γ-Al2O3 as catalyst carrier, the market demand is great.   80% of γ-Al2O3 is used as catalyst or catalyst carrier In all kinds of hydrogenation and reforming reaction in petrochemical industry.  Therefore, it is hoped that the prepared γ-Al2O3 powder has high specific surface area, pore volume and appropriate pore size and distribution.  However, in the past for a long time, people have spent a lot of  attention  on improving the specific surface area of γ-Al2O3 carrier, but the pore structure has been neglected.  In recent years, people began to realize the importance of suitable pore structure for the performance of carrier, and with the development and research of Al2O3 carrier, people put forward new requirements for the pore structure of Al2O3  carrier.  The pore size of catalyst carrier can provide reaction channels for reactants and their products, and affect the reaction speed and efficiency.  Therefore, the pore structure of catalyst support is particularly important, but there are few reports on the pore structure control.  At present, the main method is to add water-soluble organic compounds as surfactants, use its induction and self-assembly to form the network structure, and finally remove the organic compounds by calcination to achieve the purpose of regulating the carrier pore structure.  Commonly used organic matter has polyethylene glycol, poly (ethylene oxide), but these organic matter is expensive.  

Alumina is a dehydrated product of aluminium hydroxide.  All kinds of aluminum hydroxide  will  form a series of homogenous vision body (mainly is oxygen and aluminum atoms stack space ways and different moisture content) by pyrolysis, the homogenous vision, some are dispersed phase, some assumes the transition state, but when the heating temperature over 1000 ℃ above, they are transformed into the same stable end product - real anhydrous alumina, called alpha alumina,  Therefore, both of them are considered as intermediate transitional forms of alpha alumina.  According to their generation temperature can be divided into low temperature alumina and high temperature alumina two categories.  (1) The chemical composition of low temperature alumina Al2O3•nH2O, is the  various aluminum hydroxide dehydration product at the temperature of not more than 600℃, which belongs to this category of ρ-, χ-, γ- and η alumina four.  (2) High temperature alumina high temperature alumina is almost anhydrous alumina, which is generated at the temperature between 900~1000℃ and belongs to this category of κ-, δ-, θ -Al2O3.  The most widely used in catalysis is γ -Al2O3, which called activated alumina.