Enhancing resistance of carbon deposition and reaction stability over nickel loaded fibrous silica-alumina (Ni/FSA) for dry reforming of methane

Syngas production from the dry reforming of methane is now the most extensively utilized method for removing massive amounts of greenhouse emissions. Effective solutions towards the utilization of greenhouse gases such as CO₂ and CH₄ are scarce, except for power generation in the energy sector, which is a major source of CO₂. Herein, dry reforming of methane was experimented for the first time using an effective catalytic system composed of 5% Ni fibrous silica-alumina (FSA) that was successfully fabricated using a hydrothermal method. The characterization results from XRD, FESEM mapping, TEM, BET,XRF, FTIR, H₂-TPR, TGA/DTA, and Raman spectra demonstrated that Ni/FSA is composed of orderly Ni dispersion, small particles of Ni, robust basic sites, and high oxygen vacancies which enhanced the catalytic efficiency. The synthesized Ni/FSA also reduced coke formation and had long-term stability with no evidence of inactivation during and after the catalytic cycles. The superior activity of Ni/FSA was manifested in the high conversion rates of CH₄ and CO₂ at 97% and 92% respectively, with a H₂:CO ratio of ≈ 1. The stability of Ni/FSA was also sustained over 30 h of operation at 800 °C. The findings of the Raman, TEM, and TGA/DTA tests revealed that the spent Ni/FSA catalysts did not exhibit graphitic carbon or metal sintering in significant amounts when compared to commercial Ni–Si/Al catalysts.     

锚固处理对SiO_2/CE复合材料静态力学性能的影响

采用偶联剂SEA-171对纳米SiO2表面进行了处理(M-1),再由偶氮异丁腈对M-1进行锚固表面处理(M-2),对产物进行了红外,元素分析和热失重分析。研究了上述2种纳米SiO2的含量对其氰酸酯树脂复合材料静态力学性能的影响,并采用扫描电镜和透射电镜分析研究了材料界面结构特征,探讨了其作用机理。结果表明,当M-1的添加质量分数为3%时,复合材料的冲击强度增长61.9%;弯曲强度增长44.2%,添加4%M-2时,增幅分别为89.0%和53.8%。经锚固处理后,纳米SiO2颗粒团聚程度减小,在高分子有机相中的分散更加均匀。     

Study on Ce-doped Nonstoichiometric Nano-silica/PSF Composite Membrane for Separation of Chinese Yam Polysaccharide

Abstract

In order to enhance the anti-fouling ability and separation efficiency of polysulfone (PSF) membrane during separating of Chinese yam polysaccharides, a novel composite membrane was prepared through a sol-gel process after adding Ce-doped nonstoichiometric nano-silica with higher activity and hydrophilic property to the porous matrix of PSF. Ce-doped nonstoichiometric nano-silica was synthesized by doping the rare earth Ce element. Novel composite membranes and ordinary membranes without doping Ce-doped nonstoichiometric nanosilica were used to separate Chinese yam polysaccharides while the content of polysaccharide was tested. The results designate that the content of polysaccharide separated by composite membrane which reached 78.3% was higher than that of polysaccharide separated by ordinary membrane which reached 46.7%. The flux of the composite membrane increased with increasing of operation pressure. With the temperature rising, the polysaccharide solution flux of composite membrane ascended from 289 L/(m²h) to 312 L/(m²h). The flux of the composite membrane was kept at a high value for 25 h before reaching a steady state (243 L/(m²h)), which was higher than the stable flux of ordinary membrane (160 L/(m²h)). After the composite membrane was washed for six times, its flux still reached 90% of initial value. The experiment data indicate that the anti-fouling ability and hydrophilic property of composite membrane were significantly enhanced. Therefore, Chinese yam polysaccharides can be efficiently separated by the novel composite membrane.     

PMMA-b-PHEMA/纳米SiO2复合材料的制备与性能

采用分步法合成了聚甲基丙烯酸甲酯-b-聚甲基丙烯酸羟乙酯(PMMA-b-PHEMA)嵌段共聚物。采用硅烷偶联剂KH-570对纳米二氧化硅进行表面改性,然后在四氢呋喃(THF)中制备出(PMMA-b-PHEMA)/纳米SiO2复合材料。通过红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、扫描电镜(SEM)分析了复合材料的组成与结构,通过热重分析(TGA)、差热分析法(DTA)研究了SiO2质量分数对复合材料热性能的影响。结果表明,所制备的(PMMA-b-PHEMA)/纳米SiO2复合材料中嵌段共聚物与无机纳米SiO2相容性良好,复合材料的热稳定性优于嵌段共聚物PMMA-b-PHEMA。     

含纳米SiO2锂基润滑脂流变学与摩擦学性能

利用SG65三辊研磨机制备了含不同粒径和不同质量浓度SiO₂纳米颗粒的锂基润滑脂. 通过MRS-1J机械式四球长时抗磨损试验机及安东帕MCR301流变仪研究了SiO₂纳米颗粒作润滑脂添加剂的摩擦学性能和流变学性能. 结果表明,SiO₂纳米颗粒粒径为30 nm、质量浓度为4%时润滑脂摩擦学系数最小,抗磨减摩性能最好. 在中低剪切速率下对流变试验数据进行拟合,提出了含纳米颗粒质量浓度参数的润滑脂改进型流变模型. SiO₂纳米添加剂可改善锂基润滑脂触变性,提高润滑脂抗剪切能力和热稳定性能.     

