Efficient continuous synthesis of methanol by direct methane conversion on Cu-KFI zeolite catalysts

doi:10.1016/S1872-2067(26)65140-6

Abstract

Abstract:

The direct conversion of methane to methanol (DMTM) is a key technology for the efficient utilization of natural gas resources, which remains a significant challenge in heterogeneous catalysis. Here, we report the selective catalytic oxidation of methane over Cu-KFI zeolites in a continuous CH₄-H₂O-O₂ reaction system. A high methanol space-time yield of ~3120 mmol/mol_Cu/h with methanol selectivity of 71% is achieved with a low Cu loading of 0.34 wt% at 550 °C via regulating O₂/H₂O ratio. Such a high-performance catalyst further shows a highly-stable catalytic activity in a longtime continuous operation under high water content (~12.2%). The isotope labelling with H₂¹⁸O and ¹⁶O₂ reveals that O₂ is the dominant oxygen source while water is also the oxidant for methane selective oxidation. Reaction analysis indicates that high reaction temperatures (> 450 °C) and high O₂ concentrations (> 1000 ppm) lead to an apparent overoxidation and side reactions of methane into CO₂ and CO. Fortunately, this phenomenon can be inhibited via increasing water vapor content, which, however, is ineffective at higher O₂ concentrations (e.g., 5000 ppm). Besides, the present study also reveals that the catalytic performance of Cu-KFI zeolites is related to both the Cu site sizes and ring window sizes based on the experimental results and density functional theory calculations. This work evidences a great potential of Cu-KFI zeolites with low Cu loadings in methane-selective conversion to methanol and provides an insightful understanding of continuous catalytic CH₄-H₂O-O₂ reaction system.

Key words: Methane conversion, Methanol, Cu-KFI zeolite, Selectivity, Overoxidation

Xinyi Zhang, Weichen Dong, Yi Cao, Caixia Zhou, Jiaxiu Guo, Hailong Zhang. Efficient continuous synthesis of methanol by direct methane conversion on Cu-KFI zeolite catalysts[J]. Chinese Journal of Catalysis, 2026, 88: 369-381.

×
share this article

Add to citation manager EndNote|Ris|BibTeX

URL: https://www.cjcatal.com/EN/10.1016/S1872-2067(26)65140-6

https://www.cjcatal.com/EN/Y2026/V88/I9/369

Figures/Tables 7

Fig. 1. (a) Continuous DMTM on 0.5%Cu-KFI zeolite (actual Cu loading = 0.34 wt%) upon elevating reaction temperatures from 300 to 600 °C. Bars and orange stars refer to the STY of products (mmol/molCu/h) and methanol selectivity (%), respectively. (b) The methanol yield and selectivity of Cu-KFI samples as a function of copper loading. Reaction conditions: 100 mg catalyst, total flow rate of 50 mL/min; 80% CH4, 500 ppm O2, 4.2% H2O and Ar balance. (c) Methanol yield (mmol/molCu/h) and selectivity (%) of 0.5%Cu-KFI and 1%Cu-KFI samples in continuous DMTM with different water contents. Reaction conditions: 100 mg catalyst, total flow rate = 50 mL/min; 80 % CH4, 500 ppm O2, 4.2% or 12.2% H2O; reaction temperature = 550 °C. (d) The yields of COx and H2 products in (c) reaction systems. (e) Continuous DMTM over Cu-KFI zeolites with different Cu loadings. Reaction conditions: 80% CH4, 4.2% H2O and 100-10000 ppm O2, reaction temperature of 450 °C.

Fig. 2. Catalytic stability of 0.5%Cu-KFI catalyst in continuous DMTM. Reaction conditions: 100 mg catalyst, total flow rate = 50 mL/min; 80% CH4, 1000 ppm O2, 12.2% H2O; reaction temperature = 500 °C. Note: No regeneration treatments were performed after leaving the reaction for 15 d.

