SU663695A1 - Method of obtaining polyvinyl molybdate - Google Patents

Description

(54) METHOD FOR OBTAINING POLYVINYLMOLIBDAT Polyvinyl molybdate obtained by a similar procedure cannot be used as a catalyst for the epoxidation process due to its low content of polybdenum and the presence of acid residues and sodium ions in its composition. The use of polyvini molybdate in is unknown, as a catalyst for any processes. The closest technical solution is the method of obtaining polyvinyl molybdate by the interaction of polyvinyl alcohol with molar 5-containing solution 4. At the same time, the polymer and products based on it (plates, packaging forms, foamed blanks) have water resistance, as well as bactericidal activity and stable color. Therefore, the existing methods for producing polyvinyl molybdates correspond only to the above objectives. The procedure for their preparation is as follows. An aqueous solution of polyvinyl alcohol or derivatives is treated with an aqueous solution of a metal salt at a certain pH of the medium. The metal content of the polymer obtained exceeds 5%. The aim of the invention is to provide polyvinyl molybdate with a high content of polybdenum for use as a catalyst in olefin epoxidation processes. This goal is achieved by describing & m the method of obtaining polyvinyl molybdate by reacting polyvinyl alcohol in the form of granules with a solution of molybdenum in a mixture of ethyl alcohol and organic hydroperoxide. Distinctive features of the method are the use of polyvinyl alcohol in the form of granules and its treatment with a solution of molybdenum in a mixture of ethyl alcohol and organic peroxide hydroxide. The technology of the method is as follows. Granulated polyvinyl alcohol that interacts with ylibdenode dissolving soluble in a mixture of hydroperoxide and alcohol. First, a molybdenum-containing solution is prepared by mixing the metallic molyden with ethanol and hydroperoxide at 55-б® С until the molybdenum is completely dissolved. Then polyvinyl alcohol is introduced and the temperatures are raised to. The resulting product is filtered and dried. Example 1. A catalyst is prepared by dissolving 1 g (0.01 mol) of powdered metallic molybdenum in a mixture consisting of 120 g (2.6 mol) of ethanol and 80 g. 20% aqueous solution of ethylbenzene hydroperoxide in ethylbenzene (0.116 mol). The mixture is stirred for 5 hours at 5 5-60 s until the molybdenum is completely dissolved. Then, 15 g of granulated polyvinyl alcohol (0.38-10 mol) is introduced into the solution, the temperature is raised to 80 ° C and stirred for 2.5 g. The particle size of polyvinyl alcohol is 0.2 mm, the molecular weight is 40000. The resulting Polyvinyl molybdate filtered and sucked out. The molybdenum content in sample 1 is 6.6 wt.%. EXAMPLE 2 A catalyst is prepared by dissolving 1 g of powdered molybdenum in a mixture consisting of 100 g (2.18 mol) ethyl alcohol and 80 g of a 40% tert-butyl hydroperoxide solution in isobutane (0.355 mol). After stirring for 3 hours at 60 ° C, 10 g (O, 210 mol) of polyvinyl alcohol are introduced into the solution, the particle size is 0.15 mm, the molecular weight is 50,000. The mixture is heated to 75 ° C, stirred for 2 hours, then cooled, the catalyst is filtered off and dried. The molybdenum content in sample II is 10 wt.%. Example 3. The catalyst is obtained by dissolving 1.5 g (0.016 mol) of molybdenum powder in a mixture of 120 g (2.6 mol) of ethanol and 120 g of a 30% aqueous solution of cumene hydroperoxide in isopropyl benzene (0.25 mol). Subsequent operations are similar to those described in example 2. The molybdenum content in the sample of catalyst III was 15 wt.%. Examples 4-7, summarized in Table 1, show the use of the obtained samples of polyvinyl molybdate (1, 11 and III) as a catalyst for the epoxidation reaction of cyclohexene (4.1 g or 0.05 mol) with ztirybenzene peroxide (1.36 g or , 01 mol) in rastv-, thief ethylbenzene (23 g or 0.22 mol) at 70 ° C. The reaction is carried out in a glass thermostatted glass reactor equipped with a magnetic stirrer. After completion of the reaction, the catalyst is filtered off and its molybdenum content is determined. In all cases, it has not changed during the process.

In Examples 8-11, summarized in Table 2, catalyst samples were tested in an epoxidation reaction carried out in a flow tube glass reactor with a diameter of 10 mm. The reaction mixture, consisting of cyclohexene (82 g or 1 mol), ethylbenzene hydroperoxide

(70 g or 0.51 mol) and ethylbenzene. (400 g or 3.8 mol) is passed through the reactor at a rate of 20 ml / h. Temperature of 80 ° C, the reactor thermostatic over the entire length (25 cm). Analysis of molybdenum shows that molybdenum is not washed out during the reaction.

table 2

 After 100 hours of continuous operation.

As can be seen from these 4-11 preservatives, polyvinyl molybdate has a catalytic activity exceeding the catalyst activity, despite the fact that the selectivity and conversion values were obtained at a temperature of 70 ° C, rather than 100 ° C (Table 1). In addition, polyvinyl molybdate, unlike the existing heterogeneous epoxidation catalysts, does not lose its high catalytic activity with long-term use (Table 2).

Claims (4)

1. US patent 3634464, cl. 260-348.5 L, 1969. 2. The patent of Germany 2015543, cl. 1265/05, 1970. 3. US Patent 3518242, cl. 260-91.3, 1970. 4.Konovalova G.I. et al. Thermal stability of polyvinyl alcohol compounds with some metals. M., Plastics, 1960, 7, pp. 42-44.