Co-pyrolysis of lignin and waste plastics, for example polyethylene (PE), has been studied, but related reports are basically on condition optimizations. This study revealed a new perspective on ...PE-promoted lignin pyrolysis to phenolic monomers with mass transfer and radical explanation. Lignin and PE were first pyrolyzed individually to identify pyrolysis characteristics, pyrolytic products, as well as the suitable co-pyrolysis temperature. Then, co-pyrolysis of blended lignin/PE with various ratios was investigated. Yields of lignin products reached the maximum under lignin/PE ratio of 1:1, but blended approach always inhibited the production of lignin phenols. This resulted from the poor mass transfer and interactions between lignin and PE, in which PE pyrolysates could easily escape from the particle gaps. While in layered approach, PE pyrolysates had to pass through the lignin layer which contributed to the good interactions with lignin pyrolysis intermediates, thus the yields of lignin-derived products were significantly improved. Interactions between lignin and PE (or their pyrolysates) were mainly radical quenching reactions, and X-ray photoelectron spectrum (XPS) and electron paramagnetic resonance (EPR) of pyrolytic chars were conducted to verify these interactions controlled by mass transfer. The percentage of CC (sp2) and concentration of organic stable radicals in layered lignin/PE char were both the lowest compared with those in blended lignin/PE and lignin char, indicating the stabilization of lignin-derived radicals by PE pyrolysates. Moreover, the spin concentration of radicals in the char from layered char/PE was lower than that in lignin char, which further affirmed the quenching of radicals by PE in the layered co-pyrolysis mode.
Mass transfer and radical reactions together controlled the co-pyrolysis of lignin and PE. Good mass transfer in layered lignin/PE co-pyrolysis approach promoted the radical quenching reactions and favored the formation of lignin-derived phenols. Display omitted
•Mass transfer and radical reactions together controlled lignin/PE co-pyrolysis.•Layered lignin/PE demonstrated the highest yields and lowest radical concentrations.•Possible reaction pathways of PE-promoted lignin pyrolysis were proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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To increase the low yield and selectivity of aromatic hydrocarbons during the biomass pyrolysis process, we torrefied the biomass and then co-pyrolyzing with plastics such as ...high-density polyethylene (HDPE), polystyrene (PS), ethylene–vinyl acetate (EVA) and polypropylene (PP) and also single and dual catalyst layouts were investigated by Py-GC/MS. The results showed that non-catalytic fast pyrolysis (CFP) of raw bagasse (RBG) generated no aromatics. After torrefaction non-CFP of torrefied bagasse (TBG) generated low aromatic yield. Indicating that torrefaction would enhance the proportion of aromatics during the pyrolysis process. The CFP of TBG200°C and TBG240°C over ZSM-5 produced the total aromatic yield of 1.96 and 1.88 times higher, respectively, compared to non-CFP of TBG. Furthermore, the addition of plastic could increase H/Ceff ratio of the mixture, consequently, increase the yield of aromatic compounds. Among the various torrefied-bagasse/plastic mixtures, the CFP of TBG/EVA (7:3 ratio) mixture generated the highest the total aromatic yield of 7.7 times more than the CFP of TBG alone. The dual catalyst layout could enhance the yield of aromatics hydrocarbons. The dual-catalytic co-pyrolysis of TBG200°C/plastic (1:1) ratio over USY (ultra-stable Y zeolite)/ZSM-5, improved the total aromatics yield by 4.33 times more than the catalytic pyrolysis of TBG200oC alone over ZSM-5 catalyst. The above results showed that the yield and selectivities of light aromatic hydrocarbons can be improved via catalytic co-pyrolysis and dual catalytic co-pyrolysis of torrefied-biomass with plastics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Selective oxidation of lignin is increasingly investigated due to its advantage of retaining the aromatic rings to produce value-added platform chemicals. In this paper, oxovanadium complexes ...catalyzed oxidation of lignin and lignin dimers in acetonitrile/water system under O
2
was reported. Under optimal conditions of VO(acac)
2
catalyzed oxidation, 95 mol% of lignin dimer 2-phenoxy acetophenone was converted, producing 43 mol% of phenol and 83 mol% of benzoic acid. The catalytic ability of V(acac)
3
was higher than that of VO(acac)
2
, but it caused heavier repolymerization and lower product yields. VO(acac)
2
catalyzed oxidation system also cleaved various
β
-O-4 lignin dimers, achieving > 95 mol% conversion. Whereas, yields of phenols from these dimers were lower than 5 mol%. These phenolics were shown to polymerize under reaction conditions. Furthermore, this oxidation system depolymerized poplar organosolv lignin. After oxidation, aromatic and C-O aliphatic functionalities in the heavy fractionation largely disappeared, and the weight-average molecular weight decreased from 5720 to 1140 Da.
