查找使用阿拉丁产品的科研文献

Investigation of seawater mineral promoted pyrolysis at low temperature for improving the adsorption capabilities of biochar

Qin Wen,Shihan Wang,Sen Liu,Jihui Li,Yijia Chen,Run Yang,Shuying Xu

Naturally abundant seawater mineral was employed to engineer banana pseudostem and bamboo biochars through pyrolysis at different low temperatures for improving their adsorption capabilities for methylene blue (MB) and tetracycline (TC). The adsorption capabilities were greatly enhanced as the biochars were pyrolyzed at 300 °C with 50/1 (mL/g) dosage of seawater to biomass. For instance, the engineered banana pseudostem biochar exhibited 8.00 and 6.54 times higher adsorption capabilities than the corresponding pristine biochar for MB (447.79 mg/g vs 55.96 mg/g) and TC (100.59 mg/g vs 16.75 mg/g) at 25 °C, respectively. The characterization results indicated that a large number of carboxylates, lactone acid salts, and alkoxides were generated on the engineered biochar and a high cation exchange capacity was gained. The adsorption of MB was mainly attributed to cation exchange complying with hydrogen bonding and electrostatic interaction, whereas the adsorption of TC was realized by hydrogen bonding and complexation.

Photocatalytically regenerable Cu2O/Cu/biochar adsorbents by facilely synchronous carbonization-activation-functionalization pyrolysis of hemp hurds

Chuanfu Song,Kunyuan Chen,Xin Jin,Xinyu Zhao,Guangrong Liu,Feifei He,Qiang Huang

The biochar-supported Cu 2 O/Cu composite (Cu 2 O/Cu/BC) was fabricated by direct pyrolysis of hemp hurds pretreated with KOH and CuCl 2 , in which the synchronous carbonization-activation-functionalization was achieved to produce copper-modified biochars. Cu 2 O/Cu/BCs were characterized by XRD , Raman, XPS , SEM and N 2 adsorption-desorption techniques. The adsorption methyl orange by Cu 2 O/Cu/BCs showed that the incorporation of Cu 2 O/Cu has improved the adsorption capacity. The adsorption obeyed the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacity reached 379.4 mg∙g -1 at 303.5 K. Furthermore, assisted with the photoactivity of Cu 2 O/Cu heterojunction the saturated adsorbent can be regenerated under simulated sunlight, and the re-adsorption capacity was still as high as 77.1% of the fresh adsorbent after six cycles. The regeneration efficiency was much better than traditional thermal regeneration and solvent treatment. This work should allow to provide a convenient preparation of functionalized biochars and to develop solar-driven, self-regenerative sorbents for water decontamination with high efficiency.

Lanthanum-loaded peanut shell biochar prepared via one-step pyrolysis method for phosphorus removal and immobilization

Shengli Zhang,Tong Lin,Wei Li,Menglin Li,Kai Su,Junmin Chen,Hongwei Yang

Efficient and selective catalytic pyrolysis of cellulose to monocyclic aromatic hydrocarbons over Zn-containing HZSM-5

Nai-Yu Yao,Jing-Pei Cao,Jing-Ping Zhao,Zi-Meng He,Xiao-Bo Feng,Tian-Long Liu,Ze-Ying Wang,Xiao-Yan Zhao

