Nitrogen Compound Conversion and Distribution in Liaohe

Subscriber access provided by DUESSELDORF LIBRARIES

Article

Nitrogen Compounds Conversion and Distribution in Liaohe Atmosphere Residue during Slurry-bed Hydrocracking Dong Liu, Zhongtao Li, Yue Fu, Aijun Guo, Ting Hou, and Kaiyuan Zheng Energy Fuels, Just Accepted Manuscript • Publication Date (Web): 16 Dec 2013 Downloaded from http://pubs.acs.org on December 18, 2013

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Energy & Fuels is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Nitrogen Compounds Conversion and Distribution in Liaohe Atmosphere Residue during Slurry-bed Hydrocracking Dong Liu1*, Zhongtao Li1, Yue Fu2, Aijun Guo1, Ting Hou1, Kaiyuan Zheng

(1.State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266555, China; 2.China National Offshore Oil Corporation, Beijing, 100010, China;)

Abstract: The nitrogen compounds in Liaohe atmospheric residue (LHAR) have been analyzed through FT-IR and GC-MS etc. to investigate the mechanism of reaction during slurry-phase hydrocracking. Their chemical structures have been exploited and the experiment data revealed that the molecular weight of nitrogen compounds after hydrocracking were increased compared with that in crude oil in the same fraction. Basic nitrogen compounds in Liaohe light VGO were composed of quinolines, etc. And non-basic nitrogen compounds were consisted with carbazoles and amines etc. The contents of basic nitrogen compounds were decreased with the increasing of boiling point, but non-basic nitrogen compounds changed oppositely. Meanwhile, nitrogen compounds could be hydrocracked and the products were transferred into some “lighter” fractions, such as diesel, VGO.

1

ACS Paragon Plus Environment

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 23

Keywords: atmospheric residue；nitrogen compound；slurry-bed; hydrocracking; GC-MS；FT-IR；

1. Introduction

Various N-containing compounds are presenting in the petroleum, which are greatly affecting oil refining processes, product qualities and environment protection. In general, the content of Nitrogen in petroleum is typically arranged from 0.05～0.5 wt%, which is varied slightly in different diesel oils from different sources. Due to nitrogen compounds’ polarity and basicity, these molecules may poison the catalysts during the refinery processes, and also reduce the stability of refined products through gum formation, as well as imparting color and odor. Moreover, their combustion leads to the formation of NOx and consequently contributing to air pollution [1-4].

N-containing compounds, most of which are in crude oil fractions and high boiling fractions, are the mixture of aromatic Nitrogen compounds and small amount of aliphatic compounds[5], such like indoles, quinolones, acridines and carbazoles etc. The molecular weight and size of these compounds are increasing quickly with the rising of boiling point of the oil fraction [6, 7].

Because of the presence of multiple isomers, for a range of different compound classes, in a very complex mixture, with generally a relatively low concentration of the compounds, the samples are prefractionated to either isolate or concentrate the nitrogen compounds prior to analysis. In general, extraction and concentration of N-compounds have been performed by adsorption chromatography, acid extraction, 2


Page 3 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

ion exchange resin and complexion method, or integrating several methods together [8]. The quantitative and qualitative analytical methods that are commonly used to characterize the nitrogen compounds in petroleum are gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS) [9,10,11].

As a new technology, increasing attentions have been focused on slurry-phase heavy oil hydrocracking in the past decades. The technology is easily operated: well-dispersed catalyst and additive microparticles are mixed with crude oil and hydrogen in high-pressure reactor and followed by keeping high temperature for hydrocracking [12-17]. As mentioned above, due to nitrogen compounds’ polarity and basicity, the content of these compounds is one important factor in influencing slurry-phase heavy oil hydrocracking efficiency [18-20]. Ping Wen and co-workers have discussed the nitrogen compounds’ distribution in the hydrocracking [17,18,20]. But the properties and chemical structures of nitrogen components in different reacting states have not been reported so far.

Therefore, we report here the conversion regular of nitrogen compounds in heavy oil during slurry-phase hydrocracking. FT-IR and GC-MS have been use to identified their chemical structures and properties in different fractions. The experiment data are expecting to be potentially used for improving denitrogenation efficiency during slurry-phase heavy oil hydrocracking.

