Efficient oxidation of p-xylene to terephthalic acid by using N,N-dihydroxypyromellitimide in conjunction with Co-benzenetricarboxylate

Article abstract of DOI:10.1016/j.apcata.2020.117569

The MOF Co-BTC (BTC = benzenetricarboxylate) has been synthesized by a hydrothermal method, and characterized by means of N₂ physical adsorption, X-ray diffraction, scanning electron microscope, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The material has multiple crevices, as opposed to a pore structure, and shows high thermal stability, with Co in the divalent state. It has been used in conjunction with N,N-dihydroxypyromellitimide to catalyze the oxidation of p-xylene to terephthalic acid, the reaction conditions for which have been investigated and optimized. At 150 °C, with acetonitrile as solvent instead of acetic acid and in the absence of corrosive bromine, the conversion of p-xylene reached 100 % and the selectivity for terephthalic acid exceeded 97 %. Under the optimized conditions, Co-BTC exhibits stronger catalytic activity than cobalt(II) acetate, and maintains excellent stability during the reaction. The reaction mechanism has been deduced, and the roles of N,N-dihydroxypyromellitimide and Co-BTC as synergistic catalysts in the reaction have been clarified.

Full text of DOI:10.1016/j.apcata.2020.117569

AppliedCatalysisA,General599(2020)117569
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Applied Catalysis A, General
journal homepage: www.elsevier.com/locate/apcata
Efficient oxidation of p-xylene to terephthalic acid by using N,N-
dihydroxypyromellitimide in conjunction with Co-benzenetricarboxylate
Luo Xua, Dawei Chena, Haoran Jianga, Xia Yuana,b,
*
a College of Chemical Engineering, Xiangtan University, Xiangtan, 411105, China
b National & Local United Engineering Research Centre for Chemical Process Simulation and Intensification, Xiangtan, 411105, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
The MOF Co-BTC (BTC = benzenetricarboxylate) has been synthesized by a hydrothermal method, and char-
acterized by means of N2 physical adsorption, X-ray diffraction, scanning electron microscope, thermogravi-
metric analysis, and X-ray photoelectron spectroscopy. The material has multiple crevices, as opposed to a pore
structure, and shows high thermal stability, with Co in the divalent state. It has been used in conjunction with
N,N-dihydroxypyromellitimide to catalyze the oxidation of p-xylene to terephthalic acid, the reaction conditions
for which have been investigated and optimized. At 150 °C, with acetonitrile as solvent instead of acetic acid and
in the absence of corrosive bromine, the conversion of p-xylene reached 100 % and the selectivity for ter-
ephthalic acid exceeded 97 %. Under the optimized conditions, Co-BTC exhibits stronger catalytic activity than
cobalt(II) acetate, and maintains excellent stability during the reaction. The reaction mechanism has been de-
duced, and the roles of N,N-dihydroxypyromellitimide and Co-BTC as synergistic catalysts in the reaction have
been clarified.
p-Xylene oxidation
Terephthalic acid
Co-benzenetricarboxylate
NDHPI
Metal–organic framework
1. Introduction
a hot topic of research.
N-Hydroxyphthalimide (NHPI) and its derivatives are effective
In the polyester industry, terephthalic acid (TA) is an important raw
material used primarily in the manufacture of non-toxic polyethylene
terephthalate (PET), which accounts for about 20 % of the polyester
market. PET is mainly used in machinery parts, fiber materials, and
packaging for foods and medicines.
catalysts for the oxidation of organic compounds by molecular oxygen
under mild conditions [6], and are widely used as initiators for the
oxidation of hydrocarbons. Tashiro et al. [7] used NHPI/Co(OAc)2/Mn
(OAc)2 as a catalyst and acetic acid as a solvent to oxidize PX at 100 °C.
The yield of TA reached 82 % after 14 h of reaction; when the tem-
perature was raised to 150 °C, the yield of TA reached 84 % after 3 h.
