Catalytic Disproportionation of Formic Acid to Methanol by an Iridium Complex Immobilized on Bipyridine‐Periodic Mesoporous Organosilica
Catalytic Disproportionation of Formic Acid to Methanol by an Iridium Complex Immobilized on Bipyridine‐Periodic Mesoporous Organosilica
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DOI：
10.1002/cctc.201900999
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发表时间：
2019-10
期刊：
影响因子：
4.5
通讯作者：
Sho Yamaguchi;Yoshifumi Maegawa;Naoya Onishi;Ryoichi Kanega;M. Waki;Y. Himeda;S. Inagaki
中科院分区：
文献类型：
--
作者：
Sho Yamaguchi;Yoshifumi Maegawa;Naoya Onishi;Ryoichi Kanega;M. Waki;Y. Himeda;S. Inagaki
本文报道了在常压条件下使用异相铱（Ir）催化剂实现甲酸歧化制甲醇的第一个例子。以乙烷（Et）和2,2′‐联吡啶（BPy）‐桥接有机硅烷（Ir‐Et‐BPy‐PMO）为前驱体，将IrCp*配合物（Cp*=五甲基环戊二烯基（5‐C5Me5））固定在周期介孔有机硅的孔表面。与均相Ir - BPy配合物相比，Ir - Et - BPy - PMO具有独特的甲醇选择性。此外，Ir - Et - BPy - PMO表现出高度的可重复使用性，在反应过程中没有任何明显的活性下降，至少五次，没有Ir物质的浸出。Ir - Et - BPy - PMO对甲醇选择性的提高可能是由于其高宽高比的介孔对H2/CO2的保留具有独特的限制作用，抑制了甲酸的竞争脱氢，促进了甲酸的加氢。
We report the first example of using heterogeneous Iridium (Ir) catalysts under atmospheric pressure conditions to achieve the catalytic disproportionation of formic acid to methanol. IrCp* complex (Cp*=pentamethylcyclopentadienyl (ɳ5‐C5Me5)) was immobilized on the pore surface of the periodic mesoporous organosilica synthesized from a precursor mixture of ethane (Et) and 2,2′‐bipyridine (BPy)‐bridged organosilanes (Ir‐Et‐BPy‐PMO). Ir‐Et‐BPy‐PMO showed unique catalysis with higher selectivity of methanol compared to homogeneous Ir‐BPy complexes. Furthermore, Ir‐Et‐BPy‐PMO exhibited high reusability without any noticeable decrease in activity for at least five times with no leaching of Ir species during the reaction. The increase in methanol selectivity of Ir‐Et‐BPy‐PMO would be attributed to the unique confinement effect in the mesochannels with their high aspect ratio for the retention of generated H2/CO2, which suppresses the competing formic acid dehydrogenation and promotes the formic acid hydrogenation.