Modification of cellulose acetate nanofibers with PVP/Ag addition

In this work cellulose acetate (CA) nanostructures were synthesized using electrospinning process. Silver nanoparticles (Ag NPs) were synthesized using silver nitrate as the starting precursor, ethanol as solvent and polyvinyl pyrolydone (PVP) as capping agent. The Ag NPs were added to the cellulose acetate (CA) nanostructures before and after CA electrospinning. The obtained CA and Ag-CA composite were characterized by various techniques such as, Fourier Transform Infrared (FTIR) spectroscopy, Raman Spectroscopy, Scanning electron microscopy (SEM) and Differential Scanning Calorimetry (DSC). It was found that Ag NPs can be effectively coated on or embedded into the electrospun CA and the PVP can lead to noticeable change in morphology and structure.     

Engineering Silver-Enriched Copper Core-Shell Electrocatalysts to Enhance the Production of Ethylene and C2+ Chemicals from Carbon Dioxide at Low Cell Potentials

Copper catalysts are widely studied for the electroreduction of carbon dioxide (CO₂) to value-added hydrocarbon products. Controlling the surface composition of copper nanomaterials may provide the electronic and structural properties necessary for carbon-carbon coupling, thus increasing the Faradaic efficiency (FE) towards ethylene and other multi-carbon (C₂₊) products. Synthesis and catalytic study of silver-coated copper nanoparticles (Cu@Ag NPs) for the reduction of CO₂ are presented. Bimetallic CuAg NPs are typically difficult to produce due to the bulk immiscibility between these two metals. Slow injection of the silver precursor, concentrations of organic capping agents, and gas environment proved critical to control the size and metal distribution of the Cu@Ag NPs. The optimized Cu@Ag electrocatalyst exhibited a very low onset cell potential of −2.25 V for ethylene formation, reaching a FE towards C₂₊ products (FE_C2+) of 43% at −2.50 V, which is 1.0 V lower than a reference Cu catalyst to reach a similar FE_C2+. The high ethylene formation at low potentials is attributed to enhanced C C coupling on the Ag enriched shell of the Cu@Ag electrocatalysts. This study offers a new catalyst design towards increasing the efficiency for the electroreduction of CO₂ to value-added chemicals.     

Efficient,Selective, and Reversible SO2 Capture with Highly Crosslinked Ionic Microgels via a Selective Swelling Mechanism

SO₂ capture through physisorption is a promising environmental benign technology to eliminate the emission of SO₂. However, designing an efficient adsorption material with high capacity and selectivity of SO₂ as well as excellent reversibility remains challenging. Here, a class of highly crosslinked nonporous poly(ionic liquid)s (PILs) xerogels is prepared with high ionic density by photopolymerization of Gemini IL monomers and a microfluidic technology is further explored to prepare the corresponding monodisperse PIL microgels with uniform and controllable sizes at the diameter range from 43 to 250 µm. This kind of novel dense nonporous ionic xerogels/microgels completely exclude the adsorption of common gases (CO₂, CH₄, etc.), but exhibit very high SO₂ adsorption capacity (498 mg g^?1) via selective swelling mechanism. Unprecedented SO₂/CO₂ and SO₂/CH₄ uptake selectivities with the value up to 614 and 1992, respectively, are achieved. The selective swelling mechanism is validated by optical microscope and differential scanning calorimetry measurements. More importantly, these kinds of xerogels show excellent reversibility in adsorption–desorption cycles. Column breakthrough experiments confirm the excellent performance of these PIL xerogels in SO₂ capture. This work demonstrates that designing a nonporous material that has specific swelling interactions with certain molecules can be an effective strategy for realizing extremely high selectivity.     

蒙脱石复合贮热材料的制备

蒙脱石是一种层状硅酸盐矿物。本文利用季铵盐与蒙脱石进行阳离子交换反应合成有机蒙脱石 ,然后 ,采用熔融法制备新戊二醇 (NPG)与蒙脱石的复合贮热材料 ,并用 X射线衍射、IR和 DSC等手段研究了复合材料的结构和性能。     

