Nanomaterials
·
2025
·Vol. 15
·期 22
·1691
·
IF 4.3
Tiankai Zhang,Qi Wang
In this study, two potassium-based alkaline compounds, KOH and K2CO3, were utilized as catalysts for the pyrolysis of bituminous coal to directly synthesize carbon nanotubes (CNTs). During the conventional reaction process, CNTs were observed as unusual products, with respective contents reaching 9.43 and 8.98 wt.% in the pyrolysis products. The results indicate that at temperatures exceeding 600 °C, KOH undergoes complete conversion into K2CO3. The melting point of K2CO3(890 °C) serves as the critical temperature for the formation of CNTs. Under the reducing atmosphere provided by –CH2– and aromatic C–C structures in coal, the transformation process K2CO3→ K2O → K occurs. At high temperatures, highly etching K reacts with the C–O–C structures in coal, converting them into carbon atoms and exposing the iron (Fe)-containing minerals in coal to the particle surface. Finally, the carbon atoms derived from the ether bonds form CNTs under the action of the native Fe catalyst in coal. The resulting product is a mixture of activated carbon and CNTs. This method fundamentally alters the composition of traditional coal-based activated carbon and provides a new approach for the cost-effective, large-scale production of high-value CNTs.
研究领域:
材料科学
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化学工程
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纳米技术
·
能源与燃料
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DOI
PubMed
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2024
·
IF 5.6
Yuqian Zhou,Zhongxin Tan,Tuo Zhou
To overcome the challenges of high oxygen content and low energy density in converting biomass into liquid biofuels, this study proposes an efficient and eco-friendly method: first pyrolyzing rice straw biomass, then converting it into liquid biofuel. It was found that: (1) Characterizing the elemental composition, higher heating value (HHV), thermogravimetric properties, and functional groups of rice straw-biochar-liquid fuel (RS-C-LF), along with analyzing the mass and energy balance of the liquefaction process, revealed that 150 °C was the optimal low liquefaction temperature. (2) The HHV, O and S content, mass and energy yield of RS-C-LF150 were significantly enhanced compared to direct biomass-to-liquids and met the biodiesel standard, with values of 42.16 MJ/kg, 0.82 %, 0 %, 67.49 %, and 69.42 %, respectively. (3) The feasibility and commercial potential of this research was further demonstrated through economic and SWOT analysis of this study liquid biofuel (the total production expenditure is only $171.29/bbl), and the design of the zero-waste and self-circulating preparation system.
研究领域:
能源生物学
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环境科学
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DOI
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2018
·Vol. 165
·期 11
·A2415
·
IF 3.662
Lei Liu,Xinyu Fu,Guoxu Wang,Kehan Liang,Lili Zhang,Wei Wang,Aibing Chen
Carbon monolith is of particularly great interest in electrochemical applications due to its high surface area, controllable morphology and excellent electronic conductivity. Herein, a novel three-dimensional hierarchically porous carbon monolith (TD-HPCM) was synthesized by a "pyrolysis-capture" strategy. The commercial polyurethane (PU) foam concurrently acted as a template and carbon precursor. Carbonaceous organic gas pyrolyzed from PU foam was captured by mesoporous silica which coated on the branches of PU foam uniformly then converted into carbon under catalysis of Ni species at high temperature. The geometric shape and interconnected network of PU foam were preserved in TD-HPCM, with a large specific surface area (1111 m2 g−1) and uniform mesoporous size (6.7 nm). The TD-HPCM was explored as binder-free electrode in supercapacitors, with capacitance up to 162 F g−1 at 1.0 A g−1 in 6 M KOH electrolyte and favorable capacitance retention (92.7% capacitive retention after 5000 cycles). This strategy provides a controllable, energy efficient and highly repeatable method to prepare TD-HPCM with micro/meso/macroporous structures as binder-free electrodes in electrical double layer capacitors.