Graphical abstract
Oxovanadium complexes show the good ability for the catalytic oxidation of lignin and lignin dimers in MeCN/H
2
O co-solvent in the presence of O
2
, achieving higher than 95 mol% conversion of
β
-O-4 lignin dimers and lowering the molecular weight of poplar organosolv lignin from 5720 to 1140 Da.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
There are a large number of multi-clock domain circuits in the airborne equipment of aircraft. When data is transmitted across the clock domain, meta-stability may occur, resulting in data ...transmission errors and reduced circuit reliability. However, due to the occasional and non-reproducible faults caused by metastability, and the high cost of existing cross-clock domain specific verification software, cross-clock domain circuit verification in three-mode redundancy scenarios is not supported. To solve this problem, a method that combines register transfer level (RTL) validation, board-level accelerated testing and computational evaluation based on traditional tools is presented. This method can detect the cross-clock domain transmission problems in three-mode application scenarios or normal scenarios and assess potential cross-clock domain transmission risks using generic simulation tools at an early stage of design. It reduces the cost of economy and time for high safety level airborne complex electronic verification, and improves the reliability of the circuit.
在航空器的机载设备中存在大量的多时钟域电路，数据在进行跨时钟域传输时可能会产生亚稳态，导致数据传输错误，电路可靠性降低。但亚稳态导致的故障具有偶发性、不易重现，且现有的跨时钟域专用验证软件使用成本高昂，不支持三模冗余场景下的跨时钟域电路验证。针对此问题，提出了一种基于传统工具的寄存器传输级(RTL)验证、板级加速测试和计算评估相结合的方法。该方法能够在设计早期使用通用仿真工具发现三模应用场景或正常场景下的跨时钟域传输问题，并评估潜在跨时钟域传输风险，降低了高安全等级机载复杂电子验证经济成本和时间成本，提高电路可靠性。
Anhydrosugars, such as levoglucosan (LG), are high value-added chemicals which are mainly derived from fast pyrolysis of pure cellulose. However, fast pyrolysis of raw lignocellulosic biomass usually ...produces a very low amount of levoglucosan, since alkali and alkaline earth metals (AAEM) present in the ash can serve as the catalysts to inhibit the formation of levoglucosan through accelerating the pyranose ring-opening reactions. In this study, eucalyptus was impregnated with H2SO4 solutions with varying concentrations (0.25–1.25%). The characteristics of ash derived from raw and H2SO4-impregnated eucalyptus were characterized by X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD). The pyrolysis behaviors of raw and H2SO4-impregnated eucalyptus were performed on the thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). TG analysis demonstrated that the H2SO4-impregnated eucalyptus produced less char than raw eucalyptus. Py-GC/MS analysis showed that even small amounts of H2SO4 can obviously improve the production of anhydrosugars and phenols and suppressed the formation of carboxylic acids, aldehydes, and ketones from fast pyrolysis of eucalyptus. The rank order of levoglucosan yield from raw and impregnated eucalyptus was raw < 1.25% H2SO4 < 1% H2SO4 < 0.75% H2SO4 < 0.25% H2SO4 < 0.5% H2SO4. The maximum yield of levoglucosan (21.3%) was obtained by fast pyrolysis of eucalyptus impregnated with 0.5% H2SO4, which was close to its theoretical yield based on the cellulose content. The results could be ascribed to that H2SO4 can react with AAEM (e.g., Na, K, Ca, and Mg) and lignin to form lignosulfonate, thus acting as an inhibitor to suppress the catalytic effects of AAEM during fast pyrolysis of eucalyptus.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Our research has empirically supported the long-term manifestation of the resource depletion, accumulation, and investment mechanisms which have been proposed in the conservation of resources (COR) ...theory but have been under-investigated in the work–life balance (WLB) literature. Specifically, we have examined how multiple work and non-work contextual demands and resources impact working mothers' WLB satisfaction and job retention via changes in their personal resources of childcare time and family finances through these three mechanisms. The use of multilevel analysis and a longitudinal design has enabled us to evaluate the effectiveness of contextual resources for WLB in consideration of both their short-term influence as transient resources via within-individual fluctuations and their long-term impact as durable resources via between-individual differences. We have tested a total of 27 hypotheses on a nationally representative British sample of 10,983 working mothers who participated in a longitudinal study over 6 years of their children's primary education. By highlighting the critical role of both childcare time and family finances in promoting working mothers' WLB satisfaction and job retention over time, our research contributes to the WLB literature that has predominantly emphasized time-based but neglected financial-based constraints and resources. We have found that working mothers may trade their childcare time for better family finances when they undertake a managerial role. Thus, becoming a manager serves as both a time-based demand and a financial-based resource for working mothers, which points to the specific rather than generic nature of contextual demands and resources.
