分子筛杂多酸复合物的制备及其在催化反应中应用的研究进展

对浸渍法和原位合成法制备分子筛杂多酸复合物及其在催化反应中的应用进行了综述。浸渍法制备的分子筛杂多酸复合物中杂多酸在分子筛内表面高度分散,其酸强度略有降低,可作为烷基化、异构化、酯化、裂解、聚合等诸多反应的催化剂,催化活性高、选择性好,但需解决杂多酸溶脱的问题;原位合成法制备分子筛杂多酸复合物中杂多酸可有效地固定在分子筛中,目前的研究仅处于初级阶段,需对其合成机理、催化活性、多品种合成等进一步研究。     

Effects of High-Pressure Pretreatment and Calcium Soaking on the Texture Degradation Kinetics of Carrots during Thermal Processing

ABSTRACT: Carrots ( Daucus carota ) pretreated under different high-pressure conditions were thermally processed at temperatures in the range of 90°C to 110°C. Texture degradation (hardness) was monitored objectively using a texture analyzer. For a given thermal treatment, the rate constant (k-value) decreased with increasing pretreatment pressure. A high-pressure pretreatment (200 to 500 MPa) at 60°C for 15 min resulted in a more pronounced texture improvement compared with the same pretreatment at 20°C and 40°C, respectively. Calcium impregnation conferred more beneficial effects when applied immediately after the high-pressure pretreat-ment. The observed changes in texture characteristics were associated with the degree of methylation of carrot pectins, which is dependent on pectinmethylesterase (PME) activity.     

制备方法对镍催化剂重整活性的影响

利用XRD ,TPR和活性评价等手段 ,研究了NiO/γ Al2 O3 催化剂的制备方法对CH4与CO2 转化制合成气催化活性的影响。在本实验条件下 ,采用浸渍法和焙烧温度为 4 0 0℃制备的NiO/γ Al2 O3 (NiO质量分数w =0 113)催化剂 ,在反应温度为 75 0℃和空速为 2 5 0 0h 1下 ,对CH4和CO2 重整反应会显示良好的催化活性。本文还对催化剂抗积炭性能作了初步讨论。     

Enhanced cycle stability of spinel LiMn2O4 by a melting impregnation method

Spinel LiMn₂O₄ particles were successfully coated with CuO, MgO, ZnO, Al₂O₃ and CeO₂ by a melting impregnation method. Except for the CeO₂-coated sample, all the others exhibit better cycling stability than bare LiMn₂O₄ at room temperature and at 55°C. Among these samples, the ZnO-coated sample shows the best cycling stability. A capacity of 100 mA·h·g⁻¹ still remained after 100 cycles at 55°C while the bare LiMn₂O₄ retains a capacity of only 80 mA·h·g⁻¹ after the same number of cycles. The improvement in the cycling stability is attributed to the suppressed Mn dissolution caused by HF.     

Some properties of polypyrrole-paper composites

It is shown that porous materials such as paper can be impregnated with a conducting polymer by first soaking the paper in a solution of metal salt which acts as an initiator for subsequent polymerization. By using this procedure the conductivity of filter paper can be raised to as high as 2 (ohm cm)⁻¹ for an FeCl₃/H₂0/pyrrole combination. The role of the metal ion is discussea and it is pointed out that the impregnated papers exhibit both ionic and electronic conductivity. The polypyrrole paper composites exhibit some properties similar to carbon black-polymer composites.     

用于悬浮浸渗法制备短GF/PP复合材料的PVA型悬浮液稳定性的研究

发展了一种用悬浮浸渗法制备短玻璃纤维增强聚丙烯复合材料的新工艺方法。研究了以 PVA为稳定剂的悬浮液中各组分对悬浮液稳定性影响。给出了描述稳定剂浓度与悬浮液分层时间之间函数关系的经验公式。     

Effect of Vacuum Impregnation-Dehydration on the Mechanical Properties of Apples

The effect of sucrose solution concentration and vacuum/atmospheric pressure periods on the mechanical properties of apples (Gala var.) was studied through a stress relaxation test. The empiric model proposed by Peleg was used to fit the curves and the parameters a (level of relaxation) and b (relaxation rate) were evaluated. The experimental results obtained in this study showed that vacuum impregnation conditions had a great influence on the final mechanical properties of the apples. The Peleg model fitted well the data from the stress relaxation curves and may be useful for assessing sample deformation resulting from the vacuum impregnation process.     

常温下真空浸渍制备的LMC/S复合材料

在常温下,采用真空浸渍的方法,将单质硫(S)填充在大介孔炭(LMC)的孔中,制备出LMC/S复合材料。用SEM、XRD和氮吸附等方法对复合材料进行了分析,用恒流放电、循环伏安等方法对复合材料的电化学性能进行了测试。填充在LMC中的硫高度分散,复合材料的循环性能和硫的利用率都较高。当电流密度为0.4 mA/cm2时,LMC/S电极中硫的首次放电比容量达1 215.5 mAh/g,第50次循环的可逆比容量仍有535.3 mAh/g。