Application Of Molecular Sieves Catalyst In Preparation Of Bio-oils From Hydrothermal Liquefaction Of Sugarcane Bagasse

Sugarcane bagasse,as an environmental friendly biomass feedstock with lower ash content,higher volatile matter content,lower nitrogen content?0.4 wt.%?and sulfur content?1.52 wt.%?,has a wide variety of sources that are readily available and inexpensive with sustainable regeneration advantages.However,the bio-oil produced from biomass by direct hydrothermal liquefaction cannot be used directly as a fuel,due to its high oxygen content and poor chemical stability.ZSM-5 is a microporous crystalline material with good hydrothermal stability,surface acidity and good catalytic performance.It is recognized as a favorable catalyst during the hydrothermal liquefaction of biomass to produce bio-oil which can promote hydroisomerization,deoxidation and cracking reaction to raises the quality of bio-oil,while also reducing the yield of residue.In this work,the metal-modified ZSM-5 are prepared by step-by-step ion exchange,and then characterized.Firstly,the effects of ZSM-5 catalyst amount,temperature,and reaction time are investigated relative to the hydrothermal liquefaction of sugarcane bagasse.The components of each phase of bio-oil are analyzed by GC-MS and the optimal reaction conditions are selected.The effects of metal-modified molecular sieve like NaZSM-5,FeZSM-5 and NiZSM-5 on the distribution of sugarcane bagasse liquefaction products are investigated.Elemental analysis and energy analysis of bio-oil are performed to analyze the changes in oxygen content with and without the catalyst,as well as the heat value.GC-TCD is used to analyze the gas phase composition to investigate the formation mechanism.The SEM and elemental analysis are carried out to analyze the residue phase to explore the further utilization of biochar.The experimental results show that the optimal reaction condition is achieved with the following conditions:3.00 g molecular sieve,200 mL of distilled water,10.00 g of sugarcane bagasse,30 min,and 285?.The metal-modified ZSM-5 with Fe and Ni effectively increases the yield of total-oil and decreases the yield of the residue.However,it is inferior to improve the quality of bio-oil compared with NaZSM-5.It can be seen that the products of oxygenation?phenols,acids,ketones,alkenes and esters?are abundant in the bio-oil.The addtion of metal atom Na on the ZSM-5 can change the amount of acid sites and structure.In this way,NaZSM-5 can effectively decarboxylate and decarbonylate,promote the formation of aromatic hydrocarbon compounds,and reduce the oxygen content in the bio-oil by about 9.12%.Moreover,the lower O/C and higher H/C increases the heat value up to 29.17 MJ/kg.The residue phase which contains a higher C content and a lower O content has better recovery significance.The gas phase is dominated by H₂,CH₄,and CO₂.FeZSM-5 has a greater effect on promoting hydrogenation and has a relatively weak effect on the formation of CH₄ and CO₂.