Constructing PtI?COF for semi-hydrogenation reactions of phenylacetylene

Article abstract of DOI:10.1016/j.jssc.2020.121176

The great efforts have been devoted to fabricate excellent hydrogenation catalysts owing to the broad applications in industrial fields. However, the preparation processes of traditional hydrogenation catalysts are often complicated. Herein, mono-valence Pt^I?COF was synthesized as a catalyst for semi-hydrogenation of phenylacetylene for the first time. The easily prepared SO₃H-linked COF possesses a two-dimensional eclipsed layered-sheet structure, making its incorporation with metal ions feasible. The as-prepared Pt^I?COF composite exhibits excellent performance for semi-hydrogenation phenylacetylene with 93.5% conversion and 90.2% selectivity to styrene under mild reaction conditions (1 ?bar H₂, 25 ?°C) within 20 ?min. It's worth noting that the turnover frequency (TOF) value reaches at 3965 h^-1, which outperforms most of recently reported excellent Pt-based catalysts for this reaction.

Full text of DOI:10.1016/j.jssc.2020.121176

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Constructing Pt @COF for semi-hydrogenation reactions of phenylacetylene
Jian Hong Li, Zhi Wu Yu, Jian Qiang Li, Ya Ling Fan, Zhi Gao, Jian Bo Xiong, Li
Wang, Yuan Tao, Li Xiao Yang, Yu Xin Xiao, Feng Luo
PII:
S0022-4596(20)30006-2
DOI:
https://doi.org/10.1016/j.jssc.2020.121176
YJSSC 121176
Reference:
To appear in: Journal of Solid State Chemistry
Received Date: 17 December 2019
Revised Date: 2 January 2020
Accepted Date: 4 January 2020
Please cite this article as: J.H. Li, Z.W. Yu, J.Q. Li, Y.L. Fan, Z. Gao, J.B. Xiong, L. Wang, Y. Tao, L.X.
I
Yang, Y.X. Xiao, F. Luo, Constructing Pt @COF for semi-hydrogenation reactions of phenylacetylene,
Journal of Solid State Chemistry (2020), doi: https://doi.org/10.1016/j.jssc.2020.121176.
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Feng Luo: Conceptualization, Methodology, Software
Jian Hong Li: Data curation, Writing- Original draft preparation.
Ya Ling Fan
Yu Xin Xiao
Zhi Wu Yu
,
Yuan Tao, Li Xiao Yang:Visualization, Investigation.
:
Supervision.:
,
Jian Qiang Li, Jian Bo Xiong:Software, Validation.:
Zhi Gao, Li Wang: Writing- Reviewing and Editing,
,

Constructing PtI@COF for Semi-Hydrogenation Reactions of
Phenylacetylene
Jian Hong Liab,† Zhi Wu Yuc,† Jian Qiang Lia, Ya Ling Fana, Zhi Gaoa, Jian Bo Xionga, Li Wanga,
Yuan Taoa, Li Xiao Yanga, Yu Xin Xiaoa and Feng Luoa*
A noble catalyst Pt @COF was first prepared, which exhibits remarkable performance for
semi-hydrogenation of phenylacetylene, including high selectivity, turnover frequency value, good
recycle, strong stability.

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Constructing PtI@COF for Semi-Hydrogenation Reactions of
Phenylacetylene
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Jian Hong Liab,† Zhi Wu Yuc,† Jian Qiang Lia, Ya Ling Fana, Zhi Gaoa, Jian Bo Xionga, Li Wanga,
Yuan Taoa, Li Xiao Yanga, Yu Xin Xiaoa and Feng Luoa*
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aState Key Laboratory for Nuclear Resources and Environment, and School of Biology, Chemistry
and Material Science, East China University of Technology, Nanchang, Jiangxi 344000, China,
bChina Institute of Atomic Energy, Beijing 102413, China
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cHigh Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, P. R. China
†These authors are the co-first author.
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* Corresponding author. E-mail address: ecitluofeng@163.com (F. Luo).
