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• Luffa sponge was applied in the gas safety protection field for the first time. • An efficient bio-based flame retardant was synthesized. • Most of the raw materials are natural renewable resources. • Flame-retardant luffa sponge has an excellent flame and explosion-proof effect. • The flame and explosion-proof mechanisms of luffa sponge were explored. Porous materials are widely employed in the gas explosion-proof field because of their abilities to dissipate shock wave energy. Luffa sponge is a biomass material with three-dimensional network structure. Thus, it will be a promising porous explosion-proof candidate material. However, luffa sponge is flammable, limiting its development in the flame and explosion-proof field. In this work, a bio-based flame retardant integrating acid catalyst, char-forming agent and foaming source was synthesized. Then the flame-retardant luffa sponge is prepared through impregnation method, and it is employed to the gas explosion-proof field for the first time. The flame-retardant luffa sponge can completely prevent the explosive flame spread, and its explosion overpressure decay ratio can reach up to 84%. The flame-retardant luffa sponge has superior flame and explosion-proof performances, and it can be produced on a large scale. This work provides a novel idea for the research and development of efficient flame and explosion-proof materials by the utilization of renewable resources. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lean-fuel, stoichiometric and rich-fuel mixtures combustion were investigated. • Flame quenching occurred when the equivalence ratio was 0.5. • Copper foam promoted the explosion when the equivalence ratio was 1.5. • Mechanism of flame retardant and explosion suppression of copper foam was verified. This study investigates the effect of copper foam sheets on explosion suppression in hydrogen/air mixtures with different equivalence ratios (φ). The explosion experiment is conducted in a circular tube with a large aspect ratio (1 0 8). The phenomenon of flame quenching can be observed distinctly in the case of φ = 0.5. In the case of φ = 1.5, the copper foam sheets are destroyed by the reflected shock wave, and the overpressure rises by 65 %. In addition, a longer duration of peak overpressure and a lower attenuation rate can be observed due to the interaction between the shock wave and flame front. For the cases of φ = 1.0 and 2.0, the copper foam sheet effectively prevents flames and shock waves from reflecting. The experimental results provide an essential reference for the design of hydrogen flame arresters, the safety of hydrogen pipeline transportation, and engineering application. [ABSTRACT FROM AUTHOR]