Breakthrough in Microactivity Test Effluent Analysis - ACS Symposium

Chapter 12

Breakthrough in Microactivity Test Effluent Analysis Detailed Analytical Characterization of Gasolines, Light-Cycle Oil, and Bottom Cuts

Downloaded by YORK UNIV on October 29, 2012 | http://pubs.acs.org Publication Date: November 4, 1994 | doi: 10.1021/bk-1994-0571.ch012

N. Boisdron, M. Bouquet, and C. Largeteau Total Raffinage Distribution, Research Center, B.P. 27, 76700 Harfleur, France MicroActivity Tests (MAT) are commonly used to evaluate FCC feedstocks and FCC catalysts properties. Evaluation is rapid and requires only small amounts of catalyst and feedstock. However, until now, the small quantity of recovered liquid effluent didn't allow to characterize completely the whole effluent. Only two chromatographic analyses could be made on a routine basis : 1) TBP chromatographic analysis, 2) PIANO determination and octane estimation on light part of the effluent. Improved techniques of distillation and separation have been built up to characterize the whole effluent and more specifically the heaviest cuts. Using appropriate device requiring small amount of whole effluent, the method elaborates fractions such as gasoline, LCO and bottom cuts by distillation and enables to perform molecular and structural analysis on each cut. The set of analyses is devoted to such characterization and requires very small quantity of effluent fraction sample. One of the separation techniques (liquid chromatography) has been developed at purpose. Examples of applying such new concept of microanalysis are given and illustrated in this paper. Thefirsttechnique, called "microdistillation" allows to split MAT liquid effluents into four cuts. All desirable analyses can be performed on each of these cuts, provided the analysis doesn't require more product than available by microdistillation. Special emphasis has been put on the characterization of bottoms fractions. On one hand, Fisher mass spectrometry (1), which identifies aromatics and sulfur 0097-6156/94/0571-0137$08.00/0 © 1994 American Chemical Society

In Fluid Catalytic Cracking III; Occelli, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994.

138

FLUID CATALYTIC CRACKING III


compounds, can be directly applied to microdistilled bottoms fractions ; on the other hand Hood/O'Neal-Ms (2) provides data on saturated compounds but requires a further step of separation, achieved by liquid chromatography. So, to perform O'Neal analysis on microdistilled bottoms, a microtechnique of liquid chromatography has been developed. This paper presents these two new techniques still under development. The first analytical results obtained an MAT effluents are also shown. An overview of the experimental procedures is given, and the technical feasibility of microdistillation and liquid microchromatography is demonstrated. Finally, an application of microdistillation will be illustrated by Fisher-MS results obtained on bottoms fractionsfromMAT effluents. Experimental Microdistillation. Experiments were run on a modified GKR-51 Buchi apparatus. A home-made ice-cooler improvement was added to the cooling section to reach com plete condensation. Typical sequences applied to MAT total effluent were based on the following steps : - CS + light ends including light gasoline head were obtained at 95°C and atmosphe ric pressure during 40 minutes, -light and heavy gasolines were obtained at 170°C and reduced pressure (typical value : 100 mm Hg) during 1 hour, - light cycle oil (LCO) was obtained at 200°C and low pressure (typical value : 1 mm Hg) during 1 hour, - bottoms as residue in the ball tube. The feed is typically 2.4 g, including 1.8 g of carbon disulphide (CS ) and 0.6 g of effluent from the MAT pilot (CS is added as solvent to fully recover the effluent). 2

2

2

Liquid microchromatography. The microchromatography is not very different from classical chromatography, albeit the constraints of miniaturization dealing with : Column Microvalve Silica Detector.... Pump.. Syringe

6 mm i.d. Hamilton 86777 Davison CG2 Waters RI Milton Roy (1 ml/min) Exmire Microsyringe MS GIL 050

The bottoms sample is typically 100 mg and diluted with 200 μΐ of cyclohexane. The sample is injected in the column and after separation on the silica fed to a refractometer to detect the cut point of the run. Much care must be taken while evaporating the solvents to avoid the bubbles formation during the gentle heating of small vials (0.5 ml). The yield of the separation has to be close to 100 %, never less than 95 %.