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Abstract: The great efforts have been devoted to fabricate excellent hydrogenation catalysts
owing to the broad applications in industrial fields. However, the preparation processes of
traditional hydrogenation catalysts are often complicated. Herein, mono-valence PtI@COF was
synthesized as a catalyst for semi-hydrogenation of phenylacetylene for the first time. The easily
prepared SO3H-linked COF possesses a two-dimensional eclipsed layered-sheet structure, making
its incorporation with metal ions feasible. The as-prepared PtI@COF composite exhibits excellent
performance for semi-hydrogenation phenylacetylene with 93.5% conversion and 90.2% selectivity
to styrene under mild reaction conditions (1 bar H2, 25℃) within 20 min. It's worth noting that the
turnover frequency (TOF) value reaches at 3965 h-1, which outperforms most of recently reported
excellent Pt-based catalysts for this reaction.
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Keywords: hydrogenation catalysts; PtI@COF; turnover frequency; mono-valence.
1. Introduction
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As a harmful material in polymerization of styrene, phenylacetylene readily results in catalyst
poisoning during styrene polymerization and thus affects properties of polystyrene. In this sense,
removing phenylacetylene via selective hydrogenation process is necessary for improving
qualities of polymerized styrene materials .[1-3] However, the selectivity to the desired styrene is
usually unsatisfied because of the easy generation of over-hydrogenation product
phenylethane.[4-5]Up to now, intensive research endeavors have been devoted to develop excellent
catalysts for selective hydrogenation of phenylacetylene to styrene. It was found that noble metal
(Pt, Pd, Au etc.) catalysts are the ideal choice because of their high catalytic activity and durable
stability.`[6-10] Amongst Pd-based materials are used intensively in the hydrogenation of
phenylacetylene because of their strong dissociative ability for H2.[11] However, some shortcomes,
such as unsatisfied catalytic selectivity, high metal content and long reaction time, hinder their
industrial applications.[12-25] Thus, developing new catalysts for efficiently catalyzed
hydrogenation of phenylacetylene is urgent.
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To date, Pt-based catalysts loaded on different supports including carbon nanotubes, [26-27]
triphenylphosphine polymer,[28] resin,[29] zeolite-templated carbon[20] were investigated for
semi-hydrogenation of phenylacetylene. For example, Li et al. reported a CNT-supported Pt
catalyst (Pt/CNTs) for hydrogenation of phenylacetylene, where the conversion and the selectivity
of styrene can reach at 98% and 86%, respectively.17 Pt/PSiO2 catalyst reported by Fukuoka et al.
exhibited 99.1% conversion of phenylacetylene and 99.5% selectivity to styrene.[30] Nevertheless,
the low intrinsic activity (TOF value) of these catalysts stimulate us to design new catalysts. For
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aforementioned Pt-based catalysts, their catalytic activities were realized by reduction of the Pt2+
species to zero valence Pt (Pt0), which endowed the metal active site for catalysis. In contrast to the
zero-valence state Pt0, mono-valence PtI metal composite, which may improve the instrical activity
of Pt-based catalysts, has not been studied for catalyzing hydrogenation of phenylacetylene ever.
In recent years, covalent organic frameworks (COFs) have attracted considerable interest since
the first discovery by Yaghi and co-workers in 2005,[31] which comprised of periodically extended
and covalently bound crystalline porous network structures.[32] Our group has synthesized a novel
material named COF-SO3H for uranium extraction from sea water, in which the COF-SO3H can
bear strong acid and alkali.[33-34] Thus, we believe that COF-SO3H should be excellent support to
prepare Pt-based catalysts, which are not well investigated in heterogeneous catalysis.
