Molecular dynamics simulation on the diffusion coefficients of the carbon and hydrocarbon radicals in the hydrogen production process in supercritical water gasification

Supercritical water (SCW) gasification is a kind of high efficient and low-carbon conversion technology of biomass, fossil energy or organic matters for hydrogen production. Molecular dynamics (MD) simulation has been a convenient effective method to study intrinsic microscopic mechanisms of supercritical water properties and SCW gasification, in which the diffusion of free radicals is crucial. Thus, free radical diffusions with SCW were investigated using MD calculations in current work. Besides, the impacts of pressure and temperature on diffusion coefficients for radicals were explored and obtained respectively. The results showed that higher temperature could promote the free radical diffusions under SCW circumstances in the work. Lower pressure had a positive impact on diffusion coefficients relatively for hydrocarbon radicals. The study is prospective to reveal the diffusion behaviors for carbon and hydrocarbon radicals with SCW and may offer a basis in theory to accomplish effective and entire low-carbon coal/biomass gasification for producing hydrogen.

Automated summary

This article investigates the diffusion behavior of free radicals in supercritical water using molecular dynamics simulation. The results show that higher temperatures promote free radical diffusion under supercritical water conditions, while lower pressure has a positive impact on diffusion coefficients for hydrocarbon radicals.