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INTRODUCTION
 Due to depleting supplies of quality petroleum crudes,
refineries world-wide are increasingly being forced ...
 Overall, new and more effective approaches and
continuing catalysis and processing research are needed
for producing aff...
Hydrodesulfurisation
(HDS)
Hydrodenitrogenation
(HDN)
Hydrodeoxygenation
(HDO) and (HDM)
REFINERY PROCESSES
Catalytic
crac...
 Hydrodenitrogenation (HDN) occurs simultaneously with
hydrodesulfurization HDS), hydrodeoxygenation (HDO),
hydrogenation...
5
HYDROTREATING
A process used in the oil
industry to remove
objectionable elements
such as nitrogen sulfur,
oxygen and me...
Compound Sulfur in wt.%
Nitrogen in
ppm level
Gas oil
1.87 wt.% 1000 ppm
Medium cycle oil (MCO) 0.49 wt.% 695 ppm
Coal liq...
IMPORTANCE
7
HDS
• Prevention of poisoning of the metal
catalysts by sulfur
• Control of pollution by SO2 produced in
the ...
• When organo sulfur compounds are decomposed, gaseous or
solid sulfur products are formed and the hydrocarbon part is
rec...
Contd…..
9
Desulfurization technologies classified by nature of a key
process to remove sulfur
10
Sulfided CoMo/Al2O3 and NiMo/Al2O3 catalysts
CONVENTIONAL HDS
11
Their performance in terms of desulfurization level,
acti...
• Hydrotreating model catalyst systems are synthesized by
impregnating and spin-coating Mo and Co precursor
compounds onto...
Schematic picture of different phases present in a sulfided
alumina-supported CoMo catalyst
13
Co is present in three
different phases.
(i) The active CoMoS
nanoparticles.
(ii) A thermodynamically stable
cobalt sulfid...
Surface structure models of a
conventional HDS catalyst and the designed catalyst
15
HDS PROCESS
16
Environmental restrictions on petroleum products to limit
the sulfur level in fuels to 50 ppm or lower necessitated
new ge...
• What is deep desulphurization of the fuels ?
More and more of the least reactive sulfur compounds must
be converted to H...
• How to approach deep desulfurization?
The modification of the physicochemical properties of the
supports is one of the s...
• Ideal hydrotreating catalysts should be able to remove sulfur,
nitrogen and, in specific cases, metal atoms from the ref...
Typical Reactivity pattern observed in HDS Catalysis
21
General classification of the catalysts
22
CHOICE OF SUPPORTS
23
Different approaches have resulted in new catalyst
formulations with improved performances
To improve catalyst performance...
• The strength of the interaction with the support controls the
dispersion, reducibility, acidity and catalytic activity.
...
APPROACHES FOR DEVELOPING BETTER CATALYSTS
Effects of various additives on the properties of
alumina-supported HDS catalys...
• Hydrotreating efficiency can also be increased by employing
advanced reactor design such as multiple bed systems within
...