12. BOISDRON ET AL.

Microactivity Test Effluent Analysis

139

Rationale of the microanalysis

Microdistillation. The microdistillation is based on the Buchi glass tube oven GKR 51. The oven allows a separation of the total effluent from MAT experiment, into four fractions. First of all, microdistillation feasibility was checked on a pilot plant effluent with no addition of CS . The pilot provided enough product to perform classical ASTM D1160 distillation. The following table compares the results given with optimized settings for the GKR 51 Buchi with ASTM distillation yields. There is a good agreement between the two methods but we still have some difficulties to split 0.6 g sample into four fractions. 2


Microdistillation yields

Pilot plant effluent / Pilot plant effluent ASTMD-1160 Buchi 2 g feed 0.6 g feed 41.1 40.4 1 15.7 16.4 \ 80.3 25.6 22.8 J 18.3 19.7 19.7 3 13 7

Light gasoline (ffiP-160°C) Heavy gasoline (160-220°C) LCO (220-3 50°C) Bottoms (350+°C) 350-°C fraction in bottoms (weight %)

Then, using CS on a common basis to fully recover the effluent at the end of MAT test, new trials were performed with small amounts of the pilot plant effluent and additional CS . Under these conditions, the effluent is split into a CS rich fraction including light gasoline head and three other fractions. The settings of the Buchi are optimized such as these fractions overlap standard LCO and bottoms cuts. The settings of the Buchi are presented in the experimental section. They have been chosen with yields derived from standardized cuts, i.e. ' IBP - 95°C heads < 95 - 220°C gasolines 220 - 350°CLCO I 350 C bottoms Feasibility was proved on bottoms fractions with a separation step lasting about 3 hours. A weight of 0.6 g of total effluent was required. LCO fraction separation is not so accurate. Repeatability was examined, particularly on bottoms yields. A set of five runs (0.6 g effluent + 1.8 g CS ) were performed with the microdistillation apparatus under similar conditions. Results with bottoms yields are illustrated on next table. 2

2

2

+o

2

Set of five runs

Run n° Microdistillation bottoms yield (weight %) 350"°C in bottoms (weight %)

1 18.95 15

2 18.84 15

3 18.56 9

4 19.88 16

5 19.28 16

Mass spectrometry (1) was used to determine the molecular structure of the compounds. Table I displays the full results of this analysis. The compounds identification from the five runs is consistent. The agreement with the reference sample is fairly good. We determined that CS has no incidence on the results. 2


140


Table I. Fisher results on bottoms fractions Statistics Reference Yields (weight %) Microdistillation run Distill Average σ ASTM D-1160 18.34 Bottoms 18.95 18.81 18.56 19.80 19.28 19.1 0.49 5 Effluent R2R test n° 3 4 1 2 28.7 Saturates 29.7 29.6 29.3 30.0 29.5 29.6 0.22 C

