
determing step, but information of the detailed distribution of
the exchanged metal sites over mordenite framework and the
promotional role of cobalt species is scare. In this work, we
studied the catalytic roles of Co species on a plate-shaped
mordenite for DME carbonylation, and interestingly found that
the Co cations, located at the 8-MR channels, facilitated the
adsorption of both CO and DME molecules and thus promoted
the activity, while the Co cations that incorporated into the 12-
MR channels reduced the amount of Brønsted acid sites and
therefore suppressed the formation of coke.
Metal-doping of the acid sites over mordenites was found
to enhance CO insertion to the adsorbed methyl group,12,13 as
a rate-determining step of DME carbonylation.8 This relies on
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 2 of 8
View Article Online
DOI: 10.1039/C8CY00407B
ARTICLE
Journal Name
pyridine was conducted at 573 K for 10 min, and the sample
was evacuated for 60 min to eliminate the physically adsorbed
pyridine before recording the spectrum. The relative numbers
of protons in the 8-MR and 12-MR channels were determined
by band deconvolution of the IR spectra in the O-H region
(~3590 cm-1 for the 8-MR and ~3610 cm-1 for the 12-MR), using
the Pearson VII model.3,18,23 The concentrations of the
Brønsted and Lewis acid sites in the 12-MR channels were
calculated from the integrated absorbance of the Brønsted
(~1540 cm-1) and Lewis (~1450 cm-1) bands in the IR spectra of
pyridine adsorption.17,18,24 In situ IR spectra of DME adsorption
/carbonylation on the Co-HMOR cataltst were also recorded; a
5 vol.% DME/He mixture was used for DME adsorption at 473
K, while a mixture of 5 vol.% DME/76 vol.% CO/19 vol.% H2
was adaped for DME carbonylation at 523 K and atomspheric
pressure.
Experimental Section
Catalyst preparation
The Na-MOR (nanosheets) was synthesized by a hydrothermal
method, as we previously described.20 The NH4-MOR sample
was obtained by three sequential ion exchanges of the Na-
MOR precursor with a 1.0 mol/L NH4NO3 solution at 353 K for
12 h. The HMOR was obtained by calcination of the NH4-MOR
sample at 773 K for 6 h in air. The Co-exchanged HMOR (Co-
HMOR) catalyst was prepared by an ion exchange method. 2.0
g NH4-MOR sample was dispersed into 20 mL aqueous solution
containing cobalt salt (Co(NO3)2∙6H2O, 0.02 mol/L); the mixture
was then refluxed at 353 K for 2 h under stirring. The solid was
collected by filtration, dried at 383 K for 12 h and finally
calcined at 773 K for 6 h in air.
Characterization
Temperature-programmed desorption of CO (CO-TPD) was
performed on a Micromeritics Autochem II 2920 instrument.
100 mg sample was pretreated at 773 K for 60 min under Ar
flow (30 mL/min). After cooling down to 273 K, the sample was
exposed to CO (30 mL/min) for 60 min and then flushed with
Ar for 30 min to remove the physically adsorbed CO.
Desorption of CO was monitored by heating the sample to 723
K at a rate of 10 K/min under He flow (30 mL/min).
Powder X-ray diffraction (XRD) patterns were recorded on a
D/MAX 2500/PC diffractometer (Rigaku, Japan) using a Cu Kα
(λ = 0.154 nm) radiation source operated at 40 kV and 200 mA.
Field-emission scanning electron microscopy (FESEM)
images were taken on a Philips FEI Quanta 200F microscope
operated at 20 kV. High-resolution transmission election
microscopy (HRTEM) analysis was performed on a G2 F30S-
Twin microscope operating at 300 kV.
X-ray photoelectron spectroscopy (XPS) spectrum was
acquired with a Thermofisher ESCALAB 250Xi spectrometer
with Al Kα radiation (1486.6 eV). The sample was pressed into
a thin disc and mounted on a sample rod placed in the analysis
chamber, where the spectrum of Co2p was recorded. The
charging effect was corrected by adjusting the binding energy
(BE) of C1s to 284.6 eV.
