Alumina yapezeka kuti ilipo mitundu yosachepera 8, ndi α- Al2O3, θ-Al2O3, γ- Al2O3, δ- Al2O3, η- Al2O3, χ- Al2O3, κ- Al2O3 ndi ρ- Al2O3, mawonekedwe awo a macroscopic nawonso ndi osiyana. Alumina yoyambitsidwa ndi Gamma ndi kristalo wozungulira, wosasungunuka m'madzi, koma wosungunuka mu asidi ndi alkali. Alumina yoyambitsidwa ndi Gamma ndi yofooka yothandizira asidi, imakhala ndi malo osungunuka kwambiri a 2050 ℃, gel ya alumina mu mawonekedwe a hydrate imatha kupangidwa kukhala oxide yokhala ndi ma porosity ambiri komanso pamwamba pake, imakhala ndi magawo osinthira kutentha kwakukulu. Pa kutentha kwakukulu, chifukwa cha kuchepa kwa madzi m'thupi ndi dehydroxylation, Al2O3surface imawoneka ngati yogwirizana mpweya wosakwanira (pakati pa alkali) ndi aluminiyamu (pakati pa acid), yokhala ndi ntchito yothandiza. Chifukwa chake, alumina ingagwiritsidwe ntchito ngati chonyamulira, chothandizira komanso cocatalyst.
Alumina yogwiritsidwa ntchito ndi Gamma ikhoza kukhala ufa, granules, strips kapena zina. Tingachite monga momwe mukufunira. γ-Al2O3, yomwe imatchedwa "activated alumina", ndi mtundu wa zinthu zolimba zofalikira kwambiri, chifukwa cha kapangidwe kake kosinthika ka pore, malo akuluakulu apadera, magwiridwe antchito abwino a adsorption, pamwamba pake pali ubwino wa acidity ndi kukhazikika kwa kutentha, pamwamba pa microporous yokhala ndi mphamvu zofunikira za catalytic action, motero imakhala chothandizira kwambiri, chonyamulira cha catalyst ndi chromatography chonyamulira mumakampani opanga mankhwala ndi mafuta, ndipo imagwira ntchito yofunika kwambiri pakuphwanya mafuta, kukonza hydrogenation, kusintha kwa hydrogenation, reaction ya dehydrogenation ndi njira yoyeretsera utsi wa magalimoto. Gamma-Al2O3 imagwiritsidwa ntchito kwambiri ngati chonyamulira cha catalyst chifukwa cha kusinthasintha kwa kapangidwe ka pore ndi acidity pamwamba. γ-Al2O3 ikagwiritsidwa ntchito ngati chonyamulira, imathanso kufalitsa ndikukhazikitsa zinthu zogwira ntchito, komanso imatha kupereka acid alkali active center, synergistic reaction ndi zinthu zogwira ntchito za catalytic. Kapangidwe ka ma pore ndi mawonekedwe a pamwamba pa catalyst zimadalira chonyamulira cha γ-Al2O3, kotero chonyamulira champhamvu kwambiri chingapezeke kuti chigwiritsidwe ntchito poyang'anira mawonekedwe a chonyamulira cha gamma alumina.
Alumina yoyendetsedwa ndi Gamma nthawi zambiri imapangidwa ndi pseudo-boehmite yake yoyambirira kudzera mu 400~600℃ kutentha kwambiri, kotero mawonekedwe a physicochemical pamwamba pake amatsimikiziridwa kwambiri ndi pseudo-boehmite yake yoyambirira, koma pali njira zambiri zopangira pseudo-boehmite, ndipo magwero osiyanasiyana a pseudo-boehmite amabweretsa kusiyanasiyana kwa gamma - Al2O3. Komabe, kwa ma catalysts omwe ali ndi zofunikira zapadera kwa chonyamulira alumina, kudalira kokha kulamulira kwa pseudo-boehmite yoyambirira ndikovuta kukwaniritsa, kuyenera kutengedwa kukonzekera prophase ndi kukonza pambuyo pophatikiza njira zosintha mawonekedwe a alumina kuti akwaniritse zofunikira zosiyanasiyana. Pamene kutentha kuli kokwera kuposa 1000 ℃ mukugwiritsa ntchito, alumina imachitika pambuyo pa kusintha kwa gawo: γ→δ→θ→α-Al2O3, pakati pawo γ、δ、θ ndi cubic close packing, kusiyana kumangokhala pakugawa kwa ma ayoni a aluminiyamu mu tetrahedral ndi octahedral, kotero kusintha kwa gawo kumeneku sikuyambitsa kusintha kwakukulu kwa kapangidwe kake. Ma ayoni a okosijeni omwe ali mu gawo la alpha amakhala pafupi kwambiri, tinthu ta aluminiyamu oxide timalumikizananso kwambiri, ndipo malo enaake pamwamba amachepa kwambiri.
Pewani chinyezi, pewani kusuntha, kuponya ndi kugwedeza mwamphamvu panthawi yoyendera, malo osagwa mvula ayenera kukhala okonzeka.
Iyenera kusungidwa m'nyumba yosungiramo zinthu youma komanso yodutsa mpweya kuti isaipitsidwe kapena kunyowa.
