沈阳化工大学

Internals-regulated pyrolysis, characterized by co-current heat and volatile flow, shows great potential for industrial application, but its sulfur transformation behavior is still unclear. This study systematically compares sulfur transformation in internals-regulated and traditional pyrolysis using waste tires and Shenmu coal as feedstocks. For both feedstocks, internals-regulated pyrolysis retains more sulfur in char and tar while reducing sulfur retention in pyrolytic gas across the entire temperature range, compared with traditional pyrolysis. The cracking of sulfur-containing oil into gaseous sulfur species is significantly suppressed in internals-regulated pyrolysis, resulting in lower gaseous sulfur yield and higher liquid-phase sulfur yield. In addition, a two-stage reactor was used to investigate the influence of temperature profiles (high-to-low in internals-regulated versus low-to-high in traditional pyrolysis) on sulfur transformation during volatile-char interactions. When volatiles from the first stage pass through a high-temperature char bed, H2S release increases and char sulfur content decreases, due to temperature-enhanced desulfurization by reducing gases (H2 and CO). In contrast, when volatiles pass through a low-temperature char bed, H2S release decreases and char sulfur content increases, primarily due to the adsorption of H2S by the char matrix. Based on these findings, a mechanistic framework for sulfur transformation in both pyrolysis modes is proposed.

The performance of eucalyptus wood catalytic pyrolysis for gas production was investigated over a NiMo/Al2O3 monolithic catalyst in a fixed bed reactor. Tests using the powder catalyst confirmed the optimal conditions of 750 degrees C, 15 wt.% water content in biomass and 1.5 g catalyst loading, under which a gas yield of 91.05 wt.% was achieved, along with H2 and CO fractions of 45.9 vol.% and 43.1 vol.%, respectively. Under the same conditions, the continuous operation of monolithic catalyst obtained a gas yield of 92.67 wt.%. Notably, the H2 and CO fractions reached 56.3 vol.% and 33.4 vol.%, respectively. Catalyst characterization results show that the catalyst coating was tightly bonded to the honeycomb cordierite support, and highly active coke deposited on the catalyst surface with negligible impact on its activity. The above-mentioned results contribute to proposing a catalytic pyrolysis mechanism: the NiMo/Al2O3 monolithic catalyst facilitates cleavage of chemical bonds, generating a large number of active hydrogen species. These ions rapidly stabilize reactive intermediates, inhibiting their polymerization and ultimately yielding a gas-rich product. This study provides a new approach for converting biomass to gas without O2 involvement and effectively verifies the technical advantages and feasibility of NiMo/ Al2O3 monolithic catalyst for gas/syngas production.

Ketone-containing oxygenates are important intermediates in biomass-derived fuel conversion, but their structure-dependent pyrolysis behavior and interactions with alcohol additives remain unclear. In this work, RMD simulations are employed to investigate the pyrolysis of methyl butyl ketone (MBK), methyl isobutyl ketone (MIBK), and their mixtures with ethanol. Product distributions reveal clear structure-dependent selectivity: linear MBK mainly produces C2H4, whereas branched MIBK gives a higher contribution of C3H6. Ethanol affects pyrolysis of two ketone isomers differently. In MBK co-pyrolysis, ethanol mainly contributes additional C2H4 and H2O, with only minor changes in MBK-derived products. In contrast, MIBK co-pyrolysis shows more evident redistribution of ketone-derived C2H4, C3H6, and CO formation. Reaction pathways further show that MBK largely retains its original decomposition network after ethanol addition, while MIBK exhibits stronger changes in C-C scission, H-abstraction, and oxygenated-fragment decomposition. These findings provide atomic-level insights into alcohol-assisted pyrolysis of ketone-containing oxygenated fuels.

Metal oxides have attracted increasing attention as photothermal conversion materials owing to their flexible electronic tunability and robust thermal endurance. Recently, diverse strategies have been developed to improve their photothermal conversion efficiency (η), including defect manipulation, phase transition regulation, and plasmon-induced enhancement. The review summarizes the recent advances of these approaches and their synergistic integration, and discusses the underlying physical mechanisms governing carrier dynamics and thermal dissipation. Finally, the review proposes key challenges and future research priorities in the development of metal oxide-based photothermal materials.

MAX-phase materials are promising candidates for thermal barrier coating applications, owing to their ultra-high thermal stability, high hardness, and excellent thermal shock resistance. The exploration of new MAX phases is therefore of great significance for developing advanced thermal barrier coating materials. The present work theoretically predicted three novel boron-based Nb2AB (A = Si, Ge, Sn) compounds using swarm intelligent optimization combined with first-principles calculations. Nb2GeB and Nb2SnB are confirmed to adopt the typical MAX-phase P63/mmc structure, whereas Nb2SiB crystallizes in an orthorhombic Pnma structure. These structures are verified to be dynamically stable at ambient pressure and thermodynamically stable from 0 to 1500 K, supporting their experimental feasibility. Notably, orthorhombic Pnma_Nb2SiB exhibits larger bulk modulus (214 GPa), shear modulus (137 GPa), Young’s modulus (338 GPa), and higher melting temperature (2919 K) than the conventional P63/mmc phase, with its melting point approaching that of 8YSZ (2973 K). The minimum thermal conductivity of the presently designed Nb2AB compounds ranges from 0.52 to 0.85 W/m·K, which is significantly lower than that of 8YSZ (2.34 2.21 W/m·K). Although their thermal expansion coefficients are slightly lower than that of 8YSZ, the outstanding overall mechanical and thermodynamic properties render Nb2AB compounds promising for thermal barrier coating applications. The present results are expected to provide valuable theoretical guidance for the experimental synthesis of Nb2AB compounds and further rational design of novel MAX-phase materials.