掺纳米硅粉和掺粉煤灰防火耐热混凝土性能的比较

对掺纳米硅粉和掺粉煤灰防火耐热混凝土性能进行了研究.测试了高温煅烧前后混凝土试件的尺寸、质量及耐压强度,试验结果表明,掺入纳米硅粉能显著降低混凝土的高温收缩变形值及高温质量损失率,能显著提高混凝土的烧后耐压强度及相对耐压强度.掺5％纳米硅粉的混凝土与掺25％粉煤灰的混凝土相比,其高温收缩变形值约降低15.2％,质量损失程度约降低10.2％,烧后耐压强度约提高25.4％,而与不掺纳米硅粉的混凝土相比,其烧后耐压强度提高41.4％ ～ 90.5％,试验表明纳米硅粉比粉煤灰更能改善混凝土内部的微结构,提高混凝土的高温耐热性能.     

无皂沉淀法制备聚乙烯醇缩丁醛

通过无皂沉淀法,以纳米二氧化硅替代表面活性剂,将丁醛通过高压均质机分散到聚乙烯醇水溶液中,制备了缩醛基含量75%以上,溶液黏度与市售树脂相当的聚乙烯醇缩丁醛(PVB)树脂(平均聚合度1700)。所得的PVB树脂粉末由粒径小于10μm的原始颗粒团聚而成,证明反应是在微小体积内进行;纳米二氧化硅黏附在颗粒的表面,起到了很好的物理隔离的作用,有效的抑制了PVB的团聚。无皂沉淀法减少了树脂洗涤用水的消耗,并且有利于树脂品质的提高。优化的反应条件为:聚乙烯醇和丁醛质量比为1∶(0.60~0.65),反应起始温度20℃,梯度升温速度为5℃/30min,pH=1.3,分散剂纳米二氧化硅用量为体系的0.07%。     

白藜芦醇纳米二氧化硅表面分子印迹聚合物的制备及吸附特性

采用分子印迹技术,以反式白藜芦醇为模板分子,通过溶胶-凝胶法制备白藜芦醇纳米二氧化硅表面分子印迹聚合物(MIPs-Res),并通过静态吸附平衡实验、扫描电镜、红外光谱研究聚合物的吸附特性、结构及形貌特征。结果表明：与化学组成相同的非印迹聚合物(NIPs)相比,MIPs-Res对白藜芦醇具有较高的选择性和吸附性,该聚合物最佳吸附溶剂为氯仿-乙腈(体积比1:11),吸附温度为室温25℃,吸附平衡常数Kd1为3.42mg/L,最大表观结合量Qmax1为11.20mg/g,3h内达到吸附平衡,将该印迹聚合物用于选择性分离/富集白藜芦醇是可行的。     

纳米二氧化硅改性聚丙烯复合材料研究进展

介绍了近年来纳米二氧化硅改性聚丙烯复合材料的研究进展,综述了纳米二氧化硅粒子表面处理和添加增容剂改性的主要方法,阐述了纳米粒子与聚合物相容性的提高对复合材料各项性能的改善作用,并讨论了不同纳米二氧化硅颗粒结构对复合材料性能的影响,最后展望了其在改善聚合物渗透性、阻燃性、导电性等方面的发展前景。     

煤灰酸浸渣碳分法制备纳米白炭黑性能研究

为实现煤灰渣资源化高效利用,本文以煤灰酸浸提铝后的高硅残渣经焙烧制得的Na₂SiO₃溶液为原料,采用碳分法制取高附加值的纳米白炭黑。通过单因素法,采用比表面积测试法（BET）、邻苯二甲酸二丁酯（DBP）吸油值测定、透射电镜（TEM）、红外光谱分析（FTIR）、X衍射分析（XRD）等分析表征手段,研究不同的实验条件对制得的纳米白炭黑性能的影响,得到碳分法制取纳米白炭黑的最佳实验工况。实验表明,当硅酸钠溶液中SiO₂质量分数为2%、CO₂通气速率为0.5/min、溶液反应温度为65~75℃、反应终点pH为8时,通过陈化、过滤、洗涤、共沸蒸馏、烘干后,可得到粒径为20~40nm、DBP吸油值为3.10mL/g、比表面积为250m²/g、质量分数91.88%的性能最优纳米白炭黑。