2. Experimental Section

2.1 General Techniques 3


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 23

Herein, Liaohe atmospheric residue (LHAR) has been adopted as raw material and the physicochemical properties are shown in Table 1.

Table 1. Physicochemical properties of Liaohe atmospheric

ρ20/(g⋅cm-3)

0.9817

wt(element)/%

--

C

86.8

H

11.58

S

0.39

N

0.81

nH /nC

1.59

ν100/(m⋅m-2⋅s-1)

314.8

wt(carbon residue) /%

13.39

wt(ash) /%

0.05

average relative molecular

3438.9

condensation point /℃

26

V/µg⋅g-1

2.16

Ni//µg⋅g-1

88.0

FT-IR was performed on a Thermo Nicolet FT-IR with the resolution of 4cm-1 and scan rate of 60t/min; thin film method was used. An Agilent 6890 type GC and an Agilent 5973N type MS were used. The GC-MS was coupled with a quartz capillary column (60m×0.25mm×0.25μm) and the GC oven was maintained at 100 ˚C for 10 min and increased to 310 ˚C with a rate of 4 ˚C/min, and then kept at 310˚C. The electron impact (EI) ionization source was operated under 70eV ionization energy and multiplier voltage was 1.4kV. The carrier gas was high purity helium with pre-column pressure of 171kPa and flow rate of 1mL/min. Vario EL elemental analyzer of

4


Page 5 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

German Elemental Analyze System GmbH was used equipping with TCD detection. The analyzing conditions were as follows: oxidation temperature of 1150℃; reduction temperature of 850℃; H2O column adsorption temperature of 50℃ and resolve temperature of 280℃; CO2 column adsorption temperature of 50℃ and resolve temperature of 130℃; Oxygen flow rate of 30 mL/min; helium flow rate of 200 mL/min. Dynamic combustion method was used to do quantities analysis of C, H, S, N-element in oil.

2.2 Slurry bed hydrocracking

Kettle-type slurry bed hydrocracking reaction was preceded to Liaohe atmospheric residue with dispersed catalyst under the following conditions: reaction temperature of 430℃, reaction time of 1h, and initial hydrogen pressure of 8.0 Mpa. After getting the liquid product, atmospheric and vacuum distillation were carried on, during which the product were divided into 180-350℃、350-400℃、400-450℃ and above 450℃ four parts, then the basic and non-basic nitrogen compounds in these distillates were respectively separated and enriched. The experiment process is shown in Figure 1.

5


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 23

LHAR

Slurry bed hydrocracking product Engler distillation

Gasoline

Basic nitrogen

Atmospheric residues

Diesel fuel

Non-basic nitrogen

>450 ℃ Vacuum residue

350-400 ℃ fraction

400-450 ℃ fraction

Basic nitrogen Basic

Non-basic

Basic

Non-basic

nitrogen

nitrogen

nitrogen

nitrogen

Soluble material

Asphaltenes

Non-basic nitrogen

Figure 1. Operation procedure of preparation of the samples after the reaction

The crude and hydrocracked atmospheric residues have been analyzed respectively. As shown in Figure 2, the nitrogen compounds of atmospheric residues before and after reaction were separated and enriched for FT-IR testing.

6


Page 7 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Atmospheric Basic nitrogen

Heptane Basic nitrogen Soluble material

Non-basic nitrogen

Figure 2. Operation procedure of nitrogen separation in atmospheric residues Basic nitrogen compounds were separated and enriched in the following steps: 50g of distillated oil was weighted and followed by addition of dewaxed solvent in a volume ratio of 1:2 between oil and dewaxed solvent. After solution, the samples were cooled in water bath for precipitation with stirring for 0.5h and then solid was moved out through filtration. Finally-dewaxed oil was pre-dried in vacuum overnight. After that, the samples were dissolved in chloroform and washed by hydrochloric acid. The inorganic layer was neutralized by NaOH and followed by extracting with chloroform. After drying with anhydrous Na2SO4, the organic layer was filtrated and then evaporated in vacuum. Basic nitrogen compounds were condensed and dried before use.

Non-basic nitrogen compounds were separated and enriched in the following steps: column chromatography on silica gel was adopted to isolate the non-basic nitrogen compounds from the oil. Saturated hydrocarbons were eluted through petroleum ether; the aromatics were eluted by the mixture of n-hexane and chloroform (in 9:1 volume ratio), the non-basic nitrogen compounds were eluted with chloroform, and

7


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 23

the basic nitrogen compounds and colloid were eluted through 95% ethanol. The column was kept at 40℃during elution. After evaporation in vacuum, non-basic nitrogen compounds were obtained.

