Theoretical Study on the Catalytic Activity and Sulfur Resistibility of Amorphous Alloy Ni-B-P

In the present paper,one hundred cluster models NinBP (n=1～6) have been designed and studied by density functional theory (DFT) to get an insight into the local structure,catalytic properties and sulfur resistibility of amorphous alloy Ni-B-P. The configurations in triplet state are found more stable than those in the singlet state. It is found that as the content of Ni in the clusters increases,the value of Fermi level in clusters fluctuated,which shows that the content of Ni can influence the Fermi level to a certain extent. Based on the Fermi level and DOS,we consider the activity of catalyst in hydrogenation reaction is the best in cluster Ni3BP. On the basis of the charge of clusters NinBP (n=1～6),we conclude the amorphous alloy Ni-B-P with high Ni content has better sulfur resistibility and the best hydrogenation activity,strong sulfur resistibility appears in clusters Ni3BP,and the amorphous alloy Ni60B20P20 with similar proportion is expected to prepare in the future.     

Ni-B非晶态合金局域结构和电荷转移性质的理论研究

根据非晶态合金结构的短程有序、Ni和B间存在较强的化学作用、结构中存在B－B键直接相连的实验事实,选择Ni~mB~2(m=1,2,4)原子簇作为非晶态局域结构的计算模型。考虑原子簇间的相互作用,又对[Ni~4B~2]~n(n=1,2,5,7)簇团进行了系统计算。结果表明在所选Ni-Br的簇模型中,都是B原子提供电荷给Ni原子,这些均与非晶态合金实验结果和一些理论计算结果相符。簇团的计算结果还表明,小原子簇Ni~4B~2内原子间存在较强的化学键作用,而簇间的相互作用相对较弱,很容易造成对称性破缺而导致产生长程无序,因此Ni-B非晶态可以被看成是由大量i上原子簇无序堆砌成的,这一点也同实验事实相吻合。计算结果也表明我们前面工作中所取的和最常见的Ni-B非晶态合金Ni~6~4B~3~6有相似组成的Ni~4B~2原子簇模型能在一定程度上反映Ni-B非晶态合金的局域结构特征。     

Ni-B非晶态合金中电子转移问题的DFT研究

根据Ni-B非晶态结构的短程有序、Ni和B之间是较强的化学作用和结构中存在B-B直接相连的实验事实,选择了Ni~mB~2^(^1^)(m=1-4)原子簇模型,用DFT方法对其进行高水平的量子化学计算,结果表明,模型体系中,B原子供给Ni原子电子,这与非晶态合金的实验结果一致,为了此较,同时选择了NiB^(^2^)(m=1-4)模型,计算结果与实验不符,这说明NiB~2^(^1^)(m=1-4)原子簇模型更能反映非晶态的结构特点。     

Ni-P非晶态合金中电子转移问题的DFT研究

根据Ni-P非晶态合金结构的短程有序、Ni和P之间具较强化学作用和结构中不存在P-P直接相连的实验事实,选择了Ni~nP(n=1-6)原子簇模型,用密度泛函理论方法对其进行计算。结果表明,在模型体系中,随着P含量的减少,电子转移方向发生变化,P原子由得电子变为失电子。这与Ni-P非晶态合金的实验结果一致,说明Ni~nP(n=1-6)原子簇模型能反映Ni-P非晶态合金的结构特点。     

原子簇Ni2Fe2P结构稳定性的密度泛函理论研究

利用DFT(密度泛函理论)方法在B3LYP/Lan12dz水平下对原子簇模型Ni₂Fe₂P的二十余种可能构型分别在二、四重态下进行优化计算,分析比较了优化结果的能量、结合能、吉布斯自由能变化和过渡态.结果表明:原子簇Ni₂Fe₂P十种异构体没有虚频,有可能稳定存在于非晶态合金中;其中以具有二重态的构型1的能量最低,结合能、吉布斯自由能变化及过渡态能垒最大,最为稳定;四重态中异构体1',2',3'和4'共存的可能性比较大.     

