Non-oxidative coupling of methane over Mo-doped CeO2 catalysts: Understanding surface and gas-phase processes

doi:10.1016/S1872-2067(23)64440-7

Abstract

Abstract:

Direct catalytic non-oxidative coupling is a promising route for the valorization of abundant methane. Understanding the mechanism is difficult because reactions at the surface of the catalyst and in the gas phase via radicals are important at the high temperatures employed. Herein, a series of Mo-doped CeO₂ samples with isolated Mo sites were prepared by flame spray pyrolysis method and screened for their performance in non-oxidative coupling of methane. The selectivity to value-added C₂ hydrocarbons (ethane and ethylene) among gas-phase products could reach 98%. During the reaction, the isolated Mo-oxo species in the as-prepared catalyst are reduced and convert into Mo (oxy-)carbide species, which act as the active sites for methane activation. By varying the available catalyst-free gas volume along the length of the reactor, we studied the contribution of gas-phase reactions in the formation of different products. Ethane is the primary product of non-oxidative methane coupling and, at least, a part of ethylene and most of benzene is formed through gas-phase chemistry. This work provides insights into the design of efficient catalysts for non-oxidative coupling of methane and highlights the importance of reducing the free volume in the reactor to limit secondary gas-phase reactions.

Key words: Methane, Non-oxidative coupling, CeO₂, Mo, Active site

Hao Zhang, Yaqiong Su, Nikolay Kosinov, Emiel J. M. Hensen. Non-oxidative coupling of methane over Mo-doped CeO₂ catalysts: Understanding surface and gas-phase processes[J]. Chinese Journal of Catalysis, 2023, 49: 68-80.

×
share this article

Add to citation manager EndNote|Ris|BibTeX

URL: https://www.cjcatal.com/EN/10.1016/S1872-2067(23)64440-7

https://www.cjcatal.com/EN/Y2023/V49/I6/68

Figures/Tables 11

Fig. 1. Synchrotron XRD patterns (a) and Mo 3d XP spectra (b) of fresh Mo@CeO2 catalysts. The experimental data are labeled using circles. The fitting results and the background are shown in grey.

Table 1 Mo/Ce ratios and actual Mo loadings obtained by XPS and ICP-OES analysis.

Catalyst	Mo loading (wt%)	Surface Mo/Ce ratio	Total Mo/Ce ratio
1Mo	1.11	0.05	0.02
2Mo	1.97	0.11	0.04
3Mo	3.14	0.33	0.06
4Mo	4.19	0.40	0.08

Fig. 2. AC-TEM (a), HAADF-STEM (b) and STEM-EDX elemental mapping analysis (c?e) of 1Mo; AC-TEM (f), HAADF-STEM (g) and STEM-EDX (h?j) measurements of 2Mo; AC-TEM (k), HAADF-STEM (l) and STEM-EDX (m?o) measurements of 4Mo.

Fig. 3. k3-weighted FT EXAFS (a) and the surface and bulk Mo content (b) of fresh Mo@CeO2 catalysts. The FT EXAFS is shown without phase correction. The Mo content was calculated using the bulk Mo loading obtained by elemental analysis and the contribution of each Mo species. The percentages (p) of Mo-O4 and Mo-O8 sites were calculated using the equation CN = 4 × pMo-O4 + 8 × pMo-O8, where the coordination number (CN) was obtained by EXAFS fitting. The insets in panel (b) show the DFT-optimized structures of Mo centers on CeO2 (111) surface (marked by Mo-O4) and in the bulk of CeO2 (marked by Mo-O8). Red: O atoms; ivory: Ce atoms; cyan: Mo atoms. Oxygen atoms coordinated with Mo in Mo-O4 are shown with smaller size balls. The atoms on the top layer in Mo-O8 are shown using smaller balls.

Fig. 4. (a) Methane conversion and product distribution over Mo-doped CeO2 catalysts, the error bar indicates the standard deviation. (b) C2 hydrocarbon yield, overall selectivity and CH4 conversion over 2Mo during two reaction-regeneration cycles. Conditions: 50 mg of catalyst, 950 °C, 20 mL/min 95 vol% CH4 and 5 vol% Ar.

Fig. 5. Pulse reaction over 2Mo catalyst (a) and bare CeO2 support (b). Conditions: 950 °C, 50 mg catalyst, 2 mL CH4 pulses every 180 s.

Fig. 6. Operando Mo-K edge XAS results of Mo species in 2Mo with XANES spectra (a) and MS signals (b) (15 °C/min to 750 °C and dwell for 20 min; 15 mL/min CH4; 150 mg of 2Mo catalyst).

Fig. 7. (a) The fraction of three components obtained from MCR-ALS analysis during reaction. (b?d) Their corresponding XANES. The relevant XANES of reference samples are also included.