Elemental analysis was performed using inductively
coupled plasma atomic emission spectroscopy (ICP-AES) on a
Plasma-Spec-II spectrometer. The content of cobalt in the Co-
HMOR catalyst was 0.98 wt.% while the Si/Al ratio of the
HMOR was 13.5.
Nitrogen adsorption-desorption isotherms were recorded
at 77 K using Micromeritics ASAP 2020 instrument. Before the
measurement, the sample was degassed at 573 K for 5 h. The
total surface area was calculated by the BET (Brunauer-
Emmet-Teller) equation using the adsorption isotherm at P/P0
between 0.005 and 0.05, and the total pore volume was
estimated from the adsorption isotherm at P/P0 = 0.99. The
micropore surface area and micropore volume were calculated
by the t-plot method.
Thermal gravimetric (TG) analysis of the spent catalysts
was done on a Diamond TG/DTA6300 (PerkinElmer). The
sample was heated from room temperature to 1073 K at a rate
of 10 K/min under air atmosphere.
Catalytic reaction
DME carbonylation was carried out on a continuous flow fixed-
bed reactor (internal diameter 8 mm). 200 mg catalyst (40-60
mesh) was loaded into the reactor and pretreated with N2 (30
mL/min) at 773 K for 1 h. After cooling down to 473 K, a
mixture of 5 vol.% DME/76 vol.% CO/19 vol.% H2 (8.33 mL/min)
was introduced through a mass-flow controller and the reactor
was pressurized to 1.0 MPa. The effluent was analyzed online
by a gas chromatograph (Agilent 7890A) equipped with a 100%
dimethylpolysiloxane column (HP-PONA, 50 m×0.20 mm×0.50
μm) that connected to a flame-ionization detector.
UV-Vis absorption spectra were recorded on a Lambda 750
(Perkin-Elmer) spectrophotometer with a diffuse reflectance
attachment with a 60 mm integrating sphere in the wave-
length range of 200-800 nm. The absorption spectra were
transformed from the diffuse reflectance spectra (DRS) by
using the Schuster-Kubelka-Munk theory. The distributions of
α-type Co2+ at site E (12-MR), β-type Co2+ at site A (8-MR) and
γ-type Co2+ at site C were estimated by integrating their
intensities of the corresponding bands, according to a well-
established precedure.21,22
Results and Discussion
Fourier transform infrared (FTIR) spectra were recorded on
a Bruker Tensor 27 spectrometer with a resolution of 4 cm-1.
The sample was pressed into a self-supporting wafer (R = 0.65
cm, about 15 mg) and loaded into an in situ IR cell. Before the
measurement, the sample was evacuated to 2 × 10−2 Pa at 673
K for 60 min to remove the physically adsorbed water. After
cooling down to room temperature, the spectrum in the
region of O-H groups was recorded. Then, the adsorption of
Textural Properties
Fig. 1a shows the XRD patterns of the parent HMOR and the
Co-HMOR. Both samples showed characteristic diffraction lines
of mordenite; and the absence of Co-related crystalline phase
indicated the well dispersion of Co species in the Co-HMOR
sample. Fig. 1b displays the nitrogen adsorption-desorption
isotherms of the two samples. They exhibited type I isotherms
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 3 of 8
View Article Online
DOI: 10.1039/C8CY00407B
Journal Name
ARTICLE
Fig. 1 XRD patterns (a) and nitrogen adsorption-desorption isotherms (b) of
the Co-HMOR and HMOR samples.
that are typical for microporous materials,25 and had quite
similar BET surface areas, micropore areas and pore volumes
(Table 1). This suggests that the incorporation of Co species
into the micropores of the HMOR did not disturb the zeolitic
structure.