Koshino et al. found that the PINO formed by the -NO-H cleavage of
NHPI is more likely to capture a proton from the alkyl group on the
alkyl aromatic hydrocarbon in acetonitrile (MeCN) than in acetic acid;
during the oxidation of PX, the effect of N,N-dihydroxypyromellitimide
(NDHPI) as an initiator is superior to that of NHPI because it bears two
-NOH groups [8].
Heterogeneous catalysts have also been used to catalyze the oxi-
dation of PX [9]. Ratnasamy et al. loaded cobalt manganese oxide into a
zeolite to catalyze the oxidation of PX at high temperature (473 K) and
an air pressure of 550 psi. The conversion of PX was 100 %, and the
selectivity for TA was over 98 %, but corrosive bromine was still needed
as a co-catalyst to capture hydrogen from the methyl group [10]. Deka
et al. prepared porous CeO2 as a catalyst to catalyze the oxidation of PX
to TA. Using only water as a solvent under extremely mild conditions
(70 °C, 1 bar O2), the conversion of PX reached 100 % and the
Oxidation of p-xylene (PX) is the main route for obtaining TA. This
process is shown in Scheme 1, and is consistent with a mechanism of
hydrocarbon radical oxidation. In general, the difficulty of hydrocarbon
oxidation lies mainly in the initiation step, that is, the formation of
hydrocarbon radicals by the removal of hydrogen from alkyl groups
[1–4]. However, in the oxidation of PX, p-methyl benzyl radical and p-
TA will also be present [5], which are resistant to oxidation. Due to the
difficult oxidation characteristics of PX, current industrial production of
TA mainly relies on the harsh Amoco process, using cobalt(II) acetate,
manganese(II) acetate, and bromine as catalysts, and acetic acid as
solvent, which is conducted at high temperature (about 200 °C) and
high pressure (1.5–3.0 MPa). The selectivity for TA is over 95 %. Under
the high-temperature operating conditions, corrosive bromine acts as a
co-catalyst, resulting in high production and equipment costs. There-
fore, the quest for an efficient and mild catalyzed route for PX oxida-
tion, leading to TA without the need for acid and bromine, has become
⁎ Corresponding author at: College of Chemical Engineering, Xiangtan University, Xiangtan, 411105, Hunan, China.
E-mail address: yxiamail@163.com (X. Yuan).
https://doi.org/10.1016/j.apcata.2020.117569
Received 21 December 2019; Received in revised form 6 April 2020; Accepted 14 April 2020
Availableonline07May2020
0926-860X/©2020ElsevierB.V.Allrightsreserved.

L. Xu, et al.
AppliedCatalysisA,General599(2020)117569
Fig. 3. TGA of Co-BTC.
Scheme 1. Oxidation of PX to TA.
Fig. 4. XPS spectrum of Co-BTC with peak fittings.
Fig. 1. N2 adsorption/desorption of Co-BTC.
the field of catalysis [18,20,19,20,21,22,23]. To date, MOFs have been
studied as heterogeneous catalysts in the selective oxidation of some
hydrocarbons, such as cyclohexane [24–27], cyclooctane [28], olefins
[27,29–32], alcohols, [27,33–35], and so on. Wang et al. used a Cu-
MOF as
a catalyst to catalyze the oxidation of PX to 4-hydro-
xymethylbenzoic acid under a mild conditions [36]. To the best of our
knowledge, however, no MOFs have hitherto been used in the oxidation
of PX to TA.
In this study, Co-BTC (BTC = benzenetricarboxylate) has been used
as a catalyst for the first time in the oxidation of PX to TA. It has been
used in conjunction with NDHPI instead of corrosive bromine as an
initiator for PX oxidation in the non-acidic solvent MeCN. The catalytic
properties of Co-BTC and cobalt(II) acetate have also been compared.
Through suitably designed experiments, the mode of action of NDHPI
and Co-BTC in PX oxidation has been investigated. Furthermore, the
stability of Co-BTC in the oxidation of PX has been studied.
Fig. 2. XRD of Co-BTC.