H

n 2n+2

C

H

n 2 n , -2, -4, -6


Aromatics Monoaromatics C

n 2n-6

C

n 2n-8

C

12.19 17.49

12.27 17.29

10.69 18.60

11.78 18.19

12.25 17.24

11.8 17.8

0.60 0.54

11.39 17.35

60.9

61.0

61.1

60.5

61.0

60.9

0.20

62.2

2.4 1.02 0.88 0.49

3.3

2.5

4.3

4.5

1.3

1.01 0.94 0.50

1.23 1.44 1.61

1.19 1.62 1.72

3.4 1.1 1.2 1.1

0.89

1.02 1.22 1.01

0.10 0.28 0.53

0.73 0.46 0.09

H

H

H

n 2n-10

Diaromatics C

H

n 2n-12

C

n 2n-14

C

n 2n-16

H

H

Triaromatics C

H

n 2n-18

C

n 2n-20

H

Tetraaromatics C

n 2n-22

H

C

n 2n-24

C

n 2n-26

H

H

Pentaaromatics C

n 2n-28

H

C

n 2n-30

H

Hexaaromatics C

H

n 2n-32

C

n 2n-34

H

Heptaaromatics C

n 2n-36

H

C

n 2n-38

H

Sulphur compounds Dtbenzothiophenes C

H

S

H

S

n 2n-16

C

n 2n-18

C

n 2n-20

H

S

16.4

17.2

17.3

17.7

18.0

17.3 0.55

16.8

7.46 8.89

7.96 9.20

8.19 9.09

8.87 8.80

8.86 9.30

8.2 9.1

0.50 0.19

8.23 8.35

22.7

22.1

23.3

21.7

21.3

22.2

0.71

22.1

13.39 4.90 4.37

13.00 4.78 4.29

14.12 4.90 4.28

13.17 4.46 4.08

12.99 4.24 4.05

0.42 0.26 0.13

13.46 3.54 5.12

9.2

8.9

8.9

8.3

8.3

6.24 2.99

6.00 2.93 6.4 4.71 1.66

6.08 2.80

5.68 2.65

5.52 2.75

13.3 4.7 4.2 8.7 5.9 2.8

6.8 5.05 1.79 3.4 1.46 1.97 9.4

0.37

9.5

0.27 0.12

6.09 3.41 7.7 5.62 2.06

6.3

5.8

6.0

6.3

0.35

4.82 1.48

4.40 1.59

4.7 1.6

3.0

3.0

1.37 1.63

1.3 1.7

0.27 0.11 0.25 0.10 0.16

3.2

2.9

1.43 1.77

1.26 1.65

4.3 1.49 2.7 1.20 1.51

9.5

9.5

9.5

9.5

9.5

0.03

9.1

2.31 0.65 0.99

2.37 0.67 1.00

2.46 0.69 1.04

2.53 0.69 1.01

2.43 0.66 0.99

2.4 0.7 1.0

0.08 0.02 0.02

2.01 0.54 0.90

2.69 0.95 0.78 0.47 0.58

2.67 0.94 0.81 0.46 0.54

2.78 0.85 0.72 0.45 0.50

2.68 0.93 0.75 0.46 0.48

2.64 0.95 0.82 0.47 0.51

2.7 0.9 0.8 0.5 0.5

0.05 0.04 0.04 0.01 0.03

2.54 0.93 0.76 0.51 0.91

4.8 1.67 3.13

Naphtalenothiophenes C

n 2n-22

C

n 2n-24

C

n 2n-26

C

H

S

H

S

H

S

H

S

n 2n-28

Disulphurised compounds


12. BOISDRON ET AL.


141

Liquid microchromatography. A liquid microchromatography method was optimi zed to separate quantitatively the "saturated species" from the "aromatics + sulphur compounds" in the bottomfractionfromthe microdistillation device. Settings were selected according to the described experimental details and applied on four samplesfrombottomfraction.The following tables present the yields obtained and exhibit the composition of these "saturated species" according to O'Neal method. Saturated compounds yields Sample (mg) Saturates (weight %) 79.1 32.8 80.3 32.4 Average = 33.6% 77.5 34.1 σ= 1 % 83.9 35.2 Downloaded by YORK UNIV on October 29, 2012 | http://pubs.acs.org Publication Date: November 4, 1994 | doi: 10.1021/bk-1994-0571.ch012

%

Saturated compounds composition (weight %) 1 2 3 31.8 Paraffins 32.3 28.5 18.8 16.1 16.6 Mononaphtenes Dinaphtenes 16.2 15.8 16.5 Trinaphtenes 18.4 21.0 18.5 Tetranaphtenes 11.1 13.5 11.4 Pentanaphtenes 3.2 5.1 5.2 Hexanaphtenes 0.0 0.0 0.0