Fig. 2 shows the SEM/HRTEM images of the samples. The
parent HMOR had a sheet-like morphology with a thickness of
20-40 nm and a width of about 1-3 μm;20 while this sheet-
morphology was fully inherited by the Co-HMOR sample,
clearly indicating that the incorporation of Co species into the
HMOR had negligible influence on the crystalline structure of
the HMOR. HRTEM images further confirmed that there were
no cobalt particles or clusters on the Co-HMOR, assuring the
well dispersion of Co species in the Co-HMOR sample.
Fig. 2 SEM/HRTEM images of the HMOR (a-b) and the Co-HMOR (c-f)
samples.
Distribution of Co Species and Acidic Properties
unfavored at site B and D.30 In our case (Co/Al = 0.14),
deconvolution of the spectrum of the Co-HMOR sample
identified that there were two type of Co species: β-type Co
cations located at site A, with bands at 16100, 17300, 19200,
and 21100 cm−1, and α-type Co cations located at site E with a
single band at 14,700 cm−1.21,22 On the basis of the absorption
coefficients for different types of Co cations,21 the relative
proportions of Co2+ cations located at site A and site E were
estimated to be 68% and 32%, respectively. In other words,
about 68% of the exchanged Co cations located in the 8-MR
side pocket. The preferential location of Co2+ in site A was
attributed to the migration of Co cation from 12-MR channel
to the side pocket upon thermal treatment.21
Fig. 3a shows the UV-Vis spectra of the Co-HMOR and HMOR
samples. Both samples displayed characteristic absorption
bands of the zeolite framework in the UV region (25000-50000
cm-1).21 In addition, the spectrum of the Co-HMOR sample
contained two distinct bands at 20080 and 16500 cm-1, which
are generally attributed to the electronic transitions (d→d*) of
Co2+ cation.21,22,26-28 According to the structural models of
mordenite framework,21,29,30 there present five possible
positions that could be exchanged by metal cations. Over a
HMOR with a Si/Al ratio of 8.5, spectroscopic study found that
Co2+ only located at site A (in a twisted 8-MR side pocket,
coordinated to six framework oxygens) at low Co loadings
(Co/Al < 0.1); while it also located at site E (in the 12-MR
channel, coordinated to four framework oxygens) at higher Co
loading, and very small amount of Co2+ located at site C as
further increasing Co loading (Co/Al > 0.25); the sites B and D
in the 8-MR channels were supposed to be too large for the
coordination of Co2+.21 Mg2+ was also found to be energetically
FTIR of pyridine absorption on the samples was adapted to
probe the acid sites. As the kinetic diameter of pyridine (0.585
nm) is larger than the size of 8-MR channels (0.28 × 0.57 nm),
it selectively adsorbs on the acidic sites located in the 12-MR
channels (0.67 × 0.70 nm). Fig. 4 shows the FTIR spectra of the
Co-HMOR and HMOR samples after adsorption of pyridine in
the “ring” vibrations of pyridine and other bands in the range
of 1400-1600 cm-1. For the parent HMOR, the two bands at
1454 and 1542 cm-1 are ascribed to the C-H deformation
vibrations of the pyridine complex bonded to the Lewis acid
sites (py:L) and the ring deformation vibrations of pyridinium
ions (pyH+) on the Brønsted acid sites, respectively.31-34 The
band at 1488 cm-1 is usually assigned to the vibrations of
pyridine species interacting with both the Brønsted and Lewis
acidic sites.17,32,35 The band corresponding to the Lewis acid
Table 1 Textural properties of the Co-HMOR and HMOR samples.
