1. Used as catalyst active component
Magnesium oxide has a strong alkalinity and can be used alone as a solid base catalyst (such as MgO, MgO/NaY and MgO/ZrO2) or in combination as an acid-base bifunctional catalyst (such as MgO/HMCM-22 and MgO-Al2O3) to catalyze transesterification For reactions such as Knoevenagel condensation and Claisen-Schmidt condensation, the activity of the catalyst depends on the preparation method and reaction conditions. To study the effect of preparation method on the surface morphology and properties of MgO, the Meerwein-Ponndorf-Verlev reduction reaction was selected as the model reaction. It is found that the direct roasting method has a wide range of sources of reaction raw materials, and the prepared magnesia has high catalytic activity. After the reaction, the magnesia is activated and reused, and the specific surface area and catalytic activity remain unchanged.
2. Used as a catalyst carrier
There are usually two preparation methods for magnesium oxide supported catalysts: one is to prepare MgO earlier, select a suitable method to optimize the specific surface area and pore size distribution of MgO, and then deposit active components on MgO, by improving the deposition technology of active components ( heterogeneous impregnation or thermal diffusion) to avoid damage to the support. The other is to simultaneously deposit active metals, metal oxides or their precursors when preparing Mg0, such as calcining Co(Ni) and MoO3 or their precursors together with Mg(OH)2.
3. Used as a catalyst additive
As an additive, magnesium oxide can improve the activity and stability of the catalyst, improve the structure and pH of the catalyst, and be used in reactions such as synthesis gas conversion, hydrogenation and dehydrogenation. The doping amount of MgO affects the structure and performance of the catalyst. Preparation of MgO-doped bifunctional catalyst Cu-Zn-Mg/y-Al2O3 catalyzed synthesis gas to dimethyl ether. When the MgO content was 20mol%, the catalytic performance was the best (37% CO conversion, 83% DME selectivity, and 14% by-product selectivity). The components of the catalyst are uniformly dispersed, with proper acid sites, small pore size and malachite crystal structure. When the Mg0 content increased to 30mol%, the crystalline structure of the catalyst disappeared, resulting in a decrease in catalytic activity.
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