The raw materials for the industrial production of moto- and air-alkylates are isobutane and butane-butylene fractions containing in their composition a component, n-butane, which is inert for the reaction of sulfuric acid alkylation of isobutane with olefins. In accordance with the Specifications TU 0272-024-00151638-99, the content of n-butane in the isobutane fraction, depending on the grade of the fraction, is 0.7÷20% wt. Its presence reduces the useful reaction volume of the alkylation reactor, and when separating the components of the alkylation reaction mass, it is necessary to use a distillation column (debutanizer). The possibility of including an additional column in the technological scheme for removing n-butane from the composition of the fraction (respectively, isobutane concentration) before it is fed into the alkylation reactor is being considered. This is of particular importance for factions with a brand below "High Brand". The study is conducted using the Honeywell UniSim Design software system. The Peng-Robinson method was used to calculate the properties of process stream components. The theoretically optimal design of the apparatus was calculated: when using a distillation column with a pressure in the apparatus of about 400 kPa to reduce the content of n-propane in the distillate (obtained isobutane fraction) to 0.001 mol. the share will require 48 theoretical plates, the accepted reflux ratio R = 8.9, the temperatures in the condenser and reboiler are 26.88 and 47.27 °C, respectively. A computational experiment has shown that in order to achieve the practical absence of n-butane in the obtained isobutane fraction (concentration of about 0.1% wt.), it is possible to use a distillation column with the following technological modes: the number of plates is 60, the feed plate is 15, the efficiency of contact devices is 0.8; the pressure in the column is about 400 kPa, the temperature in the condenser and reboiler is Тk=28.91÷29.05 ℃ and Тр=46.72÷47.25 ℃, respectively, reflux ratio R=20.41. This fraction also does not contain pentanes.

1. Solodova N.L., Khasanov I.R. Promising processes of alkylation of isoparaffins with olefins // Bulletin of the Technological University. – 2015, v. 18, no. 9, p. 117–121 (in Russian).

2. Alkylation. Research and industrial design of the process / Ed. L.F. Albright and A.R. Goldsby. – Per. from English. / Ed. V.G. Lipovich. – M.: Chemistry, 1982. – 336 p. (in Russian).

3. Shiriyazdanov R.R. Scientific and applied foundations of the process of alkylation of isobutane with olefins on zeolite-containing catalysts: Diss. Dr. tech. Sciences. Ufa, 2017. – 409 p. (in Russian).

4. Solodova N.L., Khasanov I.R. Analysis of the operation of the HF-alkylation unit of OOO LUKOIL-NIZHEGORODNEFTEORGSINTEZ // Bulletin of the Technological University. – 2015, v. 18, no. 7, p. 119–123 (in Russian).

5. Boyarintsev L.A., Popov S.V., Khabibrakhmanova O.V. On the clarity of separation of the components of the reaction mixture of the unit for alkylation of isobutane with olefins // Young scientist. – 2021, No. 23 (365). – p. 24–29 (in Russian).

6. Ushakov A.S. et al. Development of a computer modeling system for the process of sulfuric acid alkylation of isobutane with olefins, taking into account catalyst deactivation // Proceedings of "Chemistry and Chemical Technology in the 21st Century", Tomsk, May 29 – June 01, 2017. – Tomsk: NI TPU, 2017 – p. 556 (in Russian).

7. Ivashkina E. et al. Modeling the H2SO4catalyzed isobutane alkylation with alkenes considering the process unsteadiness // Catalysis Today. – 2019. – Vol. 329. – p. 206–213.

8. Semenov I.A., Shelkovnikov A.N. Modeling of the process of sulfuric acid alkylation of isoparaffins // Modern technologies and scientific and technical progress. – 2021. – No. 8. – S. 72–73. (in Russian).

9. Specifications TU 0272–027–00151638–99 (in Russian).

10. Combined sulfuric acid alkylation unit with n-butane isomerization unit" TR 2.041.044–19, 2019. (in Russian).

11. Technological regulations "Installation of sulfuric acid alkylation of isobutane with butylenes" TR 24–36, 2013 (in Russian).

12. Honeywell, Unisim Design User Guide, 2013