The Preparation And Modification Of Alumina Used As Carrier Of Catalysts

Catalyst is used more and more with the industry fast development. Catalyst plays a very important role that not only in speeds up the reaction rate which is in industry production, but also in waste gas cleans which is in environments protection. The carrier of catalyst plays an extremely vital part in catalyst. The carrier is a kind of material which loads catalyst. Its major function is that guarantees the catalyst's application and enhances the catalyst's using efficiency, on the other hand also preserves the intensity, heat-resisting, anti-corrosive and so on performance under the bad working conditions. Alumina is used widely in the industry catalyst's carrier.The paper takes the alumina synthesis and the modification as a starting point, prepares the different structure performance alumina through the reagent choice and the control of synthesis technological conditions. Then add different metal oxide compound to modify the product. Fanally prepare the single Pd catalyst with the constant volume impregnation. The analysis and the catalysis performance test methods include BET, XRD, TG-DTA, SEM, TPR and methane activeness test. The actual content is as follows:1. The research of alumina precursor. Prepared alumina precursor selected the ammonia water, the ammonium bicarbonate and six methyl radical tetramines as the precipitation agent precipitating aluminium nitrate. It showed that selected ammonia water as precipitation, we could get the alumina which had 406.582m²/g surface area, 0.4957cm³/g total pore volume and 24.3815m-10 average aperture. We would get the alumina which had 80.222m²/g surface area, 0.3684cm³/g total pore volume and 90.9381m-10 average aperture after calcinating at 1050℃. The dispersing agent selected the polyethylene glycol and the polyvinyl alcohol. The result showed the polyethylene glycol has a better scattered effect. We got that when the mass was 2wt% though prepared alumina chosed different mass of the polyethylene glycol, the alumina had best the best surface area and pore structure. The adjustment of pH was occurred durning preparing alumina. When pH<10.0, the alumina precursor and the alumina which calcinated at 1050℃had good performance.When pH>10.0, the alumina which calcinated at 450℃had good performance. When pH=10.0, the product synthesis situation is good.2. The dryness of alumina precursor. We could get the alumina which had different surface area by controlling the speed which was the alumina dryness elevation of temperature and the time of heat insulation. The analysis showed we could prepare the good performance alumina which calcinated at 450℃and 1050℃, when we used the fastest elevation of temperature speed and 3h heat insulation.3. We got complex substance, by adding La and Zr that had the allocated proportion to the response solution. The result was that the product had the maximum surface area and OSC could achieve 503.737μm/g, when the proportion of La and Zr was 2:1. The product had a general surface area, but had the maximum OSC after aging, when the proportion of La and Zr was 1:2.4. The alumina and the lanthanum zirconium compound were loaded the precious metal Pd. It showed that Pd/Al₂O₃ had serious agglomeration after calcinated at 1050℃, the other product which added La and Zr had anti-agglomeration ability. The Pd/Al₂O₃ had the best activation temperature in the fresh catalysts which calcinated at 700℃, and the product which had the proportion of La and Zr was 1:2 were worst. The product which the proportion of La and Zr was 2:1 had the best activation temperature and Pd/Al₂O₃ was worst after calcinated at 1050℃.