查找使用阿拉丁产品的科研文献

Light limitation reduces proportion of the released methane to assimilated carbon and nitrogen in the N2-fixing cyanobacterium Trichodesmium

Zou Chuze,Gao Kunshan

Trichodesmium , a nitrogen-fixing cyanobacterium, has recently been shown to release methane through utilization of the organic phosphorus methylphosphonate (MPn), which is commonly found in surface oceans. We demonstrated previously that methane production (MP) increased with rising temperatures and was positively correlated with assimilations of carbon and nitrogen under optimal light conditions. Here, we show that when grown under light-limitation, elevated temperatures within a range of 23 °C to 31 °C reduced growth by 67% and MP by 91%, with altered relationship of MP to assimilations of C, N and P. This indicates that light-limitation disrupted the synergy of MP with the C/N/P assimilations, highlighting that photosynthetic energy supply affects methane production to differential extents with increasing temperatures. Our results imply that Trichodesmium in deeper waters or exposed to low light conditions produces much less methane even under ocean warming scenarios.

Enhancing CH4/N2 separation performance within aluminum-based Metal-Organic Frameworks: Influence of the pore structure and linker polarity

Zhenghui Huang,Peng Hu,Jia Liu,Fang Shen,Youquan Zhang,Kungang Chai,Yunpan Ying,Chengjun Kang,Zhaoqiang Zhang,Hongbing Ji

Efficient CH 4 /N 2 separation is necessitated for obtaining purified methane from natural gas. Aluminum-based metal–organic frameworks (Al-MOFs) have potential for industrial separation applications due to their structure-tunable, low-cost, and scalable features. Intrigued by the impressive selectivity of a recently reported Al-MOF (Al-CDC) toward CH 4 over N 2 , we herein further study the potential of Al-MOFs as adsorbent for CH 4 /N 2 separation, mainly considering the effects of pore geometry and linker polarity. Utilization of two bent ligands and two linear ligands with different polarity afforded two one-dimensional square-shaped Al-MOFs i.e., CAU-10-H, MIL-160, and two rhombic-shaped counterparts i.e., Al-Fumarate (Al-Fum), MIL-53(Al)), respectively. Afterward, pure CH 4 and N 2 adsorption experiments were conducted at 273–313 K for assessing the CH 4 /N 2 separation performance. The results indicated that all the Al-MOFs exhibited superior affinity toward CH 4 over N 2 , and the CH 4 uptake followed the sequence of Al-Fum > CAU-10-H > MIL-53(Al) > MIL-160. Exhilaratingly, Al-Fum exhibited unprecedented CH 4 /N 2 selectivity (17.2) and high CH 4 uptake at 273 K and 1.0 bar. The mechanism underlying the disparity of Al-MOFs affinity toward CH 4 was deciphered via theoretical simulation, suggesting that the synergetic effects of accessibility of strong affinity sites (μ 2 -OH) on AlO 6 chains and polar pore surface induced by varying linkers highly promoted the CH 4 uptake. Furthermore, the results of cyclic adsorption–desorption experiments and binary breakthrough tests validated the feasibility of Al-Fum for practical application.

Enhancement of N2 adsorption by Z-scheme porous g-C3N4/ZnFe2O4 composite material for high-efficient photocatalytic nitrogen fixation

Zhang Shixian,Rong Xinshan,Sun Ting,Gao Ping,Liu Jun,Qiu Xuchun,Zhou Xiangtong,Wu Zhiren

An energy-efficient and environmentally friendly nitrogen fixation process is urgently needed to solve problems of high energy consumption and high emissions in the traditional ammonia industry. In this work, a Z-scheme porous g-C 3 N 4 /ZnFe 2 O 4 photocatalyst was synthesized, characterized and employed for N 2 photofixation. Temperature programmed desorption characterization confirmed that the adsorption capacity of nitrogen was improved for the porous structure. From N 2 photofixation evaluation experiments, the highest ammonia production efficiency can reach 147.33 μmol/L within 120 min. Photocatalytic performance is greatly improved because of the increasing of specific surface areas, enhancement of N 2 adsorption ability and synergistic effect of Z-scheme photocatalytic system. In the ammonia production process of the research, visible light is used as energy; N 2 and H 2 O are used as raw materials, which possesses a good application potential due to the advantages of being energy-efficient, environmentally friendly and pollution-free.

