炭分子筛的结构和表面性质对其吸附分离CH4/N2和CO2/N2的影响

对日本Takeda(CMS-1)、Kuraray(CMS-2)和德国BF(CMS-3)3种炭分子筛(CMS)的孔结构和表面官能团进行了表征,分析了它们对CH4/N2和CO2/N2的吸附平衡和吸附动力学分离性能,以及CMS的结构与表面性质对吸附性能的影响。结果表明,CMS-1和CMS-2可实现CH4/N2的动力学分离,还可实现N2/CO2的平衡分离;CMS-3平衡分离CH4/N2和CO2/N2的效果要优于动力学分离。孔结构是影响炭分子筛分离性能的直接因素,孔径分布的差异使CMS-1和CMS-2对CH4/N2的位阻-动力学分离效应表现得更为明显;表面含氧官能团有利于提高炭分子筛的吸附分离性能。     

Room temperature CO and H2 sensing with carbon nanoparticles

We report on a shell-shaped carbon nanoparticle (SCNP)-based gas sensor that reversibly detects reducing gas molecules such as CO and H(2) at room temperature both in air and inert atmosphere. Crystalline SCNPs were synthesized by laser-assisted reactions in pure acetylene gas flow, chemically treated to obtain well-dispersed SCNPs and then patterned on a substrate by the ion-induced focusing method. Our chemically functionalized SCNP-based gas sensor works for low concentrations of CO and H(2) at room temperature even without Pd or Pt catalysts commonly used for splitting H(2) molecules into reactive H atoms, while metal oxide gas sensors and bare carbon-nanotube-based gas sensors for sensing CO and H(2) molecules can operate only at elevated temperatures. A pristine SCNP-based gas sensor was also examined to prove the role of functional groups formed on the surface of functionalized SCNPs. A pristine SCNP gas sensor showed no response to reducing gases at room temperature but a significant response at elevated temperature, indicating a different sensing mechanism from a chemically functionalized SCNP sensor.     

Quantitative CARS spectroscopy of CO2 and N2O

Experimental and theoretical investigations of the CARS spectroscopy of CO2(2v2) and N2O(v3) were carried out. The experimental spectra were measured in a heated test cell, and excellent agreement with the observed temperature dependences was obtained from numerical simulations. Assignments were made for all hot bands, and the role of collisional narrowing was quantified. Observed nonresonant susceptibility effects in pure N2O have made it possible to estimate the nonresonant background susceptibility for this molecule by using the resonant contribution as a reference calibration.     

Pore development process according to burn-off of activated carbon black with CO2 gas

Abstract

This study examined the pore development of carbon black according to burn-off (BO) ratio of carbon black activated in CO₂atmosphere. A horizontal tube furnace was charged with carbon black when the internal temperature reached 1000?°C, and activation time was adjusted to obtain BO ratios of 7.2%, 15.4%, 30.4%, 48.2%, 59.9%, and 83.2%. SEM observations showed that the primary particles of carbon black were aggregated, and varying BO ratios did not cause significant differences in shape and size. Carbon black was presumed to contain pores since the size of primary particles remained largely the same with varying BO ratios, and TEM observation revealed that pores existed within primary particles. The nitrogen adsorption isotherms were of type IV, which is characterized by a hysteresis loop. The specific surface area of raw carbon black was 61.4 m²/g, while that of BO at 83.2% increased 18.0 times to 1107.6 m²/g.     

Liquid-in-Aerogel Porous Composite Allows Efficient CO2 Capture and CO2/N2 Separation

The pursuit of efficient CO₂ capture materials remains an unmet challenge. Especially, meeting both high sorption capacity and fast uptake kinetics is an ongoing effort in the development of CO₂ sorbents. Here, a strategy to exploit liquid-in-aerogel porous composites (LIAPCs) that allow for highly effective CO₂ capture and selective CO₂/N₂ separation, is reported. Interestingly, the functional liquid tetraethylenepentamine (TEPA) is partially filled into the air pockets of SiO₂ aerogel with left permanent porosity. Notably, the confined liquid thickness is 10.9–19.5 nm, which can be vividly probed by the atomic force microscope and rationalized by tailoring the liquid composition and amount. LIAPCs achieve high affinity between the functional liquid and solid porous counterpart, good structure integrity, and robust thermal stability. LIAPCs exhibit superb CO₂ uptake capacity (5.44 mmol g⁻¹, 75 °C, and 15 vol% CO₂), fast sorption kinetics, and high amine efficiency. Furthermore, LIAPCs ensure long-term adsorption–desorption cycle stability and offer exceptional CO₂/N₂ selectivity both in dry and humid conditions, with a separation factor up to 1182.68 at a humidity of 1%. This approach offers the prospect of efficient CO₂ capture and gas separation, shedding light on new possibilities to make the next-generation sorption materials for CO₂ utilization.     

