УДК 665.656.2

Aliyeva Aynura Anver qizi, Karimov Hikmat Nazim oglu

CONVERSION OF NATURAL GASOLINE OVER THE MULTICOMPONENT CATALYSTS

Aliyeva Aynura Anver qizi1, Karimov Hikmat Nazim oglu2
1Azerbaijan State Oil and Industry University, doctor of chemical sciences in philosophy, docent
2Azerbaijan State Oil and Industry University, master student

Abstract
The article is devoted to the study of conversion of natural gasoline on multicomponent catalysts. The activation of natural gasoline has been studied on the Ni-MOR/(SO42-)ZrO2 catalytic systems.

Keywords: alkanes, catalyst, catalytic systems, conversion, natural gasoline


Рубрика: 02.00.00 ХИМИЧЕСКИЕ НАУКИ

Библиографическая ссылка на статью:
Aliyeva A.A.q., Karimov H.N.o. Conversion of natural gasoline over the multicomponent catalysts // Современные научные исследования и инновации. 2021. № 4 [Электронный ресурс]. URL: https://web.snauka.ru/issues/2021/04/95112 (дата обращения: 24.11.2021).

Introduction. The main consumers of hydrocarbon raw materials are engines, the demand for which has been increasing in recent years. There are two main reasons which arise the search for additional sources of hydrocarbon raw materials, alternative ones and moreover the need to protect the environment from emissions of motor gases. The modern requirements to gasoline require decrease of toxic aromatic hydrocarbons in order to maintain high octane number and to improve the environmental performance of motor gasolines [1].

In terms of solutions, it is proposed to subject normal and weakly branched paraffin hydrocarbons to low temperature isomerization process [2]. In world practice, several modifications of the isomerization process are used, which differ in the catalysts used and the process conditions. The use of new modificated catalysts enable to increase the high octane components of modern gasolines, so that the involvement of saturated hydrocarbons to the process contributes to the solution of this problem.

Natural gasoline is the mixture of C5-C7 and C7+ paraffins, that have certain difficulties. For instance, the presence of C7+ n-paraffins can lead to the formation of undesirable gaseous products due to the hydrocracking or hydrogenolysis of branched isomeric structural hydrocarbons [3]. In order to maintain the high efficiency of isomerization process catalyst, it is necessary to limit the content of C7 + paraffins in the feedstock. Furthermore, due to the importance of C5-C6 izomers which have high-octane number, it is important to increase the amount of normal and weakly branched paraffin hydrocarbons.

Experimental Part

The multicomponent catalysts consist of А(γ-Al2O3) or HMOR zeolite (SiO2/Al2O3=17) and anion SO42- modified sulfated zirconia (SZ). The components of the composite catalyst were prepared by modifying the initial MOR zeolite with cobalt, nickel or zirconium. The modification of the original zeolites was carried out by decationization, dealumination, ion-impregnation of various metals, impregnation with a solution of a sulfating agent (NH4)2SO4, based on the number of ions.

As a active components ZrO (NO3)2∙ 2H2O and (NH4)4W5O17 ∙ 2.5H2O salts were used so as to prepare catalysts. For the synthesis of catalysts zirconium dioxide gel was obtained by hydrolysis of ZrOCl2 with a solution of 25% ammonia at pH = 8-9 [3]. The deposition of the salts on the H-form of the zeolite was carried out by impregnation for 24 hours with further evaporation, drying, mixing with a binder component Al2O3 (25% of the catalyst mass) and subsequent heat treatment at different temperatures during 4 hours. The new prepared composite catalyst is 65 wt.% of Al2O3 or zeolite, 15% SZ and the rest is binder. The main features of the reaction resulting products have been done be means of «Auto System XL, Perkin Elmer» chromatography provided with the relevant computer program.

Results and Discussion

Catalytic isomerization process is one of the predominant processes in modern oil refining that is used in order to obtain high-octane isocomponents for motor fuels. The process should be carried out in such a way as to maintain a minimum yield of aromatics and olefins, which is achieved by selecting the catalyst and the process conditions.

