Carrying out thermodynamic calculations and definition of the main reactions of decomposition of vapours of ethyl alcohol

Transcription

1 Carrying out thermodynamic calculations and definition of the main reactions of decomosition of vaours of ethyl alcohol A I Sechin, O S Kyrmakova, T A Ivanova National Research Tomsk olytechnic university, 645, Tomsk, Lenin Avenue,, Russia olia_917@mail.ru Abstract. Thermodynamic oortunities of course of chemical reactions of decomosition of the vaors of ethyl alcohol necessary at develoment of devices where these reactions will take lace are considered. The entaliyny method of calculation of constants of balance of robable chemical reactions is given in the Excel editor. Indeendent reactions of rocess of oxidation are defined. By result of thermodynamic calculation of each reaction schedules of deendence of a constant of balance on environment temerature from which follows are constructed that one reactions roceed until the end of aside formation of the final roducts, and others are imrobable or imossible. The analysis of the received results shows that reactions of oxidation will successfully roceed in the established directions, and for an intensification of rocess of decomosition it is necessary to rovide a suly of some energy which quantity will be sufficient for oxidation of vaors of ethyl alcohol. Results of calculations showed good convergence with rograms of thermodynamic calculations like "Aster 4" and "TERRA". 1.Introduction Problem of ollution of atmosheric air one of the most serious global roblems which the mankind faced. Danger of ollution of the atmoshere that harmful substances get to clean air, ernicious for live organisms. Gravity of the environmental roblems connected with ollution of the atmoshere is illustrated by the following statistical data: only 15% of urban oulation of Russia breathe rather clean air. In 15 cities of the Russian Federation the exceeding maximum concentration limits of concentration of ollution of the atmoshere are annually fixed at 5-1 times [1]. Hit in it uncharacteristic hysical, chemical and biological substances in the course of activity of the erson is the main reason for air ollution. In the course of roduction of medicinal substances, there is a need of cleaning of organized emissions in environment of vaors of various organic substances which are emitted as in synthesis rocesses, and rocessings of a number of chemicals. The main share of ollution of the atmoshere belongs to drying rocesses. The dividing systems reresenting two-level cleaning of dust fractions most often dont rovide cleaning of a steam hase. There is a need of the solution of a question of cleaning of organized atmosheric emissions of vaors of organic chemistry. For successful fight against similar ollution it is necessary to know as hysical and chemical roerties of the substances deleted from roduction volume, and the thermodynamic oortunities of course of chemical reactions necessary at develoment of devices where these reactions will take lace. This work is also devoted to the thermodynamic analysis of chemical catalytic reactions of decomosition of vaors of ethyl alcohol and definition of the main reactions..calculated art The chemical thermodynamics considers interrelations between work and energy in relation to chemical transformations. As chemical transformation usually is followed by release or absortion of a certain amount of heat, it submits to the fundamental rinciles (beginnings) of thermodynamics. The chemical thermodynamics defines, first of all, conditions (such as temerature and ressure) courses Content from this work may be used under the terms of the Creative Commons Attribution. licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by Ltd 1

2 of chemical reactions and equilibrium states which they reach []. For carrying out thermodynamic calculations it is necessary from ossible reactions to define indeendent reactions of rocess of oxidation of ethyl alcohol. For calculation of thermodynamic arameters of rocess of oxidation of ethyl alcohol balance reactions were made: 1) С Н 5 ОН + О = СО + Н О; ) С Н 5 ОН С Н + Н ; ) С Н 5 ОН СН 4 + Н О + С; 4) С Н 5 ОН СН 4 + СО + Н ; 5) С Н 5 ОН С Н 4 + Н О; 6) С Н 5 ОН С Н + Н О + Н. Number of indeendent reactions equally to number of substances (С Н 5 ОН, О, СО, H O, С Н, Н, СН 4, С Н 4, С) in system minus number of diverse atoms (to Н, О, С) of which reagents are formed, i.e. the number of indeendent reactions is equal to six (9-=6) []. Therefore, all resented reactions are indeendent. Thermodynamic calculations were imlemented on a method of calculation of the balance [] considering deendence ΔН = f (Т), by means of which lgкр = f (Т), and ΔН, lgk in the range of temeratures 1 C are counted. Influence of temerature on a constant of balance is described by Vant Hoffs equation [4]. d ln K H dt RT () where, ΔН standard thermal effect of reaction; R universal gas constant; T temerature is К; Кр a balance constant. In case of exact calculation and at big temerature intervals the equation () considers deendence of thermal effect of reaction on temerature. For this urose we will substitute the equation C a b T c T () in the equation of the law of Kirchhoff [5]. Integrating, we will receive: in a final formula: d( H) dt C b T c T c H H a T (5) T T Combining the equation () with the equation (4) and integrating, we will receive the equation in technical system of coordinates: lg H a lg b T c T c K T T J. RT R. R.6 R. R According to the equation of an isobar of chemical reaction G RT ln K. RT lg K (6) T J G T. R J. H b T a T ln T c T 6 c T J T where, In the equations 6 unknown sizes are Δа, Δв, Δс, Δс, ΔН 98, Δ G 98, ΔН, J, which are in comliance of the equations: (4) (7)

