Preparation Forming And Application Of Boehmite With Large Specific Surface Area And Controllable Pore Size

Boehmite is a precursor for preparing alumina,which has the characteristics of large specific surface area and large pore volume It is widely used as an industrial catalyst support and adsorbent in industry.However,the primary particles of the boehmite which produced currently are usually approximately spherical or cubic,the specific surface area is usually less than 350 m2·g-1,the pore volume is less than 1.0 cm3·g-1,the pore size is less than 6nm.So it is impossible to obtain the boehmite both with large specific surface area and large pore size at the same time.Therefore,the preparation of boehmite and alumina support with large specific surface area and effective pore size control becomes an urgent problem to be solved.In this paper,boehmite was synthesized hydrothermally by adding sodium metaaluminate and aluminum sulfate with a neutralization method without adding any organic matter.By changing the reaction conditions such as raw material concentration and crystallization time,the pore size can be adjusted simply and effectively.Boehmite with a specific pore size can be prepared.The primary particles of boehmite are in the form of nanosheets,with a specific surface area of 707.4 m2·g-1,a pore volume of 3.05 cm3·g-1 and a pore size of 29.8 nm,which breaks through the obstacles that the large specific surface area and large size of boehmite are hardly to be achieved.When the specific surface area is greater than 700 m2·g-1,the pore diameter is adjustable from 5.5nm to 30nm.The extrusion forming method was used to shape the boehmite,and the effects of factors such as calcination temperature,alcohol content,water powder ratio,acid-aluminum ratio,acid type and additives were studied.The alumina supports with different surface area and pore size is used for the adsorption of the food-grade dye sunset yellow.Compared with the industrial support,it has a significantly adsorption effect.The saturated adsorption capacity can reach 276.9mg·g-1,the adsorption rate can reach 92.3%and effect of pH and the initial concentration were studied.