Role of phosphorous in transition metal phosphides for selective hydrogenolysis of hindered C–O bonds
Role of phosphorous in transition metal phosphides for selective hydrogenolysis of hindered C–O bonds
复制标题
过渡金属磷化物中磷对受阻 C–O 键选择性氢解的作用
DOI：
10.1016/j.jcat.2023.02.011
复制
发表时间：
2023
影响因子：
7.3
通讯作者：
Hibbitts, David
中科院分区：
文献类型：
--
作者：
Waldt, Conor;Montalvo-Castro, Hansel;Almithn, Abdulrahman;Loaiza-Orduz, Álvaro;Plaisance, Craig;Hibbitts, David
C-O氢解可以将生物质升级为更高价值的化学品，但通常需要空间位阻C-O键的选择性活化。研究甲基四氢呋喃（MTHF）的C-O氢解的先前工作表明，与纯Ni催化剂相比，Ni 2 P和Ni 12 P5对受阻（3C-O）键的活化具有更高的选择性。这些测量到的选择性差异-排除3C-O活化的材料具有较高的P含量-与计算的自由能垒的2C-O和3C-O活化途径，使用密度泛函理论（DFT）是一致的。然而，P在导致这种选择性转变中的作用仍然未知。在这项工作中，我们使用DFT研究其他过渡金属磷化物（Co2 P，Pd 2 P，Rh 2 P，Fe 2 P和Ru 2 P），并将它们与纯金属对应物进行对比，以确定P在Ni 2 P材料中的作用是否与其他过渡金属一致。要做到这一点，我们构建了这些其他过渡金属磷化物的Ni 2 P（0 0 1）表面的同构的理论模型。在将磷化物材料与其纯金属对应物进行比较时，我们看到了几乎普遍存在的对受阻C-O活化的选择性的转变。然而，这些位移的幅度显着变化，只有Ni 2 P和Pd 2 P预测显示出高选择性toward 3C-O激活。周期性趋势和电荷分析表明，不同的选择性变化（比较金属磷化物的纯金属）可以合理化的基础上的电负性的金属和P和附近的金属原子之间的所得电荷转移，这通常会导致在金属与正的部分电荷，显示chlorater 3C-O的选择性。这些结果有助于解卷积的电子和几何的影响，P掺入过渡金属催化剂，并确定新的催化剂的选择性C-O活化受阻的C-原子。
C–O hydrogenolysis can upgrade biomass to higher value chemicals, but often requires the selective activation of sterically hindered C–O bonds. Previous work examining C–O hydrogenolysis of methyltetrahydrofuran (MTHF), a model biomass-derived molecule, has shown that Ni2P and Ni12P5show higher selectivities toward activation of the hindered (3C–O) bond over the unhindered (2C–O) bond compared to pure Ni catalysts. These measured selectivity differences—favoring3C–O activations for materials with higher P content—were consistent with calculated free energy barriers for the2C–O and3C–O activation pathways using density functional theory (DFT). However, the role of P in causing this shift in selectivity is still unknown. In this work we use DFT to study other transition metal phosphides (Co2P, Pd2P, Rh2P, Fe2P, and Ru2P) and contrast them to their pure metal counterparts to determine if the role of P in Ni2P materials is consistent across other transition metals. To do this, we constructed theoretical models of these other transition metal phosphides that were isostructural to the Ni2P(0 0 1) surface. In comparing the phosphide materials to their pure metal counterparts, we saw a nearly ubiquitous shift in selectivity towards hindered C–O activation. However, the magnitudes of these shifts were significantly varied, with only Ni2P and Pd2P predicted to show high selectivity toward3C–O activation. Periodic trends and charge analysis suggest that the varied selectivity shifts (comparing metal-phosphide to pure metal) can be rationalized based on the electronegativity of the metal and the resultant charge-transfer between P and the nearby metal atoms, which typically results in metals with a positive partial charge showing greater3C–O selectivity. These results help to deconvolute the electronic and geometric impacts of P incorporation into transition metal catalysts and identify new catalysts for selective C–O activation at hindered C-atoms.