Study On Tar Removal In Hydrogen Production From Biomass Gasification

Biomass gasification can convert solid biomass into combustible gas such as CH₄and H₂.And high-purity H₂ can be prepared after purifying,which can be used as low-carbon and clean vehicle fuel.In the process of biomass gasification,tar is produced inevitably.It will block pipelines and endanger human health and ecological environment.Therefore,tar removal is the key to the stable operation and efficient gas production of biomass gasification system.The effects of activation temperature,activation time,steam concentration and Fe loading on the micro physicochemical properties of biochar are studied by this paper.Biochar was produced by pyrolysis of rice husk and activated with steam.Then Fe₂O₃was selected as a metal load to make biochar-Fe₂O₃ catalyst successfully.Finally,toluene was selected as a tar model compound to remove the above catalyst and the effect of Fe loading on removal efficiency was analyzed.The results show that activation treatment can significantly improve the specific surface area of biochar,and activation temperature and time can also promote it.The influence of activation atmosphere on the specific surface area increases first and then decreases.With the increase of Fe loading,the toluene removal efficiency of the catalyst also increases first and then decreases.When the Fe loading is 4%,the removal efficiency is up to 94.1%.According to the characterization results before and after the catalyst reaction,the removal of toluene mainly depends on n-πeffect,pore filling and catalytic action of Fe.In this paper,the carbon deposition mechanism of the catalyst is investigated by TG,Raman and SEM.It is found that the carbon deposition appears in spherical form and is layered with the reaction.With the increase of Fe loading,the carbon content decreases gradually.Due to the richness of Fe₂O₃ in lattice oxygen,the higher the load of the Fe₂O₃ is,the higher the possibility of the reaction with carbon deposition has.At last,Material Studio was used to conduct molecular dynamics simulation and calculation for the diffusion and adsorption of tar model compounds inside the porous structure of catalyst.And the effects of oxygen-containing functional groups on the diffusion and adsorption characteristics of different tar model compounds were discussed.It was found that both-OH and C-O had the effect of reducing porosity and pore volume,and the increase of C-O bond would lead to structural instability,which verified the mechanism of action of some experimental functional groups on tar model compounds.