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ActivatedAlumina Catalyst Support
载体用活性氧化铝
载体用活性氧化铝为白色、球状多孔性物质、无毒、无臭、无味、不粉化、不溶于水、乙醇。远影载体用活性氧化铝微孔分布均匀，孔径大小适宜，孔容大，吸水率高，堆积密度小，机械性能好，具有良好的稳定性，适合做催化剂载体。
氧化铝已发现存在至少8种以上的形态，即α- Al2O3，θ-Al2O3，γ- Al2O3，δ- Al2O3,η- Al2O3,χ- Al2O3，κ- Al2O3和ρ- Al2O3型，其各自宏观结构性质也不尽相同。γ-Al2O3为立方紧密堆积晶体，不溶于水，但能溶于酸和碱。γ- Al2O3载体是偏弱酸性的载体，具有高的熔点2050℃，其水合物形式存在的氧化铝凝胶可制成高比表面积、高孔隙率的氧化物，在很宽的温度范围内存在过渡相。在温度较高时，Al2O3表面由于脱水和脱羟基出现了配位不饱和的氧（碱中心）和铝（酸中心），具有催化活性。因此，氧化铝可用做载体、催化剂以及助催化剂。
被称为“活性氧化铝”的γ-Al2O3是一种多孔性、高分散度的固体材料，因其具有孔结构可调、比表面积大、吸附性能好、表面具有酸性和热稳定性好等优点，其微孔表面具备催化作用所要求的特性，因此成为化工和石油工业中最广泛应用的催化剂或催化剂载体和色层分析载体，在石油加氢裂化、加氢精制、加氢重整、脱氢反应及汽车尾气净化等反应过程中发挥着重要作用。
由于γ-Al2O3载体的孔结构、表面酸性等性质的可调性，γ-Al2O3载体被广泛应用于催化剂载体领域。γ- Al2O3被用作载体时，除可以起到分散和稳定活性组分的作用外，还可提供酸、碱活性中心，与催化活性组分起到协同作用。催化剂的孔结构、表面性质均取决于γ-Al2O3载体，因此通过掌握γ-Al2O3载体性质的可调变规律就可制备出适合特定催化反应的高性能载体。
ActivatedAlumina Catalyst Support is a white, spherical porous material, non-toxic,odorless, not powdering, insoluble in water and alcohol. Yuanying Activated Alumina Catalyst Support has even micro-holes,appropriate aperture size, big pore volume, high water absorption, small bulkdensity, good mechanical properties, good stability, suitable for catalystsupport.
Aluminahas been found to exist at least 8 form, they are α- Al2O3, θ-Al2O3, γ- Al2O3,δ- Al2O3, η- Al2O3, χ- Al2O3, κ- Al2O3 and ρ- Al2O3, their respectivemacroscopic structure properties are also different. Gamma -Al2O3 is a cubicclose packed crystal, insoluble in water, but soluble in acid and alkali. GammaAl2O3 carrier is weak acidic support, has a high melting point 2050 ℃, alumina gel in hydrate form can be made into the oxide withhigh porosity and high specific surface, it has transition phases in a widetemperature range. At higher temperature, due to dehydration anddehydroxylation, the Al2O3 surface appears coordination unsaturated oxygen(alkali center) and aluminum (acid center), with catalytic activity. Therefore,alumina can be used as support, catalyst and cocatalyst.
γ-Al2O3, was called “ activated alumina”, is a kind of poroushigh dispersion solid materials, because of its adjustable pore structure,large specific surface area, good adsorption performance, surface with theadvantages of acidity and good thermal stability, microporous surface withrequisite properties of catalytic action, therefore become the most widely usedcatalyst, catalyst carrier and chromatography carrier in the chemical and oilindustry, and plays an important role in the oil hydrocracking, hydrogenationrefining, hydrogenation reforming, dehydrogenation reaction and automobileexhaust purification process.
γ-Al2O3 is widely used as catalyst support because of theadjustability of its pore structure and surface acidity. When γ- Al2O3 is usedas a carrier, besides can have the effects to disperse and stabilize activecomponents, also can provide acid alkali active center, synergistic reactionwith the catalytic active components. The pore structure and surface propertiesof catalyst depend on γ-Al2O3 support，so high performance support would be found for specificcatalytic reaction by controlling the properties of γ-Al2O3 support.
GammaAl2O3 is generally made of its precursor pseudo-boehmite through 400 ~ 600℃ high temperature dehydration, so the surface physicochemicalproperties is largely determined by its precursor pseudo-boehmite, but thereare many ways to make pseudo-boehmite, and different sources of pseudo-boehmiteleads to the persity of gamma - Al2O3. However, to those catalysts withspecial requirements to alumina support, only rely on the control of precursorpseudo-boehmite is difficult to achieve, must be taken to prophase preparationand post processing combining approaches to adjust the properties of alumina tomeet different requirements. When the temperature is higher than 1000 ℃ in use, alumina occurs following phase transformation: γ→δ→θ→α-Al2O3, among them γ、δ、θ are cubic close packing, the difference only lies in thedistribution of aluminum ions in tetrahedral and octahedral, so these phasetransformation does not cause much variation of the structures. Oxygen ions inalpha phase are hexagonal close packing, aluminum oxide particles are gravereunio, specific surface area declined considerably.
Application
(1)The Co-Mo sulfur-resistant shift catalysts produced by Activated AluminaCatalyst Support has good low-temperature activity, width working temperature,short vulcanization time and other merits, it is applicable to small and mediumsized ammonia factory.
(2)In the natural gas and petrochemical refining industrial process, to thehydrogen sulfide, can use activated alumina as catalyst for sulfur recovery.
(3)The most widely application for activated alumina catalyst support ishydrotreating, it can raise H/C ratio and get rid of O, S, N, finally canremove V, Ni and other contaminants.
(4)Another application for the activated alumina catalyst support is automobileexhaust catalyst, it can promote the oxidation of hydrocarbons, carbon monoxideand nitric oxide in exhaust gas, reduce air pollution.
(5)In the petroleum hydrocracking, hydrogenation refining, hydrogenationreforming, drogenation reaction and automobile exhaust purification process,activated alumina catalyst support plays an important role.
(6)Used for Alcohol dehydration, olefin isomerization, hydrogenation, oxidationand polymerization.