Coffee grounds derived porous nitrogen-rich biochar as a metal-free catalyst for efficient selective oxidation of hydrogen sulfide to sulfur

Abstract

The development of metal-free catalysts for efficient selective catalytic oxidation of hydrogen sulfide (H₂S-SCO) to elemental sulfur represents a sustainable solution for toxic gas purification. Herein, we synthesized a regenerable metal-free catalyst through facile activation and pyrolysis of coffee grounds. The optimized catalyst demonstrated exceptional H₂S-SCO performance at 180 ℃, achieving>99% H₂S conversion with near-perfect sulfur selectivity (~100%) while maintaining remarkable stability under humid conditions and high CO₂ concentrations. These superior properties originate from the synergistic effects of elevated nitrogen doping (17.33 at.%), abundant defect edge sites, and hierarchical porosity. Density functional theory (DFT) calculations revealed that carbon atoms adjacent to pyridine-N configurations serve as dual-active sites, facilitating H₂S adsorption/dissociation and O₂ activation through optimized electron redistribution. A plausible reaction mechanism was established based on experimental and theoretical analyses. This work provides fundamental insights into designing cost-effective, biomass-derived carbon catalysts for industrial gas purification while addressing agricultural waste valorization.

Keywords

H₂S / Biochar / Catalytic oxidation / Coffee grounds

References

[1] Adio SO, Ganiyu SA, Usman M, Abdulazeez I, Alhooshani K. Facile and efficient nitrogen modified porous carbon derived from sugarcane bagasse for CO₂ capture: experimental and DFT investigation of nitrogen atoms on carbon frameworks. Chem Eng J, 2020, 382: 122964

[2] Battista F, Barampouti EM, Mai S, Bolzonella D, Malamis D, Moustakas K, Loizidou M. Added-value molecules recovery and biofuels production from spent coffee grounds. Renew Sustain Energy Rev, 2020, 131: 110007

[3] Brazhnyk DV, Zaitsev YP, Bacherikova IV, Zazhigalov VA, Stoch J, Kowal A. Oxidation of H₂S on activated carbon KAU and influence of the surface state. Appl Catal B Environ, 2007, 70(1): 557-566

[4] Chan YH, Lock SSM, Wong MK, Yiin CL, Loy ACM, Cheah KW, Chai SYW, Li C, How BS, Chin BLF, Chan ZP, Lam SS. A state-of-the-art review on capture and separation of hazardous hydrogen sulfide (H₂S): recent advances, challenges and outlook. Environ Pollut, 2022, 314: 120219

[5] Chen F, Wu X-L, Yang L, Chen C, Lin H, Chen J. Efficient degradation and mineralization of antibiotics via heterogeneous activation of peroxymonosulfate by using graphene supported single-atom Cu catalyst. Chem Eng J, 2020, 394: 124904

[6] Cychosz KA, Thommes M. Progress in the physisorption characterization of nanoporous gas storage materials. Engineering, 2018, 4(4): 559-566

[7] de Rink R, Klok JBM, van Heeringen GJ, Keesman KJ, Janssen AJH, ter Heijne A, Buisman CJN. Biologically enhanced hydrogen sulfide absorption from sour gas under haloalkaline conditions. J Hazard Mater, 2020, 383: 121104

[8] Feng J, Jia L, Wang F, Sun X, Ning P, Wang C, Li Y, Li K. Urea-modified Cu-based materials: highly efficient and support-free adsorbents for removal of H₂S in an anaerobic and dry environment. Chem Eng J, 2023, 451: 138815

[9] Franca AS, Oliveira LS. Potential uses of spent coffee grounds in the food industry. Foods, 2022, 11(14): 2064

[10] Grieger S, Szydłowska BM, Rao VJ, Steinmann E, Dodds M, Gholamvand Z, Duesberg GS, Zaumseil J, Backes C. Site-selective oxidation of monolayered liquid-exfoliated WS₂ by shielding the basal plane through adsorption of a facial amphiphile. Angew Chem Int Ed Engl, 2020, 593313785-13792

[11] He R, Xia F-F, Bai Y, Wang J, Shen D-S. Mechanism of H₂S removal during landfill stabilization in waste biocover soil, an alterative landfill cover. J Hazard Mater, 2012, 217–218: 67-75

[12] Kan X, Chen X, Chen W, Mi J, Zhang J-Y, Liu F, Zheng A, Huang K, Shen L, Au C, Jiang L. Nitrogen-decorated, ordered mesoporous carbon spheres as high-efficient catalysts for selective capture and oxidation of H₂S. ACS Sustain Chem Eng, 2019, 7(8): 7609-7618

[13] Khabazipour M, Anbia M. Removal of hydrogen sulfide from gas streams using porous materials: a review. Ind Eng Chem Res, 2019, 58(49): 22133-22164

[14] Kim M-J, Choi SW, Kim H, Mun S, Lee KB. Simple synthesis of spent coffee ground-based microporous carbons using K₂CO₃ as an activation agent and their application to CO₂ capture. Chem Eng J, 2020, 397: 125404

