分别采用尿素法和滴定共沉淀法(包括高过饱和法和低过饱和法)制备了镁铝水滑石,利用 X 射线衍射、傅里叶变换红外光谱、热重-差热分析和扫描电子显微镜等方法对镁铝水滑石进行表征,并考察了不同方法制备的镁铝水滑石催化环氧丙烷与甲醇...分别采用尿素法和滴定共沉淀法(包括高过饱和法和低过饱和法)制备了镁铝水滑石,利用 X 射线衍射、傅里叶变换红外光谱、热重-差热分析和扫描电子显微镜等方法对镁铝水滑石进行表征,并考察了不同方法制备的镁铝水滑石催化环氧丙烷与甲醇进行醚化反应合成丙二醇单甲醚的性能。表征结果显示,尿素法制备的镁铝水滑石结晶度高、晶粒规整均匀。实验结果表明,尿素法制备的镁铝水滑石的催化活性明显好于高过饱和法制备的镁铝水滑石的催化活性,前者在500℃下煅烧6～7 h 后制得的镁铝复合金属氧化物的催化活性更高,可使环氧丙烷转化率达93.8%,丙二醇单甲醚选择性达97.2%,其中丙二醇单甲伯醚的选择性达100.0%。该催化剂使用后无需处理即可重复使用,是一种稳定性好、选择性高的环境友好催化剂。展开更多
The volatile oils from \%Houttuynia cordata \%Thunb. were obtained with supercritical CO\-\{2\}, steam distillation and petroleum ether extraction and analyzed qualitatively and quantitatively by GC\|MS. The results s...The volatile oils from \%Houttuynia cordata \%Thunb. were obtained with supercritical CO\-\{2\}, steam distillation and petroleum ether extraction and analyzed qualitatively and quantitatively by GC\|MS. The results showed that the chemical constituents of the volatile oils by three different methods are very different. The extraction rates of volatile oil by above\|mentioned three extraction methods are 1.764%, 0.040% and 0.082%, respectively. The volatile oil extracted by supercritical CO\-\{2\} extraction, which the content of houttuyninum reached 14.393%, is better than those with traditional methods.展开更多
文摘分别采用尿素法和滴定共沉淀法(包括高过饱和法和低过饱和法)制备了镁铝水滑石,利用 X 射线衍射、傅里叶变换红外光谱、热重-差热分析和扫描电子显微镜等方法对镁铝水滑石进行表征,并考察了不同方法制备的镁铝水滑石催化环氧丙烷与甲醇进行醚化反应合成丙二醇单甲醚的性能。表征结果显示,尿素法制备的镁铝水滑石结晶度高、晶粒规整均匀。实验结果表明,尿素法制备的镁铝水滑石的催化活性明显好于高过饱和法制备的镁铝水滑石的催化活性,前者在500℃下煅烧6～7 h 后制得的镁铝复合金属氧化物的催化活性更高,可使环氧丙烷转化率达93.8%,丙二醇单甲醚选择性达97.2%,其中丙二醇单甲伯醚的选择性达100.0%。该催化剂使用后无需处理即可重复使用,是一种稳定性好、选择性高的环境友好催化剂。
文摘The volatile oils from \%Houttuynia cordata \%Thunb. were obtained with supercritical CO\-\{2\}, steam distillation and petroleum ether extraction and analyzed qualitatively and quantitatively by GC\|MS. The results showed that the chemical constituents of the volatile oils by three different methods are very different. The extraction rates of volatile oil by above\|mentioned three extraction methods are 1.764%, 0.040% and 0.082%, respectively. The volatile oil extracted by supercritical CO\-\{2\} extraction, which the content of houttuyninum reached 14.393%, is better than those with traditional methods.