炭化温度对CO2活化PAN基活性炭纤维微结构的影响

将PAN坝氧化纤维在400℃～900℃炭化，经CO2活化得到一系列活性炭纤维，表征了其比表面、孔容和孔径分布等微结构参数，研究了炭化温度对CO2活化PAN基活性炭纤维微结构的影响。结果表明，炭化温度对活性炭纤维的比表面和孔结构有显著影响，适中的炭化温度（600℃）有利于得到高比表面积、大的孔容和孔径。     

没食子酸和硫脲合成具有N,O和S排列孔的碳骨架用于高效CO2吸附和超级电容器

"C2N"是一种很有前途的材料,在吸附、气体分离和能量存储方面具有类似碳的应用,且具有更高的极性和功能性.然而,"C2N"的可控合成仍基于复杂且不可持续的单体,阻碍了其更广泛的工业应用.本文报道了一种具有特定结构的C2(NxOySz)1碳材料,即以简单的没食子酸和硫脲为结构单元,通过简单的加成缩合制备,无需活化.所制备的碳材料具有高的N/O/S杂原子含量和大的比表面积(高达1704 m^2g^-1).此1,4-对位三掺杂孔结构使得C2(NxOySz)1具有较好的CO2吸附能力(在273 K,1 bar下为3.0 mmol g^-1)和较高的CO2/N2选择性(在273 K,CO2/N2=0.15/0.85下为47.5).此外,由于碳骨架高极性的特征,其在以离子液体为电解质的对称超级电容器中展现了高达3.5 V的电势窗口和255 F g^-1的比容量.本工作为制备新型多功能、高含量杂原子掺杂多孔材料提供了一种通用的方法.     

Advanced Ni-Nx-C single-site catalysts for CO2 electroreduction to CO based on hierarchical carbon nanocages and S-doping

Nano Research - Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced...     

Equilibrium, kinetics and mechanism of malachite green adsorption on activated carbon prepared from bamboo by K(2)CO(3) activation and subsequent gasification with CO(2)

In this work, the adsorption of malachite green (MG) was studied on activated carbon prepared from bamboo by chemical activation with K(2)CO(3) and physical activation with CO(2) (BAC). Adsorption studies were conducted in the range of 25-300 mg/L initial MG concentration and at temperature of 30 degrees C. The experimental data were analyzed by the Freundlich isotherm, the Langmuir isotherm, and the multilayer adsorption isotherm. Equilibrium data fitted well with the Langmuir model with maximum adsorption capacity of 263.58 mg/g. The rates of adsorption were found to confirm to pseudo-second-order kinetics with good correlation and the overall rate of dye uptake was found to be controlled by pore diffusion throughout the entire adsorption period. The results indicate that the BAC could be used to effectively adsorb MG from aqueous solutions.     

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

Abstract

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g^-1 at a 20 mV s^-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.     

Structural and textural effects of TeO2 added to MoO3

Morphological and microstructural characterization of the MoO₃-TeO₂ system has shown interparticle cementation of MoO₃ agglomerates by Te₂MoO₇ and second phase deposition along the cleavage planes in MoO₃ crystallites. The main morphological parameters of the binary system reflect the behaviour of the liquidus curve in the phase diagram. The size and shape of the component grains in the solid were determined. The porosity of the grains diminishes with increasing mobility of the matter during activation. Intergranular embrittlement of the solid and brittle fracture of MoO₃ crystallites due to oxygen depletion during reduction were examined by optical microscopy. The results are discussed in relation to the use of the MoO₃-TeO₂ system in oxidation catalysis.     