Fig. 3. (a) Temperature-programmed surface reactions (TPSR) of continuous DMTM on 0.5%Cu-KFI with isotopically labelled system of CH4 + H218O + O2. Reaction conditions: 100 mg catalyst, total flow rate = 50 mL/min; 80% CH4, 4.2% H218O, 500 ppm O2, Ar as the balance. (b) The ratio of dihydrogen to methanol in continuous DMTM over 0.5%Cu-KFI zeolite at different reaction temperatures. Reaction conditions: 100 mg catalyst, total flow rate = 50 mL/min; 80% CH4, 4.2% H2O, 500 ppm O2. (c) The product yields in continuous DMTM reaction over Cu-KFI zeolites. Reaction conditions: 80% CH4, 4.2% H2O, 100-10000 O2, reaction temperature of 450 °C. (d) The ratio of dihydrogen to methanol in continuous DMTM over 0.5%Cu-KFI zeolite under the reaction conditions of (c).

Fig. 4. The representative HAADF-STEM images of 0.5%Cu-KFI (a-c) and 1%Cu-KFI (d-f) samples. (c) and (f) energy distribution maps obtained through image-matrix transformation for the red boxes in (b) and (e). (g) Element mappings of Cu, O and Al in 1%Cu-KFI.

Fig. 5. (a) 29Si MAS NMR spectrum of the as-prepared KFI zeolite. EPR results (b), UV-Vis spectra (c) and H2-TPR results (d) of Cu-KFI zeolites with different Cu loadings. (e) FTIR spectra of Cu-KFI zeolites using KFI zeolite as the background. (f) In-situ FTIR spectra of Cu-KFI zeolites for NO adsorption at 30 °C.

Fig. 6. (a) The selectivities of methanol and COx as a function of Cu loadings on KFI and CHA [37] zeolites. (b) The structure of KFI zeolite and the size of ring windows.

Fig. 7. The energy diagram for the reaction path of methane-steam to methanol on [Cu-OH]+ and hydrated [Cu(OH2)-OH]+ active sites hosted on 6MR in KFI zeolite.

