Science China-Technological Sciences
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2022
·Vol. 65
·期 10
·2337-2347
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IF 3.903
Hou ShengPing,Zhang Da,Xie ZhiPeng,Kang Yao,Tang ZhengGang,Dai YongNian,Lei Yong,Chen Jian,Liang Feng
As the quantity of waste tires increases, more pyrolysis carbon black (CBp), a type of low value-added carbon black, is being produced. However, the application of CBp has been limited. Therefore, it is necessary to identify and expand applications of CBp. This work focuses on the preparation of activated carbon (AC) from CBp using the physicochemical activation of carbon dioxide (CO 2 ) and potassium hydroxide (KOH). Thereafter, AC is applied to the electrode of the electrical double-layer capacitor (EDLC). The AC prepared by CO 2 /KOH activation exhibited a hierarchical pore structure. The specific surface area increased from 415 to 733 m 2 g −1 , and in combination with low ash content of 1.51%, ensured abundant ion diffusion channels and active sites to store charge. The EDLC comprising the AC (AC-2) electrode prepared by excitation of CO 2 (300 sccm) and KOH had a reasonable gravimetric specific capacitance of 192 F g −1 at 0.5 A g −1 , and exhibited a good rate capability of 73% at 50 A g −1 in a three-electrode system. Moreover, the EDLC device comprising the AC-2 electrode delivered excellent cycling stability (capacitance retention of 106% after 10000 cycles at 2 A g −1 in a two-electrode system). Furthermore, a symmetric supercapacitor based on an AC electrode that exhibits a supreme energy density of 4.7 Wh kg −1 and a maximum power density of 6362.6 W kg −1 is demonstrated.
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Physica Status Solidi-Rapid Research Letters
·
2021
·Vol. 16
·期 1
·2100348
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IF 2.821
Mingrui Tang,Junsheng Yu,Hua Tang,Jiang Cheng,Lu Li
Silver antimony sulfide (AgSbS 2 ) is considered a promising photovoltaic absorber material because of its suitable bandgap, large absorption coefficient, and environmental friendliness. However, the photovoltaic performance of AgSbS 2 -based solar cells is far from expectation and the applications of AgSbS 2 are limited by the underdeveloped fabrication technology. Herein, an effective method is developed to improve the photovoltaic performance of devices by adding indium (In) into the Ag–Sb–S system followed by a selenization process. With the addition of In, the morphology uniformity and the crystallinity of the films are simultaneously improved due to the diminished defects such as pinholes and cracks, leading to a better heterojunction interface between Ag 1− x In 2 x Sb 1− x S y Se 2− y and CdS. The Hall effect measurements demonstrate that the carrier concentration of the films effectively increases to 8.16 × 10 14 cm −3 on adding In. The optical characterization suggests that In addition significantly enhances the optical absorption and broadens the absorption wavelength range. Furthermore, the conduction band offset between the absorber and the buffer layer is substantially reduced by adding In, which lessens the carrier recombination at the interface, increasing the carriers transport efficiency. The power conversion efficiency of the Ag 1− x In 2 x Sb 1− x S y Se 2− y device is largely improved from 0.74% (In/Sb = 0) to 1.98% (In/Sb = 0.47).
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WASTE MANAGEMENT
·
2021
·
IF 7.145
Chengyu Li,Jun Zhang,Jing Gu,Haoran Yuan,Yong Chen
In the present research, a series of metal oxides were employed to investigate the role of varied acid-base site on kinetics and mechanism for catalytic fast pyrolysis of cellulose using TG-MS and Py-GC/MS. The results showed that the modulation of acidity-to-basicity value via altering metal oxides constituents significantly affected the transformation pathway for cellulose pyrolysis. Higher acidity-to-basicity ratios accelerated the proceeding of deoxygenation process, wherein 39.4% aromatics and 34.7% aliphatic hydrocarbons were achieved using Al 2 O 3 (acidity-to-basicity value of 1.38) at 750 °C with a catalyst/cellulose mass ratio of 15:1. In comparison, lowering acidity-to-basicity ratios mainly facilitated the ketonization and aldol condensation, therefore over 70% ketones was attained in the case of CaO catalysis. The kinetic studies further verified the promotional role of acid-base sites on cellulose pyrolysis with apparent activation energy as low as 33.72 kJ/mol, in comparison with that of cellulose pyrolysis without adding catalysts. From another aspect, the composite metal oxides with better porous structures contributed to deoxygenation conversion for the production of aromatics and aliphatic hydrocarbons. Moreover, plausible reaction pathway for cellulose pyrolysis over metal oxides was proposed. This work would provide a good reference for the realization of product regulation from cellulose pyrolysis via adjusting acid-base sites in metal oxides.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Ji Liu,Wei Zhao,Shuang-wei Yang,Bin Hu,Ming-xin Xu,Shan-Wei Ma,Qiang Lu
