Selective conversion of biomass-derived furfuryl alcohol into n-butyl levulinate over sulfonic acid functionalized TiO_(2) nanotubes

Sulfonic acid functionalized titanate nanotubes were prepared by the sulphonation reaction of hydrothermally synthesized TiO_(2) nanotubes(TNTs) using chlorosulfonic acid as the sulfating agent.The as-prepared catalysts were characterized by fourier transform infrared(FT-IR)spectroscopy,transmission electron microscopy(TEM),scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX),Xray diffraction(XRD) analysis,thermogravimetry-differential thermal gravimetry(TG-DTG) and X-ray photoelectron spectroscopy(XPS)techniques.The characterization results revealed that the catalysts retained the tubular structure of the TNTs and possessed a large number of active sulfonic acid sites.The catalytic performance of the catalysts for the synthesis of n-butyl levulinate was investigated via the alcoholysis of biomass-derived furfuryl alcohol under atmospheric pressure.The effects of the reaction factors such as the catalyst dosage,reaction time,and temperature on the alcoholysis of the furfuryl alcohol were systematically studied.Under mild conditions,about 79.9% yield of n-butyl levulinate was achieved.In addition,the catalysts showed a stable catalytic performance after four consecutive cycles.Furthermore,no leaching of the active species was observed during the hot filtration testing,which can be attributed to the covalently linked –SO_(3)H groups on the TNTs surface.In addition,the opened tubular nanostructure of the catalyst and the introduced strong Br?nsted acid sites exhibited synergistic effects,which facilitated the selective conversion of the furfuryl alcohol to butyl levulinate.

Efficient base-free oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over copper-doped manganese oxide nanorods with tert-butanol as solvent

2,5-Furandicarboxylic acid(FDCA)is an important and renewable building block and can serve as an alternative to terephthalic acid in the production of biobased degradable plastic.In this study,Cu-doped MnO_(2) nanorods were prepared by a facile hydrothermal redox method and employed as catalysts for the selective oxidation of 5-hydroxymethylfurfural(HMF)to FDCA using tert-butyl hydroperoxide(TBHP)as an oxidant.The catalysts were characterized using X-ray diffraction analysis,Fourier transform infrared spectroscopy,thermo-gravimetric analysis,and transmission electron microscopy.The effects of oxidants,solvents,and reaction conditions on the oxidation of HMF were investigated,and a reaction mechanism was proposed.Experimental results demonstrated that 99.4% conversion of HMF and 96.3% selectivity of FDCA were obtained under suitable conditions,and tert-butanol was the most suitable solvent when TBHP was used as an oxidant.More importantly,the Cu-doped MnO_(2) catalyst can maintain durable catalytic activity after being recycled for more than ten times.