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Herein, an ammonium-modified material of [NH4]+ [COF-SO3 ] as a support to load Pt
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nanoparticles for semi-hydrogenation of phenylacetylene was studied. Apart from stabilizing Pt
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nanoparticles, the [NH4]+[COF-SO3 ] can also form strong chelates with Pt+ and thus enhances the
activity.[35]
16 2. Experimental section
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2.1 Synthesis of catalysts
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2.1.1 Synthesis of 1,3,5-triformylphloroglucinol
The ligand material 1,3,5-triformylphloroglucinol was synthesized in the light of the reported
literature.[36] Firstly, the hexamethylenetetramine (15.098g, 108mmol) and dried phloroglucinol
(6.014g, 49mmol) were added in a three-necked round-bottomed flask with 90mL trifluoroacetic
acid. Then the mixture solution was stirred for 2h at 100ºC under N2 condition in oil bath pan.
150mL 3mol/L HCl was added in the flask and continued to stir 2h. After that, the mixture solution
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was filtered by kieselguhr and extracted with dichloromethane at room temperature. The obtained
yellow solution was steamed using rotary evaporation at 50ºC and washed with hot ethanol after
dried over magnesium sulfate. Finally, the yellow powder was obtained after dried under vacuum.
2.1.2 Synthesis of 2, 5-dihydroxy benzenesulfonate amine
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Briefly, 63mg 1,3,5-triformylphloroglucinol and 84.7mg 2, 5-diaminobenzene sulfonic acid,
3mL N-butyl alcohol and 3mL o-dichlorobenzene were added to a 100 mL Schlenk tube in order.
After that the turbid solution was flash frozen in liquid nitrogen for three times after added acetic
acid(0.5mL,3mol/L). In the end, the tube was put into the muffle and set the temperature slowly
raised to 120 at 10 /min. The reaction was kept 120°C for 3 days and cooled to room temperature
at 6°C/h. Crimson powders were obtained by centrifugation with acetone and dried under vacuum.
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2.1.3 Synthesis of [NH4]+[COF-SO3 ]
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The ion-exchange material of [NH4]+[COF-SO3 ] is obtained by immerging COF-SO3H in
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NH3·H2O(1%) for 24 h and washed by water and methanol. Crimson powders were obtained by
centrifugation with acetone and dried under vacuum.
2.1.4 Synthesis of PtI@COF
The catalyst material was synthesized as followed. 100mg [NH4]+[COF-SO3 ] is dispersed in
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14mL deionized water and then added 400uL 0.125mol/L [Pt(NH3)4](NO3)2 stirring for 2h. After
that, the mixture washed by deionized water and methanol and dried at drying oven. Then, the dried
power is dispersed in 14mL deionized water and dropwise NaBH4(4mL 1mol/L) to reduce for 6 h
under N2 atmosphere. Finally, the crimson power sample was washed and dried at 60°C overnight
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and marked as [NH4]+[COF-SO3 ]. The content of Pt in [NH4]+[COF-SO3 ] is around 0.83 wt.%
confirmed by ICP.
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2.1.5 Synthesis of Pt0@COF
The prepared Pt0@COF was obtained by NaBH4(4mL 1mol/L) sprayed into
[Pt(NH3)4](NO3)2(400uL 0.125mol/L) solution for stirring at N2 atmosphere. After that, the 100mg
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[NH4]+[COF-SO3 ]was added and stirring for 2h. Finally, the mixture solution was dried under
vacuum oven at 60℃.
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2.2 Characterization
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The morphologies of the material were obtained by SEM-EDS (scanning electron microscope-
Energy Dispersive Spectrometer) measurements using a Hitachi S-4800 microscope. The powder
data were collected by PXRD (X-ray powder diffraction) using a Bruker AXS D8 Discover powder
diffractometer with monochromatized Cu-Kαradiation (at 40 kV, 40 mA, λ = 1.5406Å) in the rang
of 2θ = 3–85° with a step size of 0.018 and a count time of 5 s per step. The simulated powder
patterns were calculated by Mercury 1.4. IR (Infrared Spectra) measurements were measured by a
Bruker VERTEX 70 spectrometer in the 500-4000 cm–1 region. X-ray photoelectron spectroscopy
(XPS) was conducted using an ESCALAB250 spectrometer. The gas adsorption isotherms were
collected on a Belsorp-max. Ultrahigh-purity-grade (>99.999%) N2 gases were used during the
adsorption measurement. The Pt content in catalyst was measured by inductively coupled
plasma-mass spectroscopy (ICP-MS, NexION 300X). The catalytic reaction was traced and
identified by gas chromatography (GC, Agilent 7890A with a 0.25 mm×30 m DB-5 capillary
column) using an internal standard technique. Transmission electron microscopy (TEM)
micrographs were collected on a FEI Tecnai G2 F20 transmission electron microscope at an
accelerating voltage of 200 kV.