3. Results and Discussion

3.1 Nitrogen distribution of Liaohe crude oil during slurry-phase hydrocracking

Contents of nitrogen in various fractions are shown in table 1. For investigating the distribution of nitrogen, the sample was distilled in vacuum to different fractions according to the boiling point and following by calculating of the nitrogen concentration in each fraction. Before hydrocracking, the percentages of nitrogen in different fractions have been calculated in table 2 (0.81% nitrogen in LHAR initially), which revealed that the concentrations of nitrogen had the linear-ship with the boiling point. Most nitrogen compounds are presented in ＞450℃ fraction.

Table 2. Weight percent of fraction and nitrogen in crude oil

IBP-180℃

Fractions before

180-350

350-400℃

400-450℃

＞450℃

℃diesel

Light VGO

Heavy

Vacuum

VGO

residue

--

--

14.68

18.59

66.73

--

--

0.12

0.20

1.14

reaction (wt %)

Nitrogen in each

8


Page 9 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

fraction before reaction (wt %)

Fractions after

10.46

30.86

11.81

13.30

33.57

0.01

0.04

0.57

0.76

1.88

reaction (wt %)

Nitrogen in each fraction after reaction (wt %)

After hydrogenation, the mass ratio of various fractions and nitrogen in each fraction are shown in Table 2 (0.57% nitrogen in LHAR after reaction). The weight percent of gasoline and diesel oil was increased over 40%, and content of VGO fraction, especially vacuum residue (>450℃ fraction) decreased obviously. However, the VGO fraction percentage reached 40% in atmospheric residue (>350℃ fractions). Compared with the original oil, the content of nitrogen compounds in >350℃ fractions somewhat became higher, and trace nitrogen could be found in gasoline [8]. So, only diesel oil and >350℃ fractions were used in high resolution MS analyses.

Table 3. Nitrogen distribution in crude oil and hydrocracking product

350-400℃ 400-450℃ ＞450℃ IBP-180℃ 180-350 gasoline

Light

Heavy

Vacuum

VGO

VGO

residue

℃diesel

9


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 23

nitrogen distribution in

--

--

2.16

4.56

93.28

0.13

1.52

8.28

12.43

77.64

crude oil (wt %)

nitrogen distribution in hydrocracking product (wt %)

The distribution of nitrogen in crude oil and hydrocracking product have been investigated in Table 3 (nitrgen in each fraction vs total nitrogen), which revealed that the concentrations of nitrogen in “light” fractions became higher after reaction. The reason would be some nitrogen compounds were hydrogenated and become “lighter” after reaction. However, most of nitrogen compounds were still in the high boiling point fractions. Even one in fifth of the nitrogen was transferred from vacuum residue into 450℃ fraction. The experiment data revealed that the basic nitrogen compounds became “lighter” after hydrocracking, which could be easily distilled in a lower temperature.

Table 4. Basic nitrogen and no-basic nitrogen distribution in crude oil and hydrocracking product

basic nitrogen/wt%

no-basic nitrogen/wt%

350-400℃ fraction from raw material 2.23

1.31

400-450℃ fraction from raw material 1.06

3.16

11


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 23

＞450℃ fraction from raw material

0.57

27.64

180-385℃ diesel from product

2.17

2.74

350-400℃ fraction from product

2.47

11.53

400-450℃ fraction from product

1.36

16.41

＞450℃ fraction from product

0.30

20.96

As shown in table 4, the higher boiling point of fractions, the more none-basic compounds could be found. The percentages of none-basic compounds became higher than that of basic compounds in the fraction with boiling point over 400℃. Contrary to basic nitrogen compound, none-basic compounds mostly preferred to “stay” in heavy fractions. However, hydrogenation reaction also changed none-basic compounds structures. As the result, their concentration became higher in 350-450℃ fractions and decreased in ＞450℃ fraction.