References

[1]	M. H. Mahyuddin, Y. Shiota, K. Yoshizawa, Catal. Sci. Technol., 2019, 9, 1744-1768.
[2]	Y. Konno, T. Fujii, A. Sato, K. Akamine, M. Naiki, Y. Masuda, K. Yamamoto, J. Nagao, Energy Fuels, 2017, 31, 2607-2616.
[3]	H. Zhang, J. Li, D. Wang, Y. Wang, H. Xiong, Coord. Chem. Rev., 2024, 503, 215637.
[4]	F. Bu, Y. Xue, M. Sun, B. Huang, J. Yan, L. Qi, S. Zhao, Y. Li, Nat. Commun., 2025, 16, 7466.
[5]	Y. Tang, Y. Li, F. Feng Tao, Chem. Soc. Rev., 2022, 51, 376-423.
[6]	B. G. Hashiguchi, M. M. Konnick, S. M. Bischof, S. J. Gustafson, D. Devarajan, N. Gunsalus, D. H. Ess, R. A. Periana, Science, 2014, 343, 1232-1237.
[7]	P. Schwach, X. Pan, X. Bao, Chem. Rev., 2017, 117, 8497-8520.
[8]	H. Zhang, X. Zhang, X. Shi, X. Liu, J. Liang, S. Li, S. Ma, X. Xiao, J. Guo, L. Zhang, M. Tan, Appl. Catal. B Environ. Energy, 2025, 361, 124648.
[9]	L. Sun, Y. Wang, C. Wang, Z. Xie, N. Guan, L. Li, Chem, 2021, 7, 1557-1568.
[10]	V. L. Sushkevich, D. Palagin, M. Ranocchiari, J. A. van Bokhoven, Science, 2017, 356, 523-527.
[11]	B. Feng, D. Feng, Y. Pei, B. Zong, M. Qiao, W. Li, Chin. J. Catal., 2025, 76, 96-107.
[12]	H. Zhang, P. Han, D. Wu, C. Du, J. Zhao, K. H. L. Zhang, J. Lin, S. Wan, J. Huang, S. Wang, H. Xiong, Y. Wang, Nat. Commun., 2023, 14, 7705.
[13]	K. A. Lomachenko, A. Martini, D. K. Pappas, C. Negri, M. Dyballa, G. Berlier, S. Bordiga, C. Lamberti, U. Olsbye, S. Svelle, P. Beato, E. Borfecchia, Catal. Today, 2019, 336, 99-108.
[14]	G. Brezicki, J. D. Kammert, T. B. Gunnoe, C. Paolucci, R. J. Davis, ACS Catal., 2019, 9, 5308-5319.
[15]	D. K. Pappas, A. Martini, M. Dyballa, K. Kvande, S. Teketel, K. A. Lomachenko, R. Baran, P. Glatzel, B. Arstad, G. Berlier, C. Lamberti, S. Bordiga, U. Olsbye, S. Svelle, P. Beato, E. Borfecchia, J. Am. Chem. Soc., 2018, 140, 15270-15278.
[16]	J. Zheng, I. Lee, E. Khramenkova, M. Wang, B. Peng, O. Y. Gutiérrez, J. L. Fulton, D. M. Camaioni, R. Khare, A. Jentys, G. L. Haller, E. A. Pidko, M. Sanchez-Sanchez, J. A. Lercher, Chem, 2020, 26, 7515.
[17]	V. L. Sushkevich, R. Verel, J. A. van Bokhoven, Angew. Chem. Int. Ed., 2020, 59, 910-918.
[18]	Y. R. Jeong, H. Jung, J. Kang, J. W. Han, E. D. Park, ACS Catal., 2021, 11, 1065-1070.
[19]	O. Memioglu, B. Ipek, Chem. Commun., 2021, 57, 1364-1367.
[20]	E. Borfecchia, D. K. Pappas, M. Dyballa, K. A. Lomachenko, C. Negri, M. Signorile, G. Berlier, Catal. Today, 2019, 333, 17-27.
[21]	A. Koishybay, D. F. Shantz, J. Am. Chem. Soc., 2020, 142, 11962-11966.
[22]	K. T. Dinh, M. M. Sullivan, K. Narsimhan, P. Serna, R. J. Meyer, M. Dincă, Y. Román-Leshkov, J. Am. Chem. Soc., 2019, 141, 11641-11650.
[23]	Y. Tsuchimura, H. Yoshida, M. Machida, S. Nishimura, K. Takahashi, J. Ohyama, Energy Fuels, 2023, 37, 9411-9418.
