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THE HYDROGENATION OF COAL DISTILLATES WITH APPLICATION OF Mo-Hu OF CATALYSTS ON METAL CARRIERS

УДК 541.28

Приведены исследования по совершенствованию технологии гидрогенизации угольных дистиллятов для получения экологически чистого топлив путем гидрирования бензиновой фракции на основе никель скелетных катализаторов. Показано, что нанесение Мо-Гу комплексов определенного состава на поверхность Ni-Re приводит к существенному повышению активности и селективности скелетного никелевого катализатора в реакциях гидрообессеривания, гидроизомеризации и гидрокрекинга бензиновой фракции угольного дистиллята.

Никель қаңқалы катализатор қатысында гидрлеу арқылы экологиялық таза отындарды алу үшін көмірлі дистилляттарды гидрогендеу технологиясын жақсарту мақсатында көптеген зерттеулері жүргізілді. Мо-Гу комплексін Ni-Re катализатор бетіне отырғызу нәтижесінде көмірлі дистиляттың бензин фракциясын гидрокрекинглеу, гидроизомерлеу, гидрокүкіртсіздендіру реакцияларында никель қаңқалы катализатордың активтілігі және селективтілігі жоғарлайтынын көруге болады.

Abstract

Investigation results on improvement of hydrogenation technology of coal distillates are given for obtaining ecologically friendly fuels by means of hydrogenation of gasoline fractions on the basis of Ni-skeleton catalysts. It is shown that coating of Mo-Humate complexes of a definite composition on the surface of Ni-Re results in a significant increase of activity and selectivity of Ni-skeleton catalyst in reactions of hydrodesulfurization, hydroisomeration and hydrocracing of gasoline fraction of a coal distillate.

Keywords: molybdenum, catalyst, octane number

1. Introduction

At the present time, of particular interest is the search for new types of catalysts on the basis of natural materials and wastes different chemical productions which are highly active and selective and operate under soft technologically profitable conditions, for a small-scale production of liquid products from brown-coals of the Republic of Kazakhstan. The use of catalytic systems will allow to exclude, using expensive and deficit Mo catalyst, which is used in foreign technologies that to a great extent will allow to improve the ecological situation in industry in the whole [1-5].

2. Experimental

To obtaining “coal” distillates by the method developed in Scientific-Research Institute of Petroleum-Chemical Technology and of Materials at al-Farabi Kazakh National University (the laboratory of complex refining of hydrocarbon raw material) with the aim synthesize commercial engine fuels, we have chosen the coal of Karazhyra deposit of the Republic of Kazakhstan with the following physic-chemical properties : Wa -8.0 %, Aa –7.2 %, Vdaf -45.4 %, Cdaf -69.7%, Hdaf –5.7%, Ndaf –1.41%, Odaf –22.03%.

The results of determination of elementary composition of coal (C:H = 13.4/12.4; 100H:C = 7.5/8.0; Н/С = 0.89/0.96; Vг = 37.1/39.9 %) according to literature data indicate the fact that the coal can be liquifaction.

The mineral composition of coal includes: SiO2- 59.5/42,2 %, Al2O3-24.54/26.0%, Fe2O3-5.04/22.78%, CaO-2.24/2.59%, MgO-2.01/2.52%, TiO2-1.35/1.57%, K2O-1.57/0.32%, Na2O-1.53/0.94%, SO3-1.83/0.54%, as well as 0.39/0.54 % rare earth elements Σ13.1/1.26, Σ2 – 4.02/23.8; Σ1 = Na2O + K2O < 3; Σ2 = Fe2O3 + CaO + MgO + TiO2 + SO3 / Na2O + K2O>2.

The heavy oil fraction with the boiling point over 773 K from the oil-field Karazhambas was used as a paste forming material. The thermo stable natural zeolite from the deposit Semeu-Tau which makes oneself near Karazhyra deposit was used as a catalyst of hydrogenation process of coal. The physic-chemical properties of zeolite are given in Table 1.

As it is seen in Table 1, zeolite from Semeu-Tau refers to the type of minerals- klinoptillite with SiO2/AI2O3 ratio. Such Properties of natural as sorption, catalytically and molecular stability are observed in its dehydrogenational state. So, natural zeolite was thermally treated in the range of temperatures from 473 to 1073 K.

It is shown by the method of spectroscopic analysis that zeolite treated at 673 K contains a considerable amount of elements which are catalysts of hydrogenation (Мо = 6•10-4, Ni = 2•10-3, Ti = 1.8•10-1, Zn = 50•10-3). Those elements contribute to the increase of catalytically activity of natural zeolite in hydrogenation process of coal.

Experiments on liquefaction of coal spent in a rotating autoclave in volume 0,25 dm3 at temperature 653-713 K, pressure to 4,0 MPa and time of isothermal endurance of 10-40 minutes. Catalytically hydrogenation of coal was studied on the zeolites treated thermally at different temperatures. The results are given in Table 2.

