Studying effects of hydrotreatment on PAC compositions in refinery streams using GC GC-FID/SCD and GC GC-ToFMS. Asger B.

Transcription

1 Studying effects of hydrotreatment on PAC compositions in refinery streams using GC GC-FID/SCD and GC GC-ToFMS Asger B. Hansen, HTAS

2 Presentation outline Petroleum refining Refinery streams Hydrotreatment (HDS, HDN, HDA, HYC) Analytical methodology GC GC Hydrodesulphurisation (HDS) of light gas oils Kinetics for the removal dibenzothiophenes (DBTs) Direct and indirect reaction paths for DBT/M-DBT Hydroprocessing of unconverted oils (UCO) Fate of PNAs Saturation hydrocracking condensation Summary 2

3 Petroleum refining refinery streams Visbreaker thermal cracking Fluid catalytic cracking (FCC) 3

4 The hydrotreating (HDT) process Recycle gas Quench gas Heater Reactor Gas purification H 2 S Feedstock high sulphur Separator Product low sulphur 4

5 Hydroprocessing reactions Sulphur conversion (hydrodesulphurisation - HDS) Nitrogen conversion (hydrodenitrogenation - HDN) Metals removal (hydrodemetallation - HDM) Oxygen conversion (hydrodeoxygenation - HDO) Hydrogenation of: Olefins (HYD) Aromatics (hydrodearomatization - HDA) Hydrocracking (HYC) (Isomerisation, Ring Opening) 5

6 Analytical methodology: GC GC Instrumentation: GC GC-FID/SCD and GC GC-ToFMS Thermo Trace Ultra GC GC LECO Pegasus 4D GC GC - GC GC with one oven - GC GC with two ovens - thermal modulator (liq. CO2) - thermal modulator (liq. N2) - parallel FID and SCD detectors - ToF-MS detector 6 1D column: BP1/BP5 2D column: BPX50

7 GC GC 2D-chromatograms (colour plots) Structured 2D-chromatograms Orthogonal separation mechanism (e.g. nonpolar polar) Enhanced peak capacity Diesel sample GC GC- FID Polarity (1/g 0 ) C15 C20 C25 C30 C10 Volatility (1/p 0 ) 7

8 GC GC-SCD of LGO feed Phenanthrothiophenes (NDBT) Napthobenzothiophenes (NBT) Dibenzothiophenes (DBT) C0 C1 C2 C3 C4 C5 Naphthenobenzothiophenes (NBT) Benzothiophenes (BT) Naphthenothiophenes (NT) Thiophenes (T) 8

9 HDS as a function of catalyst volume Feed 5% 10% CoMo cat LGO S = wt ppm 33% S 2000 wt ppm. All Ts and BTs has been removed S 800 wt ppm. Most DBT without substituents in 4,6 or both has been removed ULSD diesel, S = 10 wt ppm S 120 wt ppm. 2/3 of the catalyst volume is being used for removal of 4,6-alkylsubstituted DBTs! 9

10 HDS conversion: reactivity of S-compounds Most abundant sulphur compounds Sulphur, wt ppm BTs DBTs N Basic N Nitrogen, wt ppm % HDS conversion 10

11 Reactivity of DBT and C1-DBTs Reactivity order 250 S, wt ppm k = 30 h DBT-C12 DBT-C13-1M DBT-C13-2/3M DBT-C13-4M %HDS conversion k = 6 h -1 4-MethylDBT k = 0.5 h -1 11

12 Reactivity of C2-DBTs C14-DBTs in feed 4,6-DimethylDBT DBT-C14-2.3dM DBT-C14-1.3/3.4/1.8dM No substituents at 4 or 6 position DBT-C14-1.2dM DBT-C14-1.7/1.9/2.3dM DBT-C14-1Et DBT-C14-2/3.7dM DBT-C14-1.4/1.6/2.8dM DBT-C14-3/2.6dM DBT-C14-4/3Et DBT-C14-2.4dM DBT-C14-4.6dM S, wt ppm S, wt ppm %HDS conversion %HDS conversion 12

