Kinetic study for thermocatalytic degradation of waste mixed cloth over antibiotic residue derived carbon-based solid acids

In the present study, the kinetics for waste mixed cloth (WMC) pyrolysis over antibiotic residue derived carbon-based solid acids was investigated for the first time. The kinetic parameters for direct pyrolysis and WMC catalyzed pyrolysis were calculated through isoconvertional method, and different types of mechanism function models were employed to elucidate the catalytic pyrolysis process of WMC. Meanwhile, the most suitable pyrolysis mechanism model was determined by matching the apparent activation energy (E-a). From the kinetical results, the carbon-based solid phosphoric acids significantly reduced the E-a of the main reaction of WMC pyrolysis, which significantly decreased from 366.79 similar to 434.26 kJ/mol to 141.07 similar to 184.85 kJ/mol. The matching of mechanistic models confirmed that the catalytic reaction largely depended on both phase boundary control and diffusion control, which corresponded to the interaction of the primary pyrolysis products with the outer surface and inner acidic sites from carbon-based solid acids, respectively. The more acidic sites on the outer surface of the catalyst, the better its catalytic pyrolysis kinetic process matches the phase boundary-control model. This kinetical investigation will provide a promising reference for the rational design of carbon-based solid acids in WMC pyrolysis, with the aim of realizing the high-value utilization of organic solid wastes

Electrocatalytic hydrogenation of phenol by active sites on Pt-decorated shrimp shell biochar catalysts: Performance and internal mechanism

The development of highly-active electrocatalysts and identification of active sites contribution are necessary for electrocatalytic hydrogenation (ECH) of bio-oil. Herein, the Pt-decorated shrimp shell biochar (SSB) catalysts with high nitrogen content was prepared successfully. The biochar-based catalysts were first used for the ECH of bio-oil model compounds. Results showed that the Pt/SSB catalysts exhibited excellent electrocatalytic activity and stability, realizing 100 % conversion of phenol and 98 % total selectivity of cyclohexanone and cyclohexanol within 5 h. By correlation analysis and density functional theory (DFT) calculations, the Pt, Pt-N-x, and C=O sites in Pt/SSB catalysts were found to play an important role in the stepwise hydrogenation of phenol. Furthermore, the Pt-N-x sites were identified as the main contributor to the high selectivity of cyclohexanol generation. This study lays the foundation for the controllable preparation of electrocatalysts with high activity and stability, which is significant for large-scale upgrading of bio-oil in the future

Reaction performance and mechanism of a NiO/Ca2Fe2O5 oxygen carrier in Chemical looping gasification of cellulose

Chemical looping gasification (CLG) is a novel technology created to realize the clean and efficient utilization of solid fuels, where the syngas product avoids dilution by N2 and the pollutants are inhibited by using metal oxide as oxygen carrier (OC) instead of molecular oxygen. Cellulose, as the main component of biomass-based solid waste, was evaluated in the CLG process with NiO/Ca2Fe2O5 prepared by the impregnation method. Reaction mechanism and morphology evolution of the OC as well as the influence of key reaction parameters were investigated by fixed-bed reactor and thermogravimetric analysis experiments coupled with various characterization techniques. The results indicated that the addition of Ni not only improved the oxygen release performance of Ca2Fe2O5 but also helped tar cracking and carbon conversion. On the other hand, the excellent activity in the solid-solid reaction of Ca2Fe2O5 promoted the performance of the Ni-based OC. The test results revealed that Ca2Fe2O5 was a better base than CaFe2O4, and the carbon conversion efficiency reached 98% with the OC sample at 850 degrees C. NiO markedly improved the reactivity of Ca2Fe2O5 after 10 cyclic reactions. The temperature notably affected activity below temperatures of 850 degrees C and slightly above. Due to the limited reduction of Ca2Fe2O5 below 800 degrees C and the redox behavior improvement being minor above 850 degrees C, the temperature of 850 degrees C was marked as the optimum for the studied process Addition of water inhibited OC inactivation in cyclic reactions, which was mainly attributed to the crystal separation and agglomeration of OC particles. However, water inhibited the deep reduction of metal on the surface, which reduced the activity on tar cracking and carbon conversion to a certain extent

