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The pyrolysis of Huadian oil shale was carried out in a non-isothermal thermorgravimetric thermal analyzer system. The particle size (0.3–0.45 mm, 0.2–0.3 mm, 0.15–0.2 mm, 0.088–0.15 mm, 0.075–0.088 mm, and <0.075 mm), heating rate (5, 10, 20, and 50℃ min−1), and specimen mass (approximately 5 mg, 10 mg, and 15 mg) were considered to study the effects which caused by mass and heat transfer limitations. The kinetic parameters were determined using Kissinger–Akahira–Sunose (KAS), Friedman, and Coats-Redfern method combining the Avrami-Erofeev AE2 kinetic model. And the gray relational analysis method was employed to investigate the influence of particle size, heating rate, and specimen mass on the pyrolysis behavior as well as kinetic parameter. It is showed that, in the second stage, average activation energy of Huadian oil shale was 225 ± 7 KJ mol−1, 240 ± 6.5 KJ mol−1, and 244 ± 21.5 KJ mol−1, calculated by KAS, Friedman, and Coats-Redfern-Avrami-Erofeev method, respectively, indicating that the second stage can be modeled by Avrami-Erofeev AE2 equation. The order of the gray relational grade showed that the particle size, heating rate, and specimen mass exhibit a noticeable relevance to pyrolysis behavior of Huadian oil shale. The heating rate has a significant effect on both the product release rate and average activation energy. The particle size has the least effect on the product release rate, while specimen mass has the least influence on the average activation energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ternary Mn 0.5 Cd 0.5 S/CB/CuS hierarchical multiheterojunction system was designed. • Synergetic effect between multifunctional CB and CuS dual cocatalysts discussed. • High H 2 -production rate achieved over composite, 4.79-fold higher than Mn 0.5 Cd 0.5 S. Developing exceptionally robust and cost-effective cocatalysts to suppress charge recombination and reduce the reaction energy barrier remains an enormous challenge for producing high-valued and storable hydrogen fuel from photocatalytic water splitting. Herein, novel Mn 0.5 Cd 0.5 S nanoparticles modified with multifunctional carbon black (CB) nanowires and CuS nanotubes as dual cocatalysts were fabricated via sonochemical loading, and subsequent in-situ deposition routes. In this ternary hierarchical architecture, both CB nanowires and CuS nanotubes can serve as normal electron cocatalysts to markedly promote the hydrogen generation performance by lowering the thermodynamic overpotential for hydrogen evolution. Moreover, due to the high electrical conductivity, the multifunctional CB material can also function as a bridge to effectively capture and transmit the photoexcited electrons from Mn 0.5 Cd 0.5 S to CuS with outstanding electrocatalytic hydrogen evolution activity, thus maximizing the carrier separation and H 2 -evolution reaction kinetics. Interestingly, the cooperative effects between CB and CuS dual cocatalysts are also helpful for improving the oxidation capacity of photoexcited holes by lowering the valence band position of Mn 0.5 Cd 0.5 S, which further accelerates the electron-hole separation. As a result, the constructed Mn 0.5 Cd 0.5 S/CB/CuS hierarchical multiheterojunction catalyst shows the superior hydrogen generation efficiency of 819.9 μmol h−1 and excellent stability under simulated solar light irradiation. [ABSTRACT FROM AUTHOR]

Oil shale pyrolysis is normally extremely complicated because many reactive processes simultaneously occur and different products are therefore continuously generated and serve as a new reactant, as a multi-stage processes with competing or parallel reactions. To probe deeply into the pyrolysis kinetics of Huadian oil shale, we have employed multi-stage parallel reaction model and bi-Gaussian distribution method to fit the non-isothermal thermogravimetric data. Friedman, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose methods were utilized to estimate activation energy, and two master plots methods were introduced to establish kinetic models. Two reactions were involved in devolatilization of organic matter in oil shale, and the Reaction II was a principal process of Stage II and dominated kinetic property of overall Stage II. The heating rate had some impact on the pyrolysis process but exerted little influence on kinetic parameters. The comparison of these results indicated the inherent property and thermal stability of oil shale pyrolysis. [ABSTRACT FROM AUTHOR]