[15] Kourmentza C, Economou CN, Tsafrakidou P, Kornaros M. Spent coffee grounds make much more than waste: exploring recent advances and future exploitation strategies for the valorization of an emerging food waste stream. J Clean Prod, 2018, 172: 980-992

[16] Laksaci H, Khelifi A, Trari M, Addoun A. Synthesis and characterization of microporous activated carbon from coffee grounds using potassium hydroxides. J Clean Prod, 2017

[17] Lei G, Tong Y, Shen L, Liu F, Xiao Y, Lin W, Zhang Y, Au C, Jiang L. Highly active and sulfur-resistant Fe–N4 sites in porous carbon nitride for the oxidation of H₂S into elemental sulfur. Small, 2020, 16(42): 2003904

[18] Li D, Ding L-X, Chen H, Wang S, Li Z, Zhu M, Wang H. Novel nitrogen-rich porous carbon spheres as a high-performance anode material for lithium-ion batteries. J Mater Chem A, 2014, 23916617-16622

[19] Li S, Gu Q, Cao N, Jiang Q, Xu C, Jiang C, Chen C, Pham-Huu C, Liu Y. Defect enriched N-doped carbon nanoflakes as robust carbocatalysts for H₂S selective oxidation. J Mater Chem A, 2020, 8(18): 8892-8902

[20] Li S, Fu H, Zhang X, Liu X, Tuci G, Giambastiani G, Pham-Huu C, Liu Y. Hierarchically porous, N-defect enriched C-nanosheets boost the H₂S selective oxidation to elemental sulfur. Appl Catal B Environ, 2024, 343: 123505

[21] Liang S, Mi J, Liu F, Zheng Y, Xiao Y, Cao Y, Jiang L. Efficient catalytic elimination of COS and H₂S by developing ordered mesoporous carbons with versatile base N sites via a calcination induced self-assembly route. Chem Eng Sci, 2020, 221: 115714

[22] Liu Y, Song C, Wang Y, Cao W, Lei Y, Feng Q, Chen Z, Liang S, Xu L, Jiang L. Rational designed Co@N-doped carbon catalyst for high-efficient H₂S selective oxidation by regulating electronic structures. Chem Eng J, 2020, 401: 126038

[23] Liu X, Zhou Y, Wang C-L, Liu Y, Tao D-J. Solvent-free self-assembly synthesis of N-doped ordered mesoporous carbons as effective and bifunctional materials for CO₂ capture and oxygen reduction reaction. Chem Eng J, 2022, 427: 130878

[24] Liu X, Shan L, Sun X, Wang T, Liu Z, Liu Y. Reusable salt-template strategy for synthesis of porous nitrogen-rich carbon boosts H₂S selective oxidation. Green Energy Environ, 2024, 9(12): 1866-1877

[25] Liu X, Zhai X, Zhao Y, Shan L, Liu Z, Liu Y. Sulfur modified N-doped carbocatalysts promote the selectivity for H₂S selective oxidation. Appl Catal B Environ Energy, 2025, 362: 124717

[26] Martínez-Ahumada E, López-Olvera A, Jancik V, Sánchez-Bautista JE, González-Zamora E, Martis V, Williams DR, Ibarra IA. MOF materials for the capture of highly toxic H₂S and SO₂. Organometallics, 2020, 39(7): 883-915

[27] Meng F-N, Di X-P, Dong H-W, Zhang Y, Zhu C-L, Li C, Chen Y-J. Ppb H₂S gas sensing characteristics of Cu₂O/CuO sub-microspheres at low-temperature. Sens Actuators B Chem, 2013, 182: 197-204

[28] Pagett M, Teng KS, Sullivan G, Zhang W. Reusing waste coffee grounds as electrode materials: recent advances and future opportunities (Global Challenges 1/2023). Glob Chall, 2023, 7(1): 2370011

[29] Pan Z, Gao Q, Chen Z. Removal of As(III) and As(V) from mine groundwater using bimetallic Fe/Cu nanoparticles. Process Saf Environ Prot, 2023, 180: 192-204

[30] Phatyenchuen S, Pongthawornsakun B, Panpranot J, Praserthdam P. Effect of transition metal dopants (M=Nb, La, Zr, and Y) on the M-TiO₂ supported V₂O₅ catalysts in the selective oxidation of H₂S to elemental sulfur. J Environ Chem Eng, 2018, 6(5): 5655-5661

[31] Shah MS, Tsapatsis M, Siepmann JI. Hydrogen sulfide capture: from absorption in polar liquids to oxide, zeolite, and metal-organic framework adsorbents and membranes. Chem Rev, 2017, 117(14): 9755-9803

[32] Wang H, Ding H, Wang Z, Zhu Y, Chen Z, Song B. Heteroatoms-doped mesoporous carbon nanosheets with dual diffusion pathways for highly efficient potassium ion storage. Small, 2024, 20(27): 2310908