Sample
HMOR
SBETa (m2 g-1) Smicrob (m2 g-1) Vtotc (cm3 g-1) Vmicrod (cm3 g-1)
387
385
363
354
0.22
0.21
0.14
0.14
Co-HMOR
a Calculated at P/P0 0.005-0.05; b Estimated using the t-plot method;
=
c Evaluated at P/P0 = 0.99; d Calculated using the t-plot method.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 4 of 8
View Article Online
DOI: 10.1039/C8CY00407B
ARTICLE
Journal Name
Fig. 3 (a) UV-Vis spectra of the Co-HMOR and HMOR samples; (b) deconvolution of the spectrum of the Co-HMOR using Gaussian function fitting;
(c) possible positions that could be exchanged by metal cations in HMOR.21
sites slightly shifted to 1449 cm-1 on the Co-HMOR sample, due the 12-MR channels of HMOR were 0.398 and 0.154 mmol∙g-1,
to the new Lewis sites generated from Co cations.18 The respectively; they decreased to 0.276 and 0.096 mmol∙g-1 in
amounts of the Brønsted and Lewis acid sites in the 12-MR the Co-HMOR sample. This suggests that Co cation replaced
channels of the two samples, as shown in Table 2, were the Brønsted acid sites simultaneously within the 8-MR and
estimated from the integrated absorbance of the bands at 12-MR channels upon ion-exchange.
~1540 and ~1450 cm-1, respectively.17,18,24 For the parent
HMOR, the amounts of Brønsted (B12-MR) and Lewis (L12-MR
XPS analyses on the Co-HMOR sample identified the
chemical state of Co species. The binding energies at 782.7 and
)
acid sites in the 12-MR channels were 0.154 and 0.016 mmol∙g- 799.0 eV, accompanied by an intense 3d→4s shake-up satellite
1, respectively. On the Co-HMOR sample, the amounts of B12-MR peak at 787.7 eV, were characteristic for Co2+ incorporated
and L12-MR were 0.096 and 0.033 mmol∙g-1, respectively. The into the framework of zeolite sites.13,39,40 Moreover, the
number of B12-MR in the Co-HMOR sample reduced to about 62% surface Co/Si ratio (0.003), estimated from the XPS data, was
of the parent HMOR, indicating that ~38% of the protons in dramatically smaller than the bulk Co/Si ratio (0.01) measured
the 12-MR channels was exchanged by cobalt.
by ICP, reaffirming that the Co species were located mostly
The acid sites in the 8-MR channels of the two samples within the zeolite framework.
were derived from the O-H stretching bands in the FTIR
Catalytic Performance for DME Carbonylation
spectra. The band at 3665 cm-1 corresponded to the O-H
stretching vibration of the extra-framework Al atoms.18,36,37
The bands at 3611 and 3595 cm-1 represented the Brønsted
acidic sites in the 12-MR and the 8-MR pores of mordenite,
respectively.3,18,23,38 Deconvolution of the two characteristic
bands yielded the relative population (B8-MR/B12-MR) of hydroxyl
in the 8-MR and the 12-MR channels: 72/28 for HMOR and
74/26 for Co-HMOR. Combining these B8-MR/B12-MR ratios with
the amounts of B12-MR that were determined from the FTIR
spectra after adsorption of pyridine, the total number of the
Brønsted acid sites and the amount of the Brønsted acid sites
in the 8-MR channels (B8-MR) were obtained (Table 2). As a
result, the amounts of the Brønsted acid sites in the 8-MR and
Fig. 5 compares the catalytic performances of the Co-
HMOR and the parent HMOR samples for DME carbonylation.
In both cases, the conversion of DME increased rapidly at the
initial stage (induction period), approached the maximum with
a relatively stable period, and then gradually declined, showing
a typical reaction pattern of DME carbonylation over HMOR
catalysts.20,35,41 The parent HMOR had an induction period of
about 2.5 h, during which the conversion of DME increased to
17%, a relatively stable performance for about 6 h with DME
conversions of 17-19%, followed by a deactivation to 5% after
22 h. The reaction pattern over the Co-HMOR catalyst was
characterized by the significantly enhanced conversion of DME.
