An Efficient and Practical System for the Synthesis of
N,N-Dimethylformamide by CO
2Hydrogenation using a
Heterogeneous Ru Catalyst: From Batch to Continuous
Flow
Gunniya Hariyanandam Gunasekar+,[b] Sudakar Padmanaban+,[a] Kwangho Park+,[c] Kwang-Deog Jung,[b] and Sungho Yoon*[a]
Contents
Materials and Characterization Synthesis of PP-POP
Synthesis of 1
Representative procedure for the hydrogenation in batch process Representative procedure for the hydrogenation in trickle bed reactor
List of figures
Figure S1. STEM- and SEM-EDX mapping image of 1 Figure S2. XPS C1s-Ru3d region of 1
Figure S3. PXRD of 1
Figure S4. Gas chromatography results Figure S5. Filtration test results
Figure S6. STEM-EDX mapping image of recovered catalyst Figure S7. XPS of recovered catalyst
Figure S8. Flow diagram of the trickle-bed process
Figure S9-13. 1H NMR of the reaction mixture after hydrogenation
List of Tables
Table S1. Catalytic activity of previously reported heterogeneous catalysts Table S2. Atomic composition of 1 by SEM-EDX
Table S3. Effect of FA addition
Materials and Characterization
All chemicals purchased were of analytical grade and used without further purification unless otherwise mentioned. 1,2-bis(dichlorophosphino)ethane, n-butyllithium (1.6 M in hexanes), phenyllithium (1.8 M in ether), Ruthenium chloride hydrate, and Dimethylamine in water were purchased from Sigma Aldrich. Tetrakis(4-bromophenyl)methane and Dimethylamine in methanol or ethanol or iso-propanol or tetrahydrofuran were purchased from Tokyo Chemical Industry Co., Ltd. CO2 (99.99%)
and H2 (99.99%) were purchased from Sinyang gas industries.
The instrument INSPECT F JEOL LTD (JAPAN) JEM-7610F operated at an accelerating voltage of 20.0 kV was used to measure SEM and EDS. Powder X-ray diffraction (PXRD) was measured on an RIGAKU D/Max 2500V using Cu (40 kV, 30 mA) radiation. N2 sorption measurements were carried out K in an automated gas
sorption system of Belsorp II mini, BEL Japan, Inc., at 77; the samples were degassed at 80 °C for 12 h before the measurements. 13C cross-polarization magic-angle spinning
solid-state nuclear magnetic resonance spectroscopy (13C CPMAS ssNMR) data were
acquired at ambient temperature on 400 MHz Solid state NMR spectrometer (AVANCE III HD, Bruker, Germany) at KBSI Western Seoul center with an external magnetic field of 9.4 T. The operating frequency was 100.66 MHz for 13C and the spectra were
referenced to TMS. The samples were contained in HX CPMAS probe, with 4 mm o.d. Zirconia rotor. Ruthenium content in 1 was measured by ICP-OES (iCAP-Q, Thermo fisher scientific) using microwave assisted acid digestion system (MARS6, CEM/U.S.A):
1 (10.0 mg) were digested in a mixture conc. HNO3 (5.0 mL) solution under microwave
rays at 280 °C for 20 min (ramp rate = 25 °C/min). A TEM-Talos; F 200X system was used for the transmission electron microscope (TEM) measurements. XPS data’s were
acquired on an ESCA 2000 (VG microtech) at a pressure of ~3 x 10-9 mbar using Al-Ka
as the excitation source (hγ=1486.6 eV) with concentric hemispherical analyzer.
Solution state 1H NMR spectroscopy was measured on a 400 MHz NMR spectrometer
(ASCEND III HD, Bruker, Germany).
Synthesis of PP-POP
PP-POP was synthesized inside a glovebox by following the reported procedure
with Tetrakis(4-bromophenyl)methane.[1] To a solution of
4,4′′-tetrakis(p-bromophenyl)methane (1.062 g, 1.572 mmol) in Et2O (30.0 mL) was added n-BuLi
(0.806 g, 12.580 mmol) and left to stir for 1.5 h. The resulting white solid was filtered over a glass filter and washed with ether (100 mL) followed by hexane (100 mL). The isolated solids were then suspended in THF (50 mL). To this, a solution of bis(dichlorophosphino)ethane (0.364 g, 1.572 mmol) in THF (8.0 mL) was slowly added dropwise and the pale pink suspension was stirred at 20 °C for 2 h. Subsequently, phenyllithium (0.125 g, 1.494 mmol) was added and the dark purple suspension left to react for 24 h. Then, the reaction as quenched by the addition of MeOH (50 mL) and left to stir for 10 min. The pale suspension was filtered over a glass filter and the isolated solid was repeatedly washed with MeOH (50 mL × 2) followed by Et2O (200 mL). After filtration, the obtained solid was finally dried overnight under vacuum at 60 °C for 16 h. (Yield = 0.582 g, white powder).
