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In a WHF-08-type reactor, three kinds of semicokes (Hongce lignite semicokes, Shenmu bituminous coal semicokes, and Jincheng anthracite semicokes) were activated with ammonia at high temperatures and high pressures. Results showed that the catalytic activity of the semicokes was significantly enhanced after activation. It was observed that the conversions of methane and carbon dioxide increased with increases in the concentration of ammonia and the activation temperature and increased and then stabilized as the activation time increased. It was also observed that the activation pressure had relatively weaker effects on the re-forming reaction and the optimal conditions were as follows: 8% ammonia, 300 °C, 6 MPa, and 3 h. The surface structures of semicokes before and after activation were characterized. The results showed that the content of -NO 2 , -NH 2 , -CN, and other basic groups increased while the content of acidic groups decreased after activation, and the TNB of the three kinds of semicokes improved to 0.373, 0.325, and 0.249 mmol g −1 , respectively, which increased the number of active centers of semicoke and promoted the adsorption of methane and carbon dioxide on the surface of semicokes.
Metaconcrete is a newly manmade concrete where traditional aggregates are partially replaced by resonant aggregates. The metaconcrete slab can attenuate vibration in the specific frequency bandgap which are created by the locally resonant aggregates. To enhance the attenuation performance of metaconcrete slab, a dual-resonant aggregate was designed and embedded into the metaconcrete slab. Firstly, a mass-in-(massin-mass) analytical model is used to predict the bandgap characteristics of dual-resonant aggregates metaconcrete. Then, eigenfrequency investigation is conducted to acquire the dispersion curve of the periodic unit cell by using finite element software COMSOL Multiphysics. The effects of the mass and stiffness ratios parameters on the characteristics of bandgap are studied. The frequency responses of the dual-resonant aggregates metaconcrete reveal that the dual-resonant aggregates metaconcrete slab can acquire vibration wave mitigation in two designed frequency bands. The results offer a base for the optimal design of the metaconcrete slab for structural protections resist vibration loading.
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