A series of Zn-containing HZSM-5 (HZ5) with hierarchical pores (xZn(DS)) were obtained by adding different amounts of Zn(NO 3 ) 2 solution in a hydrothermal synthesis process. The performances of xZn(DS) in catalytic reforming of cellulose pyrolysis volatiles were investigated at 500 °C. The results showed that the addition of Zn during synthesis increased in the total pore volume of xZn(DS) and reduced the content of strong acid sites, and introduced new weak acid sites. The Zn species were highly dispersed inside the zeolite, and enhanced the accessibility of acid sites, so that the yields of light aromatic hydrocarbons and monocyclic aromatic hydrocarbons (MAHs) over 0.7Zn(DS) (The molar ratio of ZnO/Al 2 O 3 in the synthesis process of xZn(DS) was 0.7) were higher than those over S-HZ5 (Zn was not added in the synthesis process) and commercial HZ5. Compared with S-HZ5, the yield of MAHs over 0.7Zn(DS) increased from 92.8 to 114.1 mg/g and the coke yield decreased by 2.9%. The selectivity of MAHs over 0.7Zn(DS) was 87.7%, which was 5.3% higher than that over S-HZ5. Simultaneously, the increase in mesopores of xZn(DS) accelerated the mass transfer process, shortened the diffusion path and improved the anti-coking performance of the catalysts. In addition, this study also proposed a possible mechanism for the catalyst to adjust the distribution of aromatic products and provided a new idea for promoting the selective production of MAHs for the pyrolysis of cellulose.

Simultaneous dual pyrolysis synthesis of heterostructured FeCo/C porous hollow microspheres for highly efficient microwave absorption

Ran Liu,Gaiping Du,Bin Liao,Weixin Xiao,Zhenguo An,Jingjie Zhang

Due to their multiple dissipation mechanisms, low density and easily tailored impedance matching, heterogeneous hollow structures are promising candidates for microwave absorbents towards wideband absorption and lightweight design. In this work, a new type of hollow microspheres with a porous carbon shell embedded with crystalline FeCo alloy nanoparticles have been prepared via a stepwise spray drying–calcination strategy. The effects of both the FeCo/C molar ratio and the calcination temperature on the structure and property of the porous hollow microspheres (PHMs) have been studied. It is found that the effective absorption bandwidth of the as-prepared FeCo/C PHMs surpassed 7.44 GHz at a matching thickness of 2.64 mm, which covers the full Ku-band. Moreover, with an elevated calcination temperature, high microwave absorbing performance can be achieved at a much reduced matching thickness. A probable absorbing mechanism has been proposed involving the synergistic effect of the hollow interior, the porous shell structure, and the electric and magnetic dissipation due to the coexistence of carbon and magnetic metals. This work opens a new pathway to synthesize microwave absorbents with a heterogeneous hollow structure, and may shed some light on the design and controlled preparation of other hollow structures with various shell compositions.

Complex SiC-based structures with high specific strength fabricated by vat photopolymerization and one-step pyrolysis

Jiwei Cao,Muhammad Idrees,Guoqiang Tian,Jian Liu,Shufeng Xiong,Jingkun Yuan,Pei Wang,Zhiyuan Liu,Changyong Liu,Zhangwei Chen

Lightweight and strong silicon carbide (SiC) ceramics with complex lattice structures were fabricated by vat photopolymerization 3D printing technology followed by a one-step pyrolysis process . The UV-light penetration depth of the SiC ceramic slurries was increased more than three times based on the formation of SiC@SiO 2 core@shell structured particles through pre-oxidation processing. To reduce the sintering temperature and shrinkage of SiC ceramics, 40 vol% solid loading SiC@SiO 2 ceramic slurries mixed with photocurable resins containing 0–70 wt% of polysiloxane were prepared. SiC@SiO 2 /SiOC ceramic with less than 8% linear shrinkage rate was obtained after pyrolysis at 1000–1200 ℃. The pyrolyzed SiC@SiO 2 /SiOC lattice ceramics exhibited a specific strength of 4.6 × 10 4 N m/kg with a cellular density of 0.87 g/cm 3 , surpassing various other lattice structures and porous ceramics with similar porosity. The complex structure forming ability, mechanical performance and its short developing cycle make this technology to be a promising method for structural integrated SiC ceramic manufacturing.