2. Materials and methods
selectivity for TA exceeded 99 % [11]. Guo et al. used a metallopor-
phyrin (T(p-Cl)PPMnCl) as a catalyst to catalyze the oxidation of PX
with acetic acid as a solvent, although its concentration was as high as
20 %. Under these operating conditions (3.5 h, 180 °C, 2.0 MPa), the
conversion rate of PX was 41.8 %, the selectivity for p-TA is 82.1 %, but
the selectivity for TA was only 12.4 % [12].
2.1. Materials and reagents
MeCN (AR), PX (AR), Co(OAc)2·4H2O (AR), Co(NO3)2·6H2O (AR),
trimesic acid (H3BTC, AR), NDHPI (AR), dimethyl sulfoxide (DMSO,
AR), and ethanol (AR) were purchased from Macklin. Water was pur-
ified and deionized in our laboratory.
Porous metal-organic frameworks (MOFs), due to their variable
combinations of metals and organic ligands, offer great diversity in
their structures and properties, making them suitable for adsorbing
drugs [13] and harmful substances [14,15] as well as gas absorption
[16–18] and storage [19]. They also have broad prospects and value in
2.2. Synthetic procedure
Co-BTC was synthesized according to a method in the literature
[37], with some modifications. The specific process was as follows: Co
2

L. Xu, et al.
AppliedCatalysisA,General599(2020)117569
Fig. 5. SEM images of Co-BTC.
acetonitrile) were combined in the quartz vessel. The autoclave was
then closed, and the inside of the reactor was flushed twice with oxygen
through a valve. The reactor was finally supplied with oxygen (3 MPa,
room temperature), then heated to 150 °C, and the reaction was al-
lowed to proceed for 12 h. Thereafter, the product was taken up in
DMSO and analyzed by high-performance liquid chromatography [38].
Table 1
Study of catalytic performance.
NDHPI
/g
Co-BTC
/g
Conversion
/%
Selectivity/%
p-TALD
p-TA
4-CBA
TA
1a
2a
3a
4b
5b
6b
7c
0.1
0
0.1
0.372
0
0
0
0
0
0
0
0
0
0
0.1
0.1
0
0.05
0.02
0
0
0
57.0
93.5
3.1
100
100
3.6
0
97
0
89.4
30
3
2.5
10
1.6
2.5
0
1.3
0.9
5.4
67.5
0
96.2
89.1
2.4. Characterization
The specific surface areas and pore structures of samples were
measured by N2 adsorption using an ASAP 2020 Plus physisorption
instrument, whereby the specific surface area was calculated by the
Brunauer-Emmett-Teller (BET) method. X-ray diffraction (XRD) ana-
lysis was carried out using a Rigaku D/max-2500 X-ray diffractometer
employing Cu-Kα radiation at 40 kV and 30 mA. The XRD pattern was
recorded in the 2θ range 5−45°. A scanning electron microscope (SEM)
image was obtained using an Hitachi S-4800 electron microscope. The
thermal stability of the catalyst was measured by thermogravimetric
analysis (TGA) using a Netzsch TG209 analyzer. The temperature was
raised from ambient to 800 °C at 10 °C/min under a flow of air/N2. The
chemical state of cobalt was characterized by X-ray photoelectron
spectroscopy (XPS).
0.372
0.372
0
a
b
c
Reaction carried out at 100 ℃ for 12 h, 10 g PX, 20 g MeCN, 3.0 MPa O2.
Reaction carried out at 150 ℃ for 12 h, 0.54 g PX, 25 g MeCN, 3.0 MPa O2.
Reaction carried out at 150 ℃ for 12 h, 0.54 g PX, 25 g MeCN, 3.0 MPa O2;
0.025 g Co(OAc)2·6H2O was added.
(NO3)2·6H2O (4.8 g) was dissolved in deionized water (20 mL), and
H3BTC (2.0 g) was dissolved in absolute ethanol (130 mL). When the
two materials had completely dissolved, the two solutions were mixed,
and the mixture was transferred to a 200 mL Teflon crystallization
vessel. After agitation in an ultrasonicator for 20 min, the mixture was
transferred to an incubator for crystallization by programmed tem-
perature control. First, the temperature was quickly raised to 140 °C
within 22 min and maintained at this level for 24 h; it was then uni-
formly lowered to 120 °C in 200 min. After 5 h, the temperature was
steadily reduced to 100 °C over a period of 200 min and maintained at
this level for 5 h. Finally, the mixture was cooled to room temperature.