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2.3 Catalyst test
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2.3.1 General Procedure for the Catalytic Hydrogenation of Phenylacetylene
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In a typical procedure for catalytic activity test of PtI@COF, 114uL (1mmol) of
phenylacetylene, 15 mg of catalyst and 15 mL of ethanol as solvent were charged into a
three-necked, round-bottomed flask. Afterwards, the flask was purged with 1 MPa H2 for several
minutes to allow pure H2 atmosphere for the reaction. At this time, the mixture was magnetically
stirred at 25 ºC temperature and the reaction time was calculated at this point. Samples with 0.5 mL
withdrawn at regular intervals of reaction time were analyzed by GC (GC-2014) equipped with an
FID detector and a capillary column (DB-5, 30 m 0.45 mm 0.42 mm). The conversion, selectivity
and turnover frequency (TOF) were calculated on basis of the following equations:
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ꢋ
ꢎ
Conversion %=ꢀꢁꢂꢃꢄꢅꢆꢇꢂꢈꢄꢅꢂꢃꢂ ꢉꢂꢂꢊ ꢌꢍꢅ ꢏꢀꢁꢂꢃꢄꢅꢆꢇꢂꢈꢄꢅꢂꢃꢂ ꢐꢂꢑꢒꢊꢓꢂꢋꢌꢍꢅꢎX100%
ꢀꢁꢂꢃꢄꢅꢆꢇꢂꢈꢄꢅꢂꢃꢂ ꢉꢂꢂꢊꢋꢌꢍꢅꢎ
ꢔꢈꢄꢐꢂꢃꢂ ꢕꢐꢍꢊꢓꢇꢈꢋꢌꢖꢅꢎ
Selectivity %= ꢀꢁꢂꢃꢄꢅꢆꢇꢂꢈꢄꢅꢂꢃꢂ ꢉꢂꢂꢊ ꢌꢍꢅ ꢏꢀꢁꢂꢃꢄꢅꢆꢇꢂꢈꢄꢅꢂꢃꢂ ꢐꢂꢑꢒꢊꢓꢂꢋꢌꢍꢅꢎ X100%
ꢋ
ꢎ
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TOF(h-1)=( n PhenylacetyleneXCconversionXCselectivity)/nPtXt
2.3.2 Reuse experiment
In the reuse experiment, the catalyst was isolated by centrifugation and washed with ethanol
and dried at 70°C under vacuum. The same amount of phenylacetylene was added at every catalytic
reaction. After every catalytic reaction, the conversion and the selectivity of the products were
determined by GC.