Effect of Cu-modified HZSM-5 zeolites on catalytic pyrolysis of lignin to producing aromatic hydrocarbons

Yang Shen,Chunjiang Liu,Cunhao Cui,Hairong Ren,Mingming Gu,Haoran Liu,Zhongyue Zhou,Fei Qi

Lignin catalytic pyrolysis presents a promising and sustainable approach to producing aromatic molecules. Herein, we investigated the effect of modified zeolite with copper (Cu/HZSM-5) catalyst on efficiently pyrolyzed kraft lignin into aromatic hydrocarbons (AHs) production, especially mononuclear aromatic hydrocarbons (MAHs). Time-of-flight mass spectrometry (TOF-MS) was employed to compare the volatile product profiles of lignin during catalytic pyrolysis. The highest yield of MAHs reached 70.59 mg/g based on dry lignin at 550 °C, accounting for 70.23% among lignin pyrolysis products, compared to the pristine HZSM-5 zeolite catalytic system with MAHs yield of only 54.31 mg/g and of 40.34% in products. At 550 °C and 60 s residence time, the 5% Cu/HZSM-5 catalyst demonstrated the best performance compared to all other catalysts in terms of selectively producing MAHs. The results are ascribed to the enhancement of decarboxylation and aromatization processes by the doping of copper. This work demonstrates a cost-effective pathway that potentially converts kraft lignin into aromatic hydrocarbon production at a phenomenally high selectivity, providing a concept for industrial application toward biomass utilization and high value-added production.

Highly selective production of phenolic compounds from lignin pyrolysis with the strategy of hydrogen self-supply

Chao Liu,Zhanghong Xie,Lili Tong,Yuyang Fan,Xiangchen Kong,Rui Xiao

In this study, a sealable fixed-bed reactor was developed to investigate the influence of gaseous products on lignin pyrolysis with a strategy of hydrogen self-supply, and lignin pyrolysis performances at various temperatures were monitored by the comprehensive characterization of the generated products, including gas, bio-oil and char. The results showed that the release of volatiles (both gas and bio-oil) from lignin was strengthened in this sealable system when the temperature rose, and therefore less char was left. Meanwhile no H 2 was detected under any of the operating conditions, which is a common component in pyrolysis gas from conventional reactors, indicating its participation in lignin pyrolysis. Furthermore, the formation of CO and CO 2 in the employed pyrolyzer benefited from not only the thermal evolution of feedstock, but also the interactions between char residues and generated gas components. Meanwhile, because of the hydrogen self-supply, compounds in bio-oil were enriched and only nine species were detected, which were all phenolic compounds. Vanillic acid was dominant, and its relative content was up to 38.86% for Alcell organosolv lignin and 34.41% for soda alkali lignin. This illustrates that highly selective production of phenolic compounds from lignin pyrolysis can be achieved by self-supplying hydrogen from pyrolysis gas.

Phosphorus-modified mesoporous niobium pentoxide catalyst for fast pyrolysis of cellulose to selective production of levoglucosenone

Ji Liu,Hao Fu,Bin Hu,Wan-yu Fu,Kai Li,Li Zhao,Bing Zhang,Qiang Lu

Catalytic fast pyrolysis of biomass/cellulose is a promising way for the production of levoglucosenone (LGO) and other value-added anhydrosugars. Herein, ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) modified mesoporous niobium pentoxide (P-Nb 2 O 5 ) was first applied to selectively produce LGO. The catalyst had a stable amorphous mesoporous structure with abundant activity species (Nb-O-Nb, Nb-O-P, P-OH, and PO 4 3- ), which affected the dehydration and depolymerization reactions of cellulose to alter the competing relationship between levoglucosan (LG) and LGO. Micro-scale pyrolysis experiments demonstrated that the yield of LGO reached 19.6 wt% under the optimized condition (P loading of 50 wt%, pyrolysis temperature of 400 °C, and catalyst-to-cellulose mass ratio of 7). In lab-scale experiments, the highest yield of LGO attained 16.5 wt%, and the catalytic activity could maintain over 80% after five recycles. Overall, the P-Nb 2 O 5 has been proven to be a promising catalyst to produce LGO from cellulose.

