Preparation And Properties Of Biochar-based Catalyst Based On The Production Of Aromatic Hydrocarbons

With the depletion of fossil fuels,the alternative energy resource needs to be found urgently.Biomass was a clear energy resource that has drawn much attention due to its sustainability and renewability.Catalytic pyrolysis is a method for conversion of biomass toward bio-oil of rich in high-value chemicals.Catalysts play an important role in the process of biomass catalytic pyrolysis.There are few reports on the preparation of high-value chemicals by biochar-based catalysts in biomass catalytic pyrolysis.Biochar-based catalysts have many advantages,such as well-developed porous structure,pore size easy to control,simple preparation and low cost.They have obvious advantages in the preparation of high-value chemicals by catalytic pyrolysis of biomass.In this paper,the walnut shell,palm kernel shell,wheat straw and pine were used as feedstocks to prepare the biochar-based supports/catalysts.And the HZSM-5molecular sieve catalyst was used as the contrast.Fruit shell,especially palm kernel shell,was the best material for the preparation of biochar-based supports.The biochar-based supports were prepared using carbonization and activation method.The results showed that the pyrolysis temperature has a significant influence on the physicochemical properties of the biochar-based supports.As the pyrolysis temperature increased,the surface area of the biochar was 36.70-365.52 m²·g^-1,and the pore size was between 1 and 4 nm.Activation time was an important factor that affects the structure of biochar-based supports.With the extension of steam activation time,the surface area of activated-biochar support reached 1175.86 m²·g^-1,and the average pore diameter was 2-5 nm.The activated-biochar catalysts simultaneous micropore and mesopore properties,it makes the catalyst advantaged porous structure.The biochar-based support under 800^oC?800BC?,for converting the mixed microalgae/palm kernel shell to aromatics production with relative content values of 38.94 area%.The relative aromatics content of activated-biochar support at steam activated 50 min?50minBC?was 49.53 area%,and the yield of aromatic hydrocarbons was 2.37 times higher than that of the non-catalyst process.The service life of the biochar-based support was longer than the HZSM-5 catalyst.Metal active components were introduced into biochar-based supports by wet impregnation method.To study the effect of metal type,loading amount and the synergistic effect with biochar-based supports on the yield and selectivity of aromatic hydrocarbons,four kinds of biochar-based catalyst loaded with Cu,Ni,Zn and Mg were prepared and used to catalytic fast pyrolysis of biomass,respectively.Mg has the most significant effect on the promotion of aromatic hydrocarbon selectivity.The aromatics yield reached a maximum of 49.10 area%when the Mg loading was 3 wt.%on 800BC.Mg loaded on 50minBC and the loading was 3 wt%,the maximum yield?70.394 area%?of aromatic hydrocarbons obtained,especially benzene,toluene and ethylbenzene.In order to study the regeneration of the biochar-based catalyst,the regeneration experiments of the deactivated catalyst were carried out.The results showed that the coking on the catalyst surface could be effectively removed by steam activation method.The deactivated biochar-based catalyst regenerated by steam activated 20min,the relative aromatics content achieved 62.52 area%.This paper provided a basic research for the application of biochar-based catalysts in conversion biomass to aromatic hydrocarbons.