[24]	G. Brezicki, J. Zheng, C. Paolucci, R. Schlögl, R. J. Davis, ACS Catal., 2021, 11, 4973-4987.
[25]	M. H. Groothaert, P. J. Smeets, B. F. Sels, P. A. Jacobs, R. A. Schoonheydt, J. Am. Chem. Soc., 2005, 127, 1394-1395.
[26]	P. J. Smeets, R. G. Hadt, J. S. Woertink, P. Vanelderen, R. A. Schoonheydt, B. F. Sels, E. I. Solomon, J. Am. Chem. Soc., 2010, 132, 14736-14738.
[27]	S. Zhang, J. Ye, J. Shen, Y. Guo, W. Zhan, L. Wang, X. Tang, S. Dai, Y. Guo, ChemCatChem, 2024, 16, e202401137.
[28]	X. Tang, L. Wang, B. Yang, C. Fei, T. Yao, W. Liu, Y. Lou, Q. Dai, Y. Cai, X.-M. Cao, W. Zhan, Y. Guo, X.-Q. Gong, Y. Guo, Appl. Catal. B, 2021, 285, 119827.
[29]	A. A. Gabrienko, S. A. Yashnik, A. A. Kolganov, A. M. Sheveleva, S. S. Arzumanov, M. V. Fedin, F. Tuna, A. G. Stepanov, Inorg. Chem., 2020, 59, 2037-2050.
[30]	Y. Jangjou, Q. Do, Y. Gu, L.-G. Lim, H. Sun, D. Wang, A. Kumar, J. Li, L. C. Grabow, W. S. Epling, ACS Catal., 2018, 8, 1325-1337.
[31]	J. Luo, D. Wang, A. Kumar, J. Li, K. Kamasamudram, N. Currier, A. Yezerets, Catal. Today, 2016, 267, 3-9.
[32]	B. Ipek, M. J. Wulfers, H. Kim, F. Göltl, I. Hermans, J. P. Smith, K. S. Booksh, C. M. Brown, R. F. Lobo, ACS Catal., 2017, 7, 4291-4303.
[33]	L. Tao, I. Lee, R. Khare, A. Jentys, J. L. Fulton, M. Sanchez-Sanchez, J. A. Lercher, Chem. Mater., 2022, 34, 4355-4363.
[34]	X. Yu, L. Zhong, S. Li, Phys. Chem. Chem. Phys., 2021, 23, 4963-4974.
[35]	M. H. Mahyuddin, T. Tanaka, Y. Shiota, A. Staykov, K. Yoshizawa, ACS Catal., 2018, 8, 1500-1509.
[36]	M. H. Mahyuddin, T. Tanaka, A. Staykov, Y. Shiota, K. Yoshizawa, Inorg. Chem., 2018, 57, 10146-10152.
[37]	X. Zhang, S. Ma, M. Tan, J. Guo, J. Li, Z. Wu, J. Tian, L. Zhang, S. Mushina, H. Zhang, Chem. Eng. J., 2025, 522, 167726.
[38]	S. Sogukkanli, T. Moteki, M. Ogura, Green Chem., 2021, 23, 2148-2154.
[39]	J. Ohyama, A. Hirayama, Y. Tsuchimura, N. Kondou, H. Yoshida, M. Machida, S. Nishimura, K. Kato, I. Miyazato, K. Takahashi, Catal. Sci. Technol., 2021, 11, 3437-3446.
[40]	C. Zhou, S. Li, S. He, Z. Zhao, Y. Jiao, H. Zhang, Fuel, 2022, 329, 125483.
[41]	H. Zhang, J. Guo, Y. Cao, Chem. Commun., 2023, 60, 228-231.
[42]	E. Borfecchia, P. Beato, S. Svelle, U. Olsbye, C. Lamberti, S. Bordiga, Chem. Soc. Rev., 2018, 47, 8097-8133.
[43]	M. B. Park, E. D. Park, W.-S. Ahn, Front. Chem., 2019, 7, 514.
[44]	D. K. Pappas, E. Borfecchia, M. Dyballa, I. A. Pankin, K. A. Lomachenko, A. Martini, M. Signorile, S. Teketel, B. Arstad, G. Berlier, C. Lamberti, S. Bordiga, U. Olsbye, K. P. Lillerud, S. Svelle, P. Beato, J. Am. Chem. Soc., 2017, 139, 14961-14975.
[45]	G. Kresse, J. Furthmüller, Phys. Rev. B, 1996, 54, 11169-11186.
[46]	J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 1996, 77, 3865-3868.
[47]	S. Grimme, J. Antony, S. Ehrlich, H. Krieg, J. Chem. Phys., 2010, 132, 154104.
