Synthesis of Surface Covered Solid Acid and Base

在MgO和CaO的固体碱和硫酸氧化锆的固体超强酸表面覆盖不具有或不具有酸性和碱性的金属氧化物，制备出耐H_2O和CO_2的固体酸碱催化剂。铝、硅、钛和锆的氧化物被用于覆盖固体酸和碱催化剂。提出了一种新的表面凝胶法制备方法。这是一种将溶解在乙酸乙酯中的金属醇盐在金属氧化物或氢氧化物表面利用其酸碱性质进行分解的技术。采用表面凝胶化技术制备了MOx/MgO （M=Al, Si, Ti, Zr）和M' ox /CaO （M'=Al, Si, Ti）。在所合成的固体碱催化剂中，Al_2O_3/MgO、Al_2O_3/CaO和TiO_2/CaO对二丙酮醇的反醛醇反应具有较高的催化活性。单次沉积过程中覆盖SiO2不会影响CaO的溶解度。双重沉积法对Ca^<2+>的洗脱有较强的抑制作用。通过表面凝胶作用，在氧化锆表面覆盖氧化锆，抑制了与氧化锆表面结合的硫酸盐离子的洗脱。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.