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Chapter 6b -_hydrotreating_hds_catalyst

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Chapter 6b -_hydrotreating_hds_catalyst

  1. 1. INTRODUCTION  Due to depleting supplies of quality petroleum crudes, refineries world-wide are increasingly being forced to use inferior quality heavy oils (HO) for producing clean transportation fuels.  Unfortunately, the low grades HO are considerably more difficult to process and can significantly reduce the efficiency of clean fuels production.  From the viewpoint of continual efficient supply of clean fuels, it is therefore critical to improve key HO processes such as sulphur and nitrogen removal. 1
  2. 2.  Overall, new and more effective approaches and continuing catalysis and processing research are needed for producing affordable ultra-clean (ultra-low-sulfur and low-aromatics) transportation fuels.  The society at large is stepping on the road to zero sulfur fuel, so researchers should begin with the end in mind and try to develop long term solutions. Contd….. 2
  3. 3. Hydrodesulfurisation (HDS) Hydrodenitrogenation (HDN) Hydrodeoxygenation (HDO) and (HDM) REFINERY PROCESSES Catalytic cracking Hydrocracking Catalytic reforming Hydrotreating PROCESSES IN REFINERIES 3
  4. 4.  Hydrodenitrogenation (HDN) occurs simultaneously with hydrodesulfurization HDS), hydrodeoxygenation (HDO), hydrogenation (HYD) and hydrodemetallization (HDM) during hydroprocessing. Effects of these reactions upon each other are rather complex.  The extent of the mutual effects depends on the origin of feed, type of catalyst, and operating conditions.  The HDN has been the focus of attention because nitrogen removal is required to attain the level of sulfur (S) required by fuel specifications. If not removed, nitrogen (N)-compounds would inhibit HDS and other reactions because of their preferential adsorption on catalytic sites. HYDROTREATING 4
  5. 5. 5 HYDROTREATING A process used in the oil industry to remove objectionable elements such as nitrogen sulfur, oxygen and metals from petroleum distillates by reacting them with H2 over a catalyst. Hydrodenitrogenation (HDN): is the removal of nitrogen from nitrogen containing feeds in the form of NH3. The resulting products are hydrogenated . Hydrodesulfurisation (HDS): is the removal of sulfur from sulfur containing feeds in the form of Hydrogen Sulfide, H2S. The resulting products are hydrogenated Hydrodeoxygenation (HDO) and hydrodemetalization (HDM) are the removal of oxygen and metals from the feed. respectively.
  6. 6. Compound Sulfur in wt.% Nitrogen in ppm level Gas oil 1.87 wt.% 1000 ppm Medium cycle oil (MCO) 0.49 wt.% 695 ppm Coal liquid 2.5 wt.% 5600 ppm Vacuum gas oil (VGO) 1.7 wt.% 125 ppm Desulfurized vacuum gas oil (DS-VGO) 0.289 0.028 Light cycle oil (LCO) 2.19 wt.% - Nitrogen And Sulfur Content Present in Different Crude 6
  7. 7. IMPORTANCE 7 HDS • Prevention of poisoning of the metal catalysts by sulfur • Control of pollution by SO2 produced in the combustion of gasoline • Removal of the unpleasant odor of lube oil caused by the presence of sulfur HDN • Nitrogen containing compounds severely reduce the activity of cracking, hydrogenation, isomerization, reforming and HDS catalysts • High nitrogen concentrations are undesirable to product quality • To meet the NOx ,mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide)emission restrictions. • If present, N-compounds affect the stability of fuels (fuel storage degradation and contamination). A fuel is considered unstable when it undergoes chemical changes that produce undesirable consequences such as deposits, acidity
  8. 8. • When organo sulfur compounds are decomposed, gaseous or solid sulfur products are formed and the hydrocarbon part is recovered and remains in the refinery streams. Conventional HDS • Sulfur compounds are separated from refinery stream without decomposition • Organo sulfur compounds are separated from the streams and simultaneously decomposed in a single reactor unit rather than in a series of reaction and separation vessels Classification of Desulphurization Technology 8
  9. 9. Contd….. 9
  10. 10. Desulfurization technologies classified by nature of a key process to remove sulfur 10
  11. 11. Sulfided CoMo/Al2O3 and NiMo/Al2O3 catalysts CONVENTIONAL HDS 11 Their performance in terms of desulfurization level, activity and selectivity depends on The properties of the specific catalyst used (active species concentration, Support properties, synthesis route) The reaction conditions nature and concentration of the sulfur compounds present in the feed stream, and reactor and process design. (sulfiding protocol, temperature, partial pressure of hydrogen and H2S),