[48]	G. Henkelman, H. Jónsson, J. Chem. Phys., 2000, 113, 9978-9985.
[49]	G. Henkelman, H. Jónsson, J. Chem. Phys., 1999, 111, 7010-7022.
[50]	V. L. Sushkevich, D. Palagin, J. A. Van Bokhoven, Angew. Chem. Int. Ed., 2018, 57, 8906-8910.
[51]	K. Mlekodaj, M. Bernauer, J. E. Olszowka, P. Klein, V. Pashkova, J. Dedecek, Chem. Mater., 2021, 33, 1781-1788.
[52]	K. Mlekodaj, J. Dedecek, V. Pashkova, E. Tabor, P. Klein, M. Urbanova, R. Karcz, P. Sazama, S. R. Whittleton, H. M. Thomas, A. V. Fishchuk, S. Sklenak, J. Phys. Chem. C, 2019, 123, 7968-7987.
[53]	J. Meyet, K. Searles, M. A. Newton, M. Wörle, A. P. Van Bavel, A. D. Horton, J. A. Van Bokhoven, C. Copéret, Angew. Chem. Int. Ed., 2019, 58, 9841-9845.
[54]	J. J. Bravo-Suárez, B. Subramaniam, R. V. Chaudhari, J. Phys. Chem. C, 2012, 116, 18207-18221.
[55]	J. Kim, S. J. Cho, D. H. Kim, ACS Catal., 2017, 7, 6070-6081.
[56]	F. Gao, Y. Wang, N. M. Washton, M. Kollár, J. Szanyi, C. H. F. Peden, ACS Catal., 2015, 5, 6780-6791.
[57]	H. Lee, J. Kim, I. Song, S. W. Jeon, S. J. Cho, D. H. Kim, Catal. Sci. Technol., 2022, 12, 7470-7480.
[58]	H. Zhang, J. Lv, Z. Zhang, C. Du, S. Wang, J. Lin, S. Wan, Y. Wang, H. Xiong, ChemCatChem, 2022, 14, e202101609.
[59]	D. Wang, L. Zhang, J. Li, K. Kamasamudram, W. S. Epling, Catal. Today, 2014, 231, 64-74.
[60]	Y. J. Kim, J. K. Lee, K. M. Min, S. B. Hong, I.-S. Nam, B. K. Cho, J. Catal., 2014, 311, 447-457.
[61]	H. Jiang, B. Guan, H. Lin, Z. Huang, Fuel, 2019, 255, 115587.
[62]	Y. Zhang, Y. Peng, K. Li, S. Liu, J. Chen, J. Li, F. Gao, C. H. F. Peden, ACS Catal., 2019, 9, 6137-6145.
[63]	J. Han, J. Li, W. Zhao, L. Li, M. Chen, X. Ge, S. Wang, Q. Liu, D. Mei, J. Yu, J. Am. Chem. Soc., 2024, 146, 7605-7615.
[64]	S. Yang, X. Guo, A. Verma, M. B. Shiflett, D. R. Corbin, A. Navrotsky, J. Phys. Chem. C, 2020, 124, 26193-26202.
[65]	J. Szanyi, J. H. Kwak, H. Zhu, C. H. F. Peden, Phys. Chem. Chem. Phys., 2013, 15, 2368.
[66]	J. Pokhrel, D. F. Shantz, J. Catal., 2023, 421, 300-308.
[67]	R. Zhang, J.-S. McEwen, M. Kollár, F. Gao, Y. Wang, J. Szanyi, C. H. F. Peden, ACS Catal., 2014, 4, 4093-4105.
[68]	M. A. Newton, A. J. Knorpp, V. L. Sushkevich, D. Palagin, J. A. van Bokhoven, Chem. Soc. Rev., 2020, 49, 1449-1486.
[69]	D. Palagin, A. J. Knorpp, A. B. Pinar, M. Ranocchiari, J. A. van Bokhoven, Nanoscale, 2017, 9, 1144-1153.
[70]	M. Gallego, A. Corma, M. Boronat, J. Phys. Chem. A, 2022, 126, 4941-4951.
[71]	J. Jae, G. A. Tompsett, A. J. Foster, K. D. Hammond, S. M. Auerbach, R. F. Lobo, G. W. Huber, J. Catal., 2011, 279, 257-268.
[72]	A. R. Kulkarni, Z.-J. Zhao, S. Siahrostami, J. K. Nørskov, F. Studt, ACS Catal., 2016, 6, 6531-6536.
[73]	E. Grifoni, G. Piccini, J. A. Lercher, V.-A. Glezakou, R. Rousseau, M. Parrinello, Nat. Commun., 2021, 12, 2630.