Water is the most abundant compound inherently existing in bio-oils. Thus understanding the role of water within bio-oils upgrading process is essential for future engineering scale-up design. In this study, furfural ...Water is the most abundant compound inherently existing in bio-oils. Thus understanding the role of water within bio-oils upgrading process is essential for future engineering scale-up design. In this study, furfural was chosen as bio-oils model compound, and the catalytic hydrogenation of furfural over commercial 5%, Ru/C catalyst was firstly investigated in a series of gradient variable water/ethanol mixture solvents. Water had a significant effect on the distribution of product yields. The dominant reaction pathways varied with the water contents in the water/ethanol mixture solvents. Typically, when ethanol was used as the solvent, the main products were obtained by the hydrogenation of carbonyl group or furan ring. When pure water was used as the solvent, the rearrangement reaction of furfural to cyclopentanone should be selectively promoted theoretically. However, serious polymerization and resinification were observed herein in catalytic hydrogenation system of pure water. The catalyst surface was modified by the water-insoluble polymers, and consequently, a relative low yield of cyclopentanone was obtained. A plausible multiple competitive reaction mechanism between polymerization reaction and the hydrogenation of furfural was suggested in this study. Characterizations(TG,FT-IR,SEM)were employed to analyze and explain our experiments.展开更多
文摘目的探讨可变剂量(Variable Dose,VD)技术在下肢全长摄影中的应用价值。方法筛选2021年1—4月间行双下肢全长摄影检查患者80例为研究对象。根据剂量模式将受检者分为研究组A和对照组B,各40人,A组、B组分别采用VD模式和不变剂量模式进行全景摄影。A组随机对20例采用普通狭缝拼接摄影(A1);余采用高清狭缝拼接摄影(A2);B组随机对20例分别采用普通狭缝拼接摄影(B1);余采用高清狭缝拼接摄影(B2)。采用3分法评价图像质量,记录总剂量面积乘积(Dose Area Product,DAP)和总空气比释动能(Air Kerma,AK),每组数据取均值进行对比。分别对每两组患者的图像质量和辐射剂量进行比较。结果A1、B1两组总DAP值比较,差异有统计学意义(P<0.05),A1、B1两组总AK值比较,差异有统计学意义(P<0.05);A2、B2两组总DAP值比较,差异有统计学意义(P<0.05);A2、B2两组总AK值比较,差异有统计学意义(P<0.05)。A1、B1两组与A2、B2两图像质量评分比较,差异均无统计学意义(P>0.05)。结论VD狭缝拼接摄影技术在图像质量无明显差异的情况下,可显著降低患者辐射剂量,具有临床应用及推广价值。
基金Supported by the National Basic Research Program of China("973"Program,2014CB260408)Tianjin Natural Science Foundation(No.13JCYBJC19300)
文摘Water is the most abundant compound inherently existing in bio-oils. Thus understanding the role of water within bio-oils upgrading process is essential for future engineering scale-up design. In this study, furfural was chosen as bio-oils model compound, and the catalytic hydrogenation of furfural over commercial 5%, Ru/C catalyst was firstly investigated in a series of gradient variable water/ethanol mixture solvents. Water had a significant effect on the distribution of product yields. The dominant reaction pathways varied with the water contents in the water/ethanol mixture solvents. Typically, when ethanol was used as the solvent, the main products were obtained by the hydrogenation of carbonyl group or furan ring. When pure water was used as the solvent, the rearrangement reaction of furfural to cyclopentanone should be selectively promoted theoretically. However, serious polymerization and resinification were observed herein in catalytic hydrogenation system of pure water. The catalyst surface was modified by the water-insoluble polymers, and consequently, a relative low yield of cyclopentanone was obtained. A plausible multiple competitive reaction mechanism between polymerization reaction and the hydrogenation of furfural was suggested in this study. Characterizations(TG,FT-IR,SEM)were employed to analyze and explain our experiments.
