Valorization of olive mill waste fractions and production of furfural and 5-hydroxymethylfurfural by heterogeneous catalysis over Nb2O5,NbOPO4 and TiO2-PO4catalysts

Theproductionof furansfromthevalorizationofolivemillbiomasswastestreamsincludingolivemillwaste water(OMW),olivevirginpomace(OVP),drypelletizedpomace(DPP),andolivedryleaves(DL)was inves tigatedusingacidicNb2O5,NbOPO4andTiO2-PO4heterogeneouscatalysts.Batchreactionswereperformedin anautoclaveat210◦Cinthepresenceofthesuspendedcatalystsandtheyieldoffurfuraland5-hydroxymethyl furfural(5-HMF)wasdetermined.ThevalorizationofOMWwasfoundmoreeffectiveinthepresenceofNbOPO4 asaresultofitshighaciditynature.TheamountandstrengthoftheacidsitesofNbOPO4weremuchhigherthan theothercatalysts.ThehighestyieldofhexosessugarsinOMWto5-HMFwas44%,whilefurfuralwasaminor product.The5-HMFyieldfurther increasedto91¯terpre-extractionof thepolyphenolicspecies fromthe OMW.RecyclingtestsofNbOPO4catalyst, themostperformantone, indicatedtheverygoodstabilityof this material.Asresultofthehighestxylosecontentintheolivemillsolidsfractions(olivepomace,drypelletpomace anddryleaves),furfural’syieldsof100%,57%and31%,respectively,wereobserved,while5-HMFincontrast toOMWwasaminorproduct.Thisworkdemonstratesthefeasibilityofusingacidiccatalystsforthevalorization ofolivemillwastestreamstargetingthedesiredfuranproduct.