Ni-Co-B非晶态合金的结构和催化活性的理论研究

利用一系列原子簇模型Ni~xCo~3~-~xB~2(x=1～3)对Ni-Co-B非晶态合金的电子结构进行了SCC-DV-Xα计算。结果表明,Ni-B非晶态合金的催化加氢活性可通过Co的引入而得到改进。结合EXAFS和活性试验的结果,得出Ni和Co对非晶态Ni-Co-B合金的结构的稳定性有一种协同作用的结论。     

Ni-P非晶合金催化剂的制备、结构和性能

超细非晶态合金ＭＰ或ＭＢ(Ｍ=Ｎｉ,Ｃｏ,Ｆｅ)的高比表面和结构不规整性使其表现出催化加氢的高活性和选择性,有可能成为新型石油化工加氢催化剂[1-3].其制备主要有物理和化学两类方法[3-5].从提高催化活性角度,化学还原法是最为优越的方法.ＮｉＢ催化活性明显高于ＮｉＰ...     

团簇Ni4P催化析氢性能研究

为探究团簇Ni₄P催化析氢最强的结构,基于密度泛函理论,在B3LYP/Lan12dz水平下,对团簇Ni₄P的初始构型进行计算和优化,得到5种优化构型。从热力学稳定性、前线轨道图和前线轨道能级差对团簇Ni₄P的析氢性能分析发现,构型1^（4）和1^（2）的热力学稳定性较强;团簇Ni₄P各优化构型均易吸附水中的氢原子,Ni原子为团簇Ni₄P催化活性位点,且构型1^（4）、1^（2）和2^（4）催化析氢的活性更强。(1^（2）)-H、(2^（2）)-H在电化学脱附法和化学重组法中均具有较强的催化活性。以上说明构型1^（2）是团簇Ni₄P催化析氢最强的结构。     

Highly selective hydrogenation of acetophenone over supported amorphous alloy catalyst

Alpha-phenylethanol (PE) is an essential chemical in the field of medicine and synthetic perfumery. Therefore, in this work, we used a supported Ni–B–P amorphous alloy catalyst (Ni–B–P/SiO₂) in the hydrogenation of acetophenone (AP) to α-PE, which demonstrated excellent catalytic activity and selectivity, compared with Ni–B/SiO₂ (KBH₄ reduction of nickel salt). Ni–B–P/SiO₂ exhibited a high AP hydrogenation conversion of approximately 99%, whereas the PE selectivity reached up to 94%, which is approximately 1.4-fold higher than that of Ni–B/SiO₂ (about 69%), thereby directly proving the unique inhibition of AP hydrogenation over hydrogenation of P in the Ni–B catalytic system. The doped P in Ni–B–P/SiO₂ enhances the oxidation resistance and maintains the valence stability of Ni and B. Furthermore, sufficient experimental data were collected to determine the kinetic parameters. Based on the Langmuir–Hinshelwood model, we assumed that (i) AP and H₂ compete for adsorption on Ni–B–P/SiO₂; (ii) AP has strong adsorptive capacity on Ni–B–P/SiO₂; and (iii) PE coverage on the catalyst was negligible. Then, the dynamic equation was derived, which indicated that experimental data agree well with the dynamic model. Finally, the activation energy was confirmed to be 50.73 KJ/mol. This report will open up an avenue for the industrialization of amorphous alloy catalysts.     

原子簇NixFe和NiFex(x=1-5)电子性质的DFT研究

More than one hundred models were designed to reflect the local structure and electronic property of Ni-Fe amorphous alloys. After calculating by DFF method, a series of configurations of clusters NixFe and NiFex （x = 1 - 5） were gained. The configurations, which possessed the lowest energies and non-imaginary frequencies, were considered the most stable optimized structures. The catalytic activity, charge and magnetic properties were analyzed and discussed. The different Fe content changed the catalytic properties of clusters through altering the value of Fermi level of every cluster. However the density of state （DOS） nearby Fermi level and average 3d orbital population of atom Ni, which were also important properties related to the catalytic activation, were little changed. Based on the Fermi level, the activity of catalyst toward hydrogenation reaction would be considered best when the ratio of Ni to Fe was close to 1. The Fermi level of clusters was far distant to the level of nitrogen in singlet state. It would be the reason why the reaction condition in ammonia synthesis and nitrogen fixation process was rigorous. When Fe atom contents were higher than 75% （NiFe3）, the electrons transferred from atom Fe to Ni, but when the ratio was decreased, the transfer was reversed. The ratio of atoms of local structure also played an important role in the aspect of electron transition. On the average 3d orbital population of atom Fe, the average magnetic moments of Fe atoms in clusters were calculated. When Fe atom contents were 50% nearly, the average magnetic moment achieved the highest point.     