Fig. 4 (a) FTIR spectra of pyridine adsorption on the Co-HMOR and HMOR samples; (b) FTIR spectra of the OH stretching region of the Co-HMOR and HMOR
samples; (c) XPS of Co2p in the CO-HMOR sample.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 5 of 8
View Article Online
DOI: 10.1039/C8CY00407B
Journal Name
ARTICLE
Table 2 Distributions of the acid sites in the Co-HMOR and HMOR samples
b
Sample
HMOR
L12-MR a (mmol∙g-1)
0.016
B12-MR a (mmol∙g-1)
0.154
B8-MR b (mmol∙g-1)
0.398
Total B b (mmol∙g-1)
0.552
B8-MR/B12-MR
72/28
74/26
Co-HMOR
0.033
0.096
0.276
0.372
a Measured by FTIR spectra of pyridine adsorption; b Calculated according to FTIR spectra of the O-H stretching region.
The maximum conversion of DME reached 42%, which is two bridge and atop sites of Co2+ species, respectively.43 but the
times greater than that obtained on the HMOR sample (19%). HMOR sample only showed a minor desorption at 317 K,
On both catalysts, the selectivity of MA during the whole test probably due to the weak adsorption of CO on the acidic sites
was more than 90%, which was much less affected by the of HMOR. This comparative study indicates that the metal sites
incorporation of cobalt cations into mordenite.
in the Co-HMOR catalyst significantly promoted the adsorption
The reaction rate of DME carbonylation was reported to be of CO, which might be responsible for the enhanced activity
proportional to the number of the O-H groups within 8-MR during DME carbonylation.
channels of mordenites.3,11 As listed in Table 2, the amount of
Moreover, the Co2+ species also facilitated the adsorption
the Brønsted acid sites in the 8-MR channels of the Co-HMOR and activation of DME. Fig. 6 shows the FTIR spectra of DME
(0.276 mmol∙g-1) only accounted for 69% of the parent HMOR adsorption over the HMOR and Co-HMOR samples. The band
(0.398 mmol∙g-1). However, the reaction rate (at the maximum at 3008 cm-1 was assigned to the C-H symmetric vibration of
DME conversion) on the Co-HMOR catalyst (7.8 mol molAl-1 h-1) hydrogen-bonded DME on the Brønsted acid site; the band at
was three times greater than that of the parent HMOR (2.4 2968 cm-1 referred to the C-H vibration in Al-O-CH3; the band
-1
mol molAl h-1). This result implies that the Co2+ species that at 2939 cm-1 was ascribed to asymmetric stretching vibration
exchanged with the protons in the 8-MR channels dominantly of physically adsorbed DME.44,45 It is worthy of noting that the
contributed to the overall activity. This promotional effect of C-H symmetric stretching vibration of physically adsorbed DME
Co2+ is similar to the case of Cu2+ incorporation into a nano- appeared at 2835 cm-1 on HMOR,12,44 while it shifted to 2842
sized mordenite,15 but the increase in the reaction rate is cm-1 over Co-HMOR, indicating the interaction between DME
much more significant.
molecule and the Co2+ site. Under DME carbonylation at 523 K
The interaction between CO and the surface methyl (Fig. 7), the band at 1454 cm-1, ascribed to C-H deformation
species, formed through DME dissociative adsorption on vibration of DME, increased initially with time and almost
mordenite, plays a crucial role in DME carbonylation; CO saturated after 90 min over both catalysts. The band at around
insertion into the surface CH3* to form the acetyl intermediate 1680 cm-1, which was ascribed to C=O vibration in the acetyl
is the rate-determining step.4,8,42 With this regard, the metal intermediate (CH3CO*),35 increased dramatically over time on
Lewis acid sites, generated upon ion exchange on the Co- the Co-HMOR catalyst, but it intensified very slowly over the
HMOR catalyst, may provide additional sites for CO binding.13 parent HMOR. The band at 1382 cm-1, representing the
This is verified by the CO-TPD profiles of the Co-HMOR and symmetric stretching vibration of the CH3 group in methyl
HMOR catalysts (Fig. S1), CO desorption on Co-HMOR occurred acetate,12,35 intensified over time in both cases, but the
at 322 and 359 K, which are ascribed to CO adsorptions on the increase on Co-HMOR was more significant than that over
Fig. 5 DME conversion (a) and MA selectivity (b) during DME carbonylation over the Co-HMOR and HMOR catalysts.
