JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2020
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IF 7.489
Lin Zhong,Hu Zhou,Ruifeng Li,Ting Bian,Sheng Wang,Aihua Yuan
The design and preparation of metal-organic frameworks (MOFs) as self-sacrificed precursors/templates has been considered as a promising strategy in recent years for fabricating metal/carbon electrocatalysts with intriguing architectures and outstanding properties. However, the serious aggregation during the calcination and the poor electron conductivity are still obstacles for these electrocatalysts which need to be urgently solved. Herein, an in situ confinement pyrolysis protocol is reported to transform ZIF-67 nanocrystals on hollow carbon spheres (HCS) to cobalt and nitrogen-enriched carbon shell, resulting in the formation of hierarchical HCS@Co/NC. This is the first study of electrochemistry for HCS decorated with MOFs or MOFs derivatives. In the structure, metallic Co nanoparticles (NPs) and N species are strongly anchored and dispersed in the network of nanocarbon shell, which not only affords a boosting conductivity but also greatly alleviates the aggregation of active sites. Meanwhile, the unique structure with hollow feature provides an effective pathway for mass transport and shortens the transmission path of electrons. Thanks to the advantages of structure and composition , the HCS@Co/NC catalyst exhibits a superb performance of oxygen reduction reaction , which outperforms the commercial Pt/C benchmark.
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高影响因子
Energies
·
2020
·Vol. 13
·期 19
·5105
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IF 2.702
Deliang Xu,Liu Yang,Ming Zhao,Yu Song,Karnowo,Hong Zhang,Xun Hu,Hongqi Sun,Shu Zhang
The simple incineration of wood-based panels (WBPs) waste generates a significant amount of NOx, which has led to urgency in developing a new method for treating the N-containing biomass residues. This work aims to examine the N evolution and physiochemical structural changes during the co-pyrolysis of fiberboard and glucose, where the percentage of glucose in the feedstock was varied from 0% to 70%. It was found that N retention in chars was monotonically increased with increasing use of glucose, achieving ~60% N fixation when the glucose accounted for 70% in the mixture. Pyrrole-N (N-5) and Pyridine-N (N-6) were preferentially formed at high ratios of glucose to fiberboard. While the relevant importance of volatile–char interactions to N retention and transformation could be observed, the volatile–volatile reactions from the two feedstocks played a vital role in the increase in abundance of glucose. With the introduction of glucose, the porous structure and porosity in chars from the co-pyrolysis were dramatically altered, whereas the devolatilization of glucose tended to generate larger pores than the fiberboard. The insignificant changes in carbon structure of all chars revealed by Raman spectroscopy would practically allow us to apply the monosaccharides to the WBPs for regulating N evolution without concerns about its side effects for char carbon structures.Keywords:nitrogen;evolution;co-pyrolysis;fiberboard;glucose
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高影响因子
Energies
·
2020
·Vol. 13
·期 23
·6202
·
IF 2.702
Xuyan Song,Min Wei,Qiang Gao,Xi Pan,Junpeng Yang,Fan Wu,Hongyun Hu
The condensation-collection and quantitative analysis of bio-oil limit its component investigation and utilization. In order to find a convenient method for the analysis of bio-oil, the present study conducted an attempt for bio-oil quantitative analysis with the addition of internal standards before pyrolysis. Based on their good thermal stability, phenethyl acetate and naphthalene were selected as standards in the study and experiments were carried out to compare the effects of two added modes (adding into the biowaste before pyrolysis or adding into bio-oil after pyrolysis) on the bio-oil analysis. The results showed that both phenethyl acetate and naphthalene were mainly volatilized under testing conditions, which could be transferred into the oil with the volatile matters during biowaste pyrolysis. Through the co-pyrolysis experiments of the internal standards with lignin and cellulose, almost no interactions were found between the internal standards and such components. Furthermore, adding these standards before pyrolysis hardly affected the properties of noncondensable gas and biochar from the used biowaste samples (tobacco and sawdust waste). Compared with the bio-oil analysis results via traditional methods by adding standards into the bio-oil after pyrolysis, the results regarding the component distribution characteristics of the bio-oil were similar using the proposed method through the addition of standards before pyrolysis. Considering adequate mixing of the added standards (before pyrolysis) in the generated bio-oil, the proposed method could partly help to avoid inaccurate analysis of bio-oil components caused by incomplete collection of the pyrolytic volatiles.Keywords:biowaste;pyrolysis;bio-oil quantitative analysis;phenethyl acetate;naphthalene
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高影响因子
JOURNAL OF THE ENERGY INSTITUTE
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2020
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IF 4.748