Incineration of food waste leads to the release of NO x pollutants, whereas the formation mechanism of the NO x precursors (HCN, NH 3 , and HNCO) during the initial pyrolysis process is far from well-studied, limiting the source control on NO x release. In this work, 2,5-diketopiperazine (DKP) was selected as the N-containing model compound to study the formation mechanism of NO x precursors in food waste pyrolysis, by combining experiments and density functional theory (DFT) calculations. The C1-N2 bond broken via the N2-to-N5 H-transfer possesses the lowest energy barrier, together with the largest reaction rate constants in the range of 400–800 °C. NH 3 can be easily generated with low energy barriers and high rate constants at low temperatures (below 630 °C). Whereas, the rate constants of the pathways for HCN formation will exceed those for NH 3 generation in the range of 630–740 °C. In addition, the DKP pyrolysis can also lead to the formation of HNCO with a very low energy barrier, and it can convert into HCN and NH 3 through further hydrogenation and decomposition. These calculation results are exactly consistent with the experimental results that NH 3 was the main precursor in the range of 400–600 °C, and the yield of HCN exceeded that of NH 3 when the temperature was over 600 °C. Our current work on the formation mechanism of NO x precursors during the pyrolysis of DKP can provide theoretical guidance for the development of NO x control technology in the pyrolysis/combustion process of organic waste.
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Journal of the Taiwan Institute of Chemical Engineers
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2021
·
IF 5.876
Wenbo Liu,Jiabin Zhou,Dan Liu,Su Liu,Xianjie Liu,Shuang Xiao,Choujing Feng,Changhong Leng
Background The combination of Fenton catalyst and photocatalyst will lead to the decrease in light absorption on the photocatalyst, and it is difficult for Fe 3+ to be converted into Fe 2+ on the Fenton catalyst, resulting in poor Fenton-like process and photocatalysis effect. Preparing catalysts containing oxygen vacancies (OVs) can simultaneously increase the light absorption and the cycle of Fe(Ⅲ) to Fe(Ⅱ) to improve the catalytic efficiency of Fenton-like process and photocatalysis. Methods A mesoporous H-MIL53 with OV was constructed by ligand selective pyrolysis. The formation mechanism of H-MIL-53 vacancy was analyzed by XPS, EPR, FTIR and TG. Significant findings XPS, EPR, FTIR and TG showed that calcination caused the fracture of Fe-O bond resulted in OV and coordinative unsaturated Fe site. H-MIL-53 showed higher degradation efficiency of tetracycline hydrochloride (93%) and high recycling performance. The electron-rich OV could activate the dissolved oxygen to produce •O 2 − through phot-introduced electrons, while the electron-poor iron site can activate H 2 O 2 to produce •OH. These results provide a new direction for the construction of metal-organic framework (MOF) containing OV for application in Fenton-like process and photocatalysis.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2021
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IF 19.503
Qiuhao Wu,Linyao Ke,Yunpu Wang,Nan Zhou,Hui Li,Qi Yang,Jiamin Xu,Leilei Dai,Rongge Zou,Yuhuan Liu,Roger Ruan
Pulse pyrolysis was carried out to realize real-time monitoring of CaO catalyst deactivation and regeneration in the catalytic pyrolysis of waste cooking oil (WCO) and free fatty acids (FFAs) based on the pyrolysis characteristics of feed stocks. The high unsaturation of the feedstock decreases the initial decomposition temperature and reduces the content of oxygen-containing compounds. CaO catalyst was completely deactivated after several times of pulse pyrolysis. During the pyrolysis of WCO, the catalytic activity of CaO did not recover after the pause of pulse pyrolysis. However, the catalytic activity all recovered during the pyrolysis of FFAs, but the rate of deactivation was accelerated. A large amount of Ca(OH) 2 and CaCO 3 were detected in the deactivated catalyst, and soluble coke was not detected. The research suggested that the change of crystal phases and agglomeration were the vital cause that impact the CaO catalyst stability.
