Chemistry water distillation. It is showin that the nature of amida The analysis of experimental data allows us to state ting agent determines the composition of reaction pro that the reaction of amination occurs through the con ducts: at amination of DA I with unsubstituted carbami nection of isocyante molecule, being a product of car de the main product is imide IVa, and at amination with bamide dissociation, to diphenic acid. Then a molecule substituted carbamides and amines the main products of СО2 is ejected from the intermediate acylurethane are corresponding monamides IIIbf. On the basis of ex and the corresponding monamide is formed, which is perimental data the mechanism of reaction is suggested. cyclized into imide, when losing a molecule of Н2О. REFERENCES 6. Bakibaev A.A., Yagovkin A.Yu., Vostretsov S.N. Methods of synthe 1. 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Arrived on 07.09.2006 UDC 541.128;547.239.2;547.292 PROCESS OF CATALYTIC SYNTHESIS OF ACETONITRILE FROM ACETIC ACID AND AMMONIA AT γAl2O3 O.I. Sidorova, S.I. Galanov, V.D. Filimonov* Tomsk State University Email: [email protected] *Tomsk Polytechnic University In the reaction of catalytic synthesis of acetonitrile from acetic acid and ammonia the influence of ratio of reagents, reactor temperatu re, addition of acetic acid, acetic anhydrite and acetamide into the reaction mixture of ethyl ether as well as catalyst promotion (γAl2O3) by phosphoric acid on the parameters of the process. Optimal conditions of the reaction are determined and the scheme of commercial prototype process is suggested. Acetonitrile is widely used in organic synthesis as an Synthesis of acetonitrile from acetic acid is perspecti intermediate reagent, solvent, azeotrope – forming at ve for realization owing to little consumptions for separa substances separation [1, 2], as well as at synthesis of tion and purification of a target product. Wellknown CNx nanotubes [3]. In industry acetonitrile is produced syntheses of acetonitrile from acetic acid and ammonia as a byproduct of acrylonitrile synthesis. Processes di [4–6] were carried out in tubular reactors with volume rected at target synthesis of acetonitrile become per velocity of acid supplying 0,3 h–1 or 0,008...0,060 mo spective because of increasing requirement of acetoni le/sec·l acetonitrile yield higher than 80 % was observed trile in petrochemical syntheses. Methods of at temperatures 440...480 °С. But carrying out the reac acetonitrile obtaining from ammonia and acetic acid, tions at above mentioned temperatures results in thermal alcohols, paraffins and olefines [4] are developed. pyrolysis of an acid and products of synthesis with cata Syntheses from alcohols, paraffins and olefines are cha lyst carbonizing and desired product – acetonitrile con racterized by insufficient selectivity and low process tamination, besides high expenditure of energy for reac productivity. Until recently none of methods of purpo tor heating. At high temperatures formation of seful acetonitrile synthesis is realized in industry. hydrocyanic acid is possible when using steel reactor. 145 Bulletin of the Томsк Pоlytеchnic University. 2007. V. 310. № 1 Synthesis process temperature decreasing to 350...380 °С de reactions decrease may be also reached by catalyst is perspective due to the fact that water vapor may be us promoting with admixtures of different nature. ed instead of furnace gases for reactor heating. Thus, the aim of the given paper is to examine the in а) Influence of reaction temperature and reaction mixture fluence of the following factors: variation of reagents ratio; composition reactor temperature; reaction mixture dilution; catalyst Reactor temperature increase higher than 400 °С al promotion on the catalytic synthesis reaction of acetoni lows obtaining acetonitrile high yield at large loads for trile from acetic acid. According to obtained regularities acetic acid, but at the same time a part of nontarget re to suggest optimal conditions for carrying out the reaction actions increases – decarboxylation of acetic acid to of acetonitrile with high productivity obtaining. acetone and СО2, and also sealing products formation on catalyst surface with its activity decreasing. After Experiments 5 hours of work at temperature 440 °С acetonitrile yield decreases from 98,5 to 91,5 %. Reaction temperature The investigations were carried out in a flow steel decrease to 350...380 °С allows to reduce significantly (12Х18Н10Т) reactor with reagents incoming flow at the amount of formed of compaction products (CP) prior heating of reaction mixture to reaction temperatu (from 0,19 at 400...450 °С to 0,04 at 350...380 °С) (tab re. Ratio NH :CH COOH varied in the range 1,5...5,0, 3 3 le) and to prolong the catalyst period of work. reaction temperature – 350...450 °С, load for acetic acid and acetamide 0,49...1,02 g/sm3·h. The presented In the given process catalyst carbonization starts from contact time was calculated as ratio of catalyst volume the initial part of catalyst layer in the coarse of reaction mix to volume velocity of steamandgas mixture at reaction ture, tail end of the layer is less and last carbonized. Probab temperature. Ethyl ether of acetic acid and acetic ly, it is connected with storage of water, generating during anhydride of «ch.p.» qualification were added into reac the reaction, in reaction gases and decrease of acetic acid tion mixture at 5 wt. %. The analysis of synthesis pro concentrationthe main source of CP. One of the methods of catalyst carbonization decrease may be water vapors in ducts (H2O, NH3, CH3COONH4, CH3CN, troduction into reaction mixture, but as it was mentioned in CH3CONH2, CH3COCH3, СН2О and НСN) was carri ed out chromatographically (chromatograph [6] use of diluted acetic acid results in decrease of acetoni LChM80) using sorbent Separon SDA, detector trile yield and catalyst productivity. Therefore it is justified katharometer, carrier gashelium. The percent of com to add into reaction mixture substances which would dec paction products (% CP) was determined as a ratio of rease rate of CP formation and at the same time participa generating sealing products to catalyst mass on 1 sm3 of te in reaction with target product formation, for example: 2 acetamide, ethyl acetate or acetic anhydride. transmitted acid. γAl2O3 (А64, Ssp=205 m /g, total vo 3 lume of pores is 0,68 sm /g) and γAl2O3 promoted with phosphoric acid of «ch.p.» qualification at the rate of Table. Influence of temperature and reaction mixture com 2...6 wt. % were used as catalysts. position on CP formation and productivity (P) of sample Reaction mixture Results and their discussion Т, °С % CP Acetonitrile yield, % Р composition Acetonitrile formation from acetic acid and ammo 400…460 СН3СООН 0,19 75,2 0,425 nia is equilibrium twophase reaction: СН3СООН 0,04 68,7 0,535 I CH3CONH2 0,03 80,7 0,489 CH COOH + NH←⎯⎯⎯⎯ ⎯→ CH CONH + 3332 CH3CONH2+NH3 0,03 97,8 0,643 II ⎯⎯⎯→ 350…400 95 % СН3СООН+ +H232 O←⎯ ⎯⎯ CH CN + 2H O (1) 0,02 83,1 0,546 5 % (СН3СО)2О 95 % СН СООН+ The calculation of thermodynamic functions and 3 0,73 67,5 0,215 equilibrium constant for phases I and II (scheme 1) gi 5 % СН3СООС2Н5 ven in the paper [7] showed that the reaction of aceta % CP is the percent of compaction products from catalyst weight mide formation from acetic acid and ammonia in the per 1 sm3 of feeding acid; Р is the acetonitrile productivity of cata range of temperatures 250...450 °С is weakexothermic lyst, kg/dm3.h (ΔН =–2,18 kJ/mole), Gibbs’s energy av Addition of ethyl acetate to acetic acid promotes high (Δ=–(3,56...4,22) kJ/mole) and equilibrium constant er coal deposit, in comparison with pure acetic acid (tab (C =2,76...2,26) change insignificantly in comparison eq le).