Da Zou,Lijun Jin,Mei Zhong,Haoquan Hu,Fengyun Ma
A serials of modified kaolinites were prepared by calcination and further acid treatment and characterized by in-situ XRD, N 2 adsorption, NH 3 -TPD, Py-IR and 27 Al MAS-NMR. And their catalytic performance in pyrolysis of methanol/benzyl phenyl ether (MeOH-BPE), a model compound of low-rank coal, were investigated at 400 °C in a fixed-bed reactor to explore the correlation between the structure of modified samples and their catalytic performances. The results show that calcination temperature above 500 °C causes the collapse of kaolinite structure. Further acid leaching facilitates the formation of micropores and mesopores. The calcination of kaolinite leads to the transformation of six-coordinate Al atoms (Al VI ) into four and five coordinate species (Al IV and Al V ), while the subsequent acid treatment increases the contents of Al IV and Al VI and removes Al V . Total acid sites exhibit a first increase and then decrease tendency with the raising calcination temperature. In the presence of the modified kaolinites, BPE conversion significantly enhances and reaches the highest value of 91.41% over K-A-700 prepared by calcination at 700 °C of kaolinite and further acid leaching. Besides, the maximum content of phenol and toluene is also achieved due to the highest acid sites and Al IV content of K-A-700, which favors the generation of ·H, thus resulting in an obvious inhibition of bibenzyl formation but a significant increase of 2-benzylphenol. In-situ pyrolysis by time-of-flight mass spectrometry suggests that the cleavage of C al -O bond of BPE to form phenol radicals and benzyl radicals is the primary way, while insufficient ·H results in the formation of dominant product of 2-benzylphenol.
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高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
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IF 3.573
Zhichang Bao,Lei Yang,Zhenmin Cheng,Zhiming Zhou
A non-noble NiZn3/α-Al2O3 catalyst was prepared by a urea co-precipitation method, which showed good stability and high selectivity to styrene (ST) (92% selectivity at above 99% conversion of phenylacetylene (PA)). The high selectivity was mainly attributed to the electronic effect of the Ni–Zn alloy. The selective hydrogenation of the C8 aromatic fraction on NiZn3/α-Al2O3 was well described by a Langmuir–Hinshelwood-type kinetic model. The estimated activation energies for the hydrogenation reactions of PA → ST, ST → ethylbenzene (EB), and PA → EB were 70.31, 81.65, and 74.88 kJ/mol, respectively. A reactor model allowing for an intraparticle diffusion-reaction and external mass transfer was further developed to describe the selective hydrogenation of the C8 aromatic fraction on larger NiZn3/α-Al2O3 particles in a fixed-bed reactor. The observed changes in product composition with the reaction conditions were well predicted by the model, and the results demonstrated that phenylacetylene can be completely removed without loss of styrene under certain conditions.
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高影响因子
POLYMER JOURNAL
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2020
·Vol. 52
·期 5
·539-547
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IF 2.826
Wang Jianhong,Zhang Zhijie,Zhao Jing,Liu Rui
Herein, hydrophobic tannic acid–iron (TA–Fe) coordination composites were encapsulated within polystyrene-copolyacrylonitrile (PS-c-PAN) nanospheres using the flash nanoprecipitation (FNP) technique. Carbon materials with uniform and dense distributions of metal NPs were obtained after carbonization under the protection and confinement of the polymer matrix. The as-prepared Fe and nitrogen codoped carbon materials exhibited enhanced electrocatalytic performance in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In addition, the catalytic ability of the carbon/metal composites could be affected by tuning the morphology and composition.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2020
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IF 5.162
Weimin Chen,Min Luo,Kai Yang,Xiaoyan Zhou
Searching for a sustainable precursor that is capable of absorbing microwave energy is crucial for its rapid conversion into porous carbon via microwave heating. Here, alginate-based hydrogel beads cross-linked by bivalent ions (Cu 2+ , Zn 2+ , and Ca 2+ ) are converted into porous carbons (SPCs) in 10 min by applying simple microwave-assisted pyrolysis . Water wrapped in hydrogel beads and bivalent ions serve as initial microwave absorbers to convert alginate into char which acts as a good microwave absorber in the following stages. Additionally, bivalent ions also act as a gelling agent to generate hydrogel beads, as a porogen to obtain a highly porous structure, and as a metal donor to form the SPC/Cu composite. The resultant SPC has a high specific surface area of 1336 m 2 g −1 , a large total pore volume of 0.56 cm 3 g −1 , interconnected macropores, as well as a high oxygen content of up to 13.2%. These attractive characteristics give SPC a remarkable rate capability of 72% at 50 A g −1 . Interestingly, the interconnected macropores in SPC offer sufficient space for Cu growth via the redox reactions of Cu 2+ ; thus, the SPC/Cu composite without acid wash shows a specific capacitance as high as 804 F g −1 at 0.5 A g −1 .