Co-P非晶态合金电子性质和局域结构的理论研究

In order to study the electron property and the microlocal structure of Co-P amorphous alloy,a series of single-P（ConP）and two-P（ConP2）cluster models were chosen according to the experiment fact of the possible presence of direct P-P contact and short-range-ordering in the amorphous alloy. ConP and ConP2 cluster models were calculated with the DFT method and calculations showed that P（phosphor）accepted electron from Co（cobalt）in single-P（Co2P（2）,Co3P（1）and Co4P（2））cluster models,which agrees well with the Pauli electronegative rule,and a very strong interaction between Co and P resulted in formation stable clusters Co2P（2）,Co3P（1）and Co4P（2）. However,two-P（ConP2）cluster models and single-P cluster Co5P（1）were unstable,and it was impossible to present direct P-P contact in two-P（ConP2）cluster models. It could be concluded that the clusters Co2P（2）,Co3P（1）and Co4P（2） is more reasonable to represent the local structure of Co-P amorphous alloy.     

铁、钴、镍/磷二元团簇离子的形成与光解

利用激光直接溅射法产生了铁、钴、镍／磷二元团簇正负离子,并用串级飞行时间质谱仪研究了团族离子的组份和激光光解规律,质谱研究表明,铁、钴、镍易与磷结合成簇,而且样品中磷含量的增加有助于大尺寸团簇离子的生成,当形成的团族簇离子中含金属原子数目较少时,磷原子数目可在较大范围内变动,其中ＭＰ２＾＋、ＭＰ４＾＋、Ｍ２Ｐ４＾＋（Ｍ＝Ｆｅ、Ｃｏ、Ｎｉ,ｎ＝２、３、４）团簇离子均具有较高的丰度;随着金属原子数目的     

原子簇Ni2Fe2P结构稳定性的理论研究

利用DFT(密度泛函理论)方法在B3LYP/Lan12dz水平下对原子簇模型Ni2Fe2P的二十余种可能构型分别在二、四重态下进行优化计算,分析比较了优化结果的能量、结合能、吉布斯自由能变化和过渡态.结果表明原子簇Ni2Fe2P十种异构体没有虚频,有可能稳定存在于非晶态合金中;其中以具有二重态的构型1的能量最低,结合能、吉布斯自由能变化及过渡态能垒最大,最为稳定;四重态中异构体1',2',3'和4'共存的可能性比较大.     

非晶态合金Fe80P20局域结构和性质的量子化学研究

According to the structure features of Fe80P20, A series of clusters Fe4P were designed and focused on studying the stability of local structure, charge distribution and chemical bond. Using the DFT method,energy and structure of Fe4P clusters were optimized and analyzed. The computational results showed that the energy of cluster 1(2) has the lowest energy, and the possibility of its existence in the Fe8oP20 is high. Analyzing the transition states among the clusters, it was found that the clusters in the doublet state are more stable than those in the quartet state. The numbers of the Fe-P bond in the clusters play important roles in the cluster stability and electrons transfer properties. The more numbers of Fe-P bonds in the clusters, the higher the cluster stability, and the weaker the ability of P atom to get electron. The number of Fe atoms, which has bonding interactions with the P atom, is direct proportional to the average 3d orbit population of Fe atom. Basing on the orbital population, average magnetic moments of each Fe atom in the Fe4P clusters were calculated, and they are all smaller than that of single metal Fe atom. This suggests that all Fe4P clusters have soft magnetic property and they are expected to be perfect material for preparing soft magnetic apparatus.     

