Biochar has attracted wide interest due to its important role in the synthesis of functionalized carbon materials. Molten alkali carbonates (MC) pyrolysis as a novel mean was explored to obtain superior bamboo biochar compared with alkali impregnation pretreating bamboo powder associated with pyrolysis. The properties of biochar produced by MC pyrolysis were enhanced, suggesting an increase in BET surface area of 43.59 m 2 /g compared with non-pretreat biochar of 5.76 m 2 /g, and possessed preferable pore structure than the alkali impregnation one of 39.82 m 2 /g and 16.98 nm for catalyst support. Besides, pyrolysis temperature reinforced the porosity and the degree of carbonization as it rising, however, the optimized temperature for top-grade biochar materials was 450 °C. The MC weakened the hydrogen bonds network in bamboo powder acting a similar role just as alkaline pretreated, meanwhile neutralized the acid produced during pyrolysis process supported by the analysis of FTIR and TGA . The potential pathways of biomass pyrolysis with MC had also been proposed. In addition, the biochar obtained was utilized as a catalyst support of biochar-bearing sulfonic acid groups, which achieved the remarkable yields of TRS and glucose (52.8% and 43.5%) in hydrolysis of cellulose.
Molten alkali carbonates (MC) pyrolysis technology is proposed to dispose digestate waste and convert it into high value-added phenolics in this work. The results showed that temperature strongly affected phenolic production by promoting the depolymerization of lignin, while particle size had less influence on phenolic productions owing to the catalysis and dynamic diffusion of alkali metal ions. Meanwhile, the effect of mass ratio between sample and molten carbonates was investigated by a series of differentiated proportions from 5 to 25%. The optimum reaction conditions were 10% of mass ratio in a particle size from 0.6 to 0.85 mm at 450 °C, with the maximum phenolics yield of 67.08% in organic. In sum, 5.6 g of phenolics and 0.96 g of guaiacols were generated from 100 g of digestate. Compared with conventional pyrolysis method, the methoxyl group in liquid product could be efficiently removed at atmosphere in molten carbonates. Additionally, thermogravimetric analysis further demonstrated that alkali metal ions (Li + , Na + and K + ) promoted the primary degradation of lignin and secondary monomolecular dissociation reactions of methoxyphenol.
Ishioma Laurene Egun,Bamidele Akinwolemiwa,Haiyong He,Mingchan Ma,Zhengfei Chen,George Z. Chen,Di Hu
Non-lignin-rich biomass has abundant reserves but remains underutilised as a sustainable carbon source for producing functional carbon materials in energy storage applications. The primary challenge is to develop an efficient and sustainable process to convert these resources into high-performance carbon as electrode active material for supercapacitors. To address this issue, a facile, low-cost molten base carbonisation and activation (MBCA) process is investigated to convert wet Radish (a non-lignin–rich biomass) into hierarchical porous carbon via a single thermal stage. This approach integrates carbonisation, in-situ activation, and heteroatom retention, yielding carbon with a specific surface area of 1172 m 2 g −1 , ultramicropores (0–0.7 nm), partial graphitic structure and nitrogen/oxygen-rich functional groups. The optimised carbon, obtained at 700 ˚C, as a supercapacitor electrode active material exhibited electrochemical performance, with a specific capacitance of 257F g −1 at 5 mV s −1 and 96F g −1 at 2 A g −1 , alongside remarkable cycle stability (92.6 % capacitance retention over 20,000 cycles) and low self voltage decay over 50 h. These results highlight the MBCA process as a viable solution for converting non-lignin-rich biomass into high-performance carbon materials, offering a practical and sustainable alternative for energy storage applications while mitigating environmental pollution from biomass decomposition.
Wenhao Zhang,Huan Li,Jianping Xiao,Xuefeng Zhu,Weishen Yang
Electrochemical ammonia synthesis (EAS) and nitrogen oxyanion / nitrogen oxides (NO x − /NO x ) conversion are important aspects of the artificial nitrogen cycle. Herein, we report a molten alkali electrolysis reactor for converting NO x − /NO x to NH 3 . A 110.3 ± 4.7 mg · h −1 · cm −2 yield of ammonia synthesis from nitrite was achieved with the Faradaic efficiency close to 100 %. By coupling NO oxidation with NO x − reduction, the NO conversion above 99 % was achieved with ammonia yield of 57.75 mg · h −1 · cm −2 . More importantly, the produced ammonia can escape from the electrolyte, thus avoiding the energy-consumed separation process. Revealed by density functional theory calculations, the excellent activity of EAS can be attributed to low barriers of electrochemical hydrogenation and the facile breaking of N O bonds with the assistance of Na/K cation at the interface. This work opens a new sight in EAS and enriches the artificial nitrogen cycle.
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