Journal of Catalysis, Vol.375, 371-379, 2019
Enhancing catalytic performance via structure core-shell metal-organic frameworks
A core-shell structure metal-organic framework based on the Zr clusters bridging with BDC linkers (UiO-66) as a core-structure and BPYDC linkers (UiO-67-BPY) as a shell-structure was developed (UiO-67-BPY@UiO-66). The combination of several techniques such as XRD, FTIR, SEM, TEM, and surface area analysis etc. were applied for the characterization and confirmed a core-shell structure of UiO-67-BPY@UiO-66. Taking advantage of the high porous stability of the core-structure (UiO-66) and the presence of active Lewis basic sites from the bipyridinic linker in the shell layer (UiO-67-BPY) could be advantageous for basic-catalyzed reactions. The synthesized core-shell material was applied as a heterogeneous catalyst for the Knoevenagel condensation as a model reaction. An excellent catalytic performance was obtained by the core-shell material over traditional MOFs and other previous reports based on MOFs. The excellent dispersion of the active sites (Lewis basic) in the outer layer of the designed core-shell structure was a breakthrough to prevent mass diffusion limitation during catalysis. Additionally, the catalyst can be recycled and maintained its high catalytic performance at least for four cycles. (C) 2019 Elsevier Inc. All rights reserved.