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The pyrolysis of asphaltenes under hydrothermal environments covering the subcritical and supercritical regions of water was applied, and the influence of the presence of H-donors was surveyed by a reaction kinetics analysis based on the lumping approach. Under hydrothermal environments, the pyrolysis of asphaltenes consisting mainly of condensation to coke and decomposition to maltenes is significantly faster than that under a N2 environment. The H-donors introduced, decalin or maltenes, may provide nonaromatic H atoms, capping the carbon radicals essential to pyrolysis. Accordingly, the apparent activation energies of the condensation and the decomposition of asphaltenes both increase to varying degrees. The pyrolysis of asphaltenes in the presence of a small quantity of decalin is seriously retarded in subcritical water but recovers rapidly in supercritical water owning to the promoted initiation efficiency at high temperature. Accompanied by a large amount of maltenes, the decomposition to maltenes involved in the original pyrolysis network of asphaltenes can be neglected.

Key indicatorsSingle-crystal X-ray study T = 293 K Mean (e-O) = 0.003 Å R factor = 0.024 wR factor = 0.059 Data-to-parameter ratio = 10.6For details of how these key indicators were automatically derived from the article, see

Solid acid catalysts show good catalytic depolymerization behavior for lignocellulose. A stable core-shell structured magnetic solid acid catalyst (MSAC), Fe3O4/C-SO3H, was prepared from glucose, concentrated sulfuric acid, and modified magnetic particles of Fe3O4, which was used as the core. The effects of the carbonization and sulfonation processes on the activity of the catalyst were investigated. The results showed that preparation conditions had great influence on the quantity of the acidic groups (sulfonic, carboxyl, and hydroxyl groups) and the stability of magnetic catalysts. The best preparation conditions for MSAC were 3 h of carbonization time, 450 °C as the carbonization temperature, 9 h of sulfonation time, and 90 °C as the sulfonation temperature. Its surface topography, functional group, chemical composition, and magnetic properties were characterized by analysis instrument. Furthermore, the catalyst was stably dispersed in the reaction system, quickly separated from the reaction system using an external field, and reused many times; 44.3% of xylose yield was obtained at 160 °C for 16 h. The catalyst was used repeatedly more than 3 times, and the recovery over 89%. The depolymerization of corncobs was achieved by magnetic catalyst, representing the depolymerization characteristics of real lignocellulose. This data can be used as a reference for the subsequent use of biomass resource.

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a b s t r a c tZeolitic imidazolate framework-8 (ZIF-8) nanoparticles decorated Zn 2 GeO 4 composites, denoted as ZIF-8@Zn 2 GeO 4 , were prepared through a chemical deposition route. The obtained ZIF-8@Zn 2 GeO 4 heterostructure was characterized by X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results showed that the ZIF-8 nanoparticles have been successfully assembled on the surface of Zn 2 GeO 4 nanorods, and 100 mg of ZIF-8@Zn 2 GeO 4 photocatalyst can reduce nearly 100% of Cr(VI) in aqueous solution (100 mL 1 × 10 -5 mol L -1 ) in 90 min under UV-light irradiation. The obtained ZIF-8@Zn 2 GeO 4 photocatalysts exhibited 14.1 and 1.8 times higher photocatalytic activity toward the photoreduction of Cr(VI) than pure Zn 2 GeO 4 nanorods and ZIF-8 under UV light irradiation, respectively. The synthetic strategy used is also promising for implementing MOF structures in other semiconductor photocatalysts for reduction of Cr(VI) to Cr(III) with enhanced photocatalytic performance and high stability in aqueous media.

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