Reaction conditions: 473 K, DME/CO/H2 = 5/76/19 (vol.%), GHSV = 2500 mL (g h)-1, 1.0 MPa.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 6 of 8
View Article Online
DOI: 10.1039/C8CY00407B
ARTICLE
Journal Name
into account (Fig. 5a), the Co-HMOR catalyst is characterized
by a much less percentage of coke formation in the total
amount of DME converted. Meanwhile, the ratios between the
hard to soft cokes were 74/26 in HMOR and 59/41 for Co-
HMOR. It is also worth noting that combustion of the hard coke
shifted to lower temperature on Co-HMOR (753 K); this was
due to the presence of Co that could catalyze hydrocarbon
combustion. The lower proportion of hard coke on the spent
Co-HMOR might be attributable to the cobalt species in 12-MR
channels that suppressed the formation of hard coke. Since
the deposition of coke is mainly related with the acid sites in
the 12-MR pores,9,10,23,35 the much slow accumulation of hard
coke in the Co-HMOR catalyst, considering the amount of
converted DME, demonstrates that the Co2+ species in 12-MR
channels effectively eliminated the deposition of coke during
DME carbonylation, presumably because of the reduced
number of the Brønsted acid sites.
Fig. 6 FTIR spectra of DME adsorption over HMOR and Co-HMOR.
Conclusions
The Co-HMOR catalyst showed significantly enhanced activity
and durability for DME carbonylation, relative to the parent
HMOR. Co2+ cations preferentially located at site A in the 8-MR
pores and site E in the 12-MR channels; the former greatly
facilitated the adsorption and activation of both CO and DME
molecules, and thus significantly promoted the activity; while
the latter effectively suppressed the deposition of coke and
therefore essentially improved the durability.
Conflicts of interest
There are no conflicts to declare.
Fig. 7 In situ FTIR spectra of DME carbonylation at 523 K over HMOR
(a-b) and Co-HMOR (c-d).
Acknowledgements
We acknowledge the financial support from the National Key
R&D Program of China (2017YFB0602200), and the National
Basic Research Program of China (2013CB933100).
HMOR. For example, the normalized peak intensity on Co-
HMOR was 1.6 times that of HMOR at 150 min. All these IR
data clearly evidenced that the incorporation of Co2+ to HMOR
enhanced the adsorption and activation of CO and DME, and
therefore enhanced the carbonylation activity.
References
1
2
3
4
5
6
K. Fujimoto, T. Shikada, K. Omata and H.-o. Tominaga, Chem.
Lett., 1984, 13, 2047-2050.
P. Cheung, A. Bhan, G. J. Sunley and E. Iglesia, Angew. Chem. Int.
Ed., 2006, 45, 1617-1620.
A. Bhan, A. D. Allian, G. J. Sunley, D. J. Law and E. Iglesia, J. Am.
Chem. Soc., 2007, 129, 4919-4924.
M. Boronat, C. Martínez-Sánchez, D. Law and A. Corma, J. Am.
Chem. Soc., 2008, 130, 16316-16323.
X. A. Li, X. G. San, Y. Zhang, T. Ichii, M. Meng, Y. S. Tan and N.
Tsubaki, Chemsuschem, 2010, 3, 1192-1199.
D. B. Rasmussen, J. M. Christensen, B. Temel, F. Studt, P. G.
Moses, J. Rossmeisl, A. Riisager and A. D. Jensen, Angew. Chem.