研究领域:
材料科学
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电化学
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DOI
高影响因子
DIAMOND AND RELATED MATERIALS
·
2023
·
IF 4.1
Jun Shi,Ruoyu Wu,Yulong Li,Jiani Wu,Yongxi Kuang,Hongmei Xing,Yelong Zhang,KwunNam Hui
Reasonable design and development of N-doped carbon materials by post-treatment of porous carbon with melamine is an effective route to preparing low-cost and high-performance electrocatalysts toward oxygen reduction reaction . Nevertheless, melamine derivatives have been observed to rapidly escape during pyrolysis , resulting in the undesirable loss of nitrogen atoms and catalytic activity . Here, a confining-pyrolysis method was proposed to accumulate melamine in the micropores of porous carbon to prepare the object N-doped carbon material with an enhanced nitrogen doping. Because the melamine accumulated in the micropores of porous carbon, the object N-doped carbon material shows a significant enhancement in N-atom content, graphitization degree, mesopore volume, electrochemical active surface area and hydrophobic surface . Density functional theory calculations and electrocatalytic tests demonstrate that the object N-doped carbon material delivers a good electrocatalytic oxygen reduction performance. The N-doped carbon electrode displayed a close half-wave potential for alkaline ORR compared to the commercial Pt/C electrocatalyst and showed an excellent cycling stability and methanol tolerance. This work provides a cost-effective method to prepare carbon-based ORR electrocatalyst for energy devices.
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DOI
高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2023
·
IF 6.1
Zhirong Xu,Jing Zhan,Zihui Xu,Xiaowei Mu
In this study, flame retardant polyurethane rigid foam was prepared by incorporating 15 wt% ammonium polyphosphate (APP) and ionic liquid (1-butyl-2,3-dimethylimidazolium tetrafluoroborate, abbreviated as B 4 F). The flame retardant and thermal stability of the material were evaluated using vertical combustion (UL-94), limiting oxygen index (LOI), cone calorimeter (CONE), and thermogravimetric analyzer (TG) tests. Additionally, scanning electron microscopy (SEM), Raman spectroscopy (Raman), and X-ray photoelectron spectroscopy (XPS) were utilized to explore the flame retardancy mechanism in the carbon layer after combustion. The experimental results showed that the addition of 1 wt%B 4 F and 14 wt% APP to the polyurethane (RPUF/14APP/1B 4 F) significantly improved the vertical combustion test, upgrading it from the V-1 level to the V-0 level. This improvement was attributed to the increased degree of graphitization of the material, as evidenced by the reduced ratio of amorphous carbon to graphitic carbon (I D /I G ) from 2.68 to 1.38. XPS analysis revealed that RPUF/14APP/1B 4 F exhibited a higher C/O ratio in the residual carbon (3.03) compared to RPUF/15APP (1.84), indicating that B 4 F effectively enhanced the antioxidant properties of the flame-retardant materials. Under the air atmosphere, RPUF/14APP/1B 4 F demonstrated an increased char formation at 800 °C (21.24 %), which was 71.01 % higher than RPUF/15APP. The interaction between B 4 F and APP led to the formation of a more stable char layer structure in polyurethane, further enhancing its flame retardancy. In conclusion, the RPUF/14APP/1B 4 F demonstrated a synergistic flame retardancy effect and enhanced thermal stability. The addition of B 4 F improved the graphitization degree of the material and increased the C/O ratio in the residual carbon, enhancing the antioxidant properties of the system. Moreover, the interaction between B 4 F and APP promoted the formation of a more stable char layer, effectively improving the flame retardant properties of the polyurethane. These findings provide valuable insights for the development of advanced flame retardant polyurethane materials with improved fire safety in various applications.
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高影响因子
MICROCHEMICAL JOURNAL
·
2023
·
IF 4.8
Jiangle Zhang,Shiyuan Xu,Tie Liu,Jingxiong Yu,Zefeng Deng,Yihaung Jiang,Ying Zeng
As a new pollutant, microplastics (MPs) have characteristics such as environmental persistence, biological toxicity, bioaccumulation and so on, even at low concentrations in the nature. At present, the detection methods for MPs are still in the development stage, and mass spectrometry (MS) is one of the most effective methods for microplastic detection and analysis. This paper utilizes a self-developed temperature programmed system pyrolysis (Py) device and a time of flight mass spectrometer (TOFMS) to establish a Py-PI-TOFMS using a single photon ionization (PI) source, and to construct an analysis technology for microplastics. The pyrolysis of thermoplastic MPs mainly follows the free radical pyrolysis mechanism, where the energy obtained through heating reaches the bond energy connected between atoms, and the molecular chains undergo fracture to generate various small molecule compounds. We used Py-PI-TOFMS technology to analyze the pyrolysis products of microplastics of polystyrene (PS) and phenol–formaldehyde resin (PF), explore the rules of free radical reactions, composition of pyrolysis products, bond dissociation characteristics, and combine theoretical calculations to study the thermodynamic and kinetic mechanisms in the pyrolysis process.