The vessel was removed from the incubator, the supernatant was dec-
anted, and the solid was collected by suction filtration and washed with
absolute ethanol until the washings were colorless and transparent.
Thereafter, the solid was placed in a vacuum oven at 80 °C for 24 h. The
dark-blue solid product was designated as Co-BTC.
3. Results and discussion
3.1. Characterization of Co-BTC
Fig. 1 shows the N2 sorption isotherm of Co-BTC, which features a
hysteresis loop of H3 type. This implies that the synthesized Co-BTC
had a slit structure. The specific surface area and pore volume were
evaluated as 1.9 m2/g and 0.01 cm3/g, respectively, indicating that the
material had almost no pore structure. Fig. 2 shows the XRD pattern of
the synthesized Co-BTC. It features a strong diffraction peak at 10.02°,
which is distinct from the various crystal forms of Co-BTC MOFs re-
ported in the literature [13,37,39–44]. Fig. 3 shows the thermal weight
loss trace of Co-BTC, which reveals that the material was relatively
stable up to 400 °C. Fig. 4 shows the XPS spectrum of cobalt in Co-BTC.
The main peaks at 781.8 eV and 797.7 eV can be assigned to Co2p3/2
and Co2p1/2, and the corresponding accompanying peaks are located
at 786 eV and 802.7 eV, respectively. Thus, the energy gaps between
2.3. Catalysis and product analysis
All reactions were carried out in an autoclave equipped with a
100 mL quartz vessel and operated at a stirring speed of 1000 rpm. In a
representative reaction process, combined catalyst (0.372 g NDHPI,
0.05 g Co-BTC), raw material (0.54 g PX), and solvent (25 g
3

L. Xu, et al.
AppliedCatalysisA,General599(2020)117569
Fig. 6. Reaction parameter study. The conversion of PX was 100 % in Fig. 6a–f. The operating conditions of reactions a-f were varied as follows: NDHPI (0.372 g), Co-
BTC (0.05 g), PX (0.54 g), MeCN (25 g), O2 (3.0 MPa), 150 °C, 12 h.
the main peaks and the accompanying peaks are 5.8 eV and 5 eV, re-
spectively. The energy gap between the main peak of Co2p and the
satellite peak serves as an important criterion for judging the oxidation
state of the Co cation. It is generally accepted that the energy gap for a
Co(II) cation is about 5−6 eV, whereas that for a Co(III) cation is
9−10 eV. Therefore, the cobalt in Co-BTC is Co(II). Fig. 5 shows SEM
images of the prepared Co-BTC. It can be seen that the surface of the
synthesized Co-BTC was extremely irregular, with many gaps. This is
consistent with the characterization from the N2 sorption isotherm.
and Co-BTC alone as catalysts, respectively, and when the reactions
were attempted at 100 °C for 12 h, no product was detected. Only when
Co-BTC was used in combination with NDHPI was the product detected.
The conversion of PX was 57 %, and the selectivity for the main product
p-TA was 89.4 %. We then increased the reaction temperature to 150 °C,
and the amounts of reactant and solvent were shown as conditions b in
Reactions 5, 6, and 7. Under conditions b, PX was oxidized when
NDHPI and Co-BTC were used alone, and the conversion rates were
93.5 % and 3.1 %, respectively. When they were used together as co-
catalysts (Reaction 6), conversion of PX reached 100 %, and the se-
lectivity for TA reached 96.2 %. In Reactions 6 and 7, under otherwise
identical reaction conditions, we compared Co-BTC and Co(OAc)2·4H2O
with the same cobalt content, and found that the selectivity for TA was
higher when Co-BTC was used.