Int. Ed., 2015, 54, 7261-7264.
The deactivation of mordenite during DME carbonylation is
commonly attributed to the formation of coke that covered
the acid sites and blocked the diffusion pathways of the
reactants and products.3,9,10 Thermal gravimetric analysis (Fig.
S2) on the spent catalysts after DME carbonylation for 22 h
showed two major weight losses at about 540 K and 753 or
824 K, representing the combustion of the soft and hard cokes,
respectively. The soft coke consisted of reaction intermediate
species, including surface-bound methyl and acetyl species
associated with the formation of MA, while the hard coke
contained mainly polyaromatics.35,46,47 The total weight loss
was 7.47 wt.% for the spent HMOR and 8.49 wt.% on the used
Co-HMOR. However, by taking the amount of DME converted
7
A. Haynes, P. M. Maitlis, G. E. Morris, G. J. Sunley, H. Adams, P.
W. Badger, C. M. Bowers, D. B. Cook, P. I. P. Elliott, T. Ghaffar, H.
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 7 of 8
View Article Online
DOI: 10.1039/C8CY00407B
Journal Name
ARTICLE
Green, T. R. Griffin, M. Payne, J. M. Pearson, M. J. Taylor, P. W. 28 M. C. Campa, D. Pietrogiacomi and M. Occhiuzzi, Appl. Catal., B,
Vickers and R. J. Watt, J. Am. Chem. Soc., 2004, 126, 2847-2861. 2015, 168-169, 293-302.
P. Cheung, A. Bhan, G. J. Sunley, D. J. Law and E. Iglesia, J. Catal., 29 W. J. Mortier, Butterworth Scientific Limited, Guildford, 1982,
2007, 245, 110-123. pp. 54-55.
M. Boronat, C. Martínez and A. Corma, Phys. Chem. Chem. Phys., 30 K. Sun, W. Su, F. Fan, Z. Feng, T. A. P. J. Jansen, R. A. van Santen
2011, 13, 2603-2612. and C. Li, J. Phys. Chem. A,, 2008, 112, 1352-1358.
10 B. Li, J. Xu, B. Han, X. Wang, G. Qi, Z. Zhang, C. Wang and F. 31 P. Ayrault, J. Datka, S. Laforge, D. Martin and M. Guisnet, J.
8
9
Deng, J. Phys. Chem. C, 2013, 117, 5840-5847.
Phys. Chem. B,, 2004, 108, 13755-13763.
11 A. Bhan and E. Iglesia, Acc. Chem. Res., 2008, 41, 559-567.
32 F. Jin and Y. Li, Catal. Today, 2009, 145, 101-107.
12 T. Blasco, M. Boronat, P. Concepción, A. Corma, D. Law and J. A. 33 Q. Xin and M. Luo, Science Press, Beijing, 2009, p. 349.
Vidal-Moya, Angew. Chem. Int. Ed., 2007, 46, 3938-3941.
13 S. Wang, W. Guo, L. Zhu, H. Wang, K. Qiu and K. Cen, J. Phys.
Chem. C, 2015, 119, 524-533.
14 G. Yang, X. San, N. Jiang, Y. Tanaka, X. Li, Q. Jin, K. Tao, F. Meng
and N. Tsubaki, Catal. Today, 2011, 164, 425-428.
34 K. Kim, R. Ryoo, H.-D. Jang and M. Choi, J. Catal., 2012, 288,
115-123.
35 J. Liu, H. Xue, X. Huang, P.-H. Wu, S.-J. Huang, S.-B. Liu and W.
Shen, Chin. J. Catal., 2010, 31, 729-738.
36 J. P. Marques, I. Gener, P. Ayrault, J. C. Bordado, J. M. Lopes, F.
R. Ribeiro and M. Guisnet, Microporous Mesoporous Mater.,
2003, 60, 251-262.