Biomass derived 5-hydroxymethylfurfural as carbon precursor to form hollow carbon nanospheres for CO2 capture

We prepare the hollow carbon nanospheres (HCNs) by employing SiO₂ nanospheres as hard template, 5-Hydroxymethylfurfural (HMF) as carbon precursor under hydrothermal conditions. The HCNs show uniform spherical morphology copied from SiO₂ nanospheres and exhibit large cavity, thin shell structure with the surface area of 790 m² g^?1 and pore volume of 2.23 cm³ g^?1. Owing to their large internal voids and high surface area, the HCNs exhibit a promising prospect for CO₂ capture with the capacity of 3.04 mmol g^?1 at 1.0 bar and 298 K, as well as good recyclability for CO₂ after ten adsorption-desorption cycles.     

N2 and CO vibrational CARS and H2 rotational CARS spectroscopy of CH4/N2O flames

Broadband CARS spectra of N2 and CO have been obtained from the postflame gases of rich CH4/N2O flames using the nonplanar BOXCARS technique. The temperature and concentration of both N2 and CO in these flames were estimated from CARS spectra with the aid of model calculations and agreed with standard thermochemical predictions. In addition, several pure rotational H2 CARS transitions, certain of which had been previously unobserved, were seen in several spectral regions, most notably in both the CO and NO CARS regions. These observations are important in future modeling of CARS data.     

VLE data for CO2-CF2Cl2, N2-CO2, N2-CF2Cl2 and N2-CO2-CF2Cl

Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state.     

A comparison of CO2, N2, and Ar to maximize plant nutrient retention in biochar

Clean Technologies and Environmental Policy - Nutrient-rich biochar improves soil significantly; however, the nutrients nitrogen (N), phosphorous (P), and potassium (K) can be easily lost during...     

Morphology and N2 permeability of multi-wall carbon nanotube--Teflon membranes

We prepared buckypapers with surface densities in the 1.13-5.66 mg x cm(-2) range by filtering multi-wall carbon nanotube (MWCNT) suspensions in acetyl-acetone (acac) and dimethylformamide (DMF) through 0.45 microm nylon filters. Filtration curves were evaluated using the Carman equation. The average resistance of the filter itself was found to be Rm = 3.79 x 10(10) m(-1) for acac and 8.49 x 10(10) m(-1) for DMF The specific resistance a of the filter cakes decreased with increasing film surface density from 16.1 x 10(12) m x kg(-1) (for the 1.13 mg x cm(-2) film from DMF) to 4.38 x 10(12) m x kg(-1) (for the 5.66 mg x cm(-2) film from DMF). The effective diffusivity of N2 at 298 K and a pressure difference of 10 mbar was also determined for all membranes and found to fall into the 1.14 x 10(-9)-3.74 x 10(-9) m2 x s(-1) range. Both the porosity and the tortuosity of buckypapers increased with their thickness. An approx. 5 microm thick Teflon (PTFE) coating was applied to the MWCNT membranes by pulsed laser deposition. The gas permeability of the MWCNT-PTFE membranes matches that of the uncoated nanotube films. This observation is an agreement with our SEM and AFM data on porous coating morphology.     

Solid Ar, N2, CO, and O2 in Nanopores

Molecular solids enclosed in pores with diameters in the nm-range are a research field which attracts growing interest. The major questions asked in this context are: what is the structure and the dynamics? How are phase and glass transitions modified by the geometrical constraint? In this contribution we present structural information, by x-ray diffraction measurements, as well as thermodynamic characterization, by vapor pressure and heat capacity measurements, on Ar, which is usually considered the simplest of all condensates, and on the small diatomic molecules N₂, C0, O₂ in porous glasses with average pore diameters from 50 to 130Å.     

Recovering CO2 and N2 from combustion exhaust gas use membrane technology

Enerfex, Inc. is a start-up company actively involved in various process development and design activities. Most of Enerfex's processes involve gas separation membranes. Enerfex holds the patent on the Cryocogen process and apparatus that allows the application of membranes to combustion exhaust gas. Cryocogen technology is the application of gas separation membranes to combustion exhaust gas to simultaneously produce high purity carbon dioxide and nitrogen. The system is described here.