3.2. Study of catalytic performance
Table 1 shows the performance of Co-BTC in combination with
NDHPI for the catalytic oxidation of P X . It is well known that PX is
difficult to oxidize without a catalyst. Reactions 1 and 2 used NDHPI
4

L. Xu, et al.
AppliedCatalysisA,General599(2020)117569
3.3. Optimization of the reaction parameters
Fig. 6 shows an optimization of the reaction conditions for the
oxidation of PX catalyzed by NDHPI and Co-BTC. The conversions of PX
were 100 % in Fig. 6a–f. It can be seen from Fig. 6a and b that higher
temperature and oxygen pressure are favorable for obtaining TA with
high selectivity. In Fig. 6c and d, it is evident that the use of NDHPI as
the main catalyst requires a large amount, which may be due to the self-
decomposition of nitrogen-oxygen radicals by NDHPI during the reac-
tion, as mentioned in the literature [6,45,47]. Conversely, the amount
of Co-BTC required is extremely small; a loading of 0.08 wt% or more in
the reaction mixture is sufficient to obtain a good effect. Fig. 6e shows
that the reaction requires a suitable solvent ratio. In the 100 mL reactor,
25 g of MeCN and 0.54 g of PX gave a suitable ratio. Fig. 6f shows the
relationship between reaction time and the selectivity for TA. The se-
lectivity for TA reached 90 % at 6 h, but a further 6 h was needed to
raise it from 90 % to 97 %. This may be attributed to the low content of
p-TA.
Fig. 7. Reusability study of Co-BTC catalyst for PX oxidation. The conversion of
PX was 100 %. Reaction carried out at 150 °C for 12 h, 0.54 g PX, 0.372 g
NDHPI, 0.05 g Co-BTC, 25 g MeCN, 3.0 MPa O2.
3.4. Reusability study
We investigated the stability of Co-BTC in the oxidation of P X .
When the reaction was complete, the solid product was dissolved in
DMSO, and Co-BTC was separated by centrifugation. The isolated Co-
BTC was washed three times with DMSO, three times with ethanol, and
then vacuum-dried at 80 °C for 12 h for the next reaction. We performed
two reuses and found that the performance of the catalyst was almost
unchanged, as shown in Fig. 7. The first recovered catalysts were
characterized by XRD and SEM, and the results are shown in Figs. 2 and
5. The diffraction peak of Co-BTC-cycle 1 showed little change com-
pared to the fresh catalyst. SEM images showed that the catalyst was
nearly spherical before and after the reaction.
3.5. Reaction mechanism
The oxidation of PX to TA is a very important hydrocarbon oxida-
tion process, which is generally considered to follow a mechanism of
hydrocarbon radical oxidation [5], and has to overcome the barriers
associated with the following three steps:
Scheme 2. Reaction mechanism of Co-BTC catalyst for p-methyl benzyl radical
oxidation. X = CH3, COOH.
CH3(C6H4)CH3 + initiator → CH3(C6H4)CH2▪ + H-initiator
(1)
Scheme 3. Proposed reaction mechanism for the Co-BTC/NDHPI-catalyzed oxidation of P X . X = CH3, COOH.
5

L. Xu, et al.
AppliedCatalysisA,General599(2020)117569
CH3(C6H4)CH2▪ + O2 → CH3(C6H4)CH2OO▪
(2)
bromine and acetic acid make this a green, mild reaction process. A
reaction mechanism has been proposed, whereby the main function of
NDHPI is to extract hydrogen from the two methyl groups of PX, whilst
the main function of Co-BTC is to promote the reaction of hydrocarbon
radicals with oxygen to form hydrocarbon peroxy radicals.
HOOC(C6H4)CH3 + initiator → HOOC(C6H4)CH3▪ + H-initiator (3)
Eq. (1) is a common requirement in the oxidation of hydrocarbons.
However, the oxidation of PX involves requirements that do not arise in
general hydrocarbon oxidation (expressed by Eqs. (2) and (3)). Firstly,
PX undergoes the process according to Eq. (1) to afford a p-methyl
benzyl radical, which is strongly resonance-stabilized. According to Eq.
(2), the peroxy p-methyl benzyl radical is produced. In this inter-
mediate, the free electrons are separated from the ring double-bond
conjugated system, and the radicals cannot form any resonance hybrids.