15 H. Xue, X. Huang, E. Ditzel, E. Zhan, M. Ma and W. Shen, Ind.
Eng. Chem. Res., 2013, 52, 11510-11515.
16 L. Peng, G. Yang, Y. Tanaka and N. Tsubaki, Catal. Today, 2014, 37 K. Góra-Marek, K. Brylewska, K. A. Tarach, M. Rutkowska, M.
232, 22-26.
Jabłońska, M. Choi and L. Chmielarz, Appl. Catal., B, 2015, 179,
17 H. Zhou, W. Zhu, L. Shi, H. Liu, S. Liu, S. Xu, Y. Ni, Y. Liu, L. Li and
589-598.
Z. Liu, Catal. Sci. Technol., 2015,
18 H. Zhan, S. Huang, Y. Li, J. Lv, S. Wang and X. Ma, Catal. Sci.
Technol., 2015, , 4378-4389.
19 A. A. C. Reule and N. Semagina, ACS Catal., 2016,
5
, 1961-1968.
38 H. Zhou, W. Zhu, L. Shi, H. Liu, S. Liu, Y. Ni, Y. Liu, Y. He, S. Xu, L.
Li and Z. Liu, J. Mol. Catal. A: Chem., 2016, 417, 1-9.
39 J. Janas, T. Machej, J. Gurgul, R. P. Socha, M. Che and S. Dzwigaj,
Appl. Catal., B, 2007, 75, 239-248.
5
6
, 4972-4975.
20 M. Ma, X. Huang, E. Zhan, Y. Zhou, H. Xue and W. Shen, J. 40 R. M. Serra, S. G. Aspromonte, E. E. Miró and A. V. Boix, Appl.
Mater. Chem. A, 2017,
5
, 8887-8891.
Catal., B, 2015, 166–167, 592-602.
21 J. Dědeček and B. Wichterlová, J. Phys. Chem. B,, 1999, 103
,
41 Y. Liu, N. Zhao, H. Xian, Q. Cheng, Y. Tan, N. Tsubaki and X. Li,
1462-1476.
ACS Appl. Mater. Interfaces, 2015, 7, 8398-8403.
22 X. Zhang, Y. Guan, S. Zhang, M. Yang, Y. Zhao and Z. Hao, J. Mol. 42 Y. Jiang, M. Hunger and W. Wang, J. Am. Chem. Soc., 2006, 128
Catal. A: Chem., 2014, 395, 202-209. 11679-11692.
23 H. Xue, X. Huang, E. Zhan, M. Ma and W. Shen, Catal. Commun., 43 A. F. Carlsson, M. Naschitzki, M. Bäumer and H.-J. Freund, J.
,
2013, 37, 75-79.
Phys. Chem. B,, 2003, 107, 778-785.
44 T. R. Forester and R. F. Howe, J. Am. Chem. Soc., 1987, 109
5076-5082.
45 S. M. Campbell, X.-Z. Jiang and R. F. Howe, Microporous
Mesoporous Mater., 1999, 29, 91-108.
24 C. A. Emeis, J. Catal., 1993, 141, 347-354.
25 C. E. Webster, A. Cottone and R. S. Drago, J. Am. Chem. Soc.,
1999, 121, 12127-12139.
26 A. A. Verberckmoes, M. G. Uytterhoeven and R. A.
Schoonheydt, Zeolites, 1997, 19, 180-189.
,
46 M. Guisnet and P. Magnoux, Appl. Catal., A, 2001, 212, 83-96.
27 V. Indovina, M. C. Campa and D. Pietrogiacomi, J. Phys. Chem. C, 47 L. Palumbo, F. Bonino, P. Beato, M. Bjørgen, A. Zecchina and S.
2008, 112, 5093-5101.
Bordiga, J. Phys. Chem. C, 2008, 112, 9710-9716.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Catalysis Science & Technology
Page 8 of 8
View Article Online
DOI: 10.1039/C8CY00407B
Table of Content