13 Hydrotreatment using a NiMo cat Hydrotreatment of 25/75 LC/LG blend using a NiMo cat Aromatics reactions monoaro increases C15 Carbon No. Groups triaro decreases 14.0 NmonoAro increases 12.0 NdiAro decreases 10.0 C15-mNaph dinaph increases diaro constant?? area% C15- maro C15- triaro C15 - NtriAro C15- NmAro C15- NdiAro C15- dinaph C15- diaro C15-iPar C15-nPar DBT reactions 2.0 DBTs BPs conversion? 0.0 0% 63% 68% 79% 85% 90% 96% HDS conversion 13

14 HDS reactions of DBTs in middle distillates Direct conversion of DBT and M-DBTs to BPs Hydrogenation of DBTs to CHBs 1M-DBT Þ 2M-BP + xm-chb 2M-DBT Þ 3M-BP + xm-chb 3M-DBT Þ 4M-BP + xm-chb 4M-DBT Þ 3M-BP + xm-chb 14

15 Direct conversion of M-DBTs to M-BPs m/z 198 m/z 168 M-DBT M-BP Rel. Amount BP DBT BP Rel. Amount M-DBT 2M-BP 2M-BP Feed 63% 68% 73% 79% Conversion (%) 85% 90% 96% BP DBT DBT 2 0 Feed 63% 68% 73% 79% Conversion (%) 85% 90% 96% 1M-DBT 2M-BP 1M-DBT Rel. Amount Feed 63% 68% 73% 79% Conversion (%) 85% 90% 96% 4M-BP 3M-DBT 3M-DBT 4M-BP 4M-BP 3M-DBT Rel. Amount Feed 63% 68% 73% Conversion (%) 79% 85% 90% 96% 3M-BP 4M-DBT 4M-DBT 3M-BP 3M-BP 2/4M-DBT 15

16 Hydrotreatment: PNAs in unconverted oil (UCO) Gasoil feed ( C, 2% S, 1500 wt ppm N) Hydrotreating Hydrocracking Recycle hydrogen Make-up hydrogen Interstage HPS Recycle of UCO Light ends Naphtha Jet Diesel UCO 16

17 PNA reactions Polycondensation polymerisation Hydrogenation / dehydrogenation A + nh 2 AH exothermic: kj/mol H 2 T Þ A P Þ AH Hydrocracking Coke 17

18 Changing composition of PNAs in UCO Fate of PAH/HPNA in UCO during hydrotreatment RH C Feed (UCO) PAH/HPNA RH C RH C 18

19 Fate of PNAs in UCOs during hydrotreatment Sample Hydrotreatment ( C) Feed (pretreated UCO) RH 402 (250 C) RH 478 (300 C) RH 611 (350 C) 1-ring compounds (m/e) unspec 2-ring compounds (m/e) unspec mononaphthenes dinaphthenes 3-ring compounds (m/e) (210) unspec 4-ring compounds (m/e) (204)-218-(232) ring compounds (m/e) phenanthrenes H4-phenanthrenes pyrenes chrysenes H2-pyrenes H6-pyrenes benzo(x)pyrenes H6-benzo(xy)pyrenes phenalenes trinaphthenes H16-pyrenes H16-pyrenes H16-pyrenes H12-benzo(xy)pyrenes H18-benzo(xy)pyrenes H18-benzo(xy)pyrenes H18-benzo(xy)pyrenes 6-ring compounds (m/e) benzo(ghi)perylenes H2-benzo(ghi)perylenes H16-benzo(ghi)perylenes H22-benzo(ghi)perylenes H22-benzo(ghi)perylenes benzo(ghi)perylene H22-benzo(ghi)perylenes 7-ring compounds (m/e) coronenes H2-dibenzoperylenes H24-coronenes 19 coronene H24-coronenes coronene H24-coronenes

20 Summary GC GC is a versatile tool for monitoring refinery streams during hydroprocessing providing very detailed compo-sitional characterics: GC GC-SCD provides HDS kinetics of individual and isomeric groups of S- compounds GC GC-ToFMS provides detailed information of DBT conversion in HDS GC GC-ToFMS provides detailed information about PNA conversions in UCO during hydrotreatment 20

21 Acknowledgement I wish to thank my collegues for contributing to this presentation: Asbjørn S. Andersson Sylvain Verdier Rasmus G. Egeberg Duayne D. Whitehurst Thank you for your attention J