Mo（W）－Co（Ni，Fe）簇合物的加氢脱硫催化活性

对线型、立方烷型和笼状３种不同构型的Ｍｏ（Ｗ）－Ｃｏ（Ｎｉ，Ｆｅ）－Ｓ（Ｏ）簇共１２种化合物进行了噻吩加氢脱硫和环己烯加氢的催化活性研究．讨论了簇合物的组成，金属原子的配比、价态与催化活性的关系．探讨了不同构型对活性的影响．     

超细非晶镍合金的化学制备及类金属元素对性质的影响

常温下分别使用KBH4和NaH2PO2在水溶液中还原Ni^2^+制得了Ni65B35和Ni89P11超细非晶合金(UFAAP), 同时使用KBH4和NaH2PO2还原Ni^2^+制得了Ni73P13B14UFAAP. Ni-P的粒径较大, 约为110nm, Ni-B的粒径较小, 约为20nm,Ni-P-B的粒径居其之间, 约为40nm。XPS表明, Ni-P间的相互作用强于Ni-B间的相互作用, Ni-P-B中P的电子状态与Ni-P中的相似。Ni-P-B比Ni-P的比表面积高得多,Ni-P-B比Ni-B和Ni-P具有更好的非晶态稳定性, 在573K热处理, 它的非晶态保持完好。晶化结果也表明Ni-P-B中Ni-P间的相互作用比Ni-B间的强。     

Ni2Fe2P团簇结构及电子性质的DFT研究

利用DFT(密度泛函理论)方法对原子簇模型Ni2Fe2P的二十余种可能构型分别在二、四重态下进行优化计算，分析比较了优化结果的能量、成键及电荷分布情况。结果表明：原子簇Ni2Fe2P二重态比四重态稳定，二重态时以变形的四方锥构型最稳定，四重态时以变形的三角双锥构型最稳定；无论是二重态，还是四重态，Fe-P间的成键能力均要强于其它键；随着P原子周围成键金属原子的增加．P原子所带正电荷逐渐增加。     

First principle MD study on the structural and electronic properties of liquid and amorphous NI81B19 and NI80P20 alloy

Atomic and electronic structures of liquid and amorphous Ni₈₁B₁₉ and Ni₈₀P₂₀ alloys were simulated by ab initio molecular dynamics. Pair correlation function, bond pair analysis, electronic population analysis, and density of states were calculated. It was found that amorphous Ni₈₁B₁₉ and Ni₈₀P₂₀ alloys can be prepared by rapid quenching, and their structures are similar to those of liquid alloys. Bond pair analysis indicated that the environment of each atom in Ni₈₁B₁₉ system is dominated by icosahedral and distorted icosahedral inherent structures; however, in Ni₈₀P₂₀ system, the tetrahedral order is preponderant. Strong interactions occur between the d‐electrons of Ni and the p‐electrons of B (or P), which leads to the covalent interactions between Ni and B (or P) atoms. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

稀土对电沉积Ni-P合金镀层耐蚀性的影响

研究了稀土对电沉积Ｎｉ－Ｐ合金度层耐蚀性及组织的影响,通过浸泡实验和极化曲线的测定。得出在镀液中添加一定量的稀土元素能显著改善镀层的耐蚀性能。ＸＲＤ,ＴＥＭ,ＥＤＳ结果表明,稀土元素具有促进Ｎｉ－Ｐ合金形成非晶组织的作用,由于稀土的加入,在远低于８％的Ｐ含量下,获得了以非晶态为主的组织。     

Ni掺杂对Ni/MgO体系中电荷分配影响

采用密度泛函理论(DFT)计算方法,研究了载体Ni掺杂对Ni/MgO催化剂的电子结构及其对CH_4/CO_2重整反应的影响。结果显示,随着载体Ni:Mg比的增加,CH_4解离吸附和CH_x氧化过程的反应能垒均会随之升高,CH也更容易产生热解C,从而导致催化剂的活性和稳定性的下降。通过分析重整过程的Hirshfeld电荷分配,发现金属载体之间电子转移的方向会随着载体中Ni含量的上升由载体向Ni金属转移变为由Ni金属向载体转移。当Ni金属富电子时,反应物活化时电子的转移主要发生在表层Ni原子与吸附物种之间,参与氧化的CH_x物种为CH_2;当Ni金属缺电子时,反应物活化时Ni簇的电子结构基本保持稳定,电子主要在载体表层的Ni原子与反应物之间转移,CH是主要参与氧化的CH_x物种。