Chemical Environment Control and Enhanced Catalytic Performance of Platinum Nanoparticles Embedded in Nanocrystalline Metal鈥揙rganic Frameworks

详细信息    查看全文

• 作者：Kyung Min Choi ; Kyungsu Na ; Gabor A. Somorjai ; Omar M. Yaghi
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：June 24, 2015
• 年：2015
• 卷：137
• 期：24
• 页码：7810-7816
• 全文大小：464K
• ISSN：1520-5126

文摘

Chemical environment control of the metal nanoparticles (NPs) embedded in nanocrystalline metal鈥搊rganic frameworks (nMOFs) is useful in controlling the activity and selectivity of catalytic reactions. In this report, organic linkers with two functional groups, sulfonic acid (鈭扴O₃H, S) and ammonium (鈭扤H₃⁺, N), are chosen as strong and weak acidic functionalities, respectively, and then incorporated into a MOF [Zr₆O₄(OH)₄(BDC)₆ (BDC = 1,4-benzenedicarboxylate), termed UiO-66] separately or together in the presence of 2.5 nm Pt NPs to build a series of Pt NPs-embedded in UiO-66 (Pt鈯俷UiO-66). We find that these chemical functionalities play a critical role in product selectivity and activity in the gas-phase conversion of methylcyclopentane (MCP) to acyclic isomer, olefins, cyclohexane, and benzene. Pt鈯俷UiO-66-S gives the highest selectivity to C₆-cyclic products (62.4% and 28.6% for cyclohexane and benzene, respectively) without acyclic isomers products. Moreover, its catalytic activity was doubled relative to the nonfunctionalized Pt鈯俷UiO-66. In contrast, Pt鈯俷UiO-66-N decreases selectivity for C₆-cyclic products to <50% while increases the acyclic isomer selectivity to 38.6%. Interestingly, the Pt鈯俷UiO-66-SN containing both functional groups gave different product selectivity than their constituents; no cyclohexane was produced, while benzene was the dominant product with olefins and acyclic isomers as minor products. All Pt鈯俷UiO-66 catalysts with different functionalities remain intact and maintain their crystal structure, morphology, and chemical functionalities without catalytic deactivation after reactions over 8 h.