Reaction-Network Kinetics of Lignin Hydrothermal Liquefaction: Effect of Cu Incorporation Strategy
- 1Department of Chemical Engineering
- 2Indian Institute of Science
- 3Indian Institute of Technology Roorkee
Abstract
Cu-based catalysts can enhance bio-oil production during the hydrothermal liquefaction (HTL) of lignin; however, the influence of Cu incorporation strategy on individual reaction pathways remains insufficiently understood. In this study, experimental HTL of lignin under direct Cu-assisted and Cu-impregnated conditions was investigated over 200–320 °C and residence times of 5–25 min, together with a five-pathway lumped kinetic model. Apparent kinetic parameters were estimated by nonlinear regression of the experimental product yields. The model captured the principal evolution of residual solid, bio-oil, water-soluble fraction, and gas over the investigated conditions. The maximum bio-oil yield was obtained at 280 °C and 15 min, increasing from 24.87% for the direct process to 28.74% for Cu-impregnated lignin. Kinetic analysis revealed pathway-dependent effects of Cu impregnation. At 280 °C, the apparent residual-solid-to-bio-oil rate constant (k1) increased from 0.0211 to 0.0402 min-1, whereas the fitted contribution of the direct residual-solid-to-gas pathway (k3) was substantially lower following Cu impregnation. The apparent bio-oil-to-gas rate constant (k4) also increased at elevated temperatures, indicating stronger secondary conversion of bio-oil under more severe conditions. Arrhenius analysis further showed differences in the apparent activation energies and pre-exponential factors of the dominant pathways. Overall, the results demonstrate that Cu impregnation modifies the apparent distribution of reaction pathways rather than uniformly increasing all fitted rate constants, providing a quantitative kinetic framework for understanding the influence of Cu incorporation strategy on lignin HTL.
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BibTeX
@misc{kumar2026reactionnetwork,
title = {{Reaction-Network Kinetics of Lignin Hydrothermal Liquefaction: Effect of Cu Incorporation Strategy}},
author = {Ankit Kumar and Sivamohan N.},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15009969/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009969/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Reaction-Network Kinetics of Lignin Hydrothermal Liquefaction: Effect of Cu Incorporation Strategy
AU - Ankit Kumar
AU - Sivamohan N.
PY - 2026
DA - 2026/10/06
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009969/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009969/v1
AB - Cu-based catalysts can enhance bio-oil production during the hydrothermal liquefaction (HTL) of lignin; however, the influence of Cu incorporation strategy on individual reaction pathways remains insufficiently understood. In this study, experimental HTL of lignin under direct Cu-assisted and Cu-impregnated conditions was investigated over 200–320 °C and residence times of 5–25 min, together with a five-pathway lumped kinetic model. Apparent kinetic parameters were estimated by nonlinear regression of the experimental product yields. The model captured the principal evolution of residual solid, bio-oil, water-soluble fraction, and gas over the investigated conditions. The maximum bio-oil yield was obtained at 280 °C and 15 min, increasing from 24.87% for the direct process to 28.74% for Cu-impregnated lignin. Kinetic analysis revealed pathway-dependent effects of Cu impregnation. At 280 °C, the apparent residual-solid-to-bio-oil rate constant (k1) increased from 0.0211 to 0.0402 min-1, whereas the fitted contribution of the direct residual-solid-to-gas pathway (k3) was substantially lower following Cu impregnation. The apparent bio-oil-to-gas rate constant (k4) also increased at elevated temperatures, indicating stronger secondary conversion of bio-oil under more severe conditions. Arrhenius analysis further showed differences in the apparent activation energies and pre-exponential factors of the dominant pathways. Overall, the results demonstrate that Cu impregnation modifies the apparent distribution of reaction pathways rather than uniformly increasing all fitted rate constants, providing a quantitative kinetic framework for understanding the influence of Cu incorporation strategy on lignin HTL.
ER -