Study On The Preparation Of γ-valerolactone From Biomass-derived Levulinic Acid By Ni-based Catalysts

Levulinic acid(LA)is one of the twelve most important biomass platform compounds,which can be transformed to the high-valued chemical,γ-valerolactone(GVL).Notably,the safe and non-toxic GVL has been paid close attention in industry since it has been widely reckoned as a food additive,green solvent and precursor to multiple chemical materials(e.g.polymeric materials and liquid fuels).Moreover,GVL is considered as a promising fuel additive.Rencently,1,4-dioxane is widely used as the solvent for direct hydrogenation of LA to GVL.However,when non-noble metals were used as catalysts in this system,the reaction conditions were very harsh.In addition,the preparation of GVL from LA in aqueous phase may be a more economical and green choice.However,it is very difficult to realize the efficient conversion of LA to GVL in aqueous phase under mild conditions.Therefore,in this paper,a variety of non-noble metal Ni-based catalysts with high activity were designed to accomplish the efficient conversion of LA to GVL under mild conditions in the system of 1,4-dioxane or water.Firstly,to realize the conversion of LA to GVL in 1,4-dioxane system under mild conditions,the Ni-Al catalyst(xNiAl)was synthesized by urea-hydrolysis prcipitation method.The 2NiAl catalyst was successfully accomplish the efficient conversion of LA to GVL under mild conditions in the system of 1,4-dioxane(140℃,3 MPa H2,2 h).Then,the Co-Ni-Al catalyst(2NixCoAl)was successfully synthesized on the basis of 2NiAl catalyst The reaction temperature needed for LA to prepare GVL in 1,4dioxane system can be further reduced.Finally,the efficient conversion of LA to GVL can be achieved under mild conditions in the system of 1,4-dioxane(120℃,3 MPa H2,2h).Finally,in order to achieve high-efficiency conversion of LA to GVL under mild conditions in aqueous phase,a nitrogen-carbon doped Ni-Al catalyst(NixAly/NC)was designed.By using Ni0.55Al0.45/NC catalyst,100%LA conversion and 95.6%GVL yie ld were successfully achieved under mild conditions(150℃,1 MPa H2,6 h)of low hydrogen pressure.