Fig. 8. AC-TEM image (a), HAADF-STEM image (b), and STEM-EDX elemental mapping analysis (c?e) of 2Mo_used. The inset in panel (a) shows the enlarged region marked by the white square.

Fig. 9. (a) XRD patterns of used Mo@CeO2 catalysts. (b) k3-weighted FT EXAFS of used catalysts. The spectrum of the Mo2C reference is shown for comparison. EXAFS spectra are displayed without phase correction.

Fig. 10. (a) Reactor configurations employed to study gas-phase contributions of the NOCM reaction. (b) The catalytic performance of 2Mo evaluated for different reactor configurations. (c) Ar physisorption isotherms of the 2Mo catalyst upon pressing at different loads, the inset shows the pore size distribution. (d) Catalytic performance of the 2Mo catalysts pressed at different loads, the error bar indicates the standard deviation of experiments.

References

[1]	P. Schwach, X. Pan, X. Bao, Chem. Rev., 2017, 117, 8497-8520.
[2]	A. I. Olivos-Suarez, A. Szecsenyi, E. J. M. Hensen, J. Ruiz-Martinez, E. A. Pidko, J. Gascon, ACS Catal., 2016, 6, 2965-2981.
[3]	W. Taifan, J. Baltrusaitis, Appl. Catal. B, 2016, 198, 525-547.
[4]	T. V. Choudhary, E. Aksoylu, D. Wayne Goodman, Catal. Rev. Sci. Eng., 2003, 45, 151-203.
[5]	X. Meng, X. Cui, N. P. Rajan, L. Yu, D. Deng, X. Bao, Chem, 2019, 5, 2296-2325.
[6]	K. Sun, D. M. Ginosar, T. He, Y. Zhang, M. Fan, R. Chen, Ind. Eng. Chem. Res., 2018, 57, 1768-1789.
[7]	H. Zhang, E. J. M. Hensen, N. Kosinov, Comprehensive Inorganic Chemistry III (Third edition), Elsevier: Amsterdam, 2023, 6, 311-326.
[8]	D. Eggart, X. Huang, A. Zimina, J. Yang, Y. Pan, X. Pan, J.-D. Grunwaldt, ACS Catal., 2022, 12, 3897-3908.
[9]	J. H. Lunsford, Angew. Chem. Int. Ed., 1995, 34, 970-980.
[10]	Y. Xu, L. Lin, Appl. Catal. A, 1999, 188, 53-67.
[11]	Y. Xu, X. Bao, L. Lin, J. Catal., 2003, 216, 386-395.
[12]	N. Kosinov, E. J. M. Hensen, Adv. Mater., 2020, 32, 2002565.
[13]	L. Wang, L. Tao, M. Xie, G. Xu, J. Huang, Y. Xu, Catal. Lett., 1993, 21, 35-41.
[14]	X. Guo, G. Fang, G. Li, H. Ma, H. Fan, L. Yu, C. Ma, X. Wu, D. Deng, M. Wei, D. Tan, R. Si, S. Zhang, J. Li, L. Sun, Z. Tang, X. Pan, X. Bao, Science, 2014, 344, 616-619.
[15]	P. Xie, T. Pu, A. Nie, S. Hwang, S. C. Purdy, W. Yu, D. Su, J. T. Miller, C. Wang, ACS Catal., 2018, 8, 4044-4048.
[16]	D. Bajec, A. Kostyniuk, A. Pohar, B. Likozar, Chem. Eng. J., 2020, 396, 125182.
[17]	J.-H. Wen, G.-C. Wang, J. Phys. Chem. C, 2020, 124, 13249-13262.
[18]	Y. Yao, Z. Huang, P. Xie, L. Wu, L. Ma, T. Li, Z. Pang, M. Jiao, Z. Liang, J. Gao, Y. He, D. J. Kline, M. R. Zachariah, C. Wang, J. Lu, T. Wu, T. Li, C. Wang, R. Shahbazian-Yassar, L. Hu, Nat. Nanotechnol., 2019, 14, 851-857.
[19]	X. Ma, K. Sun, J.-X. Liu, W.-X. Li, X. Cai, H.-Y. Su, J. Phys. Chem. C, 2019, 123, 14391-14397.