Comprehensive effects of different inorganic elements on initial biomass char-CO2 gasification reactivity in micro fluidised bed reactor: Theoretical modeling and experiment analysis

In this study, a theoretical model of biomass char gasification reactivity was developed, focusing on the catalytic effect of inorganic elements on the char gasification process. A comparison with previous research results shows that the catalytic ability of K in a fixed bed reactor is stronger than that of Ca, while the catalytic ability of Ca in a fluidised bed reactor is stronger than that of K. The migration and transformation of K and Ca in a fixed bed reactor and fluidised bed reactor are compared. In the fluidised bed reactor, a larger proportion of Ca is transformed into an ion-exchanged state than K, which is contrary to the experimental results in the fixed bed reactor. Then, according to the equivalent-volumetric impregnation method, the saturated loading ratio of K was determined to be 35%, and the full catalytic ratio of K was determined experimentally. Finally, eight typical biomass char samples were selected to perform experiments at different temperatures in the micro fluidised bed reactor to determine the char gasification reactivity, and the results were compared with the calculated values of the model. Results show that the model can effectively predict the char gasification reactivity both in trend and accuracy

Electrocatalytic hydrogenation of phenol by active sites on Pt-decorated shrimp shell biochar catalysts: Performance and internal mechanism

The development of highly-active electrocatalysts and identification of active sites contribution are necessary for electrocatalytic hydrogenation (ECH) of bio-oil. Herein, the Pt-decorated shrimp shell biochar (SSB) catalysts with high nitrogen content was prepared successfully. The biochar-based catalysts were first used for the ECH of bio-oil model compounds. Results showed that the Pt/SSB catalysts exhibited excellent electrocatalytic activity and stability, realizing 100 % conversion of phenol and 98 % total selectivity of cyclohexanone and cyclohexanol within 5 h. By correlation analysis and density functional theory (DFT) calculations, the Pt, Pt-N-x, and C=O sites in Pt/SSB catalysts were found to play an important role in the stepwise hydrogenation of phenol. Furthermore, the Pt-N-x sites were identified as the main contributor to the high selectivity of cyclohexanol generation. This study lays the foundation for the controllable preparation of electrocatalysts with high activity and stability, which is significant for large-scale upgrading of bio-oil in the future

Thermodynamic characteristics of methane hydrate formation in high-pressure microcalorimeter under different reaction kinetics

To understand the thermodynamic characteristics of CH4 hydrate formation in a high-pressure microcalorimeter under different reaction kinetics, five typical systems including CH4-H2O, CH4-Tetrahydrofuran (THF)-H2O, CH4- Cyclopentane (CP)-H2O, CH4-Methyl cyclohexane (MCH)-H2O, and CH4-tert-Butyl methyl ether (TBME)-H2O are adopted to conduct experiments in this work. The results show that their hydrate formation thermodynamic characteristics depend greatly on the promoter. For the CH4-H2O system, a hydrate crystals film will form quickly at the beginning of the reaction, hindering the mass transfer between gas and liquid, thereby presenting an extremely slow hydrate formation kinetics. After adding the water-soluble promoter that cannot form an oil phase, like THF, a rapid hydrate formation process is observed from the cooling stage. However, if the promoter can form an oil phase (CP, MCH, and TBME), regardless of whether the promoter is soluble in water, only a slow hydrate formation kinetics can be observed. This is because the oil phase can separate the water and gas phase, reducing their mass transfer efficiency, thereby restricting the hydrate growth. Interestingly, a rapid hydrate formation process can be obtained during their heating stage. These indicate that high driving force cannot always lead to a rapid hydrate formation kinetics. It is worth mentioning that a similar hydrate formation and dissociation behavior in high-pressure microcalorimeter is observed for water-insoluble promoters (CP, MCH), indicating the hydrate structure will not significantly affect their thermodynamic behavior except for the in-tensity of the peaks