Solid phosphoric acid catalysts based on mesoporous silica for levoglucosenone production via cellulose fast pyrolysis
SANTANDER, J. A.; ALVAREZ, M.; GUTIERREZ, V.; VOLPE, M. A.
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
JOHN WILEY & SONS LTD
BACKGROUND:Biochemicals are interesting alternatives for biomass valorization owing to their much higher added value compared to biofuels and energy products. Severalmethods for the production of valuable chemicals such as levoglucosenone (LGO)via thermochemical processes over solid acid catalysts are being investigated due to their important advantages compared to conventional biomass acidimpregnation techniques. The present work explores the synthesis of catalyticmaterials for the production of this platform molecule.RESULTS:Aluminum-loaded SBA-15 mesoporous silica and the corresponding solidphosphoric acid catalysts were prepared, characterized by TEM, FT-IR, MASNMR, NH3-TPD, N2 adsorption, ICP-AES and titration of ?free H3PO4?, and testedin cellulose fast pyrolysis. Post synthesis Al deposition on the silica supportproduced an increase of bio-oil yield and LGO amount in pyrolysis products. Thepresence of Al in solid phosphoric acid (SPA) catalysts led to the formation ofaluminum phosphates, decreasing the concentration of H3PO4 species in thesurface and therefore the LGO levels. The SPAs presented relatively high LGOlevels in the GC-MS detectable liquid products (up to 85 peak area%) which wasfound to be correlated with the amount of free H3PO4 in the solid catalysts.CONCLUSION:Aluminum grafting over SBA-15 is an effective way to increase the selectivity to the target anhydrosaccharide. In SPAs, the presence of Al reduced the easilyleachable H3PO4 amount, which is desirable from the point of view of catalyststability since deactivation is mainly caused by H3PO4 leaching, but also led tolower levels of LGO in bio-oil.