Hence, it is destabilized, and the equilibrium of Eq. (2) is shifted to-
wards the p-methyl benzyl radical. Therefore, the methyl groups of p-
xylene are difficult to oxidize.
CRediT authorship contribution statement
Luo Xu: Investigation, Formal analysis, Visualization, Writing -
original draft.
Dawei Chen: Purchase of raw materials and equipment.
Haoran Jiang: Characterization of the catalyst.
Xia Yuan: Conceptualization, Writing - review & editing, Project
administration, Funding acquisition.
The oxidation of p-TA is even more difficult, because the carboxyl
group is an electron-withdrawing group, as opposed to the initially
oxidized electron-donating methyl group. Hence, electrons in the ben-
zene ring are attracted to the carboxyl group, making it difficult for the
methyl group in p-TA to generate a structurally stable CH2 group by
resonance. The presence of the carboxyl group attracts electrons and
enhances the strength of the CeH bonds in the methyl group of p-TA
[5].
Declaration of Competing Interest
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influ-
ence the work reported in this paper.
Acknowledgments
NHPI and its derivatives are excellent initiators that can easily
capture protons from alkyl groups, and they have received much at-
tention in academia and industry. In the PX oxidation process, we used
NDHPI as an initiator, the main function of which is to facilitate the
processes described by Eqs. (1) and (3), generating hydrocarbon radi-
cals that can react with oxygen.
This study was financially supported by the National Natural
Science Foundation of China (No. 21776237).
References
The process according to Eq. (2) is difficult to achieve due to the
antioxidant action of the p-methyl benzyl radical. To facilitate this step,
we used Co-BTC as a catalyst. First, Co(II) on the surface of the catalyst
coordinated by adsorbed oxygen is oxidized to Co(III). The molecular
oxygen withdraws an electron from Co(II) to form O2− and Co(III), the
p-methyl benzyl radical combines with O2−, the final Co(III)eO bond is
broken, Co(III) is reduced to Co(II), and a peroxy p-methyl benzyl ra-
dical is formed. The process according to Eq. (2) is completed, as shown
in Scheme 2. Saracco et al. [46] studied the adsorption of oxygen by Co-
ZIF-67. They surmised that most of the cobalt in Co-ZIF-67 did not
participate in the reaction with oxygen, with only the coordinatively
unsaturated cobalt at the surface being involved. We believe that our
non-porous synthesized Co-BTC undergoes a similar process.
We designed experiments to study the mechanism of the synergistic
Co-BTC/NDHPI-catalyzed oxidation of P X . In Reactions 1, 2, and 3 in
Table 1, when NDHPI is used alone, although it has strong hydrogen-
abstracting ability, PX can only be converted into p-methyl benzyl ra-
dical. Due to the resistance to oxidation, Eq. (2) is difficult to accom-
plish. When Co-BTC is used alone, it lacks hydrogen-scavenging ability,
and at 100 °C, the CH bonds of the methyl group are difficult to cleave
to form hydrocarbon radicals. Only when these components are used
together as co-catalysts can PX be readily oxidized at 100 °C.
Based on the above, we speculate that the mechanism of the Co-
BTC/NDHPI-catalyzed oxidation of PX to TA may be as shown in
Scheme 3. The main role of NDHPI is to capture hydrogen from the
methyl group, while Co-BTC catalyzes the oxidation of hydrocarbon
radicals to hydrocarbon peroxy radicals.
[1] I. Hermans, J. Peeters, P.A. Jacobs, J. Org. Chem. 72 (2007) 3057–3064.
[2] H.S. Blanchard, J. Am. Chem. Soc. 81 (1959) 4548–4552.
[3] I. Hermans, T.L. Nguyen, P.A. Jacobs, J. Peeters, ChemPhysChem 4 (2005)
637–645.
[4] I. Hermans, P.A. Jacobs, J. Peeters, Chem. Eur. J. 16 (2006) 4229–4240.
[5] R.A.F. Tomás, J.C.M. Bordado, J.F.P. Gomes, Chem. Rev. 113 (2013) 7421–7469.
[6] F. Recupero, C. Punta, Chem. Rev. 107 (2007) 3800–3842.
