Synthesis of Surface Covered Solid Acid and Base

以MgO和CaO为固体碱，硫酸化氧化锆为固体超强酸，用不显示或显示较弱酸碱性的金属氧化物包覆，制备了耐H_2O和CO_2的固体酸碱催化剂。Al、Si、Ti和Zr的氧化物用于覆盖固体酸和碱催化剂。采用一种新的表面凝胶化制备技术制备覆盖层。利用金属氧化物或氢氧化物的酸碱性，将金属醇盐溶解于乙酸乙酯中，在其表面进行分解，制备了MOx/MgO（M=Al，Si，Ti，Zr）和M 'Ox/CaO（M'= Al，Si，Ti）催化剂。在所合成的固体碱催化剂中，Al_2O_3/MgO、Al_2O_3/CaO和TiO_2/CaO对双丙酮醇的逆羟醛缩合反应具有较高的催化活性。用SiO_2覆盖CaO不影响CaO的溶解度。采用双沉淀法覆盖，强烈抑制了Ca^<2+>的洗脱，通过表面凝胶化的方法，在硫酸化氧化锆表面覆盖氧化锆，抑制了结合在氧化锆表面的硫酸根离子的洗脱。然而，没有观察到抑制作用。催化活性大大提高。

Solid bases of MgO and CaO, and solid superacid of sulfated zirconia were covered with metal oxides which show no or less acidic and basic characters to prepare solid acid and base catalysts showing tolerance to H_2O and CO_2. The oxides of Al, Si, Ti, and Zr were used for covering solid acids and base catalysts. A new preparing technique of surface gelation was applied for covering. This is the technique that a metal alkoxide dissolved in ethyl acetate is decomposed on metal oxide or hydroxide surface by their acid or base properties.MOx/MgO (M=Al, Si, Ti, Zr) and M'Ox/CaO (M'=Al, Si, Ti) were prepared by the developed surface gelation technique. Among the synthesized solid base catalysts, Al_2O_3/MgO, Al_2O_3/CaO, and TiO_2/CaO showed higher catalytic activity for retro-aldol reaction of diacetone alcohol. The solubility of CaO could not be disturbed by covering it with SiO2 bysingle deposition procedures. The elution of Ca^<2+> was strongly inhibited by covering by double deposition method.The sulfated zirconia was covered with zirconium oxide by surface gelation to inhibit the elution of sulfate ion bonded to zirconia surface. However, the inhibition effect was not observed. The catalytic activity was largely increased.