Enhanced hydrogen production and carbon suppression via a two-stage catalytic system of biochar pre-catalysis and Ni-based catalysts during biomass pyrolysis

Abstract

Abstract

A new two-stage catalytic system was developed to overcome the problems of low yield of hydrogen-rich gas and serious carbon deposition on the catalyst during biomass pyrolysis catalysis. The operating temperature, catalyst type and catalyst addition ratio were compared, and the optimum hydrogen production conditions were obtained (with yield reaching 52.21 wt% and the hydrogen yield reaching 29.15 vol%). The catalysts were modified by metals, including Ni, Ni–Co, Ni–Fe, Ni–Mo and Ni–Ce. Ni–Ce/Al₂O₃ exhibited the highest tar-cracking efficiency during one-stage catalysis, attributed to the redox cycle between Ce³⁺/Ce⁴⁺. In order to further improve the catalytic performance, the biochar pre-catalytic layer with rich porous structure and surface functional groups was introduced. Macromolecular volatiles were selectively adsorbed by the pre-catalyst and promoted in chain reactions. Macromolecular volatiles were selectively adsorbed by the pre-catalyst, in which the tar reforming reaction was promoted, resulting in an increase in hydrogen production to 29.76–48.87 vol% in two-stage catalysis. In addition, Biochar pre-catalyst promoted free radical recombination by enhancing the formation of H₂ and H· and reducing the binding of polycyclic aromatic hydrocarbons, which effectively inhibited carbon deposition. This study provides theoretical insights and proposes a novel stepwise catalytic strategy for efficient hydrogen production from biomass, highlighting its potential for practical energy conversion applications.

Highlights

• Novel two-stage catalyst (biochar + Ni/Al₂O₃) promoted H₂ yield (48.87 vol%) and redused carbon deposition.

• Biochar pre-catalysis activated volatiles via surface functional groups, promoting tar cracking and H₂ formation.

• Ni-Ce/Al₂O₃ showed excellent performance in tar cracking through Ce³⁺/Ce⁴⁺ redox, boosting the gas and H₂ production.

Keywords

Biomass pyrolysis / Biochar pre-catalyst / Metal-support catalyst / Hydrogen production / Char

References

[1] Anand V, Sunjeev V, Vinu R. Catalytic fast pyrolysis of Arthrospira platensis (spirulina) algae using zeolites. J Anal Appl Pyrolysis, 2016, 118: 298-307

[2] Aysu T, Maroto-Valer MM, Sanna A. Ceria promoted deoxygenation and denitrogenation of Thalassiosira weissflogii and its model compounds by catalytic in-situ pyrolysis. Bioresour Technol, 2016, 208: 140-148

[3] Azizi K, Moraveji MK, Najafabadi HA. A review on bio-fuel production from microalgal biomass by using pyrolysis method. Renew Sustain Energy Rev, 2018, 82: 3046-3059

[4] Di Stasi C, Cortese M, Greco G, et al.. Optimization of the operating conditions for steam reforming of slow pyrolysis oil over an activated biochar-supported Ni-Co catalyst. Int J Hydrogen Energy, 2021, 46: 26915-26929

[5] Dong H, Luo W, Yan X et al (2022) Production of catalytic-upgraded pyrolysis products from oiltea camellia shell and polypropylene using NiCe-X/Al₂O₃ and ZrO₂ catalyst (X=Fe, Co). Fuel (Lond) 325. https://doi.org/10.1016/j.fuel.2022.124812

[6] Du Z, Zhang Z, Xu C, et al.. Low-temperature steam reforming of toluene and biomass tar over biochar-supported Ni nanoparticles. ACS Sustain Chem Eng, 2019, 7: 3111-3119

[7] Fang Y, Yu X, Wan A, et al.. Closing the loop: biochar-supported nickel catalyst for efficient hydrogen-rich syngas production. Int J Hydrogen Energy, 2024, 80: 332-342

[8] Gao Y, Sun Y, Song W, et al.. Intrinsic properties of biochar for electron transfer. Chem Eng J, 2023, 475: 23

[9] Himanshu CPR, Awasthi D et al (2025) Lignocellulosic biomass to biochar: an overview on impact of production technologies on biochar yield and techno-economics. J Energy Inst: 102233. https://doi.org/10.1016/j.joei.2025.102233

