Microporosity and Catalytic Activity for Hydrodesulfurization of Pharmacosiderite Mo 4 P 3 O 16 Synthesized at a Moderate Temperature.

Pharmacosiderite Mo ₄ P ₃ O ₁₆ (Pharma-MoPO) consists of [Mo ₄ O ₄ ] cubane unit and [PO ₄ ] tetrahedral to form an open framework with a microporous structure similar to that of LTA-type zeolite. Although attractive applications are expected due to its microporous structure and redox-active components, its physicochemical properties have been poorly investigated due to the specificity of its synthesis, which requires a high hydrothermal synthesis temperature of 360 °C. In this study, we succeeded in synthesizing Pharma-MoPO by hydrothermal synthesis at 230 °C, which can be applied using a commercially available autoclave by changing the metal source. Through the study of the solids and liquids obtained after hydrothermal syntheses, the formation process of Pharma-MoPO under our studied synthesis conditions was proposed. Advanced characterizations provided detailed structural information on Pharma-MoPO, including the location site of a countercation NH ₄ ⁺ . Pharma-MoPO could adsorb CO ₂ with the amount close to the number of cages without removing NH ₄ ⁺ . Pharma-MoPO exhibited stable catalytic activity for the hydrodesulfurization of thiophene while maintaining its crystal structure, except for the introduction of sulfide by replacing lattice oxygens. Pharmacosiderite Mo ₄ P ₃ O ₁₆ was successfully obtained by hydrothermal synthesis at a moderate temperature, and its microporosity for CO ₂ adsorption and catalytic properties for hydrodesulfurization were discovered.