DEVELOPMENT OF MONOACTIVE CATALYSTS FROM OPOKA (TSEOLITE-COMPOSED KARMANA MOUNTAIN MINERAL) FOR THE SYNTHESIS OF PICOLINES AND THEIR INVESTIGATION

ABSTRACT

This article presents the results of picoline synthesis from acetylene and ammonia. The synthesis process was carried out using catalysts developed from a opoka (tseolite-composed Karmana mountain mineral) and an active cadmium oxide component. The concentration of the active component was tested in the range from 3% to 17%. The study identified the most effective catalyst as the one containing 13% active component (CO-13 (CdO-13.0%, opoka-87.0%)). Additionally, the mechanical strength of the developed catalysts was studied, and quantum-chemical calculations of the initial and synthesized substances were performed.

АННОТАЦИЯ

В данной статье представлены результаты синтеза пиколинов из ацетилена и аммиака. Процесс синтеза осуществлялся с использованием катализаторов, разработанных на основе опоки и активного компонента оксида кадмия. Концентрация активного компонента была протестирована в диапазоне от 3% до 17%. Было определено, что наиболее эффективным катализатором является тот, который содержит 13% активного компонента (CO-13 (CdO-13,0%, opoka-87,0%)). Дополнительно была изучена механическая прочность разработанных катализаторов и проведены квантово-химические расчеты исходных и синтезированных веществ.

Keywords : ammonia, acetylene, catalyst, O-opoka (siliceous clay) rock, active component, picolines (α-P, γ-P), synthesis, diffractogram, mechanical strength, quantum-chemical calculations.

Ключевые слова: аммиак, ацетилен, катализатор, горная порода О-опока (кремнистая глина), активный компонент, пиколины (α-P, γ-P), синтез, дифрактограмма, механическая прочность, квантово-химические расчеты.

Introduction. The global production volume of pyridines and their derivatives (picolines) currently exceeds 100 thousand tons per year, and further growth in demand for these products will drive the adoption of advanced technologies in the synthesis process. More than 90% of synthesized pyridine and its derivatives are produced by synthetic methods using fluorine-containing catalysts. In this regard, the improvement of synthesis technology for pyridine derivatives under conditions acceptable for environmentally safe raw materials and human health, along with the localization of sources of imported raw materials and the simultaneous introduction of new types of catalysts into practice, acquires comprehensive significance [1,2].

 In foreign industrial processes for the synthesis of pyridine derivatives, catalytic gas-phase cyclocondensation of carbonyl compounds (such as aldehydes or ketones) with ammonia is typically used in the presence of amorphous aluminosilicates impregnated with Ni, Cr, Cd, Zn, or Th compounds. The usual product yield ranges from 40 to 60 wt.% [1-3]. Studies have explored the synthesis of pyridine derivatives based on the reaction of acetaldehyde with ammonia in an autoclave at 130–160°C, with a molar ratio of C₃CHO:NH₃ = 1:3, in the presence of 1–20% catalyst, over a period of 3 hours [4-6].

Additionally, the synthesis of 2,4,6-trimethylpyridine has been studied, based on the reaction of acetone with ammonia at a temperature of 200-350°C, with a molar ratio of aldehyde to NH₃ = 1:0-2. Pyridine derivatives are formed as a result of condensation reactions with ammonia (amines or other nitrogen-containing compounds) involving aldehydes, ketones, alcohols, acetylene, etc. The most practically significant of these pyridine base syntheses involves the interaction of lower aldehydes or ketones with ammonia [7,8].

Authored by N.G. Grigorieva, N.A. Filippova, S.V. Bubennov, A.N. Khazipova, B.I. Kutepov, and V.A. Diakonov, the properties of microporous and micro–meso–macroporous Y zeolites in the synthesis of 2-methyl-5-ethylpyridine were investigated. The study examines the catalytic properties of microporous (H–Y) and micro–meso–macroporous (H–Y-mmm) FAU-type zeolites in the synthesis of 2-methyl-5-ethylpyridine (MEP) via the reaction of acetaldehyde with ammonia. At 150 °C, with a molar ratio of acetaldehyde to ammonia of 1:3 and a catalyst content of 10 wt%, the yield of the final MEP products reached 58% (0.95H–Y) and 63% (0.95H–Y-mmm) with MEP selectivities of 91% and 93%, respectively. The catalyst stability study showed that the hierarchical zeolites H–Y-mmm provide 100% [9].

Anyway, the aim of the study is to develop effective heterogeneous catalysts from local raw materials for the synthesis of pyridine derivatives. The objectives of the research are the development of new heterogeneous highly selective catalysts from local raw materials and the heterogeneous catalytic synthesis of pyridine derivatives based on acetylene and ammonia using the developed catalysts.

Methods and materials. The object of this research is the process of synthesizing picolines based on acetylene and ammonia. The study utilized catalysts based on cadmium oxide (CdO) and opoka with various monoactive components: CO-3 (CdO-3.0%, opoka-97.0%), CO-5 (CdO-5.0%, opoka-95.0%), CO-7 (CdO-7.0%, opoka-93.0%), CO-9 (CdO-9.0%, opoka-91.0%), CO-11 (CdO-11.0%, opoka-89.0%), CO-13 (CdO-13.0%, opoka-87.0%), CO-15 (CdO-15.0%, opoka-85.0%), CO-17 (CdO-17.0%, opoka-83.0%).