Table 1. The physic-chemical properties of zeolite from deposit Semeu-Tau

Index

Size of measurement

Descriptions

Appearance


Red-brown color

The total mass share of zeolite

%

50-84

Type of mineral-zeolite


Klinoptillite

Content of organic mass

%

N

Chemical composition

SiO2

Al2O3

TiO2

Fe2O3

FeO

MnO

MgO

CaO

Na2O

K2O

SO2

%


72,80

10,63

0,28

1,50

< 0,02

< 0,03

0,35

1,61

1,18

5,04

< 0,25

Ratio SiO2/AI2O3


6.04

Cationic change capacity

Ca

Mg

K

Na

Ekv /g


0.55-0.63

0.024-0.070

0.0035-0.0065

0.025-0.072

Total capacity


0.75-1.25

Content of poisoning elements:

- Pb

- Cd

- As

- Hg

%


< 0.001

-

-

-

Technical characteristics

- Specific gravity

- Volumetric mass

- Porosity

- Moisture capacity

- Crushing ability

- Thermo stability


g/sm3

g/sm3

g/sm3


%


2.34-2.44

2.18-2.28

5-9

2.33-3.70

4.4-7.9

400

As it is seen in Table, on zeolite thermally processed at 673 K the yield of liquid products, compared to their amount increased by 10 mass %. The yield of gasoline fraction increased to 9 %, but the yield of the third fraction and gas decreased. It can be explained by the changes which are observed in zeolite processed at 673 K. In comparison with the initial zeolite and the zeolite processed at 1073 K, it has an absorption band at the wave length 1423 sm-1 corresponding to OH-group related to the aprotonic Lewis centre.

3. Results

The processed zeolite is also characterized by a great specific surface determined by the BET method. The processed zeolite at 673 K was used on this basis, to determine optimum conditions of hydrogenation process of coal.

The gasoline fraction by hydrogenation of coal was hydro refining under mild conditions on Ni-Re and on Mo-Humate, Co-Humate complex catalysts coated on it. (Мо-Hu/Ni-Re) (Table 3)

2,2-dimethyl butane (0,027%), 2,4-dimethyl pentane (0,0320%), 2,3,4-trimethyl pentane (0,7280%), 2,4,4-trimethyl hexane (0,6230%), 2-methyl-4-ethyl hexane (0,6880%), 2-methyl nonane (5,331%) and others hydrocarbons, which were not present in initial gasoline, were finded. The content of some isoparaffins increased 2-5 times (2,2,3,4- tetra methyl pentane, 3,3-diethyl pentane, 3-ethyl heptane). The content of naphthenes hydrocarbons in the initial gasoline made up 9.50% and on Mo-Hu/Ni-Re catalyst it was 5.93%. In hydrogenation process, de alkylation reaction of alkyl aromatic hydrocarbons proceeds, resulting in the increase in the content of aromatic hydrocarbons 2 times. In comparison with octane number of initial gasoline -69.28, octane number of gasoline hydro refined on Mo-Hu /Ni-Re increased to 78.8. The content of sulfur after hydro refining decreased to 0.023%. This satisfies the modern requirement to the quality of engine fuels production and corresponds to European Standard. The hydro refining process of commercial gasoline (A-76) on Mo-Hu /Ni-Re catalyst was carried out for comparison the obtained results. The content of paraffins hydrocarbons in the initial gasoline of mark A-76 decreased from 23.6 to 14.77% and the content of aromatic hydrocarbons increased from 31.16 to 47.01%. The content of naphthenes hydrocarbons decreased a little. If in gasoline A-76 there were 8 olefins hydrocarbons after hydro refining their number decreased 5 times. It is shown on the basis of the carried out research that if the octane number of gasoline A-76 was 75 after hydro refining it increased and made up 82.

Conclusions

Thus, it is stated, that coating of Mo-Humate complexes of a definite composition on the surface of Ni-Re results in a significant increase of activity and selectivity of Ni-skeleton catalyst in reactions of hydrodesulfurization, hydroisomeration and hydrocracing of gasoline fraction of a coal distillate.

Table 2. The influence of thermally treatment of zeolite catalyst on the hydrogenation process of coal. (Т= 6900С, 15min, К:ПТ=1:2, mcat =0,67 g)

T,K

The specific surface by method BET, m3/g

Vgas, %

The yield of a liquid product

Residue, %

Loss of %

80-1800С

180-2500С

250-3200С

Σ l.p.

-

39.62

13.1

6.47

8.38

26.95

41.8

41.3

3.8

473

40.22

12.8

8.98

10.3

23.32

42.6

40.0

4.6

673

62.5

12.3

15.5

11.5

24.7

51.7

31.3

4.7

873

56.11

13.4

6.48

11.64

23.24

41.4

42.0

3.2

1073

28.53

14.2

5.3

7.4

22.75

35.5

46.5

3.8

Table 3. The influence of the catalyst nature on the composition of gasoline fraction

Hydrocarbons

In the absence of catalyst

Catalyst zeolite

The hydrogenation of coal

Mo-Hu/Ni-Re distillate

А-76

А-76

hydrogenation

Mo-Hu/Ni-Re

Paraffins

28,82

32,45

19,17

23,60

14,77

Isoparaffins

32,70

29,19

30,16

35,3

30,85

Aromatic hydrocarbons

17,47

28,19

38,80

31,16

47,01

Naphthenes

12,35

9,5060

5,93

8,00

7,11

Olefins

5,9

0,6622

5,43

1,940

0,2595

Cyclic olefins

1,6669

0,0

0,502

0,0

0,0

Dienes

1,1010

0,0

0,0

0,0

0,0

Octane number

65

69,2

78,8

75,0

82,0

References

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2. Kairbekov Zh.K., Aubakirov E.A., Myltykbaeva Zh.K., Esenalieva M.Z. // Vestnik KazNU. Ser. khim. 2006. № 4 (44). P. 152-154.

3. Kairbekov Zh.K., Aubakirov E.A., Myltykbaeva Zh.K. // ХVIII The convention Mendeleev’s on the general and applied chemistry. Moscow, 2007. P. 1550.

4. Kairbekov Zh.K., Aubakirov E.A., Myltykbaeva Zh.K. // VII Russian Conf. “Mechanisms of Catal. React.”. Novosibirsk, 2007. P. 270-272.

5. Kairbekov Zh.K., Aubakirov E.A., Myltykbaeva Zh.K. // RFFI Intern. Conf. Vladimir, 2006. P. 98-102.