[33] Wang Y, Liu Y, Wang L, Perumal S, Wang H, Ko H, Dong C-L, Zhang P, Wang S, Nga TTT, Kim YD, Ji Y, Zhao S, Kim J-H, Yee D-Y, Hwang Y, Zhang J, Kim MG, Lee H. Coupling photocatalytic CO₂ reduction and CH₃OH oxidation for selective dimethoxymethane production. Nat Commun, 2024, 1516047

[34] Xiong Y, Wang L, Ning P, Luo J, Li X, Yuan L, Xie Y, Ma Y, Wang X. Constructing oxygen vacancy-enriched Fe₃O₄@MnO₂ core–shell nanoplates for highly efficient catalytic oxidation of H₂S in blast furnace gas. Sep Purif Technol, 2024, 336: 126234

[35] Xu C, Gu Q, Li S, Ma J, Zhou Y, Zhang X, Jiang C, Pham-Huu C, Liu Y. Heteroatom-doped monolithic carbocatalysts with improved sulfur selectivity and impurity tolerance for H₂S selective oxidation. ACS Catal, 2021, 11148591-8604

[36] Xu C, Chen J, Li S, Gu Q, Wang D, Jiang C, Liu Y. N-doped honeycomb-like porous carbon derived from biomass as an efficient carbocatalyst for H₂S selective oxidation. J Hazard Mater, 2021, 403: 123806

[37] Xue N, Zhou H-Y, Han Y, Li M, Lu H-Y, Chen C-F. A general supramolecular strategy for fabricating full-color-tunable thermally activated delayed fluorescence materials. Nat Commun, 2024, 15(1): 1425

[38] Yang C, Ye H, Byun J, Hou Y, Wang X. N-rich carbon catalysts with economic feasibility for the selective oxidation of hydrogen sulfide to sulfur. Environ Sci Technol, 2020, 541912621-12630

[39] Yang C, Florent M, de Falco G, Fan H, Bandosz TJ. ZnFe₂O₄/activated carbon as a regenerable adsorbent for catalytic removal of H₂S from air at room temperature. Chem Eng J, 2020, 394: 124906

[40] Yang C, Wang Y, Liang M, Su Z, Liu X, Fan H, Bandosz TJ. Towards improving H₂S catalytic oxidation on porous carbon materials at room temperature: a review of governing and influencing factors, recent advances, mechanisms and perspectives. Appl Catal B, 2023, 323: 122133

[41] Yang J, Cui S, Zhao F, Wang F, Feng J, Ning P, Jia L. Waste to wealth: discarded cigarette butt-derived metal-free N-rich carbon catalysts for the selective catalytic oxidation of hydrogen sulfide to sulfur. Environ Sci Technol, 2024, 58(45): 20267-20276

[42] Yuan L, Wang X, Li X, Wang J, Wang L, Xiong Y, Xiao Y, Ning P. Activated-carbon-induced morphological and crystal transformation of α-FeOOH for efficient catalytic removal of hydrogen sulfide from blast furnace gas. Sep Purif Technol, 2024, 340: 126770

[43] Zhang X, Tang Y, Qiao N, Li Y, Qu S, Hao Z. Comprehensive study of H₂S selective catalytic oxidation on combined oxides derived from Mg/Al-V₁₀O₂₈ layered double hydroxides. Appl Catal B Environ, 2015, 176–177: 130-138

[44] Zhang X, Xu C, Li S, Liu X, Liu Y. N-doped porous carbocatalyst engineering via modulating the crystalline size of ZIF-8 for continuous H₂S selective oxidation. Appl Mater Today, 2021, 25: 101228

[45] Zhang Z, Zhang F, Song Z, Zhang L. Oxygen reduction reaction on pyridinic nitrogen-functionalized carbon: active site quantification and effects of Lewis basicity. ACS Catal, 2025, 15(1): 296-309

[46] Zheng X, Li Y, Zhang L, Shen L, Xiao Y, Zhang Y, Au C, Jiang L. Insight into the effect of morphology on catalytic performance of porous CeO₂ nanocrystals for H2S selective oxidation. Appl Catal B Environ, 2019, 252: 98-110

[47] Zheng X, Li Y, Zheng Y, Shen L, Xiao Y, Cao Y, Zhang Y, Au C, Jiang L. Highly efficient porous Fe_xCe_1–xO_2−δ with three-dimensional hierarchical nanoflower morphology for H₂S-selective oxidation. ACS Catal, 2020, 10(7): 3968-3983

[48] Zheng X, Cai J, Zhao W, Liang S, Zheng Y, Cao Y, Shen L, Xiao Y, Jiang L. Porous α-Fe₂O₃/SnO₂ nanoflower with enhanced sulfur selectivity and stability for H₂S selective oxidation. Chin Chem Lett, 2021, 32(7): 2143-2150

Funding

Yunnan Fundamental Research Projects(202401AU070028)

National Natural Science Foundation of China(52300140)

RIGHTS & PERMISSIONS

The Author(s)