[10] Kady FYAE, Wahed MGAE, Shaban S, et al.. Hydrotreating of heavy gas oil using CoMo /纬-Al₂O₃ catalyst prepared by equilibrium deposition filtration. Fuel (Lond), 2010, 89: 3193-3206

[11] Koo KY, Roh H, Seo YT, et al.. Coke study on MgO-promoted Ni/Al₂O₃ catalyst in combined H₂O and CO₂ reforming of methane for gas to liquid (GTL) process. Appl Catal a-Gen, 2008, 340: 183-190

[12] Kumar A, Wang R, Orton KA, et al.. Synthesis, performance evaluation, and economic assessment of tailored Pt/TiO₂ catalysts for selective biomass vapour upgrading via a scalable flame spray pyrolysis route. Catal Sci Technol, 2023, 13: 4941-4954

[13] Li C, Yang W, Hu C et al (2025a) Oxygen-functionalized carbon catalysts for two-electron oxygen reduction reaction: from active site identification to functionalization strategies. Chem Eng J 520:165922. https://doi.org/10.1016/j.cej.2025.165922

[14] Li P, Zhao Y, Chen H, et al.. Investigation of transition metal-modified biochar as catalysts in the co-pyrolysis of corn cob and polyethylene for enhanced hydrogen production. Energy (Oxf), 2025, 323: 12

[15] Li Q, Shan R, Wang S et al (2024) Production of carbon nanotubes via catalytic pyrolysis of waste plastics over Ni/Al₂O₃ catalyst: the influence of plastic types. J Anal Appl Pyrolysis 177. https://doi.org/10.1016/j.jaap.2023.106318

[16] Li X, Liu P, Lei T et al (2022) Pyrolysis of biomass Tar model compound with various Ni-based catalysts: influence of promoters characteristics on hydrogen-rich gas formation. Energy (Oxf) 244:123137. https://doi.org/10.1016/j.energy.2022.123137

[17] Li X, Liu Z, Shao S, et al.. A Ca-modified Ni/CeO2•Al₂O₃ bifunctional catalyst for two-stage steam reforming of biomass pyrolysis oil for hydrogen production. Ind Crops Prod, 2025, 228: 9

[18] Liu J, Zhong F, Niu W et al (2019) Effects of heating rate and gas atmosphere on the pyrolysis and combustion characteristics of different crop residues and the kinetics analysis. Energy (Oxf) 175:320–332. https://doi.org/10.1016/j.energy.2019.03.044

[19] Moonsrikaew W, Duangchan A (2022) Deoxygenation of pyrolysis vapor from palm fruit cake over NiMo /γ-Al₂O₃ catalyst: effect of CeO₂, TiO₂, and ZrO₂ additives. Mol Catal 523. https://doi.org/10.1016/j.mcat.2021.111712

[20] Muhammad WZW, Isa MR, Habib SH et al (2023) Assessment of biochar, bio-oil and biogas production from lemon myrtle waste via microwave assisted catalytic pyrolysis using CaO based catalyst and zeolite catalyst. Energy Conv Manag-X 20. https://doi.org/10.1016/j.ecmx.2023.100481

[21] Narayanan S, Tamizhdurai P, Mangesh VL, et al.. Recent advances in the synthesis and applications of mordenite zeolite—review. RSC Adv, 2021, 11: 250-267

[22] Niu Q, Du X, Li K, et al.. Coke formation and mineral accumulation on HZSM-5/Al₂O₃ catalysts during in-situ catalytic fast pyrolysis of microalgae over multiple regeneration cycles. J Anal Appl Pyrolysis, 2024, 182: 10

[23] Paya S, Diez N, Sevilla M. Biomass-derived carbon sponges for use as sodium-ion capacitor electrodes. Sustain Energy Fuels, 2023, 7: 2378-2389

[24] Qin T, Lu Q, Xiang H et al (2023) Ca promoted Ni-Co bimetallic catalyzed coal pyrolysis and char steam gasification. Energy (Oxf) 282. https://doi.org/10.1016/j.energy.2023.128374

[25] Shahirah MNN, Gimbun J, Ideris A, et al.. Catalytic pyrolysis of glycerol into syngas over ceria-promoted Ni /γ-Al₂O₃ catalyst. Renew Energy, 2017, 107: 223-234