[7] Y. Tashiro, T. Iwahama, S. Sakaguchi, Y. Ishii, Adv. Synth. Catal. 343 (2001)
220–225.
[8] N. Koshino, B. Saha, J.H. Espenson, J. Org. Chem. 68 (2003) 9364–9370.
[9] C.R. Jacob, S.P. Varkey, P. Ratnasamy, Appl. Catal. A Gen. 182 (1999) 91–96.
[10] S.A. Chavan, D. Srinivas, P. Ratnasamy, J. Catal. 204 (2001) 409–419.
[11] K. Deori, D. Gupta, B. Saha, S. Deka, ACS Catal. 4 (2014) 3169–3179.
[12] Q. Jiang, H.Y. Hu, C.C. Guo, Q. Liu, J.X. Song, Q.H. Li, J. Porphyrins
Phthalocyanines 11 (2007) 524–530.
[13] T. He, X.B. Xu, B. Ni, H.F. Lin, C.Z. Li, W.P. Hu, X. Wang, Angew. Chem. 130 (2018)
10305–10309.
[14] F. Shi, M. Hammoud, L.T. Thompson, Appl. Catal. B Environ. 103 (2011) 261–265.
[15] C. Montoro, F. Linares, E.Q. Procopio, I. Senkovska, S. Kaskel, S. Galli,
N. Masciocchi, E. Barea, J.A.R. Navarro, J. Am. Chem. Soc. 133 (2011)
11888–11891.
[16] P.Z. Li, X.J. Wang, Y.X. Li, Q. Zhang, R. He, D. Tan, W.Q. Lim, R. Ganguly,
Yanli Zhao, Microporous Mesoporous Mater. 176 (2013) 194–198.
[17] C.M. Lu, J. Liu, K.F. Xiao, A.T. Harris, Chem. Eng. J. 156 (2010) 465–470.
[18] Y.J. Ma, Z.M. Wang, X.F. Xu, J.Y. Wang, Chin. J. Catal. 38 (2017) 1956–1969.
[19] J.P. Li, S.J. Cheng, Q. Zhao, P.P. Long, J.X. Dong, Int. J. Hydrogen Energy 34 (2009)
1377–1382.
[20] P.D. Hu, M.C. Long, Appl. Catal. B 181 (2016) 103–117.
[21] R.J. Kuppler, D.J. Timmons, Q.R. Fang, J.R. Li, T.A. Makal, M.D. Young, D.Q. Yuan,
D. Zhao, W.J. Zhuang, H.C. Zhou, Coord. Chem. Rev. 253 (2009) 3042–3066.
[22] K.K. Gangu, S. Maddila, S.B. Mukkamala, S.B. Jonnalagadda, Inorganica Chim. Acta
446 (2016) 61–74.
[23] M. Cheng, C. Lai, Y. Liu, G.M. Zeng, D.L. Huang, C. Zhang, L. Qin, L. Hu, C.Y. Zhou,
W.P. Xiong, Coord. Chem. Rev. 368 (2018) 80–92.
[24] Z.G. Sun, G. Li, L.P. Liu, H.O. Liu, Catal. Commun. 27 (2012) 200–205.
[25] A.A. Alshehri, A.M. Alhanash, M. Eissa, M.S. Hamdy, Appl. Catal. A Gen. 554
(2018) 71–79.
[26] T. Zhang, Y.Q. Hu, T. Han, Y.Q. Zhai, Y.Z. Zheng, ACS Appl. Mater. Interfaces 10
(2018) 15786–15792.
4. Conclusions
[27] A. Dhakshinamoorthy, A.M. Asiri, H. Garcia, Chem. Eur. J. 22 (2016) 8012–8024.
[28] N. Nagarjun, A. Dhakshinamoorthy, New J. Chem. 43 (2019) 18702–18712.
[29] H. Noh, Y.X. Cui, A.W. Peters, D.R. Pahls, M.A. Ortuño, N.A. Vermeulen,
C.J. Cramer, L. Gagliardi, J.T. Hupp, O.K. Farha, J. Am. Chem. Soc. 138 (2016)
14720–14726.