In addition, important argument for the inclusion of an isomerization unit in the oil refining scheme is an increase in the octane stock of the entire gasoline stream, which makes it possible to reduce the “rigidity” of the reforming process. The latter leads to an increase in the yield of reformate and the concentration of aromatic hydrocarbons simultaneously decrease in commercial gasolines [4,5].

All components of the original natural gasoline over the Ni/MOR/SZ undergo considerable amount of changes. The content of the iso-C5, n-C5, and iso-C6 components in the catalyst increases, while the content of the remaining components decreases. Among the changes noted, it is necessary especially to note a decrease in the concentration of hydrocarbons C4, C6 and ∑C7 +. Changes in the distribution of hydrocarbons before and after contact with the catalyst are depend on temperature and process.

Table 1 – Conversion of natural gasoline over the Ni/MOR/S; WHSV= 2 h-1; υН2 =30 ml/min

Temperature,

ºС

Time,min

∑iso-С5 -iso-C6,%

∑n-С5-n-C6, %

Conversion ∑С7+%

RON

-

44,0

28,0

0,0

63

150

30

58,5

26,4

40,0

81

60

57,0

27,2

45,0

82

180

30

62,8

24,8

41,9

86

60

60,6

25,6

42,0

81

200

30

63,7

27,2

45,3

80

60

47,1

42,8

49,9

80

220

30

46,8

28,2

22,9

67

As can be seen from the table 1, the contact of natural gasoline with the Ni/MOR/SZ catalyst allows not only isomerization of the C5 and C6 alkanes, but also the involvement of the heptane to the process. The conversion of this component in the temperature range of 150-2000C is around 40-49%, while the products of this conversion are only high-octane alkanes iso-C5, iso-C6 and n-C5. It also should be noted that the C6 components of natural gasoline are also involved in the formation of these components. In other words it is obvious that natural gasoline is significantly enriched in higher-octane components in one pass over the catalyst due to extremely declining of low-octane heptane components. The noted changes in the distribution of hydrocarbons contribute to a natural change in the octane quality of the mixture. The evaluation of the octane characteristics of the feedstock, presented in Table 1, indicates that in one pass over the catalyst, the RON of gasoline can increase by 17-23 points. Thus, compounding of reformate with the obtained fraction can become a perspective method for producing high-octane gasolines that meet modern requirements.

Conclusions

The possibility of using Н-zeolite/SO42-(WO42-)ZrO2 catalytic systems for the conversion of hydrocarbon mixtures of natural gasoline at low temperatures of 140-2000С and the accumulation of C5-C6 alkanes are formed as a result of isomerization, decomposition of bimolecular intermediate and as well as the involvement of C7 + alkanes to the process without the formation of undesirable gaseous alkanes can open new avenue for using such catalytic systems for isomerization processing (isoforming) of stabilized gasoline containing significant amounts of C7 + alkanes.


References
  1. Palmer E.R., Kao S.H., Tung, C. Shipman D.R. Consider options to lower benzene levels in gasoline. New regulations further limit this aromatic from the refinery blending pool. Hydrocarbon processing, 2008, June, pp.55 – 66.
  2. Aqabekov V.E., Senkov T.M.  Catalytic isomerisation of light paraffin hydrocarbons, Catalysis in the chemical and petrochemical industry, 2006, №5, p.31 – 41.
  3. Ono Y. A survey of the mechanism in catalytic isomerization of alkanes. Catalysis today, Vol. 81, is. 1, 2003, pp.3-16.
  4. Matsuhashi H., Shibata H., Nakamura K., Arata K., Skeletal isomerization mechanism alkanes over solid superacid of sulfated zirconia // Appl.Catal.A:Gen., 1999,v.187, p.99-106.
  5. Kumar N., Villegas J., Salmi T. & et al. Isomerization of n-butane to isobutane over Pt-SARO-5, SARO-5, Pt-H-mordenite and H-mordenite catalysts // Catalysis Today, 2005, v. 100, No 3-4, p.355-361.


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