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yan Ma,Ningbo Gao,Cui Quan,Anbang Sun,Martin Olazar
In order to deal with the ongoing rise in plastic trash and the decline in fossil energy, effective technologies for converting plastic to hydrogen are urgently needed. This work aims to explore the function of an emerging integrated pyrolysis and plasma-catalysis reforming system for hydrogen production from high-density polyethylene (HDPE). The results showed that plasma and catalyst had strong synergy for hydrogen production under various reforming temperatures, with a synergy effect of 250.98 % at 500 °C. The yields of total gas and hydrogen gas from the plasma-catalysis reforming of HDPE were 146.50 mmol/g and 102.52 mmol/g, respectively, which were more than three times the sum of the gas yields from the plasma-alone reforming process and the catalysis-alone reforming process. Characterization of used catalysts at 500 °C revealed that catalysts from plasma-catalysis reforming had more severe carbon deposition than those from catalysis reforming, because of the long whisker-like deposited carbon in plasma-catalysis mode that kept the surface Ni species exposed and therefore maintained improved stability and activity.
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DOI
高影响因子
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2023
·
IF 7.8
Yulin Zhang,Guozhao Ji,Aimin Li
The goal of producing limonene epoxide and separating p -cymene from tire pyrolysis oil (TPO) could be achieved after epoxidation . However, the existing catalytic epoxidation process has the problem of cumbersome catalyst separation process, which is not conducive to industrial applications. In this work, the heterogeneous catalysts polyoxometalate-SBA-15 were prepared with the point of simplifying separation process. Heteropoly acid anions (phosphotungstic acid or peroxophosphotungstic acid) with catalytic active successfully enter the mesoporous pores of SBA-15, exhibiting high limonene conversion in the TPO system. The PW 4 species produced by phosphotungstic acid after oxidation of H 2 O 2 was favorable for improving the selectivity of epoxidation. The catalyst S- D -PW 4 prepared showed high catalytic activity and epoxidation selectivity with the condition of H 2 O 2 as an oxidant and free of solvent. Furthermore, A statistical experimental approach was used to comprehensively evaluate the reaction conditions. The conversion of limonene in TPO could reach 99.78%, and the yield of 1,2-limonene epoxide and diepoxide were 67.96% and 20.16%, respectively. A variety of characterization techniques such as 31 P NMR, XPS, and ICP were employed to analyze the difference in catalyst before and after epoxidation. S- D -PW 4 could be easily separated and the catalytic activity and epoxidation selectivity remained high after 5 cycles.
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DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Dongyang Liu,Hui Wang,Liang Zhao,Linzhou Zhang,Yuen Bai,Guohao Zhang,Jinsen Gao,Chunming Xu
Process modeling is considered an effective way to achieve refined management in the petrochemical industry, and is also the foundation and necessary link of intelligent chemical platform construction. This study aims to the simulation of the formation of gaseous products for the catalytic pyrolysis of representative naphtha compositions using a stoichiometric coefficient model. Firstly, the interaction mechanism of n/cyclo-paraffins was investigated using a pseudo-first-order kinetic model, and the cracking activity of hydrocarbon mixtures was quantified using the carbon number and cyclo-paraffin content. Subsequently, a database of the stoichiometric coefficients of the gaseous products was constructed. Considering the acid properties of the catalysts, a catalyst acid property-included stoichiometric coefficient model was developed to adapt to varying feedstock composition and catalyst systems, which could reflect gaseous production in the catalytic pyrolysis of multi-component mixed hydrocarbons. Moreover, the simulation using the present model shows that the production of light olefins in the catalytic pyrolysis of mixed hydrocarbons can be increased under the optimized catalyst acid properties. Hence, this study aims to provides theoretical guidance for the prediction of product distribution as well as the design and selection of catalysts used in the catalytic pyrolysis processes for multi-component mixed hydrocarbon.