22 3. Results and discussion
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As depicted in scheme 1, the synthesis of PtI@COF includes four steps. Firstly, COF-SO3H
was prepared through condensation between 1,3,5-triformylphloroglucinol and 2,5-diaminobenzene
sulfonic acid by the solvothermal method. Then the COF-SO3H was aminated by NH3·H2O to
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obtain [NH4]+[COF-SO3 ]. After that, the metal precursor [Pt(NH3)4](NO3)2 solution of Pt2+ was
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deposited in the [NH4]+[COF-SO3 ] material by ion exchange. Finally, Pt2+ was reduced to PtI under
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N2 atmosphere using NaBH4 as reducing agent. A series of characterizations were carried out for
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COF-SO3H、 [NH4]+[COF-SO3 ] and PtI@COF. The powder X-ray diffraction (PXRD) data of
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COF-SO3H and [NH4]+[COF-SO3 ] agree with the simulated one by Material Studio Forcite
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molecular dynamics method (Fig. 1a). C CP-MAS solid-state NMR spectroscopy (Fig. 2) further
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proves the β-ketoenamine-linked structure in COF-SO3H.[32] [NH4]+[COF-SO3 ] immersed in
strong acid, boiling water and strong base was characterized by PXRD testes. The results
demonstrate that the [NH4]+[COF-SO3 ] possess high chemical stability.(Fig. 3b)
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Scheme 1. Synthetic scheme of SO3H-decorated COF (COF-SO3H), the ammoniated material of
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[NH4]+[COF-SO3 ] and Pt-loaded material of PtI@COF.
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From the PXRD patterns (Fig. 1b) of PtI@COF, three intense peaks were found at 40°, 46°
and 67°, which were arranged to the (111), (200) and (220) reflections of face-centered cubic (fcc)
Pt crystal (JCPDS card, No. 04-0802), indicating the formation of Pt nanoparticles.[32] SEM image
revealed that PtI@COF still can keep the uniform fiber morphology as observed for COF-SO3H and
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[NH4]+[COF-SO3 ]. (Fig. 4) The character peak of -C-N (∼1213 m-1) and -C=C (∼1567 cm-1) was
discovered from the FTIR spectrum of PtI@COF, which almost identical to that of
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+
[NH4]+[COF-SO3 ]. Noteworthy, disappearance of NH4 with hydrogen bonds at 3210
cm-1comfirmed the ion exchange between Pt and [NH4]+ (Fig. 5)
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Fig. 1 a) The experimental and calculated PXRD patterns of COF-SO3H and [NH4]+[COF-SO3 ]. b)
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XRD patterns of [NH4]+[COF-SO3 ] and PtI@COF.
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Fig. 2 13C CP-MAS spectrum of COF-SO3H and [NH4]+[COF-SO3 ].
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+
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Fig. 3 a) TGA of [NH4 ][COF-SO3 ], b) The chemostability of [NH4]+[COF-SO3 ] under boiling
water, strong acid and strong base by PXRD patterns.
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Fig. 4 The SEM images and EDS mapping results of a)COF-SO3H, b) [NH4]+[COF-SO3 ] and c)
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PtI@COF, respectively.
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Fig. 5 FT-IR spectra of COF-SO3H、[NH4]+[COF-SO3 ] and PtI@COF.
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X-ray photoelectron spectroscopy (XPS) analysis of PtI@COF was used to probe the chemical
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valence state of Pt. Quantitative X-ray photoelectron spectroscopy (XPS) (Fig. 6) shows that most
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of the Pt2+ atoms have been reduced to Pt+ after treatmenting with NaBH4, and this value fits better
with that of unsaturated Pt+ species confined in MOFs[37] or ligated to thiols,[38] which
corresponds to formal Pt+ rather than to any typical signal for Pt(0).[39]
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Fig. 6 XPS spectra of Pt 4f electrons of PtI@COF.
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Compared with [NH4]+[COF-SO3 ], the N2 adsorption capacity at 77 K is largely reduced after
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Pt-loaded in sample, giving a BET surface area of 51 m2/g, most likely due to the occupation of
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pore by Pt nanoparticles (Fig. 7). TEM technique was used to characterize the particle sizes of Pt on
[NH4]+[COF-SO3 ] (Fig. 8). As shown in Fig. 8, PtI@COF are still keep the filiform morphology
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and Pt NPs uniformly distributed on the surface of material. The average size of Pt NPs in
PtI@COF is about 4.6 nm as displayed in Fig.8. The formation of metal NPs, especially for noble
metals, is difficult but important to improve the usage efficiency of expensive metal NPs. The
formation of small Pt clusters on PtI@COF is possibly due to the coordination ability of the
sulfonate ligand to Pt NPs. The thermogravimetric analysis (TGA) demonstrates that PtI@COF
owns excellent thermal stabilities up to 300 (Fig. 9), which provides the demands for potential
applications in catalysis. Inductively coupled plasma (ICP) analysis demonstrates that the Pt content
in the sample is 0.83 wt.%, which is close to that determined by SEM-EDS spectrum (Table 1).
