(Ni,Mg)3Si2O5(OH)4 Solid-Solution Nanotubes Supported by Sub-0.06 wt % Palladium as a Robust High-Efficiency Catalyst for Suzuki–Miyaura Cross-Coupling Reactions

摘要

(Ni1–x,Mgx)3Si2O5(OH)4 solid-solution nanotubes (NTs) with tunable compositions were hydrothermally synthesized by altering the molar ratio of Mg2+ to Ni2+. The as-synthesized NTs were loaded with sub-0.06 wt % palladium (Pd; 0.045 wt %) for Suzuki–Miyaura (SM) coupling reactions between iodobenzene or 4-iodotoluene and phenylboronic acid. The (Ni,Mg)3Si2O5(OH)4 (Mg2+:Ni2+ = 1.0:1.0) NTs supported by 0.045 wt % Pd promoted the iodobenzene-participated coupling reaction with a high yield of >99%, an excellent recycling catalytic performance during 10 cycles of catalysis with yields of 99%, and also an extremely low Pd releasing level of 0.02 ppm. High-activity Pd and PdO clusters, multitudes of dislocations, and defects and terraces contained within the NTs should contribute to the (Ni,Mg)3Si2O5(OH)4 (Mg2+:Ni2+ = 1.0:1.0) NTs supported by 0.045 wt % Pd as a robust, reusable, and high-efficiency catalyst for SM coupling reactions with an extremely low Pd releasing level. The present hydrothermally stable (Ni,Mg)3Si2O5(OH)4 (Mg2+:Ni2+ = 1.0:1.0) solid-solution silicate NTs provided an ideal alternative tubular-structured support for noble- or transition-metal catalysts with low Pd loading, good recycling, and extremely low ppb levels of Pd release, which could also be extended to some other SM coupling reactions.