4 32.6 18.3 15.4 16.5 11.0 5.2 1.0

A good agreement between the samples is reached, either for "saturated" yields or for "saturated" compositions in this selected set of results. Analytical limitations Both microanalyses described in this paper are relatively delicate and require skilled operators. Thefractionationquality obtained with microdistillation is not as good as the one obtained with a standardized 30-trays distillation. However, it is sufficient to have repeatable and significative mass spectroscopy results on bottoms fractions. Ourfirstinterest in this work is to be able to characterize heavyfractions,boiling up to 750°C. Analyses are limitated by Fisher and Hood mass spectrometry techni ques. Fisher characterization is devoted to petroleum cuts ranging from 250 to 700°C. Repeatability problems occur on fractions analysis when the feedstock contains a large amount of resid. Applied to the heaviest part of bottoms fractions, Hood-MS is used on the outer upper limit of its application, as this technique is normally used for cuts boiling from 250 to 500°C. Example of application to MAT effluents characterization MAT tests were performed on two different feedstocks to evaluate bottoms upgrading capability of two USY catalysts. The pilot used for these tests is a R2R MAT pilot, developed by TOTAL and I.F.P. (3). Both feeds contain some atmospheric resid. Feed 2 has a higher basic nitrogen level than feed 1. Catalysts comparison was made at constant coke yield as the potential industrial unit is considered to be airblower limited.


142

FLUID CATALYTIC CRACKING ΠΙ

1) FEEDSTOCK 1 : Yields at 5.7 weight % coke yield Cat to oil Fuel gas LPG Gasoline (C -220°C) LCO (220-3 50°C) Bottoms (350+°C) Coke Delta coke Downloaded by YORK UNIV on October 29, 2012 | http://pubs.acs.org Publication Date: November 4, 1994 | doi: 10.1021/bk-1994-0571.ch012

5

(weight %) (weight %) (weight %) (weight %) (weight %) (weight %)

Catalyst A 4.7 2.6 23.0 49.0 11.4 8.3 5.7 1.21

Catalyst Β 3.8 3.0 23.8 41.3 11.5 14.7 5.7 1.50

2) FEEDSTOCK 2 : Yields at 6.9 weight % coke yield Cat to oil Fuel gas LPG Gasoline (C -220°C) LCO (220-350°C) Bottoms (350+°C) Coke Delta coke 5

(weight %) (weight %) (weight %) (weight %) (weight %) (weight %)

Catalyst A 6.4 3.1 19.6 40.6 12.4 17.4 6.9 1.08

Catalyst Β 6.4 3.4 20.9 36.7 9.7 22.4 6.9 1.08

These results show clearly that Catalyst A is better than Catalyst Β for bottoms upgrading at constant coke yield, on both feedstocks. However, we were not able to determine molecular species cracked by Catalyst A and not cracked by Catalyst B. Therefore we have performed microdistillation on these four MAT effluents to charac terize bottoms by Fisher-MS analysis. Bottoms yields given by microdistillation and Fisher results are given hereafter. Feedstock Catalyst A Effluent weight (g) 0.525 Bottoms weight recovered (g) 0.084 Bottoms weight expected based on TBP effluent analy 0.088 sis (g) 350 °C in bottoms (TBP 8 analysis) (weight %)

1 Feedstock 2 Catalyst Β Catalyst A Catalyst Β 0.741 0.451 0.438 0.189 0.118 0.165 0.193

0.136

0.175

7

6

8

Fisher results, given on Tables II and III, are expressed in terms of weight % rela ted to bottoms and in terms of weight % related to feedstock. On both feedstocks, Catalyst Β does not crack all monoaromatic species and leaves more saturated and diaromatic species in the heavy fraction than Catalyst A. These results appear consistent with the difference observed in yield structures.


