Vol.1 No.3 2009

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Research paper : Development of highly-active hydrodesulfurization catalyst for sulfur-free diesel production (Y. Yoshimura et al.)−164 Synthesiology - English edition Vol.1 No.3 (2009) basicity of the coordinated sulfur (reduced Lewis acidity of adjacent sulfur coordinatively unsaturated sites), the hydrodesulfurization reaction is less susceptible to absorptive inhibition by basic aromatic compounds and nitrogen compounds in feedstock oil.Therefore, we considered that the key to the high dispersion, lower stacking of layers, and high crystallization of MoS2 and the proper coordination of Co species with the MoS2 edge sites would be a metal-containing impregnation solution, and focused on establishing the preparation method for such a solution (Fig. 6). The effectiveness of chelating agents (nitrilotriacetic acid, citric acid [7], CyDTA [8], etc.) in preparing an impregnation solution containing Mo-polyanions and Co ions has already been confirmed.We found a new chelating agent, identified the controlling factors in catalyst preparation, and confirmed that the preparation of highly active Mo-based catalysts is reproducible, although on a laboratory scale.4 Deepening and Integration of Element Technologies as an ApproachUsually, a catalyst research approach consisting of three parts (a “three-in-one” type of research approach: catalyst design and preparation technique – catalyst structure analysis/evaluation technique – catalytic reaction evaluation technique) as shown in Fig. 7 is used if a proof of principle approach is used for Section 3. This approach is a process in which, as this three-part relationship revolves, the catalyst develops into a high-performance catalyst (evolving in a spiral like a helical spring). It is a series of processes: the latest analytical machines are incorporated to characterize a catalyst that, for example, was trial-produced for specific purposes or purchased on the market; the obtained catalyst structure is correlated to active sites on the catalyst; and design guidelines for an advanced catalyst are proposed.With advances in catalyst analysis techniques and theoretical support for catalyst structures (density functional theory (DFT) calculation, etc.), atomic- and molecular-level information on catalysts is constantly updated, and the three-part relationship is evolving and successful. However, for the wet catalyst preparation method, which is the mainstream industrial catalyst preparation method and is widely used for catalyst preparation in the laboratory, information on the prepared catalyst is not necessarily fed back to the preparation stage. This might be due to the limited information available on the properties of metal ions, metal complex, or colloids in the impregnation solutions. It is more appropriate to say that information to help link information on the prepared catalyst to that on catalyst preparation is not disclosed because the preparation process is directly linked to intellectual property. Another feature of this study is that the three-part relationship for solid catalysts, such as preparation of a metal-containing impregnation solution used for catalyst preparation and structural analysis of metal ions in the impregnation solution, was investigated at the solution level, and the catalyst preparation process was reviewed from a chemical as well as engineering perspective.We assumed that the following were essential to move smoothly from beaker-scale to industrial-scale catalyst production:(1)Industrial catalyst materials are inexpensive, the impregnation solution preparation method can correspond to variations in industrial catalyst material lots, and quality control can be applied to a large-scale catalyst preparation process.(2)The catalyst preparation method can be used in existing commercial hydrodesulfurization catalyst production facilities.As a result of studying various aspects, we identified controlling factors in catalyst preparation, although for laboratory preparation; undertook an in-depth study on techniques to control controlling factors; and developed a recipe for catalyst preparation. Subsequently, based on the results obtained at AIST, we conducted joint research with a catalyst manufacturer. It was found that AIST’s recipe required improvements, but the overall direction of our (10)−Fig. 6 Catalyst preparation method based on the conventional impregnation method using the new impregnation solution.Fig. 7 Three-in-one technology in catalyst development.

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