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Fig. 7 The N2 adsorption–desorption at 77K for PtI@COF with the insert of distribution of pore
size.
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Fig. 8 STEM images of PtI@COF.
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Fig. 9 TGA of PtI@COF.
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Table 1. The element contents of the as- PtI@COF.
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Element
C
N
O
S
Pt
Total
100.00
100.00
Content(wt.%)a
Content(wt.%)b
58.86
56.75
23.36
25.13
12.08
11.79
4.87
5.42
0.83
0.91
1
a determined by element analysis
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b determined by SEM-EDS spectrum
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To test the catalytic activity of PtI@COF, selective hydrogenation of phenylacetylene was
performed. which was carried out with 114 uL of phenylacetylene, 15.0 mg of the catalyst, and 15
mL of ethanol in a 50mL three-necked round-bottomed flask under controlled H2 pressures and
temperatures. Fig. 10 shows the conversion of phenylacetylene and selectivity for styrene by the Pt
catalysts under the conditions of 1 bar H2 at different temperature. The PtI@COF catalyst afforded
93.5% phenylacetylene conversion and 90.2% styrene selectivity in 20 min, which was apparently
the best among the tested temperatures at 25 . The kinetic curve of PtI@COF indicates that the
reaction rate is fast in the initial 20 min without any induction time. Within 40 min, 100%
conversion was achieved.
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Fig. 10 The conversion of phenylacetylene and selectivity for styrene by PtI@COF over the
different temperature.
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To disclose the catalytic mechanism, a comparison experiments are carried out. Under similar
reaction conditions, Pt2+@COF (prepared by impregnation of [Pt(NH3)4](NO3)2 on
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[NH4]+[COF-SO3 ] without reduction)、Pt0@COF (prepared by spraying method)[40-41] and the
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pristine [NH4]+[COF-SO3 ] were applied to semi-hydrogenation of phenylacetylene. Seen from
Table 2, Pt including in Pt2+, Pt+ and Pt0 shows high catalytic activity for hydrogenation reaction of
phenylacetylene. However, only the PtI@COF catalyst performs high selectivity. Accordingly, Pt+
loaded on support could be a good candidate for semi-hydrogenation of phenylacetylene. In
addition, seen from Table 3, by comparing with the reported semi-hydrogenation experiments of
alkynes based on Pt catalyst in the literature, it is clearly suggesting that our catalyst presents a
highly rare example showing both high selectivity and conversion for semi-hydrogenation. Most
importantly, ultrahigh catalytic efficiency for the PtI@COF catalyst evaluated by the turnover
frequency value is up to 3965 h−1, which outperforms most of reported catalysts for such use.
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Table 2. Selective hydrogenation of phenylacetylene to styrene on different catalysts.
Catalysts
t
Conversion
(%)
Selectivity to styrene
(min)
20
72
20
20
(%)
[NH4]+[COF-SO3 ]
2.4
100.0
8.5
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Pt2+@COF
99.8
Pt0@COF
85.8
47.8
90.2
PtI@COF
93.5
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Table 3. A comparison with other reported catalysts for hydrogenation of alkyne.
Catalyst
H2(bar)
t(min)
T(℃)
C(%)
S(%)
TOF(h-1)
Ref
PtI@COF
Pt/oCNTs
1
20
60
25
50
50
45
50
50
93.5
98
90.2
86
3965
43
This work
0.4
0.4
20
17
17
20
29
30
Ru@Pt/oCNTs
Pt/PSiO2
60
88
88
132
120
120
60
99.1
100
63
99.5
90
2304
812
CN@Pt/CNTs
Pt@ZTC
0.3
0.5
85
4766
13

MPF-SO3H-Pt
Pt
1
1
1
15
550
9
80
50
51
43
30.8
90
89
90.2
69
930
31
1368
32a
32b
Pt/ABSFGF
1
2
The recycling stability of PtI@COF was also investigated. As shown in Fig. 11, neither
conversion nor selectivity exhibited any considerable decrease in comparison with the fresh catalyst.