The Importance of Molybdenum(IV) Active Sites in Promoting Electrochemical Reduction of N2 to NH3 with MoFe Bimetallic Catalysts

Kai Li,Yan Li,Kun Jiang,Tao Li,Yun-Quan Liu,Shuirong Li,Duo Wang,Yueyuan Ye

To overcome the low faradaic efficiency (FE) of single Mo or Fe based electrocatalysts in nitrogen reduction reactions (NRR) due to the competition from the hydrogen evolution reaction (HER), a series of bimetallic MoFe compound catalysts were prepared under an NH3 atmosphere through a facile precipitation-pyrolysis method. The formed tetravalent Mo was found to be capable of inducing better electronic interactions between the surface nitrogen species and the Fe metal groups, thus improving the FE. It was demonstrated that the prepared ternary MoFe-N catalyst exhibited a remarkable FE of 33.26 % and a high NH3 yield rate of 33.31 μg h−1 mg−1cat. for NRR, which was believed to have been caused by an obvious change in the valence of Mo that resulted in a lower HER activity. X-ray photoelectron spectroscopy analysis further revealed that thermal processing under an NH3 atmosphere formed the Mo(IV) active sites in Mo–N bond, which led to a significant suppression in HER activity. Finally, through the study of the surface hydrogenation mechanism, it was concluded that the synergistic effect of the adsorbed H* and Mo active sites was the main reason for the improved performance of NRR.

ZIF-8 hollow nanotubes based mixed matrix membranes with high-speed gas transmission channel to promote CO2/N2 separation

Qiuchen Wang,Yan Dai,Xuehua Ruan,Wenji Zheng,Xiaoming Yan,Xiangcun Li,Gaohong He

Carbon nanotubes (CNTs) with 1D gas transport channel has great prospect in MMMs based CO 2 separation. However, the insufficient compatibility with polymer and inner diameter of CNTs limit further improvement of their CO 2 separation performances. In this work, the unique ZIF-8 hollow nanotubes (HNTs) were proposed to construct high-speed gas transmission channel in MMMs by a three-step method (electrospinning-calcination-hydrothermal), aiming at concurrently improving the gas permeability and selectivity. The hollow inner cavity provides long-range and low-resistance gas transmission channels to ensure high gas permeability. At the same time, the ZIF-8 crystals composing the tube wall can not only screen for gas molecules pair, but also strengthen the affinity between the filler and polymer matrix by its organic ligands, thus the gas selectivity can be raised. Compared with ZIF-8 nanoparticles and ZnO HNTs, ZIF-8 HNTs based MMMs present competitive CO 2 separation. When the loading of ZIF-8 HNTs is 5 wt%, the gas separation performance shows the best, in which the CO 2 permeability is 147 Barrer and the CO 2 /N 2 selectivity is 68, approaching to the 2008 Robeson upper limit and surpassing most reported CNTs/Pebax based membranes. Therefore, the proposed ZIF-8 HNTs are promising for MMMs based CO 2 separation.

Solvent influence on the textural properties and CO2/N2 separation performance of novel Pebax-1657/attapulgite mixed matrix membranes

Siraj Ahmad,Shaohan Lian,Yaxin Tan,Run Li,Quan Zhao,Chunfeng Song,Qingling Liu,Shijian Lu

Mixed matrix membranes (MMMs) have gained significant attention in CO 2 separation. However, the symmetrical dispersion of inorganic filler nanoparticles during MMMs fabrication is still a crucial challenge. The present work investigates the outcome of N-Methyl-2-pyrrolidone (NMP) and N-N-Dimethyl-formamide (DMF) solvents on MMMs texture, perm-selectivity and nanoparticles dispersion. Scanning electron microscopy (SEM), Fourier-transform-infrared (FTIR) and X-Ray Diffraction (XRD) analyses were also performed for membrane characterization. The MMMs fabricated with NMP solvent showed competitive CO 2 permeability (120.20 barrer) and CO 2 /N 2 selectivity (69.31) compared to the membranes prepared with DMF solvent. It has been indicated that the molar volume, boiling point and solubility parameters were significant factors in the solvent selection. Moreover, the effect of operating temperature on gas transport properties showed substantial impact in perm-selectivity, at 3 bar feed-pressure, with the temperature dropping from 40 °C to 0 °C, the CO 2 /N 2 gases selectivity increased from 69.31 to 105.50, equating to a 64.8% decrease in CO 2 permeability.

