CATALYTIC SYNTHESIS OF PYRIDINE DERIVATIVES AND THEIR CORROSION INHIBITION PROPERTIES

Аннотация

The study established that acetaldehyde reacts with ammonia in an autoclave in the presence of a catalyst with a mass fraction of 1-20% for 3 hours at 130-160°C, at a mol ratio of CH CHO:NH = 1:3, 2-methyl-5-ethylpyridine 3 3 is formed as the main product. Keywords: ammonia, acetaldehyde, catalyst, alkylpyridines, catalytic synthesis, heterocycles, heterocycles, carbonyl compounds Foreign synthetic industrial processes for obtaining pyridine bases are based on the catalytic gas-phase cyclocondensation of aldehydes and/or ketones with ammonia in the presence of amorphous aluminosilicates promoted by Ni, Cr, Cd, Zn or Th compounds. The yield of pyridine bases in these processes is 40-60% [1]. In these processes, zeolite ZSM-5 was used as a catalyst in the synthesis of N- heterocycles, including pyridines. The author [2] investigated catalytic compositions for the synthesis of pyridine and pyridine bases on hierarchically porous zeolites (micro/meso; micro/macro; micro/meso/macro) and showed that the condensation of carbonyl compounds with ammonia proceeds with a high yield in the presence of 4 zeolite catalysts. It was also established that the reaction of acetaldehyde with ammonia in an autoclave in the presence of 1-20% by mass of the catalyst for 3 hours at a temperature of 130-160 °C, in a molar ratio of CH CHO:NH = 1:3, leads 3 3 to the formation of 2-methyl-5-ethylpyridine as the main product. These studies also showed that the MEP yield in the micro-meso-macro- porous structure sample was 1.5 times higher than in the initial micro-porous sample H-ZSM-5, which indicates the influence of mesoporousness formation on catalytic properties and increased selectivity towards heterocycles. In the case of N-Yh zeolite samples with different (0.70; 0.87; 0.95) showed that the selectivity for MEP increases somewhat with the increase in αNa and reaches 93% in the sample 0.95H-Yh, and it was concluded that the MEP yield also changes equally from 58% (0.70H-Yh) to 63% (0.95H-Yh). Optimal conditions for changing the decationization stage of H-Yh zeolite were established, along with an increase in the number of high-molecular-weight compounds (up to 10 wt.%), which ensured an increase in the MEP yield by 63%:150 C, with a 3-mol ratio of CH3CHO:NH = 1:3. 3 To date, methods for the technical synthesis of alkylpyridines from various organic compounds have been developed. All alkylpyridine production plants in the world use only carbonyl compounds and ammonia as raw materials.. The process of obtaining a mixture of pyridine and 3-methylpyridine from carbonyl compounds and ammonia is well-studied. "Navoiazot" JSC launched 111 DEVELOPMENT AND INNOVATIONS IN SCIENCE International scientific-online conference production of 20 thousand tons of formaldehyde per year and 7 thousand tons of formaldehyde per year. In this regard, the process of jointly obtaining pyridine and 3-methylpyridine from acetaldehyde, formaldehyde, and ammonia was of interest. The heterocyclization reaction of carbonyl compounds with ammonia (and amines) includes complex parallel-sequential reactions, including nucleophilic addition reactions of ammonia, isomerization, dehydrocyclization, and others. All these processes can be combined in the vapor phase using catalysts with multifunctional properties. Based on this, the role of each component in the pyridine and methylpyridine formation reaction was considered when selecting the catalyst composition. The heterocyclization reaction of the croton fraction with aniline and o- aminofenol in the presence of mixed polyfunctional catalysts was investigated, composition, wt.%: Cd - 3.0-5.0; ZnO - 5.0-10.0; Cr O - 3.0-5.0; Fe O - 3.0-5.0; - 2 3 2 3 Al O - 75.0-86.0. 2 3 Composition of the croton fraction, wt.%: croton aldehyde - 57.4 - 66.95; paraldehyde - 13.45 - 29.47; acetone - 0.63 - 10.56; the rest - water. Catalysts were prepared by methods of suspension, molding, washing, drying, and purification. Aluminum oxide (PPP-33%) was used as a hydrate carrier. 3-5% solutions of fluic and acetic acids were used as peptizers. The textural properties of the developed catalysts were determined (Table 1). Table 1 Physicochemical and operational properties of the developed catalysts Relative Service life until Composition, Mechanical Output, № surface regeneration, % by mass.. strength, MPa g/kg*time*h area, mg/h hour CdF – 3,0 2 ZnO – 5,0 1. 225 6,8 68,0 81,0 Cr O – 5,0 2 3 Al O – 87,0 2 3 CdF – 5,0 2 ZnO – 5,0 2. Cr O – 3,0 240 7,8 96,0 101,0 2 3 Fe O – 3,0 2 3 Al O – 84,0 2 3 CdF – 5,0 2 ZnO – 5,0 3. Cr O – 5,0 225 7,3 72,0 98,0 2 3 Fe O – 3,0 2 3 Al O – 82,0 2 3 CdF – 5,0 2 ZnO – 10,0 4. 196 8,0 120 122 Cr O – 3,0 2 3 Fe O – 5,0 2 3 CdF – 5,0 2 5. 184 8,2 184 130 ZnO – 5,0 112 DEVELOPMENT AND INNOVATIONS IN SCIENCE International scientific-online conference Cr O – 5,0 2 3 Fe O – 5,0 2 3 Al O – 80,0 2 3 The condensation reaction of the croton fraction with ammonia and amines was carried out in a stainless steel reacto