•Adequate childcare time and family finances enhance working mothers' work–life balance satisfaction and job retention.•A contextual demand/resource should be defined given its depletion/accumulation effect on a specific personal resource.•Undertaking a managerial role serves as both a time-based demand and a financial-based resource for work–life balance.•Nuanced differences are identified in the between- versus within-individual effects of some contextual factors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Effects of metal salt catalysts and gasification temperature on the gasification characteristics of combustible solid waste were studied, based on the source-classified waste in a fluidized bed ...gasifier, to provide guidance for utilizing the source-classified waste effectively. The results showed that the gasification characteristics of combustible solid waste, such as paper and sawdust, improved noticeably after adding NaCl, K2CO3, or sodium dodecyl benzene sulfonate (LAS). Adding NaCl to sawdust increased the yield of CO and CH4, while the gasification was inhibited gradually with increasing addition. Adding NaCl promoted the generation of H2 in paper gasification. NaCl played a catalytic role only when it exceeded a certain value. Adding K2CO3 increased the yield of H2 noticeably in sawdust and paper gasification. The catalytic effect of K2CO3 on sawdust was better than that on paper. Similar results were obtained for LAS in producing H2 in gasification. The carbon conversion efficiency and the gasification efficiency were increased with additional LAS. Moreover, the catalytic effect of K2CO3 was superior to that of LAS by comparison. As the temperature rises, the activity of the metal salt catalyst is enhanced, but it is inhibited if the temperature is too high.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Depolymerization of technical lignin to platform aromatic monomers can significantly increase the productivity and profitability of biorefinery. Establishing an efficient and economical way for ...technical lignin depolymerization is vital to make this process practical. Herein, we report the one-pot depolymerization of technical lignin into aromatic monomers without added catalyst and external H2 gas. Ethanol, as an inexpensive and recyclable solvent, was used to induce the technical lignin hydrogenolysis. The significant solubility and H-transfer ability of ethanol resulted in an exceptional hydrogenolysis efficiency of the β-O-4 lignin linkages, giving an aromatic monomer yield of 20.62C% at 300 °C for 4 h, rival those from technical lignin disassembly with metal catalysts and added H2 gas. Over 14.70C% of the monomers could be identified, among which phenol, guaiacol, 4-ethyl phenol, 4-ethyl guaiacol, and syringol were obtained with prominent yields. The depolymerization procedure was thoroughly recognized with GC × GC–MS, GPC, MALDI-TOF-MS, HSQC NMR, and FT-ICR-MS analyses to provide an in-depth understanding of the molecular weight, functionality, and elemental composition evolutions of the technical lignin.
Technical lignin is efficiently transformed into value-added platform aromatic monomers in ethanol under mild conditions without added catalysts and H2 gas. Display omitted
•Technical lignin depolymerization was achieved without catalyst and external H2.•Yield of aromatic monomers reached 20.62C% with ethanol as the reaction media.•The inter β-O-4 linkages of technical lignin were completely degraded.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Integrating torrefaction with chemical looping gasification (CLG) was proposed.•Tar content was reduced by 88.8% through integrating torrefaction with CLG.•Gas yield was enhanced by 27.5% through ...integrating torrefaction with CLG.•Effect of torrefaction on the possible pathways for tar formation was revealed.
The objective of this study is to investigate the effect of torrefaction pretreatment on the syngas production and tar formation from chemical looping gasification (CLG) of biomass over different oxygen carriers. The torrefaction of eucalyptus wood and subsequent CLG were systematically studied by using the fixed bed reactors coupling with various analytical methods. The experimental results demonstrate that torrefaction played significant impacts on CLG of eucalyptus wood using iron ore as an oxygen carrier. The gas yield and carbon conversion efficiency from CLG of eucalyptus wood were lowered by torrefaction, while the tar content was evidently reduced from 43.6 to 17.6 g/Nm3. These results could be due to the devolatilization, polycondensation, and carbonization of eucalyptus wood during torrefaction, resulting in the formation of fewer tar precursors and more char with lower reactivity during subsequent CLG. The negative impacts of torrefaction on the gas yield and carbon conversion efficiency of CLG can be effectively overcome by the selection of suitable oxygen carriers. Five metallic ferrites were successfully synthesized and used to replace iron ore for CLG of torrefied eucalyptus wood obtained at 280 °C. It is found that NiFe2O4 reduced the tar content by 88.8% and improved the gas yield by 27.5% compared to CLG of untreated eucalyptus wood over iron ore. These results suggest that integrating biomass torrefaction pretreatment with CLG is an efficient strategy for enhancing syngas production whilst minimizing tar formation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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