3.2 GC-Ms spectra of nitrogen compounds

12


Page 13 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 4. GC-MS spectra of basic nitrogen compounds in original light VGO

Figure 5. GC-MS spectra of basic nitrogen compounds in processed light VGO

GC-MS spectra of basic nitrogen compounds of original and hydrocracked light VGO are shown in figure 4 and 5, respectively. Compared with typical nitrogen compounds GC-MS spectra, 23 compounds could be identified from figure 4, most of which were quinolines (including C2~C3 benzoquinolines and quinoline ones), pyridines and acridines etc. The hydrocracked light VGO were containing around 29 compounds (as

13


Energy & Fuels

shown in figure 5) which were including quinolines (most are C1~C7 benzoquinolines and quinolines) and acridines (most are C1~C2 acridines). According to the data, the unstable quinoline ones and pyridines were hydrocracked after reaction. They were converted to saturated groups after reactions which lead to more stable products. But larger conjugated molecules such as quinolines and acridines, were still in light VGO[21].

80

60

Abundance

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 23

40

20

10.00

20.00

30.00

40.00

50.00

60.00

70.00

time/min

Figure 6. GC-MS spectra of non-basic nitrogen compounds in original light VGO

Figure 7. GC-MS spectra of non-basic nitrogen compounds in processed light VGO

14


Page 15 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

As shown in Figure 6 and 7, the none-basic nitrogen compounds in VGO were composed of carbazoles (including many isomers) and indoles etc. After hydrocracking, the none-basic nitrogen compounds in VGO were consisted with C2, C3, C7-indoles, which were including 13 to 15 carbons in each molecule. The carbazoles in crude oil were disappeared after hydrogen processing and including 12 to 19 carbons in each molecule, which indicated that hydrocracking increased the content of saturated groups and lower their boiling points.

Based on GC-MS spectra, molecular structures of nitrogen compounds in crude oil have been calculated in table 5, which were indicated that the numbers of types of nitrogen compounds in crude oil are larger than that in hydrocracked heavy VGO. Meanwhile, with the increasing of boiling point, the number of nitrogen compounds which could be detected was decreased, which would due to the separation efficiency of chromatogram column deteriorated in higher temperature.

Table 5. Calculated nitrogen compounds structures from GC-MS spectra in crude heavy VGO

Formula

Molecular weight

Nitrogen compounds type

C16H17N

223.14

Aniline and 2-methyl-4 ,6-diphenyl

C18H15N

245.12

pyridine

C18H13NO

259.10

Acridine

15


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

C18H15N

259.14

Acridine

C15H17NO3

259.12

Acridine

C13H8NO3

273.03

Pyridine

C17H13N

231.10

Diphenyl Pyridine

C17H17NO

251.13

Acridine

C18H15N

245.12

Quinoline

C19H15NO

273.12

Acridine

C21H21N

287.17

Pyridine

C17H19N

331.16

Pentamethyl carbazole

C18H13NO

259.1

Benzindole

Page 16 of 23

Calculated nitrogen compounds structures from GC-MS spectra in hydrocracked heavy VGO are shown in table 6. Like in table 5, the types of compounds in heavy VGO decreased because of the limitation of chromatogram column. The none-basic nitrogen compounds in heavy VGO were consisted with carbazole and its derivations; while basic nitrogen compounds were composed of acridines and its derivations. The biggest differences between crude VGO and hydrocracked VGO is that nitrogen compounds in crude oil are most in N1O1 style but in N1 style after hydrocracking.

Table 6. Calculated nitrogen compounds structures from GC-MS spectra in hydrocracked heavy VGO 16


Page 17 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

formula

Molecular weight

Nitrogen compounds styles

C16H11N

217.09

3-aminopyrene

C16H11N

217.09

Indenoquinoline

C17H13N

231.10

4-phenylvinylquinoline

C17H33N

251.26

Heptadecanonitrile

C18H15N

245.12

2,6-Dimethylquinoline

C18H15N

245.12

2 - methyl -4 ,6 - diphenyl pyridine

C18H15N

245.12

2 - diphenyl -methylpyridine

C18H13N

243.10

5 - methyl - benzo acridine

C19H15N

257.12

5,10-Dimethylbenzacridine

C19H15N

257.12


C19H15N

257.12


C16H11N

217.09

Benzocarbazole

C20H13N

267.11

Carbazole

In crude heavy VGO, the nitrogen compounds containing 13-18 carbons. After hytrocracking, the carbons in nitrogen compounds increased to 16-20. The reason would be that hydrocracking reduced the nitrogen compounds which decreased compounds’ polarity and lead to a lower boiling point. 17


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 23

3.3 IR spectra of nitrogen compounds

In IR spectra, a strong and well-identified absorbance of methyl units could be found in every fraction. The characteristic absorption bands of C-C stretching vibration of quinoline (C-C Stretching vibration at 1598cm-1) and aniline (acidamide bond vibration at 1640~1710 cm-1) have been used to monitor basic nitrogen compounds.

