本文研究了2-丙醇和1,1,1-三氟-2-丙醇在Ni(100)表面解离的可能微观反应机理,使用完全线性同步和二次同步变换(complete LST/QST)方法确定解离反应的过渡态.采用基于第一性原理的密度泛函理论与周期平板模型相结合的方法,优化了2-丙醇和...本文研究了2-丙醇和1,1,1-三氟-2-丙醇在Ni(100)表面解离的可能微观反应机理,使用完全线性同步和二次同步变换(complete LST/QST)方法确定解离反应的过渡态.采用基于第一性原理的密度泛函理论与周期平板模型相结合的方法,优化了2-丙醇和1,1,1-三氟-2-丙醇裂解反应过程各物种在Ni(100)表面的top,hollow和bridge位的吸附模型,计算了能量,并对布局电荷进行了分析,得到了各物种的有利吸附位.结果表明:2-丙醇和1,1,1-三氟-2-丙醇在Ni(100)表面都存在β-H和γ-H两个平行竞争的解离过程,其中2-丙醇在Ni(100)表面β-H解离的速控步骤活化能为64.7 k J·mol-1猯,而γ-H解离速控步骤活化能为233.1 k J·mol-1猯,故β-H解离过程占优势,主要产物是CH3COCH3;相反,1,1,1-三氟-2-丙醇在Ni(100)表面β-H解离的速控步骤活化能为257.1 k J·mol-1猯,而γ-H解离速控步骤活化能为148.1 k J·mol-1猯,故γ-H解离过程占优势,主要产物是CF3CH=CH2.由此说明,电负性更大的氟原子取代2-丙醇中的氢原子之后,2-丙醇在Ni表面的解离机理发生了改变.理论预测结果与实验结论一致.展开更多
本文研究了Fe(Ⅲ),Co(Ⅱ),Ni(Ⅱ.),Cu(Ⅱ)在5-Br-PADAP-TritonX-100体系中的析相显色反应。利用该体系具有一定选择性和富集、分离的特点,采用多波长K系数法,根据公式ΔA=A-sum from i=1 to n K_iA_i=KC,在一个测定波长和与干扰组分个...本文研究了Fe(Ⅲ),Co(Ⅱ),Ni(Ⅱ.),Cu(Ⅱ)在5-Br-PADAP-TritonX-100体系中的析相显色反应。利用该体系具有一定选择性和富集、分离的特点,采用多波长K系数法,根据公式ΔA=A-sum from i=1 to n K_iA_i=KC,在一个测定波长和与干扰组分个数相等的参比波长下,测定混合多组分体系的吸光度。求得相应K值后,再计算各待测组分含量。本法用于测定人发中微量铁、钴、镍、铜取得了满意结果。展开更多
Heat treatment of carbon nanotubes(CNTs) was carried out under ammonia atmosphere and then CNTs were modified by Triton x-100(CNTs-T). Ni-B amorphous alloy catalysts supported on CNTs and CNTs-T were prepared by impre...Heat treatment of carbon nanotubes(CNTs) was carried out under ammonia atmosphere and then CNTs were modified by Triton x-100(CNTs-T). Ni-B amorphous alloy catalysts supported on CNTs and CNTs-T were prepared by impregnation-chemical reduction method. The catalysts were characterized by TEM,ICP,XRD,BET and CO chemisorption,and studied in the acetylene selective hydrogenation. The results show that homogeneous Ni-B amorphous particles with mean size about 10 nm are successfully prepared on CNTs-T. Compared with Ni-B/CNTs,nickel loading of Ni-B/CNTs-T is increased by about 14.6%. Furthermore,the activity and selectivity of Ni-B/CNTs-T are much higher than those of Ni-B/CNTs in the acetylene selective hydrogenation under comparative condition.展开更多
文摘本文研究了2-丙醇和1,1,1-三氟-2-丙醇在Ni(100)表面解离的可能微观反应机理,使用完全线性同步和二次同步变换(complete LST/QST)方法确定解离反应的过渡态.采用基于第一性原理的密度泛函理论与周期平板模型相结合的方法,优化了2-丙醇和1,1,1-三氟-2-丙醇裂解反应过程各物种在Ni(100)表面的top,hollow和bridge位的吸附模型,计算了能量,并对布局电荷进行了分析,得到了各物种的有利吸附位.结果表明:2-丙醇和1,1,1-三氟-2-丙醇在Ni(100)表面都存在β-H和γ-H两个平行竞争的解离过程,其中2-丙醇在Ni(100)表面β-H解离的速控步骤活化能为64.7 k J·mol-1猯,而γ-H解离速控步骤活化能为233.1 k J·mol-1猯,故β-H解离过程占优势,主要产物是CH3COCH3;相反,1,1,1-三氟-2-丙醇在Ni(100)表面β-H解离的速控步骤活化能为257.1 k J·mol-1猯,而γ-H解离速控步骤活化能为148.1 k J·mol-1猯,故γ-H解离过程占优势,主要产物是CF3CH=CH2.由此说明,电负性更大的氟原子取代2-丙醇中的氢原子之后,2-丙醇在Ni表面的解离机理发生了改变.理论预测结果与实验结论一致.
文摘本文研究了Fe(Ⅲ),Co(Ⅱ),Ni(Ⅱ.),Cu(Ⅱ)在5-Br-PADAP-TritonX-100体系中的析相显色反应。利用该体系具有一定选择性和富集、分离的特点,采用多波长K系数法,根据公式ΔA=A-sum from i=1 to n K_iA_i=KC,在一个测定波长和与干扰组分个数相等的参比波长下,测定混合多组分体系的吸光度。求得相应K值后,再计算各待测组分含量。本法用于测定人发中微量铁、钴、镍、铜取得了满意结果。
基金Project (20263003) supported by the National Natural Science Foundation of China
文摘Heat treatment of carbon nanotubes(CNTs) was carried out under ammonia atmosphere and then CNTs were modified by Triton x-100(CNTs-T). Ni-B amorphous alloy catalysts supported on CNTs and CNTs-T were prepared by impregnation-chemical reduction method. The catalysts were characterized by TEM,ICP,XRD,BET and CO chemisorption,and studied in the acetylene selective hydrogenation. The results show that homogeneous Ni-B amorphous particles with mean size about 10 nm are successfully prepared on CNTs-T. Compared with Ni-B/CNTs,nickel loading of Ni-B/CNTs-T is increased by about 14.6%. Furthermore,the activity and selectivity of Ni-B/CNTs-T are much higher than those of Ni-B/CNTs in the acetylene selective hydrogenation under comparative condition.