Mixed matrix membranes with intrinsic microporous/UiO-66 post-synthesis modifications with no defects for efficient CO2/N2 separation

Fei Wang,Zhe Wang,Junjian Yu,Shuai Han,Xiangwei Li,Yan Wang

Mixed matrix membranes (MMMs) based on metal–organic frameworks (MOFs) are expected to realize efficient separation of CO 2 . However, interfacial compatibility issues between MOFs and polymer matrices limit their performance. In this work, a post-synthesis modification (PSM) strategy was adopted to convert UiO-66 into porous liquids (PLs). MMMs were prepared by incorporating PLs into PIM-1 matrix. The PLs have a liquid-like behavior and can be evenly scattered in PIM-1 matrix to form an interface without defect. The SEM morphology analysis further certified that MMMs had no interface defect and PLs had brilliant compatibility with the polymer film . In addition, the CO 2 -philic ether bonds of the EO fragments enable the MMMs to have superior CO 2 selective separation. Compared with pure PIM-1, the highest CO 2 permeability was improved by 158.0 % and 62.5 % was the increase in CO 2 /N 2 selectivity, arriving at 7211.7 Barrer and 26.0, respectively. Meanwhile, the overall separation performance of MMMs for CO 2 /N 2 exceeds the 2008 Robson upper limit, showing outstanding gas separation performance.

Mechanisms of catalytic reforming of biomass pyrolysis volatiles by Ce promoted Fe–Ni/biochar under N2 and steam atmosphere

Jinchang Liu,Tao Qin,Kuo Li,Xin Chen,Qiuxiang Lu,Jin Deng,Xiaodong Luo,Shenfu Yuan

In this work, the promotion mechanism of Ce as Fe and Ni catalyst promoter for the catalytic reforming of biomass pyrolysis volatiles was investigated. Fe–Ni–Ce/biochar catalysts were prepared and evaluated for their catalytic performance under N 2 and steam atmospheres. The yield of Fe–Ni–Ce/biochar catalyzed syngas (H 2 +CO) increased from 224.36 mL/g to 1299.14 mL/g (800 °C) with the change of N 2 to steam atmosphere. The addition of Ce can introduce a large number of oxygen vacancies to the catalyst, and the increase of oxygen vacancies reduces the reaction barrier of the tar, thus promoting the catalytic activity of the catalyst. In the N 2 atmosphere, the electron transfer of Ce 3+ ⇄ Ce 4+ during catalytic process promotes the production of Fe 2+ to ensure the catalytic activity of the catalyst. In the steam atmosphere, Ni will activate the active sites in a steam atmosphere in water molecules. The activated active sites increase the catalyst activity by cyclic reaction with the oxygen vacancies introduced by Ce, resulting in a higher catalytic capacity of Fe–Ni/biochar than Fe–Ce/biochar. To provide the theoretical basis for the preparation of efficient catalysts based on Fe and Ni.

Preparation of light weight paraffin microspheres based on CO2/N2 switchable emulsion for enhancing plugging performance of drilling fluid

Meng Cai,Chenyang Xu,Yu Tan,Weichao Du,Zhiyu Huang,Cunchuan Zheng

Ultrahigh CO2/CH4 and CO2/N2 adsorption selectivities on a cost-effectively L-aspartic acid based metal-organic framework

Daofei Lv,JiaYu Chen,Kexin Yang,Houxiao Wu,Yongwei Chen,Chongxiong Duan,Ying Wu,Jing Xiao,Hongxia Xi,Zhong Li,Qibin Xia

