Dongxia Yan

Formation of C–C bonds for the production of bio-alkanes under mild conditions

It is of crucial importance to form C–C bonds between biomass-derived compounds for the production of bio-alkanes from biomass. In this study, it was found that C–C bonds can be formed between angelica lactones, key intermediates derived from biomass, through free radical reactions under mild conditions without using a noble catalyst or solvent, which gave elongated carbon chains of di/trimers with 10 or 15 carbons, with complete conversion and 100% selectivity. The di/trimers produced serve as a novel feedstock for the carbon backbones of bio-alkanes. Hydrogenation of the di/trimers produced C6–C13 hydrocarbons suitable for use as transportation fuels.

Conversion of lignin model compounds under mild conditions in pseudo-homogeneous systems

To produce basic chemicals from lignin, depolymerization and removal of oxygen from lignin through C–O cleavage and hydrodeoxygenation (HDO) are crucial steps. In this study, a novel, pseudo-homogeneous catalyst system, consisting of uniformly stabilized noble metal nanoparticles (NPs) in ionic liquids is developed for the selective reductive cleavage of C–O and HDO. Phenol and guaiacol as lignin monomer model compounds are investigated to gain an insight into the possible HDO pathway, meanwhile, dimeric model compounds such as diphenyl ether and benzyl phenyl ether are studied for the cleavage of C–O bonds between aromatic units. Four types of NPs including Pd, Pt, Rh and Ru were synthesized in situ and well distributed in ILs without aggregation. These catalytic systems displayed almost 100% conversion for various monomeric and dimeric lignin model compounds at 130 °C and were recycled several times without loss of activity. The catalytic selectivity of metals for HDO/C–O cleavage normally decreases in the order of Pt > Rh ∼ Ru ≫ Pd, which is similar to the order of NP size, Pd ≫ Pt > Rh ∼ Ru. With a mean diameter of 5.6 nm, Pt NPs in [Bmim]PF6 are identified as the best catalytic system for the transformation of lignin monomeric and dimeric model compounds with an almost 100% conversion and maximum 97% selectivity.

Conversion of biomass derived valerolactone into high octane number gasoline with an ionic liquid

Conversion of biomass into gasoline of high octane number is challenging. In this study, conversion of biomass-derived γ-valerolactone into gasoline was achieved by decarboxylation of valerolactone to produce butenes and alkylation of the produced butenes with butane using [CF3CH2OH2][CF3CH2OBF3] as an efficient catalyst. The obtained gasoline was rich in trimethylpentane with a high research octane number of 95.4.

Fe–Zr–O catalyzed base-free aerobic oxidation of 5-HMF to 2,5-FDCA as a bio-based polyester monomer

An environment-friendly and economical route for 5-hydroxymethylfurfural (HMF) aerobic oxidation to 2,5-furandicarboxylic acid (FDCA) in an ionic liquid (IL)-promoted base-free reaction system was reported using Fe–Zr–O as a catalyst. A series of FexZr1−xO2 catalysts were synthesized by a hydrothermal method and the catalytic performance was investigated. Among these catalysts, Fe0.6Zr0.4O2 exhibited excellent catalytic activity in the HMF oxidation. A 60.6% FDCA yield and 99.9% HMF conversion could be obtained after 24 h under 2 MPa O2 pressure and base-free conditions. The good performance could be attributed to the large amount of acidic and basic sites on the surface of the catalyst and its high reducibility and oxygen mobility. In addition, the formation of humins and the reaction pathways in the ILs were also investigated, which revealed parallel reactions between FDCA and humin formation. A plausible reaction mechanism was proposed based on the results of a series of designed experiments. Finally, the catalyst was used five times without obvious loss of activity. To the best of our knowledge, this is the best result for a non-noble metal catalyzed base-free oxidation of HMF to FDCA using molecular oxygen as an oxidant.