DCC-plus技术及其产品灵活性

中国石化石油化工科学研究院开发的增强型催化裂解(DCC-plus)技术采用多反应区组合反应器型式,不仅能够实现不同反应区的分区精准控制,而且耦合了C₄馏分和轻汽油馏分循环裂化技术,强化了重质原料油的一次裂化反应和汽油馏分的二次裂化反应,在大幅度提高丙烯产率的同时可以降低干气和焦炭产率。DCC-plus技术已经在多个炼油厂得到了工业应用,其中大榭石化的2.2 Mt/a DCC-plus装置的乙烯和丙烯产率分别可以达到5.16%和21.55%。DCC-plus技术具有很好的产品灵活性,通过工艺操作参数和催化剂配方的调整,可以实现不同目标产品的灵活切换,为我国炼油行业的转型升级提供了一条可靠的途径。     

PEG/IPDI与PEG/TDI固化反应动力学研究

用二正丁胺滴定法对聚乙二醇(PEG)/甲苯二异氰酸酯(TDI)和PEG/异氟尔酮二异氰酸酯(IPDI)反应体系分别进行了研究,得到了相应体系在不同温度下的反应速率常数和活化能;并探讨了PEG分子量、固化剂的活性、燃烧催化剂和温度等因素对固化反应动力学参数和活化能的影响。结果表明:异氰酸酯和PEG反应为二级反应;PEG/IPDI和PEG/TDI体系固化反应的活化能分别为46.89kJ.mol-1和41.12kJ.mol-1;两体系的反应速率常数随着固化剂的活性和温度的增加而变大。不同活性的固化剂和燃烧催化剂虽影响两体系的固化反应速率常数,但不影响反应级数。     

玻璃纤维增强TPVA/PBST复合材料的制备及性能

研究了短玻璃纤维(SGF)增强热塑性聚乙烯醇(TPVA)/聚丁二酸对苯二甲酸丁二醇酯(PBST)复合材料的改性机理、复合材料的热学及力学性能,并对复合材料中玻璃纤维(GF)的尺寸及分布进行了分析.实验结果表明,马来酸酐接枝乙烯-乙酸乙烯酯共聚物(EVA-g-MAH)与硅烷偶联剂能够有效增容TPVA/PBST复合材料,引...     

无机盐与硫化氢对天然气三甘醇脱水的影响

目的 探究无机盐与硫化氢(H₂S)对天然气三甘醇脱水的影响规律。方法 综述了无机盐与硫化氢在三甘醇脱水性、再生性、流变性、发泡消泡性能以及腐蚀性等方面对天然气三甘醇脱水的影响。结果 随着三甘醇溶液中无机盐和硫化氢的富集,三甘醇溶液流变性下降,易发泡且消泡困难,还会与三甘醇发生反应,引起三甘醇变质,脱水效果明显下降。含硫化氢的三甘醇溶液具有腐蚀性,腐蚀管道和设备后产生铁离子,进一步影响三甘醇的性能。结论 由于三甘醇自身的化学结构易受破坏以及外界高温环境,使得三甘醇易发生变质。在天然气采用MDEA进行脱硫时,需要控制MDEA的添加量。建议：(1)深入研究三甘醇变质机理;(2)建立各无机盐离子与硫化氢对三甘醇溶液脱水性能影响的模型;(3)建立统一的三甘醇溶液废弃标准。     

Magnetic Memory Effect of Nanocomposites

The magnetic memory effect (MME) is the ability of magneto‐sensitive materials to remember the magnetic field strength (H_def), at which they were deformed recently. They respond close to H_def either by recovering their initial shape at a switching magnetic field strength H_sw under stress‐free conditions or by building up stress with a peak maximum at H_σ,max under constant strain conditions. This paper explores whether such a MME can be created for polymer‐based nanocomposites. The concept is based on temperature‐memory polymers (TMP) as matrix, in which silica coated iron(III)oxide nanoparticles (mNP) are dispersed. The MME was explored in a cyclic magneto‐mechanical test, in which the nanocomposite sample was elongated to ?_m while being exposed to an alternating magnetic field at H_def. The magnetic memory was read out by determining H_σ,max or H_sw. A linear correlation between H_σ,max (or H_sw) and H_def in a range from 15 to 23 kA m^?1 at a fixed frequency of f = 258 kHz is observed and demonstrates the excellent magnetic memory properties of the investigated nanocomposites containing either crystallizable or amorphous, vitrifiable domains as controlling units. The deformation ?m at H_def can be fixed with an accuracy of more than 72% and the initial shape can be recovered almost completely by more than 86%. The MME allows the design of magnetically programmable devices such as switches or mechanical manipulators.