In the present study, a sustainable pretreatment methodology combining liquid hot water and deep eutectic solvent is proposed for the efficient fractionation of hemicellulose, cellulose, and lignin from sugarcane bagasse, thereby facilitating the comprehensive utilization of both C5 and C6 sugars. The application of this combined pretreatment strategy to sugarcane bagasse led to notable enhancements in enzymatic saccharification and subsequent fermentation. Experiment results demonstrate that liquid hot water-deep eutectic solvent pretreatment yielded 85.05 ± 0.66 g·L–1 of total fermentable sugar (glucose: 60.96 ± 0.21 g·L–1, xylose: 24.09 ± 0.87 g·L–1) through enzymatic saccharification of sugarcane bagasse. Furthermore, fermentation of the pretreated sugarcane bagasse hydrolysate yielded 34.33 ± 3.15 g·L–1 of bioethanol. These findings confirm the effectiveness of liquid hot water-deep eutectic solvent pretreatment in separating lignocellulosic components, thus presenting a sustainable and promising pretreatment method for maximizing the valuable utilization of biomass resources.
Regulation of aluminum distribution in zeolite framework is an effective method for improving its catalytic performance for propane aromatization. Herein, we found that recrystallization and post-realuminization of ZSM-5 cannot only create hollow structures to enhance the diffusion ability, but also adjust the content and position of paired aluminum species in its framework. Various characterizations results confirmed that increase of paired aluminum content and inducement of more aluminum atoms sited in the intersection cavity are beneficial to the formation of aromatic products in propane aromatization. As a result, the hollow-structured ZSM-5 zeolite with more paired aluminum (H-200-hollow) showed higher propane conversion and aromatics selectivity than other samples at the same conditions. The catalytic performance of H-200-hollow can be further improved by ion-exchanging with a small amount of Ga(III) species. The propane conversion and aromatics selectivity of Ga-200-hollow reached as high as 95% and 70%, respectively, at 540 °C and 1 atm.
Unraveling the structure-activity relationship and improving the catalytic performance is paramount in propane dehydro-aromatization reactions. Herein, a tandem catalyst with high propane dehydro-aromatization reaction performance was prepared via coupling the PtFe@S-1 with Zn/ZSM-5 zeolites (PtFe@S-1&1.0Zn/ZSM-5), which exhibits high dehydrogenation activity, aromatics selectivity (~60% at ~78% propane conversion), and stability. The addition of zinc inhibits the cleavage of C6= intermediates on ZSM-5 and promotes the aromatization pathway by weakening zeolite acid strength, significantly improving the selectivity to aromatics. This understanding of the structure-activity relationship in propane dehydro-aromatization reaction helps develop future high-performance catalysts.
Epoxidation of propylene to propylene oxide (PO) with hydrogen peroxide (HPPO) is an environmentally friendly and cost-efficient process in which titanosilicates are used as catalysts. Ti-MWW is a potential industrial catalyst for this process, which involves the addition of HPPO to PO. The silanol groups generated during secondary crystallization unavoidably result in ring-opening of PO and inefficient decomposition of HPPO, which diminish the PO selectivity and the lifespan of Ti-MWW. To address this issue, we conducted post-treatment modifications of the structured Bf-Ti-MWW catalyst with potassium fluoride aqueous solutions. By quenching the silanol groups with potassium fluoride and implanting electron-withdrawing fluoride groups into the Ti-MWW framework, both the catalytic activity and HPPO utilization efficiency were increased. Moreover, the ring opening reaction of PO was prohibited. In a continuous fixed-bed liquid-phase propylene epoxidation reaction, the KF-treated structured Ti-MWW catalyst displayed an exceptionally long lifespan of 2700 h, with a PO yield of 590 g·kg−1·h−1.
Graphene oxide is a promising adsorption material. However, it has been difficult to recycle and separate graphene oxide in the solution. To alleviate this problem, graphene oxide was thermally reduced to produce porous hydrogel which was then functionalized with polydopamine. The functional groups act as not only adsorption sites but also nucleation sites for in situ crystallization of cobalt-doped zeolitic-imidazolate-framework-8 nano-adsorbents. The effects of cobalt-doping contents on the physicochemical and adsorption properties of the resulting aerogel were also evaluated by varying the cobalt concentration. For instance, the reduced graphene oxide-polydopamine/50cobalt-zeolitic-imidazolate-framework-8 aerogel exhibited a high surface area of 900 m2·g–1 and maintained the structure in water after ten days. The as-synthesized aerogels showed an ultrahigh adsorption capacity of 1217 ± 24.35 mg·g–1 with a removal efficiency of > 99% of lead, as well as excellent adsorption performance toward other heavy metals, such as copper and cadmium with adsorption capacity of 1163 ± 34.91 and 1059 ± 31.77 mg·g–1, respectively. More importantly, the lead adsorption stabilized at 1023 ± 20.5 mg·g–1 with a removal efficiency of > 80% after seven cycles, indicating their potential in heavy metal removal from industrial wastewater.
With the rapid iteration and update of wearable flexible devices, high-energy-density flexible lithium-ion batteries are rapidly thriving. Flexibility, energy density, and safety are all important indicators for flexible lithium-ion batteries, which can be determined jointly by material selection and structural design. Here, recent progress on high-energy-density electrode materials and flexible structure designs are discussed. Commercialized electrode materials and the next-generation high-energy-density electrode materials are analyzed in detail. The electrolytes with high safety and excellent flexibility are classified and discussed. The strategies to increase the mass loading of active materials on the electrodes by designing the current collector and electrode structure are discussed with keys of representative works. And the novel configuration structures to enhance the flexibility of batteries are displayed. In the end, it is pointed out that it is necessary to quantify the comprehensive performance of flexible lithium-ion batteries and simultaneously enhance the energy density, flexibility, and safety of batteries for the development of the next-generation high-energy-density flexible lithium-ion batteries.
A facile synthesis of hierarchical ZSM-5 with the three-dimensionally ordered mesoporosity (3DOm ZSM-5) was achieved by solid conversion (SC) of SiO2 colloidal crystals to high-crystalline ZSM-5. The products of 3DZ5_S/C and 3DZ5_S, which were severally transformed from the carbon-padded SiO2 colloidal crystals and the initial SiO2 colloidal crystals, exhibited not only a similar ordered structure and acidity but also higher crystallinity and more balanced meso-/micropore combination in comparison with 3DZ5_C obtained by the conventional confined space crystallization approach. All three synthesized 3DZ5 catalysts showed improved methanol-to-propylene performance than the commercially microporous ZSM-5 (CZ5), embodied in five times longer lifetime, higher propylene selectivity and Spropylene/Sethylene ratio (P/E), and superior coke toleration with lower formation rate of coke (Rcoke). Moreover, the 3DZ5_S catalyst in situ converted from SiO2 colloidal crystals presented the highest selectivities of propylene (42.51%) and light olefins (74.6%) among all three 3DZ5 catalysts. The high efficiency in synthesis and in situ utilization of SiO2 colloidal crystals demonstrate the proposed SC strategy to be more efficiently and eco-friendly for the high-yield production of not only 3DOm ZSM-5 but also other types of hierarchical zeolites.