12. BOISDRON ET AL.


143

Table Π. Feedstock 1 Feedstock Catalyst A Detailed HT-MS Fisher Catalyst Β analysis Weight % Weight % χ Weight % Weight % χ analysis bottoms yield bottoms yield 43.0 3.63 Saturates 24.6 22.5 1.87 C

n 2n+2

C

H

n 2 n , -2, -4, -6

H

Aromatics Monoaromatics


C

4.85 17.60

0.40 1.46

5.42 19.14

0.80 2.82

13.25 29.75

68.3

5.68

68.4 4.39

10.09 0.65

52.9 21.77

0.82 1.34 2.23

0.12 0.20 0.33

8.07 8.31 5.39

H

n 2n-6

C

H

n 2n-8

C

n 2n-10

H

Diaromatics C

H

n 2n-12

C

n 2n-14

C

n 2n-16

H

H

Triaromatics C

n 2n-18

H

C

n 2n-20

H

Tetraaromatics C

H

n 2n-22

C

n 2n-24

C

n 2n-26

H

H

Pentaaromatics C

n 2n-28

H

C

n 2n-30

H

Hexaaromatics C

H

n 2n-32

C

n 2n-34

H

Heptaaromatics C

H

n 2n-36

C

n 2n-38

H

Sulphur compounds Benzothiophenes Dibenzothiophenes C

H

S

H

S

H

S

n 2n-16

C

n 2n-18

C

n 2n-20

3.9

0.32

11.7

1.73

10.6

1.07 1.24 1.55

0.089 0.103 0.129

3.62 3.92 4.18

0.53 0.58 0.62

3.73 3.81 3.02

18.9

1.57

17.0

2.51

5.7

10.72 8.18

0.89 0.68

10.33 6.63

1.52 0.98

3.30 2.36

21.6

1.80

16.5

2.43

6.2

13.27 3.94 4.42

1.10 0.33 0.37

9.31 3.33 3.85

1.37 0.49 0.57

2.90 1.51 1.82

10.6

0.88

7.8

1.15

3.2

7.18 3.45

0.60 0.29

4.86 2.98

0.72 0.44

1.73 1.49

8.3

0.69

6.3

0.93

2.5

5.99 2.30

0.50 0.19

4.41 1.87

0.65 0.276

1.67 0.80

5.0

0.42

4.7

0.693

3.0

1.86 3.18

0.15 0.26

1.53 3.16

0.226 0.466

0.71 2.30

9.2

0.77

7.1

1.05

4.1 0.56

1.81 0.49 0.75

0.15 0.041 0.062

1.26 0.32 0.49

0.19 0.05 0.072

0.35 0.11 0.16

2.75 1.06 0.86 0.65 0.82

0.23 0.088 0.072 0.054 0.068

2.01 0.86 0.70 0.53 0.91

0.30 0.13 0.10 0.078 0.13

0.89 0.43 0.38 0.29 0.92


C

H

S

H

S

H

S

H

S

n 2n-22 n 2n-24

C

n 2n-26

C

n 2n-28

Disulphurized compounds


144


Table m. Feedstock 2 Detailed HT-MS Fisher analysis

Saturates H

3.23

0.56

3.30

0.74

10.0

H

n 2 n , -2, -4, -6

18.70

3.26

22.10

4.95

31.40

Aromatics Monoaromatics

70.1

12.22

67.2 3.33

15.05 0.75

50.4 10.89

0.70 1.05 1.58

0.16 0.24 0.35

3.06 4.15 3.68

C

n 2n+2

C

C


Feedstock Catalyst A Catalyst Β Weight % Weight % χ Weight % Weight % χ analysis bottoms yield bottoms yield 41.4 5.69 21.9 ISA 3.82

