E waru ngā āhua o te Alumina, arā, ko te α-Al2O3, θ-Al2O3, γ-Al2O3, δ-Al2O3, η-Al2O3, χ-Al2O3, κ-Al2O3 me te ρ-Al2O3. He rerekē anō hoki ō rātou āhuatanga hanganga whānui. He tioata kapi pūtoru te alumina whakahohe gamma, kāore e wairewa i te wai, engari e wairewa ana i te waikawa me te kawakore. He ngoikore te tautoko waikawa o te alumina whakahohe gamma, he teitei te ira rewa 2050 ℃, ka taea te hanga i te kirikiri alumina i roto i te āhua waikura he nui te porosity me te mata motuhake teitei, he whānui ngā wāhanga whakawhiti i roto i te awhe pāmahana. I te pāmahana teitei ake, nā te maroke me te tango waikawa, ka puta te mata Al2O3 i te hāora kore-mākū (pokapū kawakore) me te konumohe (pokapū waikawa), me te mahi whakateretere. Nō reira, ka taea te whakamahi i te alumina hei kawe, hei whakateretere me te kaiwhakatere tahi.
Ko te alumina whakahohe gamma he paura, he kirikiri, he rīpene, he aha atu rānei. Ka taea e mātou te mahi i tāu e hiahia ana. Ko te γ-Al2O3, i huaina ko te "alumina whakahohe", he momo rauemi totoka marara nui, nā te mea he hanganga pore ka taea te whakarite, he whānui te horahanga mata motuhake, he pai te mahi adsorption, he mata he painga o te waikawa me te pumau wera pai, he mata microporous me ngā āhuatanga e hiahiatia ana mō te mahi catalytic, nō reira ko ia te kaitahuri, te kawe kaitahuri me te kawe chromatography e whakamahia whānuitia ana i roto i te umanga matū me te hinu, ā, he mahi nui tana i roto i te hydrocracking hinu, te whakamahine hydrogenation, te whakahou hydrogenation, te tauhohenga dehydrogenation me te tukanga purenga hau motuka. He whānui te whakamahinga o te Gamma-Al2O3 hei kawe kaitahuri nā te mea he taea te whakarite i tōna hanganga pore me te waikawa o te mata. Ina whakamahia te γ-Al2O3 hei kawe, i tua atu i te whai pānga ki te marara me te whakau i ngā wāhanga hohe, ka taea hoki te whakarato i te pokapū hohe waikawa kawakore, te tauhohenga tahi me ngā wāhanga hohe catalytic. Ko te hanganga o ngā pūwero me ngā āhuatanga o te mata o te whakakōkī e whakawhirinaki ana ki te kaikawe γ-Al2O3, nō reira ka kitea he kaikawe mahi teitei mō te tauhohenga whakakōkī motuhake mā te whakahaere i ngā āhuatanga o te kaikawe gamma alumina.
Ko te alumina whakahohe gamma he mea hanga i tōna pseudo-boehmite mua i roto i te whakamaroke pāmahana teitei 400~600℃, nō reira ko ngā āhuatanga ā-tinana me te matū o te mata e tino whakatauhia ana e tōna pseudo-boehmite mua, engari he maha ngā huarahi hei hanga pseudo-boehmite, ā, ko ngā pūtake rerekē o te pseudo-boehmite ka arahi ki te kanorau o te gamma – Al2O3. Heoi, ki aua whakakorikori he whakaritenga motuhake ki te kawe alumina, he uaua ki te whakatutuki i te whakawhirinaki noa ki te whakahaere o te pseudo-boehmite mua, me kawe ki te whakarite prophase me te tukatuka i muri i ngā huarahi whakakotahi hei whakatika i ngā āhuatanga o te alumina kia tutuki ai ngā whakaritenga rerekē. Ina teitei ake te pāmahana i te 1000 ℃ i te whakamahinga, ka puta te alumina i muri i te huringa wāhanga: γ→δ→θ→α-Al2O3, i roto i a rātou ko te γ、δ、θ he takai tata cubic, ko te rerekētanga anake kei roto i te tohatoha o ngā katote konumohe i roto i te tetrahedral me te octahedral, nō reira kāore ēnei huringa wāhanga e puta ai he rerekētanga nui o ngā hanganga. He tata te takai o ngā katote hāora i te wāhanga ārepa ki ngā taha hexagonal, he nui te huihuinga o ngā matūriki waikura konumohe, ā, kua tino heke te horahanga mata motuhake.
Āraia te makuku, karohia te panuku, te whiu me te ru koi i te wā e kawe ana, me whakarite he wāhi ātete ua.
Me rongoa ki roto i te whare putunga maroke, kia pai ai te hauhautanga hei ārai i te poke, i te makuku rānei.
