Preparation And Application Of Microspherical Alumina-based Supports By Spray Scattered-oil Drop Method

Hydrogen peroxide is a kind of important fine chemical,the main preparation technology of industrialization has a fixed bed and fluidized bed process,the current international is given priority to with fluidized bed process,the restriction of the key technologies is still stay in a fixed bed process.Due to fluidized bed process of mass transfer performance and the reactant conversion efficiency higher advantages,it will be the mainstream of anthraquinone hydrogen peroxide process of legal system development direction.In the fluidized bed technology,micro spherical catalyst carrier and size distribution is one of the key elements,our country is still lack of relevant key preparation technology.Therefore,the research on micro spherical alumina carrier controllable preparation technology,not only for building our country independent intellectual property rights of hydrogen peroxide fluidized bed technology foundation,and for other important fine chemical products of controllable preparation of fluidized bed catalyst to provide important reference and reference.The fixed bed process with spherical alumina carrier(Φ 2.2-3.0 mm)for alumina sol oil column with the effects of the coagulant molding technology preparation,the spherical degree is high,the surface smooth,excellent pore structure and high mechanical strength,but forming mechanism can’t preparing micron grade spherical alumina carrier,and spray drying technology is suitable for the preparation of micron grade spherical particles,the particle size distribution wide,into a ball rate is low,the rough surface and low in mechanical strength.Therefore,this paper based on the oil column forming technology and spray drying technology advantages and disadvantages,put forward a new kind of alumina base microspheres particle preparation method-"spray scattered-oil drop",is a mixture of alumina sol and coagulant in the form of spray dispersion in shape in the hot oil column,the preparation of series micro spherical alumina carrier,the method of doped silicon sol in the alumina sol preparation series micro spherical SiO2-Al2O3 composite oxide carrier.Adopted series of modern analytical characterization methods for the preparation of alumina micro spherical carrier material of crystal structure,morphology,pore structure and surface properties,its catalytic properties of palladium catalyst on the target elements such as a detailed inspection,mainly carried out the following two aspects of research work.(1)With spray scattered-oil drop method displayed series micro spherical alumina carrier,investigated the effect of roasting temperature on the carrier structure.The results show that the particle size distribution of the carrier are mainly concentrated in 45～450 microns,with high sphericity,smooth surface and the characteristics of high wear resistance.Roasting temperature from 600 to 1200 ℃,micro spherical aluminum oxide crystal by gamma Al2O3 into the delta-Al2O3 and into the alpha Al2O3,its specific surface area and entrance decreases gradually,the aperture increases gradually,acid center intensity basically remain unchanged,acid center number decreased significantly.In addition,in a micro spherical delta-Al2O3 as the carrier,micro spherical Pd/Al2O3 catalysts prepared using impregnation method,focuses on the carrier size of Pd/Al2O3 catalyst structure and the influence of the fluidized bed anthraquinone hydrogenation.The results showed that 45℃75 microns size range dispersion was 21.5%,the activity of the catalyst components in the fluidized bed anthraquinone hydrogenation reaction showed higher hydrogenation efficiency and selectivity,the hydrogenation efficiency can reach 11.5 g · L-1,selective greater than 97.5%.(2)With spray scattered-oil drop method prepare Si02 doping modification series micro spherical alumina carrier,the research content of Si02 and roasting temperature on the influence law of the structure.Results show that the introduction of SiO2 can improve the thermal stability of the micro spherical alumina performance,with the increase of Si02 content,specific surface area of the micro spherical SiO2,Al2O3 and entrance are gradually increasing,aperture decreases,acid center intensity change is not obvious,acid center number increased significantly.In addition to the roasting of 960 ℃,micro spherical Si02,Si02 carrier for the preparation of Pd catalyst,focuses on the Si02 content on the micro spherical Pd/Si02,SiO2 catalyst structure and the influence of the fluidized bed anthraquinone hydrogenation.Results show that when the SiO2 content of 6%,micro spherical Pd/Si02,Si02 catalyst active component of dispersion is 27.9%,in the fluidized bed anthraquinone hydrogenation reaction show better hydrogenation efficiency and selectivity,the hydrogenation efficiency can reach 12.5 g · L-1,selective greater than 98.3%.