[20]	J. Hao, P. Schwach, G. Fang, X. Guo, H. Zhang, H. Shen, X. Huang, D. Eggart, X. Pan, X. Bao, ACS Catal., 2019, 9, 9045-9050.
[21]	J. Hao, P. Schwach, L. Li, X. Guo, J. Weng, H. Zhang, H. Shen, G. Fang, X. Huang, X. Pan, C. Xiao, X. Yang, X. Bao, J. Energy Chem., 2020, 52, 372-376.
[22]	S. J. Han, S. W. Lee, H. W. Kim, S. K. Kim, Y. T. Kim, ACS Catal., 2019, 9, 7984-7997.
[23]	V. Muravev, G. Spezzati, Y.-Q. Su, A. Parastaev, F.-K. Chiang, A. Longo, C. Escudero, N. Kosinov, E. J. M. Hensen, Nat. Catal., 2021, 4, 469-478.
[24]	J. Kieffer, V. Valls, N. Blanc, C. Hennig, J. Synchrotron Radiat., 2020, 27, 558-566.
[25]	B. H. Toby, R. B. Von Dreele, J. Appl. Crystallogr., 2013, 46, 544-549.
[26]	B. Ravel, M. Newville, J. Synchrotron Radiat., 2005, 12, 537-541.
[27]	M. Alain, M. Jacques, M.-B. Diane, P. Karine, J. Phys. Conf. Ser, 2009, 190, 012034.
[28]	M. Newville, J. Phys. Conf. Ser, 2013, 430, 012007.
[29]	G. Kresse, J. Hafner, Phys. Rev. B, 1994, 49, 14251-14269.
[30]	P. E. Blöchl, Phys. Rev. B, 1994, 50, 17953-17979.
[31]	J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 1996, 77, 3865-3868.
[32]	S. Dudarev, G. Botton, S. Savrasov, C. Humphreys, A. Sutton, Phys. Rev. B, 1998, 57, 1505-1509.
[33]	S. Fabris, S. de Gironcoli, S. Baroni, G. Vicario, G. Balducci, Phys. Rev. B, 2005, 72, 237102.
[34]	M. Cococcioni, S. De Gironcoli, Phys. Rev. B, 2005, 71, 035105.
[35]	J. L. Da Silva, M. V. Ganduglia-Pirovano, J. Sauer, V. Bayer, G. Kresse, Phys. Rev. B, 2007, 75, 045121.
[36]	K. Reuter, M. Scheffler, Phys. Rev. B, 2003, 68, 045407.
[37]	J. Zhu, F. Cannizzaro, L. Liu, H. Zhang, N. Kosinov, I. A. W. Filot, J. Rabeah, A. Brückner, E. J. M. Hensen, ACS Catal., 2021, 11, 11371-11384.
[38]	I. Diaz-Aburto, F. Gracia, M. Colet-Lagrille, Fuel Cells, 2019, 19, 147-159.
[39]	V. L. Sushkevich, O. V. Safonova, D. Palagin, M. A. Newton, J. A. van Bokhoven, Chem. Sci., 2020, 11, 5299-5312.
[40]	C. Gueret, M. Daroux, F. Billaud, Chem. Eng. Sci., 1997, 52, 815-827.
[41]	Y. Liu, H. Zhang, A. S. G. Wijpkema, F. J. A. G. Coumans, L. Meng, E. A. Uslamin, A. Longo, E. J. M. Hensen, N. Kosinov, Chem. Eur. J., 2022, 28, e202103894.
[42]	N. Kosinov, A. S. G. Wijpkema, E. Uslamin, R. Rohling, F,. J. A. G. Coumans, B. Mezari, A. Parastaev, A. S. Poryvaev, M. V. Fedin, E. A. Pidko, E. J. M. Hensen, Angew. Chem. Int. Ed., 2018, 57, 1016-1020.
[43]	C. Jimenez-Orozco, E. Florez, A. Moreno, P. Liu, J. A. Rodriguez, J. Phys. Chem. C, 2017, 121, 19786-19795.
[44]	C. Xu, A. S. Al Shoaibi, C. Wang, H.-H. Carstensen, A. M. Dean, J. Phys. Chem. A, 2011, 115, 10470-10490.
[45]	A. Puente-Urbina, Z. Pan, V. Paunovic, P. Sot, P. Hemberger, J. A. van Bokhoven, Angew. Chem. Int. Ed., 2021, 60, 24002-24007.
[46]	T. Zhang, X. Yang, Q. Ge, Catal. Today, 2021, 368, 140-147.
[47]	O. Solcova, L. Matejova, P. Topka, Z. Musilova, P. Schneider, J. Porous Mater., 2011, 18, 557-565.

