Chemoselective Hydrogenation of Crotonaldehyde Catalyzed by an Au@ZIF‐8 Composite

Abstract Au nanoparticles of size 2.2 nm were encapsulated in a zeolitic imidazolate framework ZIF‐8 framework (Au@ZIF‐8). The composite was used as a catalyst for the selective hydrogenation of crotonaldehyde to crotyl alcohol with 90–95 % selectivity. Hydrogenation of 1‐hexene yielded n ‐hexane in approximately the same conversion as crotonaldehyde, whereas cis ‐cyclohexene did not detectably react. To account for the confined environment of the ZIF, we supported Au nanoparticles on the outside of ZIF‐8 (Au/ZIF‐8). Using Au/ZIF‐8 as a catalyst, 1‐hexene and cis ‐cyclohexene were hydrogenated in low conversion whereas crotonaldehyde would only react at higher pressures in 70 % selectivity towards crotyl alcohol. Post‐experiment TEM analysis of Au/ZIF‐8 showed significant sintering whereas the median particle size of Au@ZIF‐8 remained almost unchanged. Au@ZIF‐8 was recycled as a catalyst for the hydrogenation of crotonaldehyde three times without significant loss of activity or selectivity.