Synthesis of 1
To a suspension of PP-POP (0.346 g) in 20.0 mL methanol was added a solution of RuCl3.xH2O (0.0091 g) in 10.0 mL methanol while vigorously stirring the suspension.
The reaction mixture was stirred at reflux conditions for 48 h. After 48 h, the off-white solid was filtered and repeatedly washed with methanol (10.0 mL x 6). The solid was dried under vacuum at 60 °C for 16 h. (Yield = 0.341 g).
Representative procedure for the hydrogenation in batch process
In a typical run, catalyst 1 was dispersed in a DMA-solution in the reactor vessel, and tightly closed without any leak. The reactor was initially pressurized with CO2 and
then with H2 (1:1) to the desired pressure at room temperature and heated at 80-140 °C
for appropriate time. The gases were slowly vented inside a working hood, and the reaction mixture was unloaded from the vessel. The yield of the products was analyzed by 1H NMR spectroscopy with imidazole (IMD) or 1,3,5-trimethoxybenzene (TMB) as an
internal standard. For recycling experiments, the catalyst was filtered after each run, washed with methanol (2*10 mL), and dried under vacuum at 60 °C for 12 h. The obtained solid was then used for the next run.
Representative procedure for the hydrogenation in trickle bed reactor
A schematic picture of the reactor diagram with stainless-steel bar reactor is given in Figure S8. A mixture of catalyst 1 (0.5 g, 3 wt% Ru) and silicon carbide (1.0 g) was loaded at the middle of the stainless-steel tubular reactor (i.d: 7 mm) and filled the empty space in the reactor with glass wools and beads. H2 and CO2 were supplied using
heated and mixed before entering into the reactor. The system was flushed with H2 and
CO2 gases for few minutes, and pressurized with flow rate of 14 and 7 L h-1, respectively
to 12 MPa using a backpressure valve. The reactor was then heated to 140 °C, and a solution of DMA in methanol was supplied to the reactor using a high-pressure liquid pump with a flow rate of 15 mL h-1. At this stage, the system was kept for stabilization
of about 1 h. After this time, the liquid product was started to collect and analyzed by 1H
NMR spectroscopy with 1,3,5-trimethoxybenzene (TMB) as an internal standard.
Figure S1. EDS mapping image of 1 by STEM
Figure S2. XPS C1s-Ru3d region of 1
Figure S3. PXRD of 1
Figure S4. Gas chromatography results
20 40 60 80
2()
Gas Retention Time (min)
H2 1.58
CH4 3.83
CO 4.44
CO2 6.44
0 2 4 6 8 10 12 14
Retention time (min) H2
CO2
Ru3d5/2
= 280.8 eV
290 288 286 284 282 280
Figure S5. Filtration test results
Figure S6. EDS mapping of recovered catalyst by STEM
Figure S7: XPS of recovered catalyst
0 5 10 15 20 25 0 20 40 60 80 100 YD M F+ FA (%) Time (h) 290 288 286 284 282 280 278
Binding energy (eV)
Ru 3d5/2 =
280.8 eV Ru 3d3/2 =
285.0 eV
490 480 470 460
Binding Energy (eV)
Ru3p3/2
= 462.1 eV
Ru3p3/2
Figure S8: Flow diagram of the trickle-bed process
(1): 1. Reactor; 2. Control Box; 3. CO2 pump; 4. Solvent pump; 5. Mass-flow controller; 6. Heat
exchanger; 7. CO2 feed tank; 8. Solvent feed tank; 9. Booster pump; 10. Gas chromatography;
11. Back-pressure regulator; 12. Liquid reservoir; 13. Gas cylinder; 14. Liquid sampling receiver; 15. Heating furnace and 16. Dry gas meter.
