Elucidating the atomic stacking structure of nickel phyllosilicate catalysts and their consequences on efficient hydrogenation of 1,4-butynediol to 1,4-butanediol

The hydrogenation of 1,4-butynediol (BYD) to 1,4-butanediol (BDO) plays a pivotal role in the production of biodegradable plastics, including PBAT and PBS. Herein, we prepared a range of nickel phyllosilicate catalysts with diverse atomic stacking configurations for the direct synthesis of BDO via BYD hydrogenation. In comparison to conventional supported Ni catalysts, the metal sites derived from nickel phyllosilicate demonstrated remarkable hydrogenation activity for the conversion of CC-C-OH alkynol to C-C-C-OH alkanol. Both the physical structures and -importantly- chemical properties of these catalysts were crucial for product selectivity and yield; and a BDO yield of 93.4 % with complete conversion of BYD was achieved at 50 °C and 1 MPa H2 over the Niphy@SiO2-UDP catalyst with a pure 1:1 Ni phyllosilicate structure. Kinetic experiments and theoretical calculations confirmed that the initial hydrogenation of BYD to 1,4-butenediol (BED) was the rate-determining step for the saturated hydrogenation to BDO. The metallic Ni site is responsible for the dissociation of hydrogen, while due to the enhanced synergism derived from the 1:1 atomic stacking phyllosilicate structure, a type of cooperated Ni-Niδ+-acid sites can stabilize the CC electron cloud over the carbon chain of BED intermediate, hence benefiting its further hydrogenation, and suppressing its isomerization to undesired aldol condensation byproduct. Our findings provide valuable insights into the atomic stacking structures of metal phyllosilicate catalysts, revealing the micro-environment of chemical properties and interactions that govern the state/activity of Ni species, which is helpful for the rational design of other hydrogenation catalysts with enhanced performance.