Figure 8. IR spectra of basic nitrogen compounds in LHAR

Figure 9. IR spectra of basic nitrogen compounds in hydrocracked atmospheric residue

18


Page 19 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

IR spectra of basic nitrogen compounds in atmospheric residue before and after hydrocracking are shown in Figure 8 and 9. Both of which had weak absorption at 1598cm-1 and strong absorption at 1567cm-1 that could be considered as the characteristic absorption bands of C-C stretching vibration of quinolines. The integral areas of these peaks are much larger than that in hydrocracked atmospheric residue, which have been verified previously in nitrogen compounds distribution study (table 7). Some basic nitrogen compounds converted to corresponding non-basic nitrogen compounds after hydrocracking, and some other compounds transferred into gasoline and diesel fractions.

Table 7. The basic nitrogen distribution and related integral area in two kinds of atmospheric residues

Liaohe atmospheric residues

basic nitrogen

Non-basic nitrogen

content/%

content/%

2.68

11.95

0.65

15.01

atmospheric residues of product

The IR spectra of none-basic nitrogen compounds in atmospheric residue before and after hydrocracking are shown in Figure 10 and 11.

19


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 23

Figure 10. IR of the non-basic nitrogen compounds in LHAR

Figure 11. IR of the non-basic nitrogen compounds in product atmospheric residue As shown in figure 11, the peak of 3500-3300cm-1 and 1620cm-1 represented N-H stretching vibration and bending vibration of carbazoles. It can be seen that the hydrogenation proportionally increased the non-basic nitrogen compounds contents. The reason would be some basic nitrogen compounds convert to non-basic nitrogen compounds after hydrocracking. For the heavy oil suspension-bed hydrocracking, most of the thermal reaction was radical reaction, during which radical generation and connection reacted simultaneously. So, under the high initial hydrogen pressure, the

20


Page 21 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

hydrogen radical would react with basic nitrogen compounds which would lead the increasing of non-basic nitrogen compounds.

4. Conclusion The nitrogen compounds in Liaohe atmospheric residue have been analyzed through FT-IR and GC-Ms etc. to investigate the mechanism of reaction during slurry-phase hydrocracking. Experiment data revealed that the contents of basic nitrogen compounds are decreased with the increasing of boiling point, but non-basic nitrogen compounds changed oppositely. Meanwhile, nitrogen compounds cold be hydrocracked and the products are transferred into some “lighter” fractions, such as diesel, VGO. The chemical structure also have been calculated through FT-IR and GC-MS, which indicated that the molecular weight of nitrogen compounds after hydrocracking are increased compared with that in crude oil in the same fraction. Basic nitrogen compounds in Liaohe atmospheric residue light VGO are composed of quinolines, etc. And non-basic nitrogen compounds are consisted with carbazoles and amines etc.

Acknowledgment. This work was supported by the National Natural Science Foundation of China (21176259) and supported by the Awarded foundation for excellent young and middle-aged scientist of Shandong Province, China (BS2010NJ024). References [1] S.M. Strathouse, G. Sposito, P.J. Sullivan, L.J. Lund, Geologic nitrogen: A potential geochemical 21