Study of the interaction mechanism between the components of microalgae by thermal behaviors and pyrolysis characteristics

Ziyue Tang,Yingquan Chen,Juping Liu,Wei Cheng,Xianhua Wang,Qiang Hu,Yang Yang,Haiping Yang,Hanping Chen

There is significant effect on thermal behaviors pyrolytic characteristics of the interactions between microalgal components. In order to understand the reaction process, interaction mechanism, and better utilization of microalgae, co-pyrolysis of microalgal model compounds (soybean protein (PT), sunflower oil (OL) and sucrose (SC)) was carried out with TG-FTIR and Py-GC/MS. The results showed that co-pyrolysis of PT and SC significantly changed the thermal behaviors, and accelerated decomposition at lower temperature to generate C O, CO 2 largely. And it could promote the generation of linear O-compounds (such as acetic acid), and inhibit the formation of N-heterocycles and furans. Moreover, OL co-pyrolysis with PT or SC could significantly promote the formation of long-chain acid and inhibit the generation of aliphatics. Meanwhile, co-pyrolysis of PT and OL inhibited the generation of N-heterocycles. And co-pyrolysis of SC and OL accelerated the generation of furans. Furthermore, co-pyrolysis of model compounds reduced the average activation energy of the pyrolysis process, and changed the reaction kinetic model.

Impact of heating rates on the evolution of function groups of the biochar from lignin pyrolysis

Chao Li,Jun-ichiro Hayashi,Yifan Sun,Lijun Zhang,Shu Zhang,Shuang Wang,Xun Hu

Understanding evolution of the functionalities of biochar versus temperature is a prerequisite for exploring application of biochar as functional carbon materials. In this study, pyrolysis of lignin with different heating rates was conducted. The results indicated that the higher heating rate promoted formation of more gases via the accelerated cracking of both the organic components of biochar and the volatile products. In addition, the deoxygenation reactions were suppressed at higher heating rate with short residence time, leading to the biochar with lower heating value and energy yield. The in situ Diffuse Reflection Infrared Fourier Transform Spectra (DRIFTS) characterization of the lignin pyrolysis indicated monotonous increase of the abundance of =C−H, C=C and C−O−C functionalities versus increasing pyrolysis temperature. However, the −OH, −CH 3 and C−H 2 in alkanes and the C=O were not thermally stable. Abundance of −OH maintained a plateau in 200−450 °C, while that for −CH 3 and C−H 2 in alkanes also reached maximum at ca. 450 °C and the further increasing heating temperature led to significant decomposition. The decomposition of C=O started at the lower temperatures of 200–325 °C, and the lactones, unconjugated alkyl aldehydes, alkyl esters, conjugated aldehydes/ketones experienced distinct temperature-abundance histories.

Gold-embedded fabrication of three-dimensional ordered macroporous TiO2 via in-situ pyrolysis for enhanced photocatalysis

Zhang Yakang,Liang Xuan,Jiang Mengting,Liang Qian,Xu Song,Yao Chao,Zhou Man,Li Zhongyu

Based on the three-dimensional ordered macroporous titanium dioxide (3DOM-TiO 2 ), a series of gold-embedded 3DOM-TiO 2 ( n Au@3DOM-TiO 2 ) with controlled Au loading amount ( n  = 0.24, 1.2, 2.4, 4.8, 12, and 24 wt%) was successfully fabricated via in-situ pyrolysis for the first time. Compared with the surface-modified Au/3DOM-TiO 2 by traditional impregnation–reduction route, this body-doped Au@3DOM-TiO 2 structure exhibited smaller particle size and better dispersive property which are important for photocatalysis. Therefore, the photocatalytic activities of n Au@3DOM-TiO 2 have been tested and the optimized photocatalyst of 4.8Au@3DOM-TiO 2 was identified. A possible mechanism of Au@3DOM-TiO 2 for the enhanced photoactivity was well discussed. The present work demonstrated a unique “gold-embedded” interface with potential advantages of highly dispersed, anti-aggregation, easy recovery, and enhanced catalytic performance, and that this approach could provide an ideal platform for the further design of noble metal-doped semiconductors.