Research progress on the reactivity of biomass char and its correlation with Raman spectroscopy characterization
Biomass energy,as the most extensively utilized source of renewable energy,has advantages such as substantial reserves,the absence of carbon emissions,renewability,and consistent supply.The usage of biomass char is a significant aspect of biomass energy utili-zation,and its reactivity varies greatly due to different types of raw materials,which seriously hinders the advancement of research and the utilization of biomass energy.The reactivity of biomass char is primarily influenced by inorganic components,texture properties,and car-bon structure.Raman spectroscopy,as a fast-advancing technique for characterizing carbon structures,has has been widely used in the study of the physical and chemical properties of biomass char.In this paper,starting from the spectral parameters such as band position,band width,band intensity ratio,and band area of biomass coke Raman spectroscopy,the carbon structure of biomass char at home and abroad was summarized.The changes in carbon structure during the thermochemical transformation of biomass char were thoroughly ana-lyzed.Raman spectroscopy is a reliable method for analyzing the carbon skeleton structure of biomass char.The presence of a well-organ-ized aromatic or graphitized structure in the char will decrease its reactivity.Currently,there is a limited amount of research on the rela-tionships between the reactivity of biomass char and the carbon skeleton structure characterized by Raman spectroscopy.These stud-ies mostly concentrate on a specific type of biomass,and the generalizability of its findings still needs to be verified.There are also a few studies on the char reactivity and Raman spectrum of various biomass raw materials.However,no quantitative conclusions have been giv-en.The research findings on the relationships between the char reactivity of different biomass feedstock and the Raman parameters of char were introduced,in order to offer a reference for future studies on the reactivity of biomass fuel.The future holds enormous potential for the development of Raman spectroscopy in analyzing biomass char.Currently,the primary focus of study is on analyzing the spectral region of the first-order Raman spectrum.The second-order Raman spectrum has not received much attention.In addition,advanced Raman spec-troscopy techniques,including surface-enhanced Raman spectroscopy,tip-enhanced Raman spectroscopy,and coherent anti-Stokes Ra-man scattering,have not yet been utilized in the analysis of carbon structure and reactivity in biomass char,and should be given priori-ty consideration in the future.