3 H 98 H 98( прод) H 98( (8) c ( G98 G98( прод) G98( a a( прод ) a( b b( прод ) b( c c( прод ) c( прод) ( c c Coefficients а, в, с, с and ΔН 98, ΔG 98 undertake taking into account the stekhiometricheskikh of coefficients of the equation of the counted reactions. For stay ΔН, which are an extraolation constant we will substitute in the equation () values Δа, Δв, Δс, Δс at Т=98 К and ΔН 98 we will receive in case of high temeratures: b c c H H 98 a (14) 98 For finding of J we will substitute values ΔН (the equation 14), ΔG 98 and Т = 98 К in the equation (7), we will receive ( G98 H ) bt c T c T ( G98 H ) J a lnt T 6 98 (15) 6 a 5.69 b149 c 1481 c 5.61 We will substitute values 8 15 in 5 and we will receive: H T a.lgt.5b T.5c T J lg K (16). R It is known that thermodynamic arameters share on extensive and intensive. The sizes roortional to weight (or to amount of substance) the considered thermodynamic system, carry to extensive, it is volume, internal energy, an enthaly, etc., intensive sizes dont deend on the mass of thermodynamic system. It, for examle, temerature and ressure. Results By result of thermodynamic calculation of each reaction schedules of deendence of a constant of balance of lgk on environment temerature which are reresented in figure 1 were constructed. Reactions of decomosition can go in several directions. Everything deends on energy which is alied to these rocesses. From figure 1 it is visible that reactions: С Н 5 ОН С Н + Н и С Н 5 ОН С Н + Н О + Н arent feasible as have negative value of a constant of balance of lgk and course of reaction towards formation of roducts it is imossible. Following reactions: С Н 5 ОН СН 4 + Н О + С; С Н 5 ОН СН 4 + СО + Н ; С Н 5 ОН С Н 4 + Н О have low robability of course towards formation of roducts. Reaction with high robability of course until the end of aside formation of the final roducts the following: С Н 5 ОН + О = СО + Н О. (9) (1) (11) (1) (1)

4 After the analysis of schedules of deendence of a constant of balance on temerature of the environment the directions of decomosition of reactions were defined. From schedules it is visible that one reactions roceed until the end of aside formation of the final roducts, and others are imrobable or imossible. Figure 1. Deendence of a constant of balance of reaction of oxidation of ethyl lgk alcohol on environment temerature. The analysis of the received results allows to draw a conclusion that reactions of oxidation will successfully roceed in the established directions, and for an intensification of rocess of decomosition it is necessary to rovide a suly of some energy which quantity will be sufficient for oxidation of vaors of alcohol, thereby minimizing technological emission on a steam comonent in environment. 4. Conclusion As a result of the conducted research thermodynamic calculation of ossible reactions of oxidation of alcohol was considered. Indeendent reactions of rocess of oxidation are defined. Thermodynamic calculations of rocess of oxidation of ethyl alcohol are carried out (balance constants, Gibbss energy). The entaliyny method of calculation of constants of balance of chemical reactions is given in the Excel editor. Results of calculations showed good convergence with rograms of thermodynamic 4

5 calculations like "Aster 4" and "TERRA" [6, 7]. References: [1] Smurov A., Snakin V., Komarova N. Current state of atmosheric air. Ecology of Russia, Educational edition. 1. P.1 [] Kosintsev V., Kulikova M., Sechin A., Bordunov S., Prokudin I. Physical and chemical bases of chemical rocesses of receiving inorganic salts: manual. Tomsk, Tomsk University Publ., [] Bezdenezhnyh A. Engineering methods of drawing u equations of seeds of reactions and calculation of kinetic constants. Chemistry, 197 [4] Shilyaev M, Dorokhov A Criteria of a choice and comarison of devices of gas urification. Izv. higher education institutions. Construction, 1998, 6. P [5] Vladimirov L. The accelerated methods of thermodynamic calculations of chemical reactions. LSU Publ., 1956 [6] Dyachenko A., Ftorammoniynaya technology of rocessing of mineral raw materials: the abstract of the thesis on cometition of an academic degree the Dr.Sci.Tech. Tomsk, 8 [7] Pushkarev A. The gaseous lasmochemical rocesses initiated by a ulse electron beam: the abstract of the thesis on cometition of an academic degree of doctor of hysical and mathematical sciences. The automated system of thermodynamic calculations of "TERRA" in the range of temeratures -1 K and ressure of initial mix of,1-,1 MPas. Tomsk,7 5