ACS Sustainable Chemistry & Engineering最新文献

With the evolution of hydraulic fracturing technology, shale gas development in China’s Sichuan region has become commercialized and highly active. This process consumes a substantial amount of water, currently primarily sourced from rivers and the direct reuse of flowback water. However, there is a lack of systematic water resource management, leading to high water usage per well and potentially significant adverse impacts on the regional ecosystem. This paper proposes an optimization-based water management model for shale gas development, focusing on total dissolved solids (TDS) as the key pollutant. The model considers three wastewater treatment methods: onsite treatment, commercial treatment centers, and reinjection wells, along with wastewater reuse among well pads. The model accounts for geographic factors, treatment capacities, and wastewater composition, ensuring a comprehensive approach to wastewater management in shale gas development. A case study was conducted on three well pads in the Weiyuan shale gas block in Sichuan. The results show that onsite desalination and wastewater reuse between well pads can significantly reduce water management costs and freshwater consumption. Due to geographic factors, such as the mountainous terrain and distance from existing treatment facilities, commercial treatment centers and reinjection wells are not suggested. The average optimized single-well freshwater consumption in Weiyuan is 15,078 m³, which is comparable to the Eagle Ford site’s average of 16,100 m³ in Texas, USA, but significantly lower than the average of 24,415 m³ in Sichuan.

CO₂ mineralization-coupled amine-looping has great potential for large-scale CO₂ emissions reduction. However, it remains uncertain if amine-looping successfully improves CO₂ sequestration of typical industrial solid wastes of steel slag and iron tailings and whether this enhancing occurs through an increase in CO₂ concentration in solution or by promoting the leaching of calcium ions. Herein, we systematically evaluate the CO₂ mineralization of steel slag and iron tailings in the presence of three typical amines: monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), and piperazine (PZ). Results show that all three amines could significantly enhance the CO₂ mineralization performance of steel slag and iron tailings, especially in PZ solution, where the CO₂ sequestration capacity of steel slag and iron tailings is promoted from 114.4 and 12.6 g/kg to 202.4 and 50.6 g/kg, respectively. Furthermore, Ca²⁺/Mg²⁺ leaching experiments indicate that the enhanced CO₂ mineralization by amine may be a result of more CO₃^2– provided by amine-generated carbamate, which facilitates the formation of precipitates by combining with Ca²⁺/Mg²⁺. Additionally, the carbonation efficiency of steel slag is stabilized at approximately 51 and 71% by recycling MEA and PZ in four successive reactions, showing a good potential in sequestrating CO₂ with an affordable additive cost.

Catalytic conversion of cellulose in biomass into 2,5-hexanedione is a significant step for the production of biobased p-xylene (PX), and a precise understanding about the effect of the coexisting hemicellulose and lignin components is extremely essential and desirable, but still severely deficient. Herein, we investigate the above issue by catalytic tests, structural characterizations, and composition analysis. Catalytic tests confirm that the coexisting hemicellulose does not affect cellulose conversion and could be converted into 5-chloro-2-pentanone, while the lignin component plays a detrimental role. Lignin and the oligomers from lignin hydrogenolysis can block the catalytic active sites via deposition due to the strong interaction between lignin and Pd/C catalyst. Meanwhile, there is noncovalent interaction between lignin and cellulose, reducing the accessibility of cellulose to the catalytic active sites including the Pd/C and acidic sites. Basic treatment by NaOH aqueous solution could result in simultaneous removal of lignin and fracture of the biomass structure and hence higher accessibility for the Pd/C catalyst. When the biomass is treated by NaOH with the concentration of 1.0 wt %, the amount of lignin (8.3 wt %) is low enough and the structure is fractured enough to achieve the yield of HDO and DMF comparable to that using sole cellulose as the reactant.

LiCoO₂ is widely used in lithium-ion batteries. Innovatively, this study reveals that by employing a synergistic strategy of Li volatilization and anion doping, LiCoO₂-based materials demonstrate exceptional performance as solid oxide fuel cell (SOFC) cathodes. At high temperatures, Li volatilization forms a Co₃O₄ phase. Concurrently, anionic doping is achieved by substituting F ions for O ions. The synergy of these two strategies increases the concentration of oxygen vacancies and the formation of heterogeneous interfaces, effectively enhancing the adsorption, dissociation, and diffusion rates of oxygen, thereby significantly improving the oxygen reduction reaction (ORR) of LiCoO₂ (LCO). LCOF1 (LiCoO_1.9F_0.1+Co₃O₄) exhibits an oxygen diffusion coefficient (D_chem) and surface exchange coefficient (K_chem) of 8.85 × 10^–5 cm² s^–1 and 7.61 × 10^–3 cm s^–1, respectively, which are 45% and 26% higher than those of undoped LCO. Furthermore, at 800 °C, LCOF1 achieves a PPD of 0.86 W cm^–2 and an Rp as low as 0.012 Ω cm², representing improvements of 110% in PPD and a reduction of 78.6% in Rp compared to LCO. These findings indicate that the synergistic effect of Li volatilization and F doping is an effective strategy for enhancing the performance of Li-containing cathodes, offering valuable perspectives for the development of high-performance SOFC cathodes.