[26] Shen Y. Chars as carbonaceous adsorbents/catalysts for tar elimination during biomass pyrolysis or gasification. Renew Sustain Energ Rev, 2015, 43: 281-295

[27] Smith MW, Dallmeyer I, Johnson TJ, et al.. Structural analysis of char by Raman spectroscopy: improving band assignments through computational calculations from first principles. Carbon N Y, 2016, 100: 678-692

[28] Song M, Yi Z, Xu R, et al.. Towards enhanced sodium storage of hard carbon anodes: regulating the oxygen content in precursor by low-temperature hydrogen reduction. Energy Storage Mater, 2022, 51: 620-629

[29] Su Y, Liu L, Xu D et al (2020) Syngas production at low temperature via the combination of hydrothermal pretreatment and activated carbon catalyst along with value-added utilization of tar and bio-char. Energy Convers Manag 205. https://doi.org/10.1016/j.enconman.2019.112382

[30] Su Y, Zhang Y, Zhang S, et al.. Exploring the selectivity of renewable phenol from catalytic pyrolysis of biomass via activated carbon catalyst. J Anal Appl Pyrolysis, 2025, 190: 9

[31] Tian X, Wang Y, Zeng Z, et al.. Research progress on the role of common metal catalysts in biomass pyrolysis: a state-of-the-art review. Green Chem, 2022, 24: 3922-3942

[32] Valizadeh S, Ko CH, Lee J et al (2021) Effect of eggshell - and homo-type Ni/Al₂O₃ catalysts on the pyrolysis of food waste under CO₂ atmosphere. J Environ Manage 294. https://doi.org/10.1016/j.jenvman.2021.112959

[33] Wang Y, Wang C. Sustainable production of carbon nanotubes from plastic pyrolysis using Ni- and Fe-biochar catalysts synthesized via hydrothermal treatment. Appl Catal B Environ Energy, 2025, 373 125340

[34] Wen X, Li R, Yang Y, et al.. An egg-shell type Ni/Al₂O₃ catalyst derived from layered double hydroxides precursor for selective hydrogenation of pyrolysis gasoline. Appl Catal a-Gen, 2013, 468: 204-215

[35] Wohlgemuth S, Vilela F, Titirici M, et al.. A one-pot hydrothermal synthesis of tunable dual heteroatom-doped carbon microspheres. Green Chem, 2012, 14: 741-749

[36] Wu G, Zhang C, Li S, et al.. Hydrogen production via glycerol steam reforming over Ni/Al₂O₃: influence of nickel precursors. ACS Sustain Chem Eng, 2013, 1: 1052-1062

[37] Yang H, Cui Y, Han T et al (2023) High-purity syngas production by cascaded catalytic reforming of biomass pyrolysis vapors (vol 322, 119501, 2022). Appl Energy 331. https://doi.org/10.1016/j.apenergy.2022.120417

[38] Yu Z, Xiao Y, Liang D, et al.. Selective preparation of aromatic compounds from catalytic pyrolysis polyester coating over Ni, Mo and Co metal modified ZSM-5. J Environ Chem Eng, 2025, 13 115608

[39] Zhang F, Zhang X, Song Z et al (2022) Fe/HZSM-5 synergizes with biomass pyrolysis carbon to reform CH₄–CO₂ to syngas in microwave field. Int J Hydrogen Energy 47:11153–11163. https://doi.org/10.1016/j.ijhydene.2022.01.158

[40] Zhang X, Huo L, Yao Z et al (2024a) A comparative review on the progress of thermochemical hydrogen production technologies from agricultural waste. Fuel (Lond) 366:131284. https://doi.org/10.1016/j.fuel.2024.131284

[41] Zhang X, Huo L, Yao Z, et al.. Pyrolysis characteristics and hydrogen production mechanism of biomass impregnated with transition metals. J Clean Prod, 2024, 474 143572

[42] Zhang Y, Zhang X, Zhou Z, et al.. A review of the conversion of wood biomass into high-performance bulk biochar: pretreatment, modification, characterization, and wastewater application. Sep Purif Technol, 2025, 361: 23

Funding

National Key R&D Program of China(2023YFD1701502)

Key Technologies Equipment and Product Development for Efficient Utilization of Rural Wastes(CAAS- ZDRW202510.2)

RIGHTS & PERMISSIONS

The Author(s)