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CHEMOSPHERE
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2021
·
IF 7.086
Jinyu Hou,Daoxu Zhong,Wuxing Liu
Hazardous oil sludge (OS) poses a great challenge to the environment, whereas conventional treatment methods (i.e., incineration or pyrolysis-incineration) are relatively less value-added and will bring about air pollution problems. To realize the high-value utilization of OS, catalytic co-pyrolysis with waste biomass to produce platform chemicals was studied using TG-FTIR and Py (pyrolyzer)-GC/MS methods. Results showed that for the non-catalytic co-pyrolysis of RH (rice husk) and OS, the main synergy on weight loss was the greatly lowered initial pyrolysis temperature of RH (for ∼55 °C) at the lower temperatures and the reduced weight loss ratio of OS (∼10–18 wt%) within the higher temperature range. ZSM-5 catalyst promoted the degradation of OS and RH mixtures at < 150 °C, yet showed minor effects on their weight loss at higher temperatures. The oxygenated and aliphatic compounds from non-catalytic co-pyrolysis were efficiently converted, resulting in an increased relative yield of aromatics to the highest of 46% and an elevated selectivity to BTX (as high as 60%). Despite the relatively short carbon chain length of OS components, ZSM-5 was proved effective to activate the OS pyrolysis products, thus enhancing the further aromatization reactions with biomass pyrolysis intermediates. This study provides a novel method for value-added co-utilization of hazardous OS waste and abundant biomass waste, and thus is beneficial to producing renewable chemicals while reducing the environment pollutant.
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CHINESE CHEMICAL LETTERS
·
2021
·
IF 6.779
Min Zhang,Bolong Yang,Ting Yang,Yahui Yang,Zhonghua Xiang
Unremitting and intensive researches about efficient non-precious metal electrocatalysts are necessary for large-scale commercial applications of fuel cells, while iron and nitrogen co-doped carbon (Fe-N-C) materials has become one of the most promising electrocatalysts to replace Pt-based noble metal catalysts . However, the traditional Fe-doped ZIF with rhomb dodecahedron morphology limits the exposure of active sites and the utilization of atoms, even affecting the performance of the catalyst. Herein, a Fe/N co-doped catalyst with a flower-like morphology was prepared using ferric citrate source along with secondary NH 3 heat treatment. The optimal catalyst (termed as 4Fe citrate -N-C-3) showed distinguished oxygen reduction reaction (ORR) activity with a half-wave potential of 0.8 and 0.9 V ( vs . RHE) in acid and alkaline media, respectively. In addition, 4Fe citrate -N-C-3 maintained more than 80% of original activity even after 50,000 s which is superior to the benchmark Pt/C. The strategy of controlling morphology and composition is meaningful for the optimization of non-precious metal electrocatalysts for ORR in fuel cells or metal-air batteries .
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2021
·
IF 5.541
Fangqi Wang,Fengwen Yu,Yi Wei,Ao Li,Shenzheng Xu,Xianghong Lu
Oleaginous biomass conversion to liquid hydrocarbon biofuels has emerged as an effective solution to the energy crisis and environmental problems. In this process, the removal of oxygenated compounds will directly affect the effectiveness of subsequent biofuel applications. Herein, deoxygenation of oleic acid by catalytic cracking was conducted using five various elements (La, Ni, P, Zr and Ce) modified Al-MCM-41. The related characterizations were carried out for these catalysts, including N 2 physisorption, XRD, XPS, pyridine-FTIR and NH 3 -TPD techniques. The results showed the mesoporous structure of Al-MCM-41 was maintained after different modifications, and these catalysts greatly improved the hydrocarbons content and physiochemical properties of biofuels. The modified catalysts tended to facilitate the decarbonylation pathway and showed high selectivity to alkane and aromatic hydrocarbons. Besides, La/Al-MCM-41 presented excellent anti-coking activity. Ni/Al-MCM-41 showed both high dehydrogenation and deoxygenation activities. The Zr modification and Ce modification had a promotion effect in the deoxidizing activity of the catalyst, owing to the formation of oxophilic metal oxides. Noteworthily, P/Al-MCM-41 displayed the best deoxidizing performance due to its high Brönsted acidity, which caused the highest hydrocarbons content (82.30 %) and the lowest fatty acids content (around 0 %) of the biofuel. Moreover, the resulting biofuel had not only low oxygen content (3.88 wt.%) and acid value (5.47 mgKOH g −1 ) but also a high calorific value (44.50 MJ kg −1 ), which could be processed into green diesel. Hence, the catalytic cracking of fatty acid over P/Al-MCM-41 has excellent potential to produce high-quality renewable fuels.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2021