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Yunpu Wang,Linyao Ke,Yujie Peng,Qi Yang,Yuhuan Liu,Qiuhao Wu,Yujie Tang,Haibin Zhu,Leilei Dai,Zihong Zeng,Lin Jiang,Roger Ruan
In view of the poor selectivity of aromatic hydrocarbons in bio-oil from biomass pyrolysis and the high pressure drop and rapid coking and deactivation of catalyst in industrial scale, a microwave-driven HZSM-5@SiC ceramic foam has been constructed, and applied to the ex-situ catalytic fast pyrolysis of soapstock to improve the content of aromatic hydrocarbons in bio-oil. The effects of different catalysts and heating modes and mass ratios of HZSM-5@SiC ceramic foam to soapstock on the distribution of pyrolysis products have been investigated. In addition, combined with the comparison of microwave and electric heating, the deactivation characteristics of HZSM-5@SiC ceramic foam have been studied. Finally, the process of preparing aromatic oil by microwave-driven catalytic pyrolysis of soapstock was discussed. Experimental results indicate that compared with HZSM-5, HZSM-5@SiC ceramic foam has a higher yield of bio-oil and higher aromatization activity. Under microwave heating, the relative content of aromatic hydrocarbons increases from 25.18% to 100% when the mass ratio of HZSM-5@SiC ceramic foam to soapstock increases from 0:1 to 1:1. Compared with electric heating catalysis, HZSM-5@SiC ceramic foam has the lowest yield of coke under microwave heating. After five consecutive uses, it still maintains more than 90% catalytic activity and has higher stability, which provides a scientific basis for the pilot scale experiments of soapstock catalytic pyrolysis.
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高影响因子
FUEL PROCESSING TECHNOLOGY
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2020
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IF 4.982
Wenbin Li,Yongfeng Zhu,Shuirong Li,Yi Lu,Jida Wang,Keming Zhu,Jinlei Chen,Yunwu Zheng,Zhifeng Zheng
Analytical pyrolysis-comprehensive two-dimensional gas chromatography/mass spectrometry (Py-GC × GC/MS) was employed for the on-line analysis of cellulose via catalytic pyrolysis with different catalysts and catalytic temperatures to study the products and aromatic hydrocarbons selectivity. The catalysts were subjected to characterization methods, including XRD , TEM , NH 3 -TPD, to investigate the effects of the physicochemical properties of the catalyst on the product distribution. Results showed that the Ce 0.8 Zr 0.2-x Al x O 2 could significantly promote the formation of aromatic hydrocarbons under 400–550 °C. A lower catalytic temperature (≤350 °C) favored the formation of furan compounds, and a higher catalytic temperature (≥450 °C) supported the formation of aromatic hydrocarbons. The relative peak area of the aromatics prepared by using the Ce 0.8 Zr 0.15 Al 0.05 O 2 catalyst was the highest being 85.24% at 550 °C. Moreover, the selectivity of the single-ring aromatics, such as benzene, toluene and xylene, were significantly affected by the presence of the Ce 0.8 Zr 0.2-x Al x O 2 catalysts. The higher total acidity of Ce 0.8 Zr 0.15 Al 0.05 O 2 favored the formation of benzene and toluene. Additionally, the Ce 0.8 Zr 0.15 Al 0.05 O 2 catalyst had a great thermal stability. The catalyst recycling tests showed that the Ce 0.8 Zr 0.15 Al 0.05 O 2 catalyst can be reused five times to produce aromatic-rich bio-oil via catalytic fast pyrolysis .
