Investigation of Ni–Cu-acid multifunctional synergism in NiCu-phyllosilicate catalysts toward the 1,4-butynediol hydrogenation to 1,4-butanediol†

We studied the Ni–Cu-acid multifunctional synergism in NiCu-phyllosilicate catalysts toward 1,4-butynediol hydrogenation to 1,4-butanediol by varying the reduction temperature, which can activate different bimetal and support interactions. Compared with a monometallic Ni phyllosilicate (phy), which only showed one type of metal species when reduced at ∼750 °C, there are three types of metal species for the bimetallic Ni–Cu-phyllosilicate derived catalysts, namely Cuphy, differentiated Ni, and Niphy. Thorough structure–activity/selectivity correlation investigations showed that, although the Ni₉Cu₁-P catalyst matrix can produce tiny amounts of differentiated Ni⁰ species under the induction of reduced Cu⁰ at R250 condition, it could not form Ni–Cu bimetallic interactions for the collaborative hydrogenation of 1,4-butynediol, and the product stays in the semi hydrogenated state. When the reduction temperature is raised to 500 °C, stable Ni–Cu alloy active sites exist, accompanied by the strong metal support interaction and metal acid effect derived from the intimate contact between the extracted metal sites and the surviving functional phyllosilicate support; these functionalities yield a supreme hydrogenation performance of the R500 sample with a 1,4-butanediol yield larger than 91.2%.