Figure S9. 1H NMR of the reaction mixture after hydrogenation with DMA in water
FA
Figure S10. 1H NMR of the reaction mixture after hydrogenation with DMA in methanol
Figure S11. 1H NMR of the reaction mixture after hydrogenation with DMA in ethanol
FA DMF IMD FA DMF TMB
Figure S12. 1H NMR of the reaction mixture after hydrogenation with DMA in
iso-propanol
Figure S13. 1H NMR of the reaction mixture after hydrogenation with DMA in THF
FA DMF IMD FA DMF TMB
Figure S14. Characterization of PP-POP
The physical and chemical properties of PP-POP are similar to those of previously reported alike POP.[2]
(a) 13C CP-MAS (125-150 ppm = aromatic carbons; 68.3 = aliphatic methane carbons;
26.3 = aliphatic ethane carbons)
(b) 31P{1H}solid state spectroscopy (-11.4 ppm = trivalent phosphorous species; 39.5 =
May be phosphine oxide)
(C)N2 sorption analysis (d) PXRD analysis
BET surface area = 466 m2/g
Total Pore volume = 0.457 cm3/g
* ** (a) * (b) 0 100 200 0.1 0.2 0.3 dV p /d lo g dp dVp (nm) 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 Volu me (cm 3/g ) p/p 0 BJH plot 20 40 60 80 2()
Catalyst Additive T (°C) Total Pressure (MPa) Time (h) Yield of DMF (%)
TON Recyclability (yield of DMF in %)
Ref.
[RhCl{PPh2(CH2)2Si(OEt)3}3] MeCO2H 100 21.5 15 4 530 NA 3
[IrCl{PPh2(CH2)2Si(OEt)3}3] MeCO2H 100 21.5 15 23 2900 NA 3
[RuCl2{PPh2(CH2)2Si(OEt)3}3] H3PO4 100 21.5 15 25 3230 NA 3
[PdCl2{PPh2(CH2)2Si(OEt)3}3] MeCO2H 100 21.5 15 11 1410 NA 3
[PtCl2{PPh2(CH2)2Si(OEt)3}3] H3PO4 100 21.5 15 10 1490 NA 3
[RuCl2{PMe2(CH2)2Si(OEt)3}3] H3PO4 133 21.5 60 82 110800 Values were not
reported
3
Cu/ZnO - 140 12 6 97 NA 94 [after 4th four run] 4
Ir/HSA-TiO2-A - 140 6.0 16 93 Productivity = 850
mmol gIr-1 h-1
~91 [after 5th run] 5
Pd/Al2O3-NR-RD - 130 3 24 84 NA NA for DMF synthesis 6
GO-Ir - 100 6 3 87 2592 ~82 [after 6th run] 7
Table S2. Atomic composition of 1 by SEM-EDX analysis
C O P Ru Cl
82.87 7.04 8.15 0.50 1.44
Table S3. Effect of FA addition
FA addition (mol %) YDMF+FA (%) YDMF (%) YFA (%) 0 50.1 47.3 2.7 5 51.9 49.3 2.6 10 54.2 52.0 2.2 25 60.2 56.8 3.3
Table S4. Atomic composition of recovered catalyst by SEM-EDX analysis
C P Ru Cl
89.68 4.91 0.13 0.07
Reference:
[1] P. J. C. Hausoul, T. M. Eggenhuisen, D. Nand, M. Baldus, B. M. Weckhuysen, R. J. M. Klein Gebbink, P. C. A. Bruijnincx, Catal. Sci. Technol. 2013, 3, 2571-2579.
[2] J. Fritsch, F. Drache, G. Nickerl, W. Böhlmann, S. Kaskel, Micropor. Mesopor. Mat.
2013, 172, 167–173.
[3] O. Krocher, R. A. Koppel, M. Froba, A. Baiker, J. Catal. 1998, 178, 284-298.
[4] J. Liu, C. Guo, Z. Zhang, T. Jiang, H. Liu, J. Song, H. Fan, B. Han, Chem. Commun.
[5] Q.-Y. Bi, J.-D. Lin, Y.-M. Liu, S.-H. Xie, H.-Y. He, Y. Cao, Chem. Commun. 2014, 50, 9138—9140.
[6] X. Cui, Y. Zhang, Y. Deng, F. Shi, Chem. Commun. 2014, 50, 189
[7] S. Kumar, P. Kumar, A. Deb, D. Maiti, S. L. Jain, Carbon 2016, 100, 632-640. [8] Y. Wu, T. Wang, H. Wang, X. Wang, X. Dai, F. Shi, Nat. Commun. 2019, 10, 2599.
