SU1691299A1 - Method of producing double phosphate of titanium and magnesium - Google Patents

Abstract

The invention relates to methods for producing titanium and magnesium double phosphate, which can be used as a filler, adsorbent, catalyst, for example, in the dehydration of cyclohexaiol to obtain cyclohexene. The aim of the invention is to increase the salt specific gravity and, consequently, to increase its catalytic activity. The method consists in the interaction of solutions of salts of titanium, magnesium and phosphoric acid, fed continuously into the reactor together with the precipitating solution of ammonia. The process is carried out at a temperature of 60-70 ° C, the pH is 4-5 and continue for 20-30 minutes. The molar ratio of the reagents TI4 +: Mg2 + P043 1: (1.5-2.0). (3-5). The precipitate obtained is filtered off from the mother liquor, washed and dried, the C / substantial distinctive i. To VH is the continuity of the process, and the H medium and the duration of the interaction. The resulting product of composition (ROF-ZN20 has a specific surface area of at least 230 m2 / g. 2 tab. C / 1 C

Description

The invention relates to methods for producing titanium and magnesium double phosphate, which can be used as a filler, adsorbent, catalyst, for example, in the dehydration of cyclohexanol to obtain cyclohexene.

The aim of the invention is to increase the specific surface of the salt and, consequently, to increase its catalytic activity.

EXAMPLE 1. A solution of 0.1 M ammonium titanium sulphate salt heated to 60 ° C, 0.5 M magnesium acetate salt solution and 50% orthophosphoric acid are continuously fed into the reactor, where 1 M ammonia solution is simultaneously supplied. the ratio of Ti4 +: Mg2 +: P043 is 1: 1.5: 3. Served

the components in the reactor were constantly stirred. The preset pH of the medium in the reactor, equal to 4.0, was maintained by controlling the flow rate of ammonia. Formed from the pulp by gravity flow to the filter at a rate determined by the residence time of the precipitate in the reactor for 20 minutes. The solution is filtered, the precipitate is washed and dried. The finished product composition corresponds to the formula TiMg () 2-3H20. The specific surface area of double phosphate is 235 m2 / g.

Examples 2-15. Carried out analogously to example 1, the difference in the conditions of the cooling process.

In tab. 1 presents the data obtained in examples 1-15, of which type ™ l

Yu

 YU

However, the implementation of the process below 60 ° C does not allow to obtain an individual double phosphate due to the low speed of the process. At temperatures above 70 ° C, titanium hydroxides are formed due to hydrolysis.

The preparation of titanium double phosphate and magnesium is carried out at pH 4-5. At a lower pH, the complete precipitation of magnesium is not achieved and a mixture of double phosphate and acid titanium phosphate is observed in the products. Increasing the pH leads to precipitation of the individual basic magnesium phosphate. The presence of acidic and basic phosphates in the whole product reduces their specific surface.

The interaction time of 20-30 minutes ensures the formation of double phosphate with a high specific surface. An increase in the interaction time leads to sediment aging — the interaction of the precipitate with the mother liquor, which reduces the sample surface due to aggregation and coarsening of the particles. When interacting for less than 20 minutes, products of non-stoichiometric composition are formed.

When compounds of magnesium and orthophosphoric acid are added in quantities lower than recommended, individual double phosphate is not formed. When the quantities of these components are greater than the recommended, more ammonia consumption is required.

When carrying out a continuous process, conditions are created that ensure the constancy of the molar ratio between the components

ponents of both liquid and solid phases, which allows reducing the time of interaction. When the process is carried out periodically, the concentration of the components in the solution changes as the precipitate forms, which leads to the formation of a product of unstable composition.

Claims (2)

The data table. 1 show that the implementation of the process of obtaining double phosphate of guitar and magnesium by the proposed method in comparison with the prototype reduces the interaction time by 100 times and increases the specific surface of the product by 20%, which provides an increase in catalytic activity in relation to the reaction of cyclohexanol to cyclohexene . Comparative data for this process are given in table. 2. The invention of the method for producing titanium and magnesium double phosphate by reacting aqueous solutions of titanium, magnesium and phosphoric acid salts in the presence of ammonia and acetate ions at a temperature of 60-70 ° C, followed by filtration, washing and drying the precipitate, characterized in that In order to increase the specific surface of the salt and, consequently, increase its catalytic activity, the interaction of aqueous solutions is carried out by continuously supplying reagents with a ratio of Ti +: Mg2 +: P043 equal to 1: (1.5-2.0) :( 3-5 ), pH 4-5, and Wed It reacting 20-30 min duration. The method of the prototype Table I y 200 200 200 200 200 250 250 250 250 250 250 T a b l n c a 2 51 51 51 48 36 97 97 U7 97 92 88 98 98 97 94 90 100 100 98 97 95 94