The method of mixing dry components was used to prepare the catalysts.

A certain amount of cadmium oxide (nitrate acetate) was added to 150 g of flask (TU 6-09-02-480-89). In order to increase mechanical strength, as well as create acid centers on the surface of the catalyst and ensure uniform distribution of components in the flask, 10 ml of 85% phosphoric acid solution and distilled water were added to the resulting mass until a dough-like mass was obtained. In addition, a 20 ml solution of carboxymethylcellulose was added to increase the pores of the catalysts. The resulting homogeneous mass was molded through an extruder with a diameter of 2 mm, then the obtained cylinders of catalyst samples with a length of 4 mm were screened from dust and dried at a temperature of 100 ± 5 °C for 3 hours, then calcined at a temperature of 600 ± 25 °C with a temperature rise of 50 °C per hour, while maintaining a temperature of about 600 °C for 3 hours.

A diffractogram was obtained to confirm the composition and quantity of the initial carrier—opoka rock. The study was conducted using a Shimadzu XRD-6100 powder X-ray diffractometer. The sample powders were thoroughly mixed to achieve a sample with an average composition. Semi-quantitative phase analysis by the Rietveld method was performed using “Reitveld refinement” software.

The yield of synthesized substances was determined by physicochemical methods. The mechanical strength of the developed catalysts was studied, with tests performed on a SHIMADZU AGS-X-50 kN machine at a speed of 5 mm/min to assess the durability of the catalysts.

Quantum-chemical calculations were performed using the semi-empirical PM3 method, with quantum-chemical computations carried out using the Gaussian09 software.

Results and discussion. Nowadays, special attention is given to the localization. Therefore, picolines were synthesized based on newly developed catalysts from local raw materials.

To confirm the composition of the initial carrier, a diffractogram was obtained, and the results are presented in fig.1.

Figure 1. Diffractogram of the opoka rock mineral

Analysis of the research results shows that the initial opoka rock (fig.1) primarily consists of minerals such as heulandite ([Al₂Si₆O₁₆]•5H₂O), calcite (CaCO₃), quartz (SiO₂) and sodium chloride (NaCl).

Additionally, the crystalline structure of the opoka rock mineral was obtained, and the results are presented in fig.2.

Figure 2. Crystalline structure of the opoka rock mineral

Mechanism of picolines synthesis using a catalyst with opoka rock (O) as the carrier:

Cadmium oxide (CdO) on the surface of the catalyst interacts with ammonia (NH₃) in the gas mixture at high temperatures. This interaction oxidizes nitrogen (N), while cadmium is reduced to its metallic state, and water molecules (H₂O) are formed:

The activated metal on the surface of the catalyst forms a π-complex with acetylene:

The intermediate active π-complex reacts with ammonia in the gas mixture to synthesize a vinylamine complex:

The vinylamine complex reacts again with acetylene, forming an amide-containing oligomer:

As a result of the action of ammonia and the formed water molecule, the catalyst is converted into an ammonia complex of cadmium hydroxide:

Subsequently, the obtained organic compounds undergo dihydrocyclization to form pyridine derivatives:

The yield of picolines depends on the concentration of the active component CdO in the catalyst. The concentration of CdO varied from 3% to 17%. The effects of the nature and concentration of the catalysts on the yield of picolines were investigated, and the results are presented in tab.1.

Table 1.

Dependence of picolines yield on the nature and concentration of catalysts (synthesis temperature 420°C)

Analysis of the research results (tab.1) shows that as the concentration of cadmium oxide increases up to 13.0 wt.%, the yield of picolines increases. However, further increases in concentration lead to a decrease in the primary product yield. This can be attributed to the fact that as the amount of cadmium oxide increases, the active surface of the catalyst becomes covered with cadmium oxide, causing the active surface to transition from an active to a passive state.

For example, the catalyst containing 7.0%, 9.0%, 11.0%, 13.0%, 15.0%, and 17.0% cadmium oxide yields α-P at 34.7 wt.%, 40.0 wt.%, 46.3 wt.%, 49.5 wt.%, and 45.5 wt.%, respectively, while γ-P yields 15.2 wt.%, 19.4 wt.%, 23.0 wt.%, 26.0 wt.%, and 24.4 wt.%, respectively.

Currently, the structure of substances is determined using quantum-chemical and molecular-dynamics calculations with modern computational technologies. Quantum-chemical calculations are now relatively simple, have a broader range of applications, and are a universal method widely used to study the electronic structure of molecules.

Below (fig.3 and tab.2) are shown the electronic structure and quantum-chemical calculations, including the sum of electronic and zero energies, the sum of electronic and thermal enthalpies, the sum of electronic and thermal free energies, the total energy, and the dipole moment (D) of the compounds.

