Study On The Hydrogenation Rearrangement Of Furanic Compounds To Cyclopentanone Derivatives

Biomass,as an only renewable carbon source,can be used for preparation of various chemicals and fuels.Among the three components of lignocellulose biomass,cellulose and hemicellulose can be converted into platform compound 5hydroxymethylfurfural(HMF)and furfural(FF)by acid-catalyzed hydrolysis,and further converted into various high value-added downstream chemicals.Cyclopentanone derivatives are a kind of fine chemicals which are widely used.At present,cyclopentanone derivatives are mainly prepared from fossil resources.This method has problems,such as complex process,high cost and serious pollution.Herein,in this thesis,HMF and FF were used as the raw materials and non-noble metal was adopted as the catalysts to synthesize cyclopentanone derivatives through hydrogenation ring-rearrangement in the aqueous phase,such as 3hydroxymethylfurfural(HCPN),cyclopentanol(CPL)and 2,5bishydroxymethyltetrahydrofuran(BHMTHF).Firstly,a bimetallic Ni-Fe/Al2O3 catalyst was prepared to catalyze the ringopening rearrangement of HMF to HCPN in the aqueous phase.By adjusting the active metal species and the support,the catalysts were screened for catalytic performance,and Ni4-Fei/Al2O3 catalyst possessed the best activity.The Ni4-Fe1/Al2O3 catalyst could obtain near 100%HMF conversion and 86%HCPN yield under the conditions of 160℃,4 MPa,and 4 h.The Fe element that was introduced into the catalyst as a metal additive promoted the formation of alloy,which enhanced catalyst’s absorption ability for H species,thereby improving hydrogenation efficiency.In addition,Fe could promote the coordination of aldehyde functional groups on the metal surface,thus inhibiting furan ring hydrogenation process and enhancing the selectivity towards HCPN.The results of catalyst’s reusability test showed that activity loss was attributed to that Al2O3 support underwent phase transformation to AlO(OH)in the aqueous phase and carbon was deposited on the catalyst surface,and the catalysts could be regenerated as fresh by heat treatment.Furthermore,with regard to different active sites involved in the hydrogenation rearrangement process,a Ni-Co/SiO2 catalyst was developed for the selective total hydrogenation of HMF to BHMTHF in the aqueous system.Inert SiO2 aerogel was used as the support to reduce the acid-base sites of the catalyst,thereby inhibiting ringopening,condensation,and other side reactions;and the hydrophilic SiO2 made the catalyst have good dispersion in the aqueous phase.Under the conditions of 110℃,3 MPa,4 h,near 100%HMF conversion and 82.8%BHMTHF yield could be achieved.Moreover,the catalyst had good stability.It still maintained high activity after four cycles.After the fifth use,the activity was significantly attenuated.Finally,a NiCoAl composite catalyst was prepared by urea hydrolyzation and used for the ring-opening rearrangement of furfural into cyclopentanol.The optimized Ni0.5C02.5Al catalyst can achieve near 100%conversion of FF and a CPL yield of 68%under the reaction conditions of 170℃,2 MPa,and 4 h.The ratio of the metal components had a significant effect on the metal phase,catalyst’s physical and chemical properties and product distribution.According to the characterization of XRD,XPS,BET,etc.,the Ni0.5Co2.5Al catalyst contained metal Ni and Co,while other catalysts were mainly composed of solid solution,which made it difficult for NiO and CoO to be reduced and therefore the catalysts were inefficient for hydrogenation.Meanwhile,Ni0.5Co2.5Al had the largest specific surface area and pore volume,which led to excellent activity and stability.Besides,the carbon balance during the reaction was studied,and it was found that carbon loss could be ascribed to that furfural and furfuryl alcohol were prone to undergo resinification in the high-temperature aqueous phase.