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BIORESOURCE TECHNOLOGY
·
2019
·
IF 6.669
Zhibing Yin,Shuang Xu,Sen Liu,Shuying Xu,Jihui Li,Yucang Zhang
Magnetic biochar was usually prepared using ferrous and ferric compounds as precursor of magnetic medium. Ferrate , which could be an internal oxidative modifier, was less explored for preparing magnetic biochar. Here, a magnetic biochar was prepared through K 2 FeO 4 -promoted pyrolysis of pomelo peel for adsorption of hexavalent chromium . Oxygen-containing groups and single phase ɤ-Fe 2 O 3 were simultaneously introduced into biochar matrix at 300 °C. The magnetic biochar exhibited 209.64 mg/g maximum adsorption capability at 45 °C, outperformed the best magnetic biochar with 142.86 mg/g maximum adsorption capability at 40 °C in the literature. Moreover, a good magnetism was obtained, facilitating separation of the magnetic biochar from aqueous solution by a magnet. The removal of hexavalent chromium was contributed to the hybrid adsorption of ɤ-Fe 2 O 3 and biochar matrix by reduction, electrostatic interaction and complexation. This method was attractive, required neither extra modifiers nor multiple operations for preparation of highly adsorptive magnetic biochar.
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高影响因子
INDUSTRIAL CROPS AND PRODUCTS
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2023
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IF 5.9
Dongmei Bi,Mengqian Yin,Fupeng Huang,Jiawen Zhang,Weiming Yi
To clarify the evolution mechanism of environmentally-persistent free radicals (EPFRs) in biochar as a function of pyrolysis temperature, three-component pyrolytic carbon was characterized by electron paramagnetic resonance (EPR) spectroscopy. Four types of EPFRs were distinguished by using the peak splitting method. The EPFRs in three-component pyrolytic carbon obtained at a pyrolysis temperature of 300 °C were mainly oxygen-containing free radicals (57.31–83.63 %). Upon increasing the pyrolysis temperature, simple aromatic ring radicals were formed by the dehydrogenation of biomass, and then the polymeric aromatic radicals formed, accompanied by π-electron delocalization to form phenyl-π radicals. Biomass pyrolysis was simulated by mechanically mixing the three components in different proportions. A comparison of the experimental and theoretical values indicated that interactions between the three components did not obviously affect the EPFR concentration in the range of 450–550 °C, with a maximum relative error of 12.78 %. A prediction model for the EPFRs concentration in multi-component pyrolytic carbon was proposed. This study also clarified the generation and transformation mechanisms of EPFRs in three-component pyrolytic carbon, thus providing guidance for generating and regulating biochar EPFRs.
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高影响因子
Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Yifu Hu,Tinglin Guo,Fangfang Xia,Zejuan Wang,Wentao Wang,Yi Wang,Shenghua Ma
In this research work, biochar-zirconium phosphate (BC-Zr-P) nanocomposites were utilized for the adsorption of Pb (II) in sewage through functionalization of zirconium and phosphate on the surface of biochar. A series of characterization analyses were conducted on BC-Zr-P nanocomposites to comprehend their morphology and functional groups. Furthermore, the adsorption performance of BC-Zr-P towards Pb (II) in aqueous solution was investigated and four crucial parameters including concentration, pH, adsorption time and temperature were optimized. The experimental results demonstrate that BC-Zr-P exhibits a high adsorption capacity for lead ions with a value of 82.04 mg g −1 . Comparative analysis indicates that BC-Zr-P possesses excellent potential as an effective sorbent for lead removal. The adsorption capacity of the material for Pb (II) is highly pH-dependent, with optimal performance observed at pH 2.5, indicating that ion exchange plays a dominant role in the adsorption process and leading to significant changes in adsorption capacity. Rapid kinetic performance within 2 h suggests chemisorption of Pb (II) by BC-Zr-P. We observed a strong agreement between the pseudo-second-order kinetic model and the experimental data, while the adsorption isotherms at different temperatures were well described by the Langmuir model, which outperformed the Freundlich model. These results provide evidence for a monolayer chemisorption mechanism of BC-Zr-P. In addition, the impact of varying temperatures on the adsorption capacity of BC-Zr-P was examined within the range of 278.15–318.15 K, and the thermodynamic behavior of adsorption was analyzed by determining Δ S o and Δ H o through a linear relationship between lnK d and 1/T. The positive value obtained for Δ H o suggests that the process of adsorption is endothermic. BC-Zr-P had excellent selective adsorption capacity for Pb (II) ions in various metal ion solutions and had practical application value for the adsorption of Pb (II) ions in sewage.
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