What question did this study set out to answer?

Investigate the impact of CO2-assisted steam gasification on hydrogen production from rice straw.

March 30, 2026Green Energy and Resources1 citationsOpen Access

CO2 assisted steam gasification for hydrogen-rich syngas from rice straw: Evolution of carbon structure and its effect

PLPeng LiuChangzhou University MXMeiling XieChangzhou University YCYu ChenKunming University of Science and Technology

Key Points

Investigate the impact of CO2-assisted steam gasification on hydrogen production from rice straw.
Conducted gasification experiments in a fixed-bed reactor
Analyzed gas composition using gas GC
Applied solid-state 13C nuclear magnetic resonance for structural changes
Performed elemental analysis for covalent bond quantification
Hydrogen yield significantly increased with higher temperatures
CO2 served as an oxidant and enhanced aromatic ring reactions
H2/CO ratio improved from 0.64 to 1.71 with CO2 and H2O at 700°C
Methane and carbon monoxide levels decreased substantially after gasification.

Abstract

CO 2 -assisted steam gasification of rice straw (RS) offers a promising approach for both the sustainable utilization of rice straw and the reduction of CO 2 emissions. This study investigates the transformation of RS during pyrolysis and gasification in a fixed-bed reactor, with structural changes observed through solid-state 13 C nuclear magnetic resonance and Fourier-transform infrared (FT-IR) spectroscopy. The gas composition is analyzed by gas GC, and covalent bonds are quantified through carbon structure and elemental analysis. The results demonstrate that steam acts as a key reactant in the gasification process, significantly enhancing the pyrolysis of RS and leading to higher hydrogen yields. CO 2 serves as an oxidant above 500°C, oxygenating aromatic rings and initiating ring-opening reactions to form active C(O) intermediates that are crucial for hydrogen production. The hydrogen yield increases similarly to H 2 O gasification, while methane and carbon monoxide decrease significantly after gasification over 700°C. The H 2 /CO ratio improves from 0.64 in N 2 to 1.46 in H 2 O, and further to 1.71 in CO 2 -H 2 O at 700°C. CO 2 -assisted steam gasification optimizes the reactive interface activity, promoting the selective formation of hydrogen and improving the efficiency of the gasification process. Furthermore, CO 2 plays a pivotal role in enhancing the formation of active C(O) intermediates, which further facilitates the production of high-purity hydrogen. The process also induces the formation of a regular micro-pore structure, improving the overall efficiency and selectivity of directional hydrogen generation. • Steam is acted as the reactant and catalyst for gasification of RS. • CO 2 -assisted steam gasification significantly enhances hydrogen yield and purity. • CO 2 -assisted steam gasification optimizes reactive interface activity for gas reaction. • CO 2 improves the active C(O) intermediates for Hydrogen production.

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