Research On Preparing Active Alumina By Reverse Precipitation Method

γ-Al2O3is an important technological and industrial application material which is extensively used in technological and industrial catalysis owing to its high surface area and large pore volume. Many chemical methods, such as sol-gel, co-precipitation and hydrothermal process have been used for preparing γ-Al2O3. However, in all these synthesis routes, an expensive primary materials has to be used as the Al source, and complicated preparation process lead to the industrial impracticability of the complex processes and high-costs. So, there is great value for researching the method to preparing the high quality and high thermal stable γ-Al2O3. In this method, the sodium aluminate as the Al source was pumped into nitric acid. The rare earth metals are as stabilizer and PEG and EDTA are as hole expansion agent. The effect of preparing processes, such as pH value, reaction temperature, aging time, aging temperature and wash way, the doping agents on the structure of PB and the textural properties of γ-Al2O3was investigated by XRD, FTIR, SEM, TEM and nitrogen adsorption-desorption, respectively.The best preparing processes is pH=10, reaction temperature is30℃, aging time is2h, aging temperature is60℃,and the wash agent is hot water. The surface area of the prepared γ-Al2O3is365m2·g-1.PEG and EDTA added organic alcohol easy to establish stronger hydrogen bonds with the surface of aluminum hydroxide gel tablets, prevents drying and roasting aluminum oxide particles in the process of aggregation and accumulation, reduction of porous sintered, while reducing water and formation of alumina surface hydroxyl groups, inhibit the complete shift of γ-Al2O3phase. Early reaction to join EDTA1%PEG or preparation of activated alumina has good thermal stability.In reverse precipitation method which doped6%nitric acid la or in reverse precipitation-impregnated method which impregnated1%of nitric acid la, in the surface of alumina can formed calcium titanium mine type of LaAlO3, through interface combined way solid to anchor will in Al2O3lattice of corner block has sintering and surface proliferation. So it cannot formed stability of Al-O-Al key, can further inhibition alpha phase changes, to improve alumina of high fever stability. Activated alumina obtained by the1100℃high temperature roasting of the specific surface area of about110m2·g-1, reflects the effect can improve the thermal stability of alumina modified with La.A simple and effective way to synthesis γ-Al2O3with large surface area and large pore volume combined with high thermal stability by reverse precipitation-azeotropic distillation method; the n-butanol used in the azeotropic distillation process plays an important role in preventing the hard agglomeration and lowing the phase transformation temperature. Preparation of activated alumina and specific surface area, pore volume and pore respectively426m2·g-1,2.56m3·g-1and14.5nm, after1100℃high temperature roasting by their specific surface area up to92m·g-1, reflects the good thermal stability.