Russian Federation
employee from 01.01.2025 until now
Kazan State Technological University
student from 01.01.2023 until now
Kazan, Kazan, Russian Federation
The traditional phosgene method for the production of isocyanates from carbamates is highly toxic, requires complex safety measures and is accompanied by the formation of large amounts of waste. In this regard, the thermal decomposition of carbamates is a relevant alternative, however, the process is complicated by the reversibility of the reaction, which requires rapid separation of the products. An experimental installation with a reactor unit has been developed that provides high-speed separation of the products of thermal decomposition of carbamates in the gas phase to prevent their reverse interaction. A technological scheme has been proposed, including a melter for melting the initial carbamate, an electrically heated reactor, an inert gas supply system with a heater for gas heating, a two-stage condensation system and tanks for collecting phenol and isocyanate. The proposed design solution minimizes the contact of the decomposition products and thereby increases the yield of the target product. Design dependencies for the melter and the heater have been determined. The necessity of additional heating of the reactor body to compensate for heat losses has been substantiated; the criterion for the optimal mode is the equality of gas temperatures at the inlet and outlet of the reactor. A detailed experimental procedure has been developed, including reaching the thermal regime, switching from air to nitrogen, controlling the melt flow rate and safely completing the process. Special attention is paid to ensuring the film flow regime of the melt, which contributes to uniform heating and reduces the risk of local degradation of the carbamate. The combination of design, regime and methodological solutions creates a complete engineering basis for conducting an experiment on the thermal decomposition of carbamates in a film reactor. Implementation of the approach will allow obtaining stable and reproducible results of carbamate separation.
CARBAMATES, URETHANES, ISOCYANATES, THERMAL DECOMPOSITION, THERMAL DECOMPOSITION REACTOR, FILM MODE, MELTER
1. N.M. Imasheva, V.A. Ionova, Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol., 56, 10, 3–23 (2013).
2. Methods for the synthesis of isocyanates, carbamates, and ureas by carbonylation of nitro compounds: Information review. NIITEKhIM, Moscow, 1984. 16 p.
3. V.V. Khan, S.N. Linchenko, O.M. Drobysheva, V.M. Bondina, Cytotoxic and neurotoxic substances and toxic technical liquids: Training manual. KGMU, Krasnodar, 2011. 108 p.
4. Ya.D. Samuilov, N.N. Shishkina, A.Ya. Samuilov, Vestn. Tekhnol. Univ., 15, 20, 158–160 (2012).
5. Ger. Pat. 4124671A1 (1993).
6. Eur. Pat. 0524554A2 (1997).
7. Jpn. Pat. 3238201 (2001).
8. Ger. Pat. 10209095 (2003).
9. A.Ya. Samuilov, D.R. Alekbaev, D.N. Khrizanforov, Ya.D. Samuilov, Vestn. Tekhnol. Univ., 22, 4, 34–38 (2019).
10. A.A. Orlova. Cand. Sci. (Chem.) Diss., D. Mendeleev RKhTU, Moscow, 2007. 158 p.
11. Chin. Pat. 101857556A (2010).
12. Chin. Pat. 101844064A (2014).
13. R.R. Dashkin. Cand. Sci. (Eng.) Diss., KNITU, Kazan, 2020. 226 p.
14. G.S. Borisov, V.P. Brykov, Yu.I. Dytnerskii, S.Z. Kagan, Yu.N. Kovalev, R.G. Kocharov, N.V. Kochergin, S.I. Martyushin, V.A. Nabatov, A.M. Trushin, M.A. Sheryshev, Basic processes and apparatuses of chemical technology: Design manual. Ed. by Yu.I. Dytnerskii. 2nd ed. Khimia, Moscow, 1991. 496 p.
15. U.S. Pat. 5449817 (1995)
