Study On In-suit Hydrogenation Conversion Of Biomass Derivatives To ?-valerolactone

Excessive consumption of fossil fuels lead to a persistent energy crisis and serious environmental pollution.It is urgently necessary to explore renewable clean energy for sustainable development.Biomass is the sole renewable resource that can be applied as not only energy but also carbon material source.Due to abundant,low emission,cheap and carbon-neutral characteristics,conversion of biomass into chemicals and fuels has attracted extensive attention.GVL is an excellent fuel because it possesses higher energy density,lower melting point?-31 ^oC?and higher boiling?207 ^oC?than that of gasoline,which is facile and safe for store and transportation.Meanwhile,GVL can be employed as an excellent organic solvent that can be soluble with water and most of the organic solvents.Hence,the production of GVL from biomass is significant for exploring alternatives to fossil energy.Current research on GVL preparation from biomass involves high-pressure and highly pure H₂ as a hydrogen source and precious metals as a catalyst for hydrogenation reaction,facing a high risk of hydrogen transportation and storage and high cost in large-scale production.In this paper,in situ formed hydrogen from water splitting by Fe was used as a hydrogen source and non-noble metal as a catalyst for hydrogenation of biomass derivatives?LA and glucose?into GVL.The detailed research are as follows:Firstly,study on the feasibility of producing GVL by hydrogenation of LA with hydrogen from water splitting by Fe.The results showed hydrogen from dissociation of water can efficiently reduce LA to GVL without catalyst addition.A 55%GVL yield was obtained by optimizing reaction conditions,which were listed as follows:Fe:40 mmol,LA:86mmol/L,250 ^oC,120 min.To improve the hydrogenation efficiency,the catalytic role of transition metals?Ni,Co,Cu,Mo,Cr?was investigated.A Ni displayed excellent catalytic role for hydrogenation of GVL and a 99%yield of GVL was achieved under an optimal condition?Fe:10 mmol,Ni:0.5 g,LA:86 mmol/L,250 ^oC,150 min?.Moreover,Ni can maintain the activity after 4 cycles.The mechanism study indicated pentanoic acid acted as intermediate,followed by intramolecular esterification to GVL formation.Secondly,the conversion of LA into GVL over porous catalysts Raney-Ni?R-Ni?and Raney-Co?R-Co?was studied.The results showed hydrogenation of LA into GVL was efficiently improved by the porous catalysts R-Ni and R-Co.The optimal conditions over R-Ni with 99%yield of GVL were obtained?Fe:20 mmol,R-Ni:0.2 g,filling rate:45%,150 ^oC,90 min?.Especially,a 90%yield of GVL was achieved at a milder reaction temperature,100 ^oC,for 5 h.When R-Co was employed as a catalyst,a 95%yield of GVL was achieved under optimal conditions?Fe:10 mmol,R-Co:0.3 g,filling rate:25%,220 ^oC,90 min?.Thirdly,conversion of LA into GVL with biomass-derived formic acid as H₂ source over porous catalyst was investigated.The results showed the hydrogen formed from formic acid selective decomposition can reduce efficiently LA to GVL.Optimal conditions for R-Ni as a catalyst:R-Ni:0.2 g,Formic acid:172 mmol/L,LA:86 mmol/L,filling rate:35%,150 ^oC,180 min,95%yield of GVL.Optimal conditions for R-Co as a catalyst:R-Co:0.5 g,filling rate:25%,200 ^oC,180 min,95%yield of GVL.Finally,the conversion of glucose into GVL by the 2-step process over R-Ni was studied.In the first acidic hydrolysis step,glucose was converted to LA and formic acid with 50%and 15%yield under an optimal conditions?250 ^oC,30 min,3%?v/v?HCl?.In the second step,hydrogen from water splitting by Fe as a supplementary hydrogen source and R-Ni as a catalyst for the conversion of LA into GVL was conducted and a 70%yield of GVL was achieved under an optimal conditions?220 ^oC,180 min,R-Ni:0.2 g?,Fe:25 mmol.The yield is higher than that of reported works?55%?.In this work,hydrogen from water splitting by Fe or biomass-derived formic acid decomposition was used as a safe and clean hydrogen source,and non-noble metals?Ni,Co?was employed as catalysts for hydrogenation of LA into GVL.More than 95%and 70%yields of GVL from LA and glucose were obtained,respectively.This work provided an efficient way for the production of clean energy and the resource utilization of biomass.