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DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Li Wang,Ning Wang,Longxuan Yan,Yao Ma,Zhaofa Zhang,Sen Shi,Lanjie Niu,Xiangyang Li,Bingheng Lu
Electromagnetic wave (EMW)-absorbing ceramic metamaterials without doping absorbers were prepared by direct pyrolysis of polymer-derived SiBCN ceramics (PDC-SiBCN). The pyrolytic behavior of the ceramics, the effect of the pyrolysis temperature on the mechanical strength , and the EMW absorption properties of the metamaterials are discussed in detail. The mechanism of the enhanced EMW absorption by the metamaterials was further analyzed. The results indicated that PDC-SiBCN demonstrated the optimum impedance matching and absorption performance at a pyrolysis temperature of 1500 °C. The metamaterial can effectively absorb the full X-band when its thickness is in the range of 4.3–5.7 mm. When the thickness was adjusted to 4.7 mm, the minimum reflection coefficient (RC) reached − 26.6 dB. In addition, the flexural strength of the metamaterial was 31.2 MPa, and the compressive strength was 96.9 MPa, which is 60 times higher than that of the solid structure. This study provides a feasible guide for the simple fabrication of lightweight, high-strength, and high-performance EMW-absorbing materials.
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高影响因子
Catalysts
·
2023
·Vol. 13
·期 3
·532
·
IF 3.9
Guowang Shen,Mengli Li,Yuhao Chen,Zhuang Xu,Xugen Wang,Bin Dai
The preparation method and calcination temperature of metal-organic framework (MOFs)-derived materials are critical factors affecting catalytic performance. In this work, the preparation conditions of MOFS precursors were optimized, and zinc-based catalysts with different activities (MOF5-700, MOF5-750, and MOF5-800) were obtained by pyrolysis of MOFS precursors under nitrogen, which were then applied to an acetylene acetoxylation reaction system. According to the results, the conversion rate of acetic acid under catalysis was significantly different. (MOF5-700 (48%), MOF5-750 (62%), and MOF5-800 (22%)). Comparing the activity of the catalyst with the industrial catalyst Zn(OAc)2/AC (20%), MOF5-750 showed higher activity, and the acetic acid conversion rate remained around 60% after 50 h of stability testing. By characterization analysis, MOFs-derived materials were obtained after proper temperature pyrolysis. They have high mesoporous content, defects, and oxygen-containing functional groups and can maintain a good crystal structure, greatly reducing the loss of active components. This is the main reason for the good performance of the MOF5-750 catalyst in acetylene acetoxylation. Thus, the preparation conditions and favorable pyrolysis temperature of MOF derivative catalysts play a key role in the catalytic performance of acetylene acetoxylation.Keywords:metal–organic frameworks;heteroatoms;acetylene acetoxylation;pyrolysis
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高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yu Feng,Shuang Liang,Jing-bo Zhao
In this work, a new strategy was developed to prepare magnetoceramics through a bulk pyrolysis of novel Fe-containing polyamide preceramic precursors at low pyrolysis temperature. A series of novel polyamides with different chemical structures were synthesized by bulk Michael addition and polycondensation , and their structures were characterized. Polymer precursors (PPs) were prepared by direct melt blending polyamides and FeCl 3 , and polymer-derived ceramics (PDCs) were prepared via the pyrolysis of PPs. The polyamide structure with pendant pyridine groups in repeating units makes the Fe complexes uniformly dispersed in matrix. The relationship between magnetoceramic compositions and PP structures was investigated by TGA , XPS , XRD , FE-SEM, FE-TEM and VSM characterizations. Different chemical structures and Fe catalysis effect lead to different thermal decomposition processes of PPs. Increasing crystal-Fe content in PDCs contributes to higher magnetic properties . The morphology of crystal phases in PDCs relies on the structures of PPs and pyrolysis temperature. Different pyrolysis temperatures and chemical structures of PPs bring about different Fe crystal phases and carbon crystal state of nanosheets or nanofiber bundles.
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高影响因子
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