This demonstrates that PtI@COF is highly stable and durable. To further confirmation the stability
of the sample, the XRD and XPS were detected after 1st cycle and 3rd cycle reaction. From Fig. 12,
it is demonstrated that the crystalline structure is changed slightly after 1st cycle and 3rd cycle
reaction. Fig. 13 shows that after 1st cycle and 3rd cycle reaction, there is almost no remarkable
change of the distribution of Pt NPs in the used PtI@COF catalyst. Above results indicate the
PtI@COF has high stability. Meanwhile, Fig. 14 shows the change of Pt0 of Pt0@COF after used.
As shown in Table 4, it further demonstrates the Pt @COF presents excellent catalytic
performance under mild reaction conditions for various alkynes, suggesting its superior application
in this field.
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Fig. 11 The recyclability of PtI@COF catalyst.
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Fig. 12 PXRD patterns of different samples.
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Fig. 13 XPS spectra of different samples for PtI@COF.
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Fig. 14 XPS spectra of different samples for Pt0@COF.
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Table 4. Semi-hydrogenation of various alkynes catalyzed by Pt @COF catalyst.
Entry
1
Substrate
Time
(min)
20
Product
Conversion
(%)
Selectivity
(%)
93.5
90.2
2
3
4
5
120
80
92.0
91.0
89.5
90.4
4-Octene and isomer
alkenes
25
94.0
92.0
90.0
88.7
2-pentene and isomer
alkenes
40
3
4
5
6
4. Conclusions
In conclusion, COF-supported catalyst of PtI@COF was synthesized by a simple
impregnation-reduction method as a novel catalyst for selectively catalyzing hydrogenation of
phenylacetylene. It is the first time to prepare the mono-valence PtI@COF. And the outstanding
catalytic performance is achieved with 93.5% conversion and 90.2% selectivity to styrene under
extremely mild reaction conditions (1 bar H2, 25 ). Noticeably, the turnover frequency (TOF)
value is as high as 3965 h-1, which exceeds most of reported Pt-based catalysts. A series of
experimental and characterization results disclose that Pt+ on COF can provide not only more
accessible active sites for phenylacetylene conversion, but also allow for high selectivity. Moreover,
the as-fabricated PtI@COF also shows high stability without obvious loss even after three
successive runs. This work provides a novel strategy for the fundamental design of COF-supported
metal catalysts and thereby provides a new avenue for the fabrication of catalytic materials.
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Acknowledgments:
We thanks to the National Science Foundations of China (21871047, 21661001, and
U1832148), the Natural Science Foundation of Jiangxi Province of China (20192BAB203002), the
Natural Science Foundation of Jiangxi Province of China (20181ACB20003), and the technology
program of education department of Jiangxi Province of China (GJJ1505).
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Highlights:
Ⅰ
1.This work presents the first case of mono-valence Pt @COF for semi-hydrogenation
reactions of phenylacetylene.
2.This work firstly present a simple impregnation-reduction method for the preparation
of Pt-anchored covalent organic framework (PtI@COF).
3. Pt+ and Pt0 can synergistically promote the transformation of phenylacetylene to
styrene.
Ⅰ
4. The Pt @COF exhibits remarkable performance with 93.5% conversion and 90.2%
selectivity to styrene under mild reaction conditions (1 bar H2, 25 ℃).
5.This kind of material is highly repeatable for such use.

Declaration of interests
☐ The authors declare that they have no known competing financial interests or personal relationships
that could have appeared to influence the work reported in this paper.
☒The authors declare the following financial interests/personal relationships which may be considered
as potential competing interests: