Production method of pseudoboehmite:
Natural or artificially produced alumina monohydrate and trihydrate alumina cannot be used as desiccants, adsorbents, catalysts and catalyst supports due to their low specific surface area, small pore volume, and low activity. Alumina or alumina trihydrate must be processed into pseudoboehmite. The pseudo boehmite has high specific surface area, large pore volume, large pore size, and high activity, and is suitable for use as a desiccant, an adsorbent, a catalyst and a catalyst carrier in the fields of petrochemicals, chemical fertilizers, and exhaust gas.
First, carbonization method to prepare pseudoboehmite carbonization method to prepare pseudo-boehmite Relying on the sintering production of alumina process, the use of intermediate product NaAlO2 solution and CO2 as the reaction material, the process is simple, is the lowest cost process route. The waste liquid in production can be returned to the alumina production process for reuse, and basically no waste is discharged. The environmental pollution is small and it is a comparatively competitive and promising method. The quality of the pseudoboehmite produced by the carbonization process is related to many production conditions such as raw material concentration, gelation temperature, pH, aging temperature and time, and drying temperature of wet cake. The deficiency of the carbonization method of pseudoboehmite production method is that there are miscellaneous phases in the product, the purity is not high, and the sodium washing water consumption is large.
The second is alkaline production pseudoboehmite. In order to coordinate the replacement of catalysts for fertilizer plants, research and production of chemical fertilizer catalysts have been tackled. The technical indicators of the developed alumina carrier are: apparent density 0.55 to 0.65 kg/L, alumina content 94.0% to 95.5%, sodium oxide content 0.01% to 0.03%, and specific surface area 175 to 250m2/g. , The pore volume is about 0.50 mL/g and the pore size is 3 to 6 nm. The product has a pore volume of 0.7 to 1 mL/g, a pore size distribution of 10 to 50 nm, and a maximum pore diameter of 40 nm. It is a superior product with a variety of uses.
Third, acid production of pseudoboehmite. To the solution of aluminum trichloride (or aluminum sulfate) is added ammonia (or sodium hydroxide, sodium carbonate, etc.) as a precipitant, and pseudoboehmite is obtained by precipitation, filtration, washing and drying. Alumina was prepared using aluminum chloride and ammonia as raw materials, focusing on the effects of neutralization temperature, pH, concentration of reactants, and aging conditions on the pore structure. The advantage of this production method is that it can produce pseudoboehmite with high pore volume and high specific surface area. The disadvantage is that the cost of the pseudoboehmite produced is higher.
Fourth, the production of pseudo-boehmite by the double aluminum method. The so-called "dual aluminum method" uses aluminum sulfate and sodium meta-aluminate in co-current reaction to produce pseudo-boehmite. The macroporous pseudoboehmite and alumina were prepared from aluminum sulfate and sodium metaaluminate. The battle group studied experimental conditions such as raw material concentration, reaction temperature, pH, aging time, aging temperature, and water washing. The pore volume, specific surface area and pore size of the pseudoboehmite prepared by the expansion test are all better than those of the alkali method. Double aluminum method to prepare pseudo-boehmite, than the alkaline method of acid, acid than the provincial law, low cost, is a widely used method at home and abroad