SU765252A1 - Method of styrene production - Google Patents

Description

I

The invention relates to petrochemical synthesis, in particular, a method for producing styrene, a valuable monomer for the synthetic rubber industry. .

A known method for the production of styrene by the oxidative dehydrogenation of ethylbenzene in the presence of alkaline-weave metal pyrophosphate as a catalyst is l.

With this catalyst at 525-530 ° C and using nitrogen as a diluent, the conversion of ethylbenzene is 65.4%. The styrene yield does not exceed 60.2% with a process selectivity of 92.0%.

The disadvantages of this method are the necessity of carrying out the process in the presence of a diluent and the low yields of styrene.

The closest to the proposed technical essence is a method for the production of styrene by oxidative dehydrogenation of ethylbenzene at elevated temperature in the presence of

CHKIsnogo catalyst impregnated with o-phosphoric acid f2.

In the known method, alumina impregnated with 0.1-1.0 n is used as a catalyst. solution of o-phosphoric acid. The process is carried out in a flow system at 400-500 ° C and an ethylbenzene: air ratio of 1: 6. In this case, on the optimal catalyst at 50 ° C, the styrene yield is 64%

10 with a selectivity of 88%.

The disadvantages of this method are the relatively low yield of styrene and the low selectivity of the process.

The aim of the invention is to increase

15 bottom output of the target product.

This is achieved by the proposed method of producing styrene by oxidative dehydrogenation of ethylbenzene at elevated temperature in the presence of

Claims (2)

20 calcium oxide silicate catalyst impregnated with o-} Yusphoric acid, in the following ratio of components, in terms of oxides, weight. 3 CaO 6.3-6.4 SlOi. 83.0-84.0 8.7-10.7 The process is preferably done at 480-52 ° C. The consummation of the method is to use calcium silicate and catalysis as a catalyst for oxides. at the specified ratio of components. The process of oxidative cehydrogenation of ethylbenzene (EB) is carried out in a flow-type plant (a quartz reactor 2 cm in diameter, 40 cm long, 10 cm catalyst volume). The molar ratio of ethylbenzene: oxygen is 1: 1.5-2, the feed rate of ethylbenzene is 4-6 ml / h. Air is used as a source of oxygen. A calcium silicate catalyst is obtained by the co-precipitation method. 3.75 g of calcium chloride is dissolved in 300 ml of distilled water and 32 g of hydrochloric acid is added. The resulting solution is mixed with 1OO g of water glass dissolved in 4OO ml of water. The resulting hydrogel is left in 8OO ml 2 for 2 hours, ammonia solution, and washed with distilled water until chlorine ions are absent. The paste is kept for 24 hours at room temperature, then molded into small cylinders (3-5 mm long, 1-2 mm in diameter), 3 days. dried at room temperature and subjected to step calcination at 80.150.250, 450.550 ° С (2 hours each). The resulting catalyst is X-ray amorphous, has a specific surface of 270 m / g and the following chemical composition, wt.%: CaO + 7, $ LOi + 93. The resulting catalyst has a low reactivity in the oxidative dehydrogenation of ethylbenzene. For example, at 500 C, the ratio of E1): Og. equal to 1: 1.5 and a space velocity of 0; 5, styrene yield does not exceed 35.2% (per missed tilbenzene). Psiule of catalyst regeneration at 55 ° C in air flow, treatment with water vapor at 650 ° C and its impregnation 0.2-0.5 n. solution (in terms of 4 - 1O% phosphorus by weight of calcium silicate) styrene yield at 500 ° C reaches 66.7 - 67.0% with a selectivity of 89.5 - 91.6%. In the presence of synthesized carbonates and, under these conditions, the yield of liquid catalyzate is not less than 9 O% of the missed ethyl benzene, the amount of styrene is 64.1-69.6%, benzene O, .1-0.4%, toluene 0 , O-0.2% and CO2. 4, O6, 8%. Example 1. 6.0 g of calcium silicate consisting of 7% CaO and 93% StO are impregnated at room temperature with 135 ml of 0.2 N solution (4% phosphorus by weight of calcium silicate). After 48 hours, the resulting mass is dried at 3 hours. The catalyst has the following chemical composition, wt.%: CaO 6.4; $ LOi84.9 and 8.7. Example 2. 6.0 g of calcium silicate, consisting of 7% CaO and 93% SuO, are impregnated at 135 ml of 0.5 N at room temperature. HjPO solution (10% phosphorus by weight of calcium silicate). After 48 hours, the resulting mass is dried at 12 ° C for 3 hours. The catalyst has the following chemical composition, wt.%: CaO 6.3; 5102.83.0 The test results in the presence of catalysts of various compositions are given in the table. From the above examples, it is natural that the proposed method for the yield of styrene and the selectivity of the process exceeds the known one. At 480-520 ° C, the EBV ratio is from 1: 1.5 to 1: 2 and the space velocity is 0.4-0.6 and the styrene yield is 64.1-69.6% with a selectivity of 88.2-92.1 % The process is carried out without diluents, which simplifies the process technology and increases its productivity. The catalysts are cheap and readily available calcium silicates impregnated with an aqueous solution of o-phosphoric acid. Claim 1. Method for producing styrene by oxidative dehydrogenation of ethylbenzene at elevated temperature in the presence of an oxide catalyst impregnated with o-phosphoric acid, characterized in that in order to increase the yield of the target product, a calcium silicate catalyst is used as an oxide catalyst components in peruce and oxides, wt.%: CaO 6.3–6.4 SLOi 83.0–84.9 8.7–10.7 2. Method according to p. 1, I distinguish by the fact that the process is carried out at 480-520 ° C. Sources of information taken into account in the examination 1. US patent number 3957897, cl. C 07 S 5/48, published 1976. 2. USSR author's certificate number 308996, cl. C 07 C 15 / 1O, 1969 (prototype).