Abstract
Hydrogenation of nitriles represents as an atom-economic route to synthesize amines, crucial building blocks in fine chemicals. However, high redox potentials of nitriles render this approach to produce a mixture of amines, imines and low-value hydrogenolysis byproducts in general. Here we show that quasi atomic-dispersion of Pd within the outermost layer of Ni nanoparticles to form a Pd1Ni single-atom surface alloy structure maximizes the Pd utilization and breaks the strong metal-selectivity relations in benzonitrile hydrogenation, by prompting the yield of dibenzylamine drastically from ∼5 to 97% under mild conditions (80 °C; 0.6 MPa), and boosting an activity to about eight and four times higher than Pd and Pt standard catalysts, respectively. More importantly, the undesired carcinogenic toluene by-product is completely prohibited, rendering its practical applications, especially in pharmaceutical industry. Such strategy can be extended to a broad scope of nitriles with high yields of secondary amines under mild conditions.
Highlights
Hydrogenation of nitriles represents as an atom-economic route to synthesize amines, crucial building blocks in fine chemicals
Inspired by maximized noble metal utilization in core-shell bimetallic catalysts and the unique coordination and electronic environment in single-atom alloy (SAA) catalysts[39,40,41,42,43,44,45], here we report that selective deposition of Pd on silica supported Ni NPs at low coverages using atomic layer deposition (ALD) produces quasi atomically dispersed Pd within the outermost layer of Ni particles to form a core-shell like quasi Pd1Ni single-atom surface alloy (SASA) structure as confirmed by detailed microscopic and spectroscopic characterization
A set of PdNi/SiO2 bimetallic catalysts with different Pd dispersions were precisely fabricated using a method by combining wet chemistry and ALD (Supplementary Fig. 1)
Summary
Hydrogenation of nitriles represents as an atom-economic route to synthesize amines, crucial building blocks in fine chemicals. The selectivity of DBA and the undesired hydrogenolysis by-product TOL were about 5 and 21%, respectively, consistent with literature (Supplementary Table 2)[16,19,20].
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