本文以NaH_(2)PO_(2)·H_(2)O和L-抗坏血酸为还原剂,以不同脱乙酰度壳聚糖(CHS)为稳定剂,制备氧化石墨烯(GO)负载纳米铜(CuNPs)复合物(GO-CuNPs-CHS)。利用紫外-可见光谱(UV-vis)研究了壳聚糖脱乙酰度对GO-CuNPs-CHS中CuNPs尺寸形...本文以NaH_(2)PO_(2)·H_(2)O和L-抗坏血酸为还原剂,以不同脱乙酰度壳聚糖(CHS)为稳定剂,制备氧化石墨烯(GO)负载纳米铜(CuNPs)复合物(GO-CuNPs-CHS)。利用紫外-可见光谱(UV-vis)研究了壳聚糖脱乙酰度对GO-CuNPs-CHS中CuNPs尺寸形貌的影响。利用傅里叶变换红外光谱(FT-IR)、透射电子显微镜(TEM)和X射线衍射(XRD)对GO-CuNPs-CHS进行了表征,探究了其对4-硝基苯酚(4-NP)的氢转移催化性能。结果表明,使用低脱乙酰度壳聚糖为稳定剂有利于制备小粒径、近球形的CuNPs。以脱乙酰度为52.3%的壳聚糖为稳定剂制备的GO-CuNPs-N3中CuNPs的平均粒径为(9.0±1.3)nm。GO-CuNPs-CHS的氢转移催化性能随着壳聚糖脱乙酰度的降低而逐渐增强,以GO-CuNPs-N3为催化剂时仅需8 min 4-NP转化率可达到98.4%,反应速率常数可达0.6868 min^(-1),反应活化能Ea为40.5 kJ·mol^(-1)。展开更多
Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its ...Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its active sites after adsorbing water, but the remaining was not affected. The reductions of aldehydes and ketones, when promoted by Rb_3PO_4, were allowed at room temperature. The activities of substrates at room temperature followed a descending order of 2,6-dichlorobenzaldehyde> 4-bromobenzaldehyde>benzaldehyde>acetophenone>anisaldehyde>butanone. A new catalytic cycle postulating a six-membered cyclic transition state for the reductions of aldehydes and ketones was proposed. These results exploited the catalytic usage of Rb_3PO_4 and worth in industrial application.展开更多
文摘本文以NaH_(2)PO_(2)·H_(2)O和L-抗坏血酸为还原剂,以不同脱乙酰度壳聚糖(CHS)为稳定剂,制备氧化石墨烯(GO)负载纳米铜(CuNPs)复合物(GO-CuNPs-CHS)。利用紫外-可见光谱(UV-vis)研究了壳聚糖脱乙酰度对GO-CuNPs-CHS中CuNPs尺寸形貌的影响。利用傅里叶变换红外光谱(FT-IR)、透射电子显微镜(TEM)和X射线衍射(XRD)对GO-CuNPs-CHS进行了表征,探究了其对4-硝基苯酚(4-NP)的氢转移催化性能。结果表明,使用低脱乙酰度壳聚糖为稳定剂有利于制备小粒径、近球形的CuNPs。以脱乙酰度为52.3%的壳聚糖为稳定剂制备的GO-CuNPs-N3中CuNPs的平均粒径为(9.0±1.3)nm。GO-CuNPs-CHS的氢转移催化性能随着壳聚糖脱乙酰度的降低而逐渐增强,以GO-CuNPs-N3为催化剂时仅需8 min 4-NP转化率可达到98.4%,反应速率常数可达0.6868 min^(-1),反应活化能Ea为40.5 kJ·mol^(-1)。
基金Project(21576074)supported by the National Natural Science Foundation of China
文摘Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its active sites after adsorbing water, but the remaining was not affected. The reductions of aldehydes and ketones, when promoted by Rb_3PO_4, were allowed at room temperature. The activities of substrates at room temperature followed a descending order of 2,6-dichlorobenzaldehyde> 4-bromobenzaldehyde>benzaldehyde>acetophenone>anisaldehyde>butanone. A new catalytic cycle postulating a six-membered cyclic transition state for the reductions of aldehydes and ketones was proposed. These results exploited the catalytic usage of Rb_3PO_4 and worth in industrial application.