Non-oxidative coupling of methane over Mo-doped CeO₂ catalysts: Understanding surface and gas-phase processes

RichHTML

PDF (PC)

Knowledge

Supporting Information

Abstract

Cite this article

share this article

share this article

Figures/Tables 11

References

Related Articles 15

Recommended Articles

Metrics

[1]	Binbin Zhao, Wei Zhong, Feng Chen, Ping Wang, Chuanbiao Bie, Huogen Yu. High-crystalline g-C₃N₄ photocatalysts: Synthesis, structure modulation, and H₂-evolution application [J]. Chinese Journal of Catalysis, 2023, 52(9): 127-143.
[2]	Yong Liu, Xiaoli Zhao, Chang Long, Xiaoyan Wang, Bangwei Deng, Kanglu Li, Yanjuan Sun, Fan Dong. In situ constructed dynamic Cu/Ce(OH)_x interface for nitrate reduction to ammonia with high activity, selectivity and stability [J]. Chinese Journal of Catalysis, 2023, 52(9): 196-206.
[3]	Sikai Wang, Xiang-Ting Min, Botao Qiao, Ning Yan, Tao Zhang. Single-atom catalysts: In search of the holy grails in catalysis [J]. Chinese Journal of Catalysis, 2023, 52(9): 1-13.
[4]	Xin Liu, Maodi Wang, Yiqi Ren, Jiali Liu, Huicong Dai, Qihua Yang. Construction of modularized catalytic system for transfer hydrogenation: Promotion effect of hydrogen bonds [J]. Chinese Journal of Catalysis, 2023, 52(9): 207-216.
[5]	Wei Qiao, Lice Yu, Jinfa Chang, Fulin Yang, Ligang Feng. Efficient bi-functional catalysis of coupled MoSe₂ nanosheet/Pt nanoparticles for methanol-assisted water splitting [J]. Chinese Journal of Catalysis, 2023, 51(8): 113-123.
[6]	Mingming Song, Xianghai Song, Xin Liu, Weiqiang Zhou, Pengwei Huo. Enhancing photocatalytic CO₂ reduction activity of ZnIn₂S₄/MOF-808 microsphere with S-scheme heterojunction by in situ synthesis method [J]. Chinese Journal of Catalysis, 2023, 51(8): 180-192.
[7]	Nan Yin, Weibin Chen, Yong Yang, Zheng Tang, Panjie Li, Xiaoyue Zhang, Lanqin Tang, Tianyu Wang, Yang Wang, Yong Zhou, Zhigang Zou. Tröger’s base derived 3D-porous aromatic frameworks with efficient exciton dissociation and well-defined reactive site for near-unity selectivity of CO₂ photo-conversion [J]. Chinese Journal of Catalysis, 2023, 51(8): 168-179.
[8]	Yinqi Wu, Qianqian Chen, Qi Chen, Qiang Geng, Qiaoyu Zhang, Yu-Cong Zheng, Chen Zhao, Yan Zhang, Jiahai Zhou, Binju Wang, Jian-He Xu, Hui-Lei Yu. Precise regulation of the substrate selectivity of Baeyer-Villiger monooxygenase to minimize overoxidation of prazole sulfoxides [J]. Chinese Journal of Catalysis, 2023, 51(8): 157-167.
[9]	Xiaohan Wang, Han Tian, Xu Yu, Lisong Chen, Xiangzhi Cui, Jianlin Shi. Advances and insights in amorphous electrocatalyst towards water splitting [J]. Chinese Journal of Catalysis, 2023, 51(8): 5-48.
[10]	Lu Cheng, Xuning Chen, P. Hu, Xiao-Ming Cao. Advantages and limitations of hydrogen peroxide for direct oxidation of methane to methanol at mono-copper active sites in Cu-exchanged zeolites [J]. Chinese Journal of Catalysis, 2023, 51(8): 135-144.
[11]	Chun Yin, Fulin Yang, Shuli Wang, Ligang Feng. Heterostructured NiSe₂/MoSe₂ electronic modulation for efficient electrocatalysis in urea assisted water splitting reaction [J]. Chinese Journal of Catalysis, 2023, 51(8): 225-236.
[12]	Ce Han, Bingbao Mei, Qinghua Zhang, Huimin Zhang, Pengfei Yao, Ping Song, Xue Gong, Peixin Cui, Zheng Jiang, Lin Gu, Weilin Xu. Atomic Ru coordinated by channel ammonia in V-doped tungsten bronze for highly efficient hydrogen-evolution reaction [J]. Chinese Journal of Catalysis, 2023, 51(8): 80-89.
[13]	Haifeng Liu, Xiang Huang, Jiazang Chen. Surface electronic state modulation promotes photoinduced aggregation and oxidation of trace CO for lossless purification of H₂ stream [J]. Chinese Journal of Catalysis, 2023, 51(8): 49-54.
[14]	Xiu-Qing Qiao, Chen Li, Zizhao Wang, Dongfang Hou, Dong-Sheng Li. TiO_2-_x@C/MoO₂Schottky junction: Rational design and efficient charge separation for promoted photocatalytic performance [J]. Chinese Journal of Catalysis, 2023, 51(8): 66-79.
[15]	Zhaochun Liu, Xue Zong, Dionisios G. Vlachos, Ivo A. W. Filot, Emiel J. M. Hensen. A computational study of electrochemical CO₂ reduction to formic acid on metal-doped SnO₂ [J]. Chinese Journal of Catalysis, 2023, 50(7): 249-259.