[30] H.T.D. Nguyen, Y.B.N. Tran, H.N. Nguyen, T.C. Nguyen, F. Gándara, P.T.K. Nguyen,
Inorg. Chem. 57 (2018) 13772–13782.
[31] J.W. Brown, Q.T. Nguyen, T. Otto, N.N. Jarenwattananon, S. Glöggler,
L.S. Bouchard, Catal. Commun. 59 (2015) 50–54.
A new cobalt-based metal-organic framework, Co-BTC, with a non-
porous structure, has been synthesized. It has been used in combination
with NDHPI to co-catalyze the oxidation of PX to TA. Under optimized
conditions of 150 °C in acetonitrile, the conversion rate of PX reached
100 % and the selectivity for TA exceeded 97 %. Co-BTC can be re-
cycled and reused, retaining its structure and activity. Compared to
existing procedures, the lower temperature and avoidance of corrosive
[32] Y.Y. Ma, H.Y. Peng, J.N. Liu, Y.H. Wang, X.L. Hao, X.J. Feng, S.U. Khan, H.Q. Tan,
6

L. Xu, et al.
AppliedCatalysisA,General599(2020)117569
Y.G. Li, Inorg. Chem. 57 (2018) 4109–4116.
Mater. Interfaces 8 (2016) 15352–15360.
[33] A. Dhakshinamoorthy, A.M. Asiri, H. Garcia, Chem. Commun. 53 (2017)
[41] D.H. Ge, J. Peng, G.L. Qu, H.B. Geng, Y.Y. Deng, J.J. Wu, X.Q. Cao, J.W. Zheng,
10851–10869.
H.W. Gu, New J. Chem. 40 (2016) 9238–9244.
[34] X. Shu, Y. Yu, Y. Jiang, Y. Luan, D. Ramella, Appl. Organoment. Chem. 31
(2017) 1–8.
[42] D.H. Ge, G.L. Qu, X.M. Li, K.M. Geng, X.Q. Cao, H.W. Gu, New J. Chem. 40 (2016)
5531–5536.
[35] T.W. Goh, C.X. Xiao, R.V. Maligal-Ganesh, X.L. Li, W.Y. Huang, Chem. Eng. Sci. 124
[43] F. Luo, Y.X. Che, J.M. Zheng, Eur. J. Inorg. Chem. 2007 (2007) 3906–3910.
[44] K. Liu, Z.R. Shen, Y. Li, S.D. Han, T.L. Hu, D.S. Zhang, X.H. Bu, W.J. Ruan, Sci. Rep.
4 (2014) 1–7.
[45] R. Amorati, M. Lucarini, V.E. Mugnaini, G.F. Pedulli, F. Minisci, F. Recupero,
F. Fontana, P. Astolfi, L. Greci, J. Org. Chem. 68 (2003) 1747–1754.
[46] C. Ueda, M. Noyama, H. Ohmori, M. Masui, Chem. Pharm. Bull. 35 (1987)
1372–1377.
(2015) 45–51.
[36] Y. Li, M.Z. Wu, D.M. Chen, L. Jiang, J. He, Z.H. Luo, W. Wang, J.Q. Wang, Mol.
Catal. 477 (2019) 110542.
[37] O.M. Yaghi, H.L. Li, T.L. Groy, J. Am. Chem. Soc. 118 (1996) 9096–9101.
[38] L. Xu, P.C. He, D.W. Chen, X. Yuan, Petrochem. Technol. (in China) 47 (2018)
861–866.
[39] H.X. Li, J.Q. Wan, Y.W. Ma, Y. Wang, X. Chen, Z.Y. Guan, J. Hazard. Mater. 318
(2016) 154–163.
[47] G. Saracco, S. Vankova, C. Pagliano, B. Bonelli, E. Garrone, Phys. Chem. Chem.
Phys. 16 (2014) 6139–6145.
[40] C. Li, X.B. Lou, M. Shen, X.S. Hu, Z. Guo, Y. Wang, B.W. Hu, Q. Chen, ACS Appl.
7