Figure 3. Charge distribution in molecules of acetylene, ammonia, α-picoline, and γ-picoline from quantum-chemical calculations

Quantum-chemical calculations of the three-dimensional structure with atomic charge distribution have been conducted for the molecules of acetylene, ammonia, α-picoline, and γ-picoline using the semi-empirical PM3 method.

Table 2.

Electronic structure and quantum-chemical calculations of initial and synthesized substances

One of the main operational properties of catalysts is their mechanical strength. Therefore, the strength of the developed CO-13 catalyst was investigated, with results presented in fig.4 and tab.3.

Analysis of the research results (fig.4 and tab.3) shows that the maximum force before and after using the catalyst averages 65.4032 kgf and 54.7694 kgf, respectively. This indicates a reduction in maximum force, suggesting a slight decrease in the catalyst's strength after a certain period of use.

Figure 4. Effect of compression strength before and after using CO-13 catalyst

The maximum stress of the catalyst was also analyzed. It was found that the average maximum stress before and after using the catalyst is 3.33096 kgf/mm² and 2.78938 kgf/mm², respectively. A moderate decrease in maximum stress was observed, which may indicate a reduction in the catalyst’s strength after being used for a certain period.

Table 3.

Operational properties of the developed CO-13 catalyst

Additionally, the deformation properties of the catalyst were analyzed. It was determined that before and after use, the average deformation property of the catalyst is 5.02319% and 4.57606%, respectively. A slight increase in maximum deformation was observed, which may also indicate an increase in flexibility.

Overall, the data suggest a minor decrease in strength and a possible slight increase in flexibility of the CO-13 catalyst after use in the synthesis of α- and γ-picolines. This could be due to structural changes in the catalyst caused by chemical interactions during the synthesis process.

Conclusion

The diffractogram of the opoka rock mineral was obtained and analyzed.

A mechanism for synthesizing α- and γ-picolines using a catalyst with opoka rock as the carrier was proposed.

The dependence of the yield of α- and γ-picolines on the nature and concentration of the catalysts at a temperature of 420°C was studied. The analysis of the research results shows that as the concentration of cadmium oxide increases up to 13.0 wt.%, the yield of α- and γ-picolines increases, but further increases lead to a decrease in the main product yield. Among the developed catalysts, the CO-13 catalyst is the most effective.

Quantum-chemical calculations were used to study the distribution of atomic charges, reaction centers, total energy, and dipole moments of the initial and synthesized substances.

The mechanical strength of the CO-13 catalyst was investigated. The average maximum force before and after the use of the catalyst was found to be 65.4032 kgf and 54.7694 kgf, respectively.

References:

1. Filippova N.A."Synthesis of pyridines under the influence of crystalline and amorphous aluminosilicates". Abstract of the dissertation for the degree of candidate of chemical sciences. Ufa, 2022, pp. 8-20.
2. N.G. Grigorieva, M.R. Agliullin, S.A. Kostyleva, S.V. Bubennov, V.R. Bikbaeva, N.A. Filippova, B.I. Kutepov, N. Narender."Mesoporous aluminosilicates in the synthesis of n-heterocyclic compounds".Kinetics and Catalysis. 2019, Vol. 60, No.1, pp. 81-92.
3. N.G. Grigorieva, S.A. Kostyleva, S.V. Bubennov, V.R. Bikbaeva, A.R. Gataulin, N.A. Filippova, A.N. Khazipova, T.R. Prosochkina, B.I. Kutepov, N. Narender "A hierarchically zeolite y for the n-heterocyclic compounds synthesis". Journal of the saudi chemical society. 2019, Vol. 23, No.4, pp. 452-460.
4. Turabdzhanov S.M."Chemistry and technology of pyridines and their derivatives" Monograph. Ivanovo, 2019, pp. 9-34.
5. W.Zhang. Enhanced selectivity in the conversion of acrolein to 3-picoline over bimetallic catalyst 4,6%Cu–1,0%Ru/HZSM-5(38) with hydrogen as carrier gas. React. Kinet. Mech. Catal, 2019, pp.391-411.
6. Ikramov A., Kadirov H.I., Khalikova S.Zh., Musulmonov N.H., Ikramova S.A. Modification of aluminum fluoride cadmium-fluoroaluminum catalysts// DAN ANRUz, 2016, № 1. pp.49-53.
7. Vapoev Kh.M., Umrzokov A.T., Kodirov S.M. "Influence of the nature of catalysts and peptizers on the synthesis of methylpyridines". Universum: technical sciences. 2022, No. 9-3 (102), pp. 33-36.
8. Kodirov S.M., Vapoev Kh.M., Umrzokov A.T. "Synthesis of pyridine derivatives based on heterogeneous catalysts". Universum: technical sciences. 2022, No. 12-5 (105), pp. 37-44.
9. Grigoreva N.G., Filippova N.A., Bubennov S.V., Khazipova A.N., Kutepov B.I., Dyakonov V.A. Microporous and micro-meso-macroporous Y zeolites in the synthesis of 2-methyl-5-ethylpyridine // Petroleum Chemistry.– 2021.– Т.61, №3. pp.364-369.