·
IF 5.541
Yang Li,Bin Hu,Salman Raza Naqvi,Zhen-xi Zhang,Kai Li,Qiang Lu
5-Hydroxymethylfurfural (5-HMF) is a value-added platform chemical, which can be obtained from pyrolysis of biomass materials, whereas related investigation on its selective production via catalytic fast pyrolysis (CFP) process is still insufficient. In this work, a zirconium-tin mixed metal oxide (ZrO 2 -SnO 2 ) catalyst was developed for the selective production of 5-HMF from the in-situ CFP of cellulose. According to pyrolysis-chromatography/mass spectrometry (Py-GC/MS) tests, the ZrO 2 -SnO 2 catalyst has better performance on the selective preparation of 5-HMF than single nano oxide ZrO 2 , SnO 2 , or their physical mixture. 5-HMF was sensitive to the reaction conditions, and its yield and selectivity always exhibited the tide of first increasing followed by decreasing along with the increase of Zr loading and catalyst-to-cellulose (CA-to-CL) ratio. At the optimum conditions with ZrO 2 -SnO 2 of 15 wt% Zr loading (ZrO 2 -SnO 2 -15), pyrolysis temperature of 350 °C and CA-to-CL ratio of 2:1, the 5-HMF yield was 6.49 wt%, which was 4 times more than that of the non-catalytic process (1.35 wt%). Correspondingly, the selectivity of 5-HMF was up to 23.50 %. The catalyst characterization combined with the pyrolysis texts of several typical saccharides, including cellobiose, maltose, glucose, and mannose indicated that the ZrO 2 -SnO 2 -15 could promote the breakage of glycosidic bonds with the formation of reducing ends and the selective conversion of the reducing end to 5-HMF due to its mild acidity. Overall, the ZrO 2 -SnO 2 is expected a promising catalyst for the CFP of cellulose to prepare 5-HMF.
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BIORESOURCE TECHNOLOGY
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2021
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IF 9.642
Junjie Weng,Cunhao Cui,Zhongyue Zhou,Yi Zhang,Zhanjun Cheng,Jianfeng Pan
Due to rapid deactivation of catalysts, the effective conversion of biomass with oxygen-rich and hydrogen-deficient characteristics to transportation fuels and high-valued chemicals via catalytic pyrolysis remains a challenge for commercialization. Hydrogen-rich plastic is used as feedstock co-fed with biomass to improve the catalytic pyrolysis process. The present work aims to investigate the co-pyrolysis process of cellulose and polyethylene (PE) over MgO by TG combined with photoionization time-of-flight mass spectrometry (PI-TOF-MS), which features on-line detection of catalytic pyrolysis products in real time. The MgO catalyst could improve the pyrolysis of cellulose and enhance the C C bond breaking of PE, respectively. During catalytic co-pyrolysis, the yields from olefins and furan as well as its derivatives can be enhanced obviously. Further, the formation of additional aromatics can be observed due to the Diels-Alder reaction. This work shows TG coupled to PI-TOF-MS is a powerful setup to study and optimize catalytic co-pyrolysis process.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2021
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IF 5.541
Jianjun Xiao,Minjiao Yang,Qingfeng Che,Yingquan Chen,Xu Chen,Haiping Yang,Pietro Bartocci,Francesco Fantozzi,Hanping Chen
The effect of potassium in biomass on the catalytic activity of ZSM-5 zeolite in the fast pyrolysis of biomass was investigated using 2-methylfuran (2-MF) as the typical model compound. The mechanism of action of potassium was explored in detail, along with the physicochemical properties of ZSM-5, including crystallinity, pore structure, and surface acidity. The physicochemical properties of ZSM-5 deteriorated to varying degrees after being tainted with different potassium sources (KOH, K 2 CO 3 , KAc, and KCl). Compared with neutral KCl and strong alkali KOH, K 2 CO 3 , and KAc, with weaker alkalinity but larger crystal structure, exerted a larger influence on ZSM-5. Changes in ZSM-5 tainted with K 2 CO 3 were the greatest, and crystallinity, surface area, acidity, and the corresponding yields of valuable aromatic hydrocarbons and gas products, all declined significantly, compared with raw ZSM-5. When the amount of K(CO 3 2− ) on ZSM-5 was less than 0.5 wt%, only minor (<10 %) changes were observed in crystallinity and surface area, but total acidity decreased by over 30 percent. The conversion of 2-MF was increased using ZSM-5 tainted with less than 0.5 wt% K(CO 3 2- ) and less liquid oxygenated compounds and more CO 2 were produced. Appropriate total acidity, adjusted by a tiny amount of K 2 CO 3 , could promote deoxygenation to CO 2. However, the decarbonylation reaction was inhibited, causing a negative effect on monocyclic aromatic hydrocarbons, which was attributed to the large-scale loss of both acidity and physical structure of ZSM-5 caused by more than 1.0 wt% K(CO 3 2- ).
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