Using porous materials to selectively adsorb CO 2 from flue gas or natural gas is a promising method for mitigating CO 2 emission and purifying methane. Here, we synthesized an L-aspartic acid based microporous metal-organic framework (MIP-202) and studied its adsorptive separation performance for CO 2 /CH 4 and CO 2 /N 2 mixtures. Results show that MIP-202 had ultrahigh CO 2 /CH 4 (72.9 and 241.5 for CO 2 /CH 4  = 50/50 and 10/90, respectively) and CO 2 /N 2 (1,950,000 and 2129.1 for CO 2 /N 2  = 50/50 and 15/85, respectively) IAST selectivities at 298 K and 100 kPa. The high selectivity was verified by the calculations of Henery’s law selectivity and breakthrough experiments. Metropolis Monte Carlo simulation calculations show that CO 2 with greater polarizability and quadruple moment tends to occupy the pore walls of large cages with higher polarity, while the less polar CH 4 or N 2 majorly being adsorbed in the pore walls of small cages with lower polarity, resulting in the ultrahigh CO 2 /CH 4 and CO 2 /N 2 separation selectivities. MIP-202 exhibits low CO 2 adsorption enthalpy (17.2–30.7 kJ/mol), superior persistent reusability after five cyclic adsorption experiments, easy desorption performance at 298 K, moderate water and moisture stability, good stability under dry and humid SO 2 atmosphere, and low ligand cost ($36/kg). MIP-202 extrudates were prepared by an extrusion molding method using hydroxypropyl cellulose (HPC) as the binder and they retained 97.35% CO 2 uptake of MIP-202 powder at room temperature and pressure. This work shows that MIP-202 is an industrially promising material for the separation of CO 2 /CH 4 and CO 2 /N 2 mixtures.

A Flower-like Bismuth Oxide as an Efficient, Durable and Selective Electrocatalyst for Artificial N2 Fixation in Ambient Condition

Bing Chang,Qin Liu,Ninghua Chen,Yingchun Yang

Graphical Catalysis in bloom : A flower-like beta bismuth oxide shows an excellent NH 3 yield of 19.92 μg h −1 mg −1 cat. and Faradaic Efficiency of 4.3 % at −0.8 V with good selectivity in 0.1 M Na 2 SO 4 solution.A flower-like bismuth oxide as an efficient, durable and selective electrocatalyst for artificial N2 fixation in ambient condition from @Chengdu_China Ammonia is a basic industrial chemical, which is widely used in industry and agriculture. Traditional Haber–Bosch N 2 fixation process is not environmentally friendly, which not only excessively consumes energy, but releases enormous amount of greenhouse gas. Electrochemical N 2 reduction is an ideal alternative to N 2 fixation, but it requires effective electrocatalyst for N 2 reduction reaction (NRR). Herein, we develop a flower-like β-Bi 2 O 3 catalyst for artificial N 2 fixation with outstanding NRR performance and selectivity in ambient condition. This β-Bi 2 O 3 nanoflower shows an excellent NH 3 yield of 19.92 μg h −1 mg −1 cat. and Faradaic Efficiency of 4.3 % at −0.8 V in 0.1 M Na 2 SO 4 solution, better than most reported NRR electrocatalysts. This electrocatalyst also exhibits superb electrochemical stability and durability.

Comparison of plasma-activated saline prepared with plasma gases with different N2/O2 ratios activated by gliding arc discharge

Pengyu Zhao,Yikang Jia,Sihong Ma,Rui Zhang,Kaiyu Li,Tianyi Song,Jianbao Zheng,Jingyao Zhang,Li Guo,Dingxin Liu,Xiaohua Wang,Mingzhe Rong

Methicillin-resistant Staphylococcus aureus (MRSA) presents a significant threat due to the multiple resistance to antibiotics, leading to severe and challenging-to-treat infections. Plasma-activated saline (PAS) prepared by plasma gases, could efficiently inactivate various pathogenic bacteria including both sensitive and antibiotic-resistant bacteria. In this study, the PAS was prepared by plasma gases with different ratios of N2 and O2 activated by gliding arc discharge. First, the gaseous reactive species in the plasma gases were compared, revealing that the highest levels of NOx including NO2 and N2O5 were generated in the gases with the N2/O2 ratios of 4:6, 5:5, and 6:4. Subsequently, the PAS prepared by the two plasma-activated gases at the N2/O2 ratios of 5:5 and 6:4 exhibited the strongest inactivation effects on both planktic MRSA and biofilms. Furthermore, the aqueous reactive species in the PAS exhibited varied change trends with the increasing N2/O2 ratios. Additionally, ultraviolet spectroscopy combined with the probe of N, N-diethyl-p-phenylenediamine was applied for the detection of O2NOO− in the PAS, and the levels of O2NOO− in the PAS were positively correlated with the inactivation effects. Moreover, the PAS induced varying levels of nitration modification on the soluble proteins in MRSA cells, which were related to the intensities of O2NOO− in the PAS. This study regulated the reactive species in the PAS through gas composition and explored the inactivation mechanism of the PAS, providing a new strategy to promote the preparation efficiency of plasma-activated solutions for biomedical applications.