Layered double hydroxide-derived Ni-Cu nanoalloy catalysts for semi-hydrogenation of alkynes: Improvement of selectivity and anti-coking ability via alloying of Ni and Cu

Environmental benign non-noble NiCu catalysts with well-distributed homogeneous nanoalloy structure was fabricated from layered double hydroxide for semi-hydrogenation of acetylene. Compared with monometallic Ni catalyst, the introduction of Cu enhanced ethene selectivity and decreased the deactivation rate in long-term reaction. Furthermore, to give a thorough understanding on structure dependent performance, conventional impregnation was also used to obtain bimetallic NiCu catalyst for comparison. Interestingly, imp-NiCu/MMO presented the mixture of monometallic Ni, Cu and bimetallic NiCu. Catalytic results indicated that 100% conversion was achieved at 160 °C with improved selectivity (>70%) over NiCu nanoalloy catalyst, while bimetallic NiCu catalyst with mixed structure showed both poor conversion (50%) and selectivity (65%). Enhanced activity was attributed to small particle size (3.2 nm) and high metal dispersion (31.4%). Improved selectivity and anti-coking ability were related to the alloying of Ni with Cu, which was conducive to isolate Ni atoms from one another confirmed by STEM-EDX and transfer electron from Cu to Ni certified by XPS. Additionally, superior performance was also found in semi-hydrogenations of hexyne, phenylacetylene, 1,2-diphenylethyne and ethyl phenylpropiolate over NiCu nanoalloy.