Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Mechanistic understanding of the C-C/C-O bonds cleavage-methylation tandem reaction for the conversion of phenolic resins to hexamethylbenzene using γ-Al 2 O 3
No full textThe high-value recycling of discarded phenol-formaldehyde resins (PF) remains an unresolved challenge. Herein, we propose a novel approach leveraging gamma-Al 2 O 3 to convert PF into high-value hexamethylbenzene at a low temperature using a one-pot method. This study explores the degradation capability of PF, methylation reaction efficiency, and hydrodeoxygenation capacity among various cost-effective commercial catalysts: gamma-Al 2 O 3 , ZrO 2 , and TiO 2 . It reveals the influence of different reaction times on PF pyrolysis and product distribution, and it was found that high value-added hexamethylbenzene exhibited the highest yield (73.33 wt%) with selectivity (75.83%) using gamma-Al 2 O 3 at 350 degrees C and 2 h of reaction. Experiments using PF models demonstrate the crucial synergy between gamma-Al 2 O 3 and C(aryl)-OH in the cleavage of C(aryl)-C(alkyl) bonds and methylation reactions. A pathway for PF C-C/C-O bonds cleavage-methylation tandem reaction is proposed, based on 13 C methanol isotope experiments. PF undergoes C(aryl)-C(alkyl) bond cleavage to produce phenolic intermediates, which were then methylated; this is accompanied by the cleavage of C(aryl)-OH and C(aryl)-OCH 3 , culminating in Calkylation to form hexamethylbenzene. This research provides new insights into the high-value recycling of PF
From macro to micro: Biomass-derived advanced carbon microtube assembly for sodium-ion batteries
No full textDeveloping high-rate anode materials for sodium-ion batteries is important to fulfill the requirement of highpower energy storage applications. Amorphous carbon micro-tubes (CMTs) are favorable for fast Na-ion storage, for the open carbon framework provides sufficient electrode/electrolyte contact and the one-dimensional skeleton offers fast electron and ion diffusion pathways. Herein, N, Fe co-doped carbon micron-tubes (NFCMTs) were synthesized for the high-rate anode by using bulk biomass as the precursor. The transformation from the macro-sized biomass to the micro-sized carbon tubes was endowed by pyrolysis using N and Fe as catalysts. The open carbon frameworks enable capacitive-controlled capacity contribution, while its N-Fe defects offer multiple active sites for fast Na-ion storage. A high-capacity contribution was demonstrated by the pseudocapacitive mechanism so that the NF-CMTs performed a superior rate capability of 120 mAh g- 1 at 2.0 A g-1. The NF-CMTs with stable micro-tube frameworks exhibited high cycling stability over 1200 cycles, which was much superior to the commercial hard carbon anode. This study provides a cost-effective approach to develop carbon micro-tubes from bulk biomass for high-power SIB anodes
Enhanced thermal performance of NaCH 3 COO.3H 2 O-Na 2 S 2 O 3 .5H 2 O eutectic based composite phase change materials with hybrid dimensional carbon nanomaterials and modified lotus root starch
No full textInorganic phase change materials (PCM) with relatively high thermal storage capacity and low cost suffer from serious leakge, supercooling and low thermal conductivity, impeding its large-scale application. Herein, hybrid dimensional carbon nanomaterials including carbon nanofiber and graphene, was adopted ot tackle these issues. Furthermore, modified lotus root starch was employed to enhance the overall thermal storage capacity of the composite PCM. The comprehensive properties of the composite PCM were characterized by the technology of SEM, XRD, FT-IR, hot disk, viscometer, DSC, TGA, DFT calculation method. The results show than with the addition of hybrid dimensional carbon nanomaterials, semi -crystallization time of NaCH 3 COO . 3H 2 O- Na 2 S 2 O 3 . 5H 2 O/hybrid dimensional carbon nanomaterials composite PCM decreased from 0.96 min to 0.78 min, indicating the substantial supercooling mitigiation of hybrid dimensional carbon nanomaterials. Meanwhile, the addition of hybrid dimensional carbon nanomaterials also improve the thermal conductivity of the composite PCM to 1.403 W/(m . K), 2.5 times of that of NaCH 3 COO . 3H 2 O-Na 2 S 2 O 3 . 5H 2 O eutectic. It is worth noting that the addition of modified lotus root starch increased the maximum enthalpy of the composite PCM by 9.1%. The more hygrogen bonds of the composite which can improve the PCM-holding capacity, are responsible for this enthalpy increase. The study results can provide new insight on the high-performance inorganic PCM preparation and large-scale application
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