Method of preparation of microspherical alumina carrier

 

(57) Abstract:

The invention relates to the field of preparation of microspherical alumina carriers for catalysts. The method consists in the preparation of a carrier for catalysts for petrochemical processes by hydration, drying and calcination product of thermochemical activation of the three-hydrate of alumina, and the product of thermochemical activation add 18-35 wt.% water temperature 15-30oC, the resulting mixture was placed in a dryer with a temperature of 80-150oFrom and after drying annealed at 550-950oC. Technical result: get wear-resistant porous microspherical media with a bulk density of 0.8-1.0 g/cm3. table 1.

The invention relates to methods of preparation of microspherical alumina carriers for catalysts.

The purpose of the invention to provide an economical method of wear-resistant microspherical alumina carrier with a developed specific surface area and pore structure.

The known method [Jacobsville J. R., Kurkova N. With. Forming microspheric and ball adsorbents and catalysts based on activated alumina. M: Zhitenev is rockside aluminum, precipitated from the sodium aluminate. The disadvantages of this technology include the presence of hazardous wastes, the need for initial dissolution technical three-hydrate aluminum oxide (TGA), re-precipitation and washing of the precipitate. In addition, significant energy consumption for evaporation of water in the spray drying of the suspension.

From a number of disadvantages of the above-mentioned method can be eliminated if you use the product fast dehydration, so-called thermochemical activation (THA) technical three-hydrate of aluminum oxide. [Zolotovskiy bpts, Buyanov, R. A. and other technology Development and production of spherical alumina carriers, adsorbents and catalysts // Journal of applied chemistry. 1997, T. 70, vol. 2, S. 299-305]. Thermochemical activation is carried out at a temperature of 400-800oWith in a few seconds, followed by rapid cooling of the material. Product THA is an oxide-hydroxide metastable state of matter with high reactivity. Before spray drying is conducted mechanochemical activation product THA and then hydration in the presence of nitric acid for two hours. The prepared suspension was processed CLASS="ptx2">

After annealing the dried powder obtained microspherical alumina material, which, unfortunately, cannot be used as a carrier for catalysts, because it has a low durability, low bulk density of 0.6-0.7 g/cm3), so the catalysts based on it easily abraded and are carried by the gas stream from the reactor.

The invention is aimed at simplifying technology and reducing energy intensity of a process for increasing the bulk density of the carrier to 0.8-1.0 g/cm3and increase its durability.

The invention consists in mixing the product with THA sufficient to fill the pores with plenty of water, part of which then (at a temperature of 80-150oC) spent on incomplete hydration of the product THA. Simultaneously during drying due to evaporation of the remaining water is removed, so it isn't complete hydration of the product, which would lead to the weakening and destruction of the microspherical particles of the product THA. Dried hydrated product is calcined at a temperature of 550-950oC.

The invention is illustrated by the following examples (see table).

EXAMPLE 1. 100 g of the product THA (bulk p is wt.%) at room temperature, mixed with 25 cm3of distilled water. The temperature of the resulting mixture 23oC. the Wet mixture is placed in an oven heated to 150oC, kept at this temperature for 2 hours and calcined at a temperature of 720oC. According derivatographic and x-ray phase analysis of the hydrated and dried product THA represents, basically, pseudoboehmite, which at 550oWith goes-Al2O3. The physical properties of the thus obtained carrier is shown in the table.

Durability carriers was estimated using standard MRP-1M for determining the mechanical strength of the catalysts according to the technical description of the AIF 2.769.001 and instructions for its operation. The wear resistance was calculated as the ratio, in percent, of the contents remaining after abrasion fractions larger than 63 microns to fractions of larger than 63 microns in the original product to abrasion. If ignited the UN-hydrated alumina trihydrate (example 2) or THA product (example 3), then we obtain the media with very low mechanical strength.

In examples 4-6, the media was prepared analogously to example 1, but changed the amount of added water, the temperature WEEE 18 wt.%, example 4) the hydration and hardening of microspherical particles are negligible and the durability of the carriers is reduced. When excess amounts added to the product THA water (more than 35 wt.%, example 5) durability of the medium is also reduced because of too deep hydration product. If drying the wet mass is carried out at a temperature below 80oWith the water evaporates relatively slowly, the hydration product manages to go deeper than necessary, and the durability of the medium is also reduced.

The carriers obtained according to the prototype by mechanochemical activation product THA, hydration in the presence of nitric acid, spray drying the suspension on pilot equipment Ishimbay specialized chemical plant of catalysts and calcination of the dried microspheres at 720oC for 6 hours, were light and flimsy (example 7).

In example 8 for comparison, physical properties and, in particular, the durability of imported carrier for catalyst for oxychlorination process used in JSC "caustic".

Method of preparation of microspherical alumina carrier for catalysts neftekhimiches is luminia, characterized in that the product of thermochemical activation add 18-35 wt. % water with a temperature of 15-30oC, the resulting mixture was placed in a dryer with a temperature of 80-150oFrom and after drying annealed at 550-950oC.

 

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