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 23

hazard in the San Joaquin Valley, California, Journal of Environmental Quality, 9 (1980) 54-60. [2] J. Frankenfeld, W. Taylor, D. Brinkman, Storage stability of synfuels from oil shale: 2. Effects of nitrogen compound type and the influence of other nonhydrocarbons on sediment formation in model fuel systems, Ind. Eng. Chem. Prod. Res. Dev. 22 (1983) 615–621. [3] P. Wiwel, K. Knudsen, P. Zeuthen, D. Whitehurst, Assessing compositional changes of nitrogen compounds during hydrotreating of typical diesel range gas oils using a novel preconcentration technique coupled with gas chromatography and atomic emission detection, Industrial and Engineering Chemistry Research, 39 (2000) 533-540. [4] Y. Sano, K-H Choi , Y. Korai, I. Mochida. Effects of nitrogen andrefractory sulfur species removal on the deep HDS of gas oil. Appl Catal B 53 (2004) 169–74. [5] M. Yamamoto, K. Taguchi, K. Sasaki, Basic nitrogen compounds in bitumen and crude oils, Chemical Geology, 93 (1991) 193-206. [6] C.Kwak , J. Lee, J. Bae, S. Heup. Poisoning effect of nitrogen compounds on the performance of CoMoS/Al2O3 catalyst in the hydrodesulfurization of dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene. Appl Catal B 35 (2001) 59–68. [7] S.K. Bej, A.K. Dalai, J. Adjaye, Comparison of hydrodenitrogenation of basic and nonbasic nitrogen compounds present in oil sands derived heavy gas oil, Energy and Fuels, 15 (2001) 377-383. [8] Y. Briker, Z. Ring, A. Iacchelli, N. McLean, Miniaturized method for separation and quantification of nitrogen species in petroleum distillates, Fuel, 82 (2003) 1621-1631. [9] X. Cheng, T. Zhao, X. Fu, Z. Hu, Identification of nitrogen compounds in RFCC diesel oil by mass spectrometry, Fuel Processing Technology, 85 (2004) 1463-1472. [10] G. Ventura , B. Raghuraman , R. Nelson, O. Mullins, C. Reddy. Compound class oil fingerprinting techniques using comprehensive two-dimensional gas chromatography (GC × GC). Org Geochem 41 (2010) 1026–35 [11] D. Liu, W. Cui, S. Zhang, G. Que, Role of dispersed Ni catalyst sulfurization in hydrocracking of residue from Karamay, Energy and Fuels, 22 (2008) 4165-4169. [12] D. Liu, X. Kong, M. Li, G. Que, Study on a water-soluble catalyst for slurry-phase hydrocracking of an atmospheric residue, Energy and Fuels, 23 (2009) 958-961. [13] D. Liu, M. Li, W. Deng, G. Que, Reactivity and composition of dispersed NI catalyst for slurry-phase residue hydrocracking, Energy and Fuels, 24 (2010) 1958-1962. [14] J.G. Speight, New approaches to hydroprocessing, in, Elsevier, 2004, pp. 55-60. [15] S. Zhang, D. Liu, W. Deng, G. Que, A review of slurry-phase hydrocracking heavy oil technology, Energy and Fuels, 21 (2007) 3057-3062. [16] S.-Y. Zhang, W.-A. Deng, H. Luo, D. Liu, G.-H. Que, Mechanism of slurry phase hydrocracking residue reaction, Shiyou Xuebao, Shiyou Jiagong/Acta Petrolei Sinica (Petroleum Processing Section), 25 (2009) 145-149. [17] P. Wen, S. Li, G. Que, Transformation of nitrogen compound in residue and its unconverted oil uring slurry phase hydrocracking, Petroleum Processing and Petrochemicals, 36 (2005) 35-38. [18] P. Wen, Z. Ren, B. Shi, G. Que, Effect of catalyst on distribution of nitrogen in products from residue hydrocracking, Petrochemical Technology, 35 (2006) 967-971. [19] M.S. Rana, V. Samano, J. Ancheyta, J.A.I. Diaz, A review of recent advances on process technologies for upgrading of heavy oils and residua, Fuel, 86 (2007) 1216-1231. [20] P. Wen, D.-Y. Yu, B.-Q. Mu, Z.-X. Wang, G.-H. Que, Comparison of nitrogen distribution in slurry-bed hydrocracking and thermal conversion of residues, Shiyou Xuebao, Shiyou Jiagong/Acta

22


Page 23 of 23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Petrolei Sinica (Petroleum Processing Section), 19 (2003) 27-32. [21] D. Liu, Y. Fu, W. Deng, Q. Shi, K. Ma, T. Hou, C. Wu, FT-ICR MS analysis of nitrogen-containing compounds in the products of liaohe atmospheric residue hydrocracking, Energy & Fuels, 26 (2012) 624-628.

23


Nitrogen Compound Conversion and Distribution in Liaohe

Recommend Documents