ABSTRACT
Non-noble bimetallic NiMo supported on zeolitic imidazolate framework-derived porous carbon (NiMo@FDC) catalyst for lignin depolymerization has been successfully developed. The synergism between Ni and Mo species in NiMo@FDC catalyst could promote the catalytic cleavage of C-O linkages in Kraft lignin. At a low reaction temperature of 240 °C and under 4 MPa H2, the lignin liquefaction yield was 98.85 wt% and minimum coke yield was 1 wt%, particularly when using 10%NiMo@FDC catalyst. Additionally, at a high reaction temperature of 300 °C and under 2 MPa H2, there was an overall yield of 86 wt% of liquid product and 42 wt% of petroleum ether soluble product. The higher heating value (HHV) increased from 27.65 MJ kg-1 to 34.11 MJ kg-1. In the cycling experiment, the bifunctional catalyst also demonstrated reversability and stability. The synergy of Ni hydrogenation sites and Mo coupled adsorption sites identified a possible mechanism path, which could offer considerable potential for lignin depolymerization.
ABSTRACT
Non-noble bimetallic nanoparticles anchored on Zeolitic Imidazolate Frameworks, bifunctional ReMo@ZNB catalyst, has been demonstrated to promote Kraft lignin depolymerization. In this study, the catalytic activities under different heat treatment conditions are ranked as follows: ReMo@ZNB-700 (Air) > ReMo@ZNB-500 (Air) > ReMo@ZNB-700 (N2). Particularly, bimetallic ReMo nanocatalyst with Re/Mo atomic ratio of 1/3 shows superior performance. Excellent yields of Ethyl acetate soluble products (92.18%) and Petroleum ether extracted biofuels (78%) are obtained at 300â and 24 h, and the calorific value is 32.33 MJ/kg. The ReMo@ZNB catalyst exhibits superior recyclability and regeneration after cycle experiment. Structural characterization results reveal that the incorporation of ReMo can engender the transformation of lattice morphology, the strength of hydrogenation and acid adsorption. The possible mechanism is based on the synergism of adsorption coupling and hydrogenation over ReMo@ZNB catalyst. The synergic action initiates potential perspectives for improving lignin hydroconversion.
Subject(s)
Rhenium , Zeolites , Biofuels , Lignin , MolybdenumABSTRACT
The major challenge in preparing polymer nanocomposites is to prevent the agglomeration of inorganic nanoparticles (NPs). Here, with regenerated cellulose (RC) films as supporting medium, UV-shielding and transparent nanocomposite films with hydrophobicity were fabricated by in situ synthesis of CeO2 NPs. Facilitated through the interaction between organic and inorganic components revealed by X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR) characterization, it was found that CeO2 NPs were uniformly dispersed in and immobilized by a cellulose matrix. However some agglomeration of CeO2 NPs occurred at higher precursor concentrations. These results suggest that the morphology and particle size of CeO2 and the corresponding performance of the resulting films are affected by the porous RC films and the concentrations of Ce(NO3)3·6H2O solutions. The optimized nanocomposite film containing 2.95 wt% CeO2 NPs had more than 75% light transmittance (550 nm), high UV shielding properties, and a certain hydrophobicity.
ABSTRACT
Cellulose nanocrystals (CNC) were carboxylated through an organic solvent free esterification method using l-malic acid (MA) to improve performance of transparent poly(methyl methacrylate) (PMMA) nanocomposites. A series of CNC carboxylated with a degree-of-substitution (DS) of 0, 0.035, and 0.20 were obtained. The presence of grafted carboxyl groups was characterized by Fourier transform infrared (FT-IR) spectroscopy and 13C NMR analysis, meanwhile effects of content and DS of CNC on the structure, thermal, mechanical, and optical transparency properties of the nanocomposites were assessed. The results indicated that the homogeneous dispersion of CNC and a favorable PMMA-CNC interface were necessary to enhance the properties of nanocomposites. Facilitated through hydrogen bonding interactions, the resulting films demonstrated that a low percentage loading of CNC with high DS worked as effective reinforcing agents, producing stronger and tougher films than neat PMMA films, with an improved thermal stability and retention of good transparency.