  12. 12. • Hydrotreating model catalyst systems are synthesized by impregnating and spin-coating Mo and Co precursor compounds onto flat discs with an oxidic layer as support, a process much like real catalyst preparation. • Subsequent sulfidation results in the formation of CoMoS or MoS2 particles Hydrotreating catalyst 12
  13. 13. Schematic picture of different phases present in a sulfided alumina-supported CoMo catalyst 13
  14. 14. Co is present in three different phases. (i) The active CoMoS nanoparticles. (ii) A thermodynamically stable cobalt sulfide, Co9S8. (iii) Co dissolved in the Al2O3 support. Only the CoMoS particles are catalytically active Schematic representation of the the CoMoS model under reaction conditions 14
  15. 15. Surface structure models of a conventional HDS catalyst and the designed catalyst 15
  16. 16. HDS PROCESS 16
  17. 17. Environmental restrictions on petroleum products to limit the sulfur level in fuels to 50 ppm or lower necessitated new generation hydrodesulfurization catalysts. In addition, preparing hydrocarbon fuel feeds to the fuel cell set up requires sulfur reduction to 0.1 ppm. Such a demanding task requires catalysts that are several times more active than the present catalysts used to achieve 500 ppm sulfur. It is not only the high activity but they should also have different activity profiles with respect to different functionalities. In order to modify the activity to achieve the above said objectives several approaches have been pursued among which variation of support is an important one. NEW GENERATION HDS CATALYSTS 17
  18. 18. • What is deep desulphurization of the fuels ? More and more of the least reactive sulfur compounds must be converted to H2S. • Why is deep desulphurization ? DBT and/or DBT derivatives that are known to be the most refractory S-containing compounds show reactivities 50-fold lower as compared to others. The concentration of the most refractory sulphur compounds in straight-run diesel oil and light cycle oil approaches 3000 and 5000 ppm, respectively. DEEP DESULFURIZATION 18
  19. 19. • How to approach deep desulfurization? The modification of the physicochemical properties of the supports is one of the still preferred modes of increasing catalytic activity. The synthesis of mesoporous molecular sieves with high surface area and relatively ordered pore structure offers new possibilities of using these materials as modifiers of the porous support structure. Deep desulfurization of refinery streams becomes possible when the severity of the HDS process conditions is increased. Instead of applying more severe conditions, perhaps HDS catalysts with improved activity and selectivity can be synthesized. Contd….. 19
  20. 20. • Ideal hydrotreating catalysts should be able to remove sulfur, nitrogen and, in specific cases, metal atoms from the refinery streams. At the same time they must also improve other fuel specifications, such as octane/cetane number or aromatics content, which are essential for high fuel quality and meeting environmental legislation standards. • The use of novel mesoporous supports for catalysts may help larger molecules to have access to the pores thereby enhancing the activity and minimizing the S & N content Contd….. 20
  21. 21. Typical Reactivity pattern observed in HDS Catalysis 21
  22. 22. General classification of the catalysts 22
  23. 23. CHOICE OF SUPPORTS 23
  24. 24. Different approaches have resulted in new catalyst formulations with improved performances To improve catalyst performance, all steps in the catalyst preparation-choice of a precursor of the active species, support selection, synthesis procedure and post-treatment of the synthesized catalysts-should be taken into account ADVANCED HDS CATALYSTS 24
  25. 25. • The strength of the interaction with the support controls the dispersion, reducibility, acidity and catalytic activity. • The support mesoporosity is important for better dispersion of sulfide layer. • Support design increase significantly the HDS, HYD and HDN functionalities of hydrotreating catalysts. • The nature of the support affects sulfidation of the active species, leading to better-promoted active sites and dispersion of the catalysts. FUNCTIONS OF SUPPORT - GENERAL 25
  26. 26. APPROACHES FOR DEVELOPING BETTER CATALYSTS Effects of various additives on the properties of alumina-supported HDS catalysts 26
  27. 27. • Hydrotreating efficiency can also be increased by employing advanced reactor design such as multiple bed systems within one reactor, new internals in the catalytic reactor or new types of catalysts and catalyst support (e.g. structured catalysts). • The best results are usually achieved by a combination of the latter two approaches, namely, using an appropriate catalyst with improved activity in a reactor of advanced design. CONCLUSION 27

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