Study on the effect mechanism of Ca and Mg with different anion on lignocellulosic biomass pyrolysis

Alkaline earth metals (AEMs) act an important role on biomass pyrolysis, which is significant to explore its specific mechanism for further understanding biomass pyrolysis. This study analyzed the influence of Ca and Mg with different anion (CaO, CaCO3, CaCl2, MgSO4, MgCl2) on biomass pyrolysis, and explored the influence mechanism on the pyrolytic products. Ca and Mg with different anion had obvious different effect on the pyrolytic products from biomass. CaCO3 had little effect on the distribution of products. And CaO might react with CO2 and acetic acid to form CaCO3, which resulted in that solid yield obviously increased and oil yield decreased. Besides, CaCl2 and MgCl2 intensified the ring -open reaction of pyran ring to generate furan. And the formed acidic condition from CaCl2 and MgCl2 decomposition might be beneficial to C -C fracture, carboxylation to generate linear aliphatic, CO2, and acetic acid, but inhibited the generation of CO. Compared with Ca, Mg had more promotion on the generation of linear aliphatics and cyclopentanones. For biomass, CaCl2 and MgCl2 adding might weaken the connection bond between the hemicellulose and cellulose (HC -C) and hemicellulose and lignin (HC -L) in biomass, and resulted in phenyl and CO2 decreasing but androsugar increasing. However, CaO addition could result in androsurgar decreasing with phenyl increasing.