C

C

H

n 2n-6 n 2n-8 n 2n-10 H

H

Diaromatics

8.7

1.52

11.7

2.62

12.0

2.00 3.57 3.10

0.35 0.62 0.54

3.63 4.11 3.94

0.81 0.92 0.88

3.58 4.24 4.13

Triaromatics

17.7

3.09

15.3

C

n 2n-18

8.97

1.56

3.43 1.77

C

n 2n-20

C

C

C

H

n 2n-12 n 2n-14 n 2n-16 H

H

H

H

Tetraaromatics C

C

C

H

n 2n-22 n 2n-24 n 2n-26 H

H

Pentaaromatics C

n 2n-28

H

C

n 2n-30

H

Hexaaromatics C

C

17.0

3.81

10.4

11.58 4.31 4.74

2.02 0.75 0.83

8.45 4.19 4.31

1.89 0.94

5.14 2.76 2.53

9.9

1.73

8.6

1.92

4.8

5.99 3.90

1.04 0.68

4.85 3.73

1.09 0.84

2.69 2.13

1.66

0.97

7.7

1.34

6.5

1.46

2.2

0.93

1.00

H

2.32

0.40

4.45 2.00

1.50 0.70

5.6

0.98

4.9

1.10

1.6

1.83 3.75

0.32 0.65

1.57 3.33

0.35 0.75

0.56 1.06

7.9

1.38

7.4

1.66

n 2n-36

H

C

n 2n-38

H

Sulphur compounds Benzothiophenes Dibenzothiophenes

C

1.52

3.59

5.35

C

C

8.73

20.6

4.79 3.73

H

n 2n-32 n 2n-34

Heptaaromatics

C

8.5

7.92 7.40

H

S

H

S

H

S

n 2n-16 n 2n-18 n 2n-20

0.45

8.1 1.76

1.29 0.34 0.54

0.22 0.059 0.094

0.97 0.25 0.42

0.22 0.056 0.094

0.72 0.19 0.32

2.33

0.41

2.26

0.51

2.03

1.01 0.80 0.58 1.05

0.18

1.01 0.80 0.57 1.11

0.23 0.18 0.13 0.25

0.95 0.75 0.45 0.97


C

C

C

H

n 2n-22

S

H

S

H

S

H

S

n 2n-24 n 2n-26 n 2n-28

Disulphurized compounds

0.14 0.10 0.18


12.

BOISDRON ET AL.


145


Conclusion and perspectives An original analytical tool has been developed. It consists on : • A microdistillation, using a Buchi apparatus, to separate and provide fractionsfroma MAT total effluent, i.e. gasolines, LCO and bottoms from 0.6 g sample. • A liquid microchromatography, which requires as little as 100 mg sample. It is parti cularly dedicated to the bottoms fractions to separate "saturated species" from "aromatics + sulphur compounds". • The microfractions collected are then examined for molecular analysis, using mass spectrometry. • The results on bottomsfractionsfromthese microtechniques are in good agreement with those derived from more classical techniques. Informationfromboth Fisher and O'Neal molecular analyses can help us to meet the challenge of ever higher bottoms upgrading, by a better understanding of the crack ing reactions involved. • We are still working to improve the repeatability on lighterfractions(gasolines and LCO). The table hereafter gives all the analyses we hope to be able to perform on MAT effluents in the near future. MAT EFFLUENT Φ TBP GC Detailed analysis and RON-MON estimation (IBP-220 C) GC Ψ Microdistillation o

GASOLINE (in development) IBP - 220°C Total sulphur Sulfur families

elemental analysis

SLURRY (provedfeasibility) 350+°C

LCO (in development) 220 - 350°C MS Hood

Naphtenes by ring number

MS Hood

Aromatics by MS ring number GC/SCD

MS Fisher

Aromatics by ring number

MS Fisher

Sulphur fami lies

MS Fisher

Sulphur fami lies

MS Fisher

Total sulphur

Elemental analysis

Total sulphur

Elemental analysis

Cetane

Γ RMN H \ MS IGC

Naphtenes by ring number

1

Sulphur by simulated dis GC/SCD tillation


146


Acknowledgments The authors aknowledge Gilbert Becquet and Michel Hays for performing the microanalyses. Literature cited (1) (2) (3)

Bouquet, M. and Brument, J., Fuel Science and Technology Int'l, 8 (9), 961-986 (1990) O'Neal, A., Anal. Chem., 31, 164 (1959). Mauleon, J.L., and Courcelle, J.C., Oil & Gas Journal, Oct. 21, 1985. June

17,

1994


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Breakthrough in Microactivity Test Effluent Analysis - ACS Symposium

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