PROJECT ON

HYDRODESULFURIZATION REACTOR DESIGN

By In the expert guidance of:ALOK SHUKLA Er. T.P.SINGH ANURAG CHANDRA SHEKHAR ASST. PROFESSORDEEPA KUMAR CHEMICAL ENGG. DEPT. NIVADITA GUPTA(B. TECH. FINAL YEAR )

OBJECTIVE

• To study the basic construction of a trickle bed HDS reactor.

• The experimental study of Mo catalyst on different material beds and decide the optimum condition.

• To compare the efficiencies of different catalyst systems.

WHAT IS HYDRODESULFURIZATION ?

Hydrodesulfurization (HDS) is a catalytic chemical process used to remove sulfur from natural gas and petroleum . ‘S’ is converted to H2S and removed.

NEED OF HYDRODESULFURIZATION

To reduce sulfur oxides emissions that result from fuel burning.

S ,even in small quantities, poisons the noble metal catalysts (Pt, Re) in petroleum processes like catalytic reforming.

Sulfur causes corrosion and erosion of process equipments.

S is a useful product.

PROCESS CHEMISTRYHydrodesulfurization is a type of Hydrotreating reaction where sulfur of an organic compound is converted to H₂S and removed by processes like •Absorption by regenerative solvent. Example: C₂H₅SH + H₂ → C₂H₆ + H₂S HOC₂H₄NH₂ + H₂S → HOC₂H₄NH₃⁺HS⁻•Adsorption on solid bed like zinc oxide .•Example : ZnO + H₂S →ZnS + H₂O

PROCESS CHEMISTRY : THE ACTION OF CATALYST

BASIC DESIGN OF A HDS UNIT IN A PETROLEUM REFINERY

HYDROTREATING : TRICKLE BED REACTOR STRUCTURE

BASIC DESIGN FEATURES OF A COMMONLY USED HDS REACTOR

• Generally for liquis crudes a three phase reactor of packed bed type called trickle bed reactor is used.

• Depth : 3 to 6 m.• Catalyst prticles spherical with 1/8 to 1/32 in. diameter.• Temperature 350 to 425°C .• Pressure 34 to 100 atm.• Generally cocurrent flow is used.

DIFFERENT PHASES PRESENT IN A SULFIDED ALUMINA SUPPORTED

CoMo CATALYST

EXPERIMENT FOR ACTIVITY OF UNPROMOTED Mo CATALYST ON DIFF. SUPPORT BASE

MATERIALS : METHODOLOGYUnpromoted Mo catalysts containing varying amounts of Mo were prepared on commercial support materials consisting of alumina , silica and titania. (NH₄)₆Mo₇O₂₄.4H₂O was introduced by the method of incipient wetness. The catalyst were dried overnight at 390 K and calcined for four hours at 673 K. reaction temperature was 648 K and activity was expressed as a first order rate constant. Reagent was thiophene.

CATALYST CHARACTERISTICS AND ACTIVITIES FOR HDS OF THIOPHENE AT 648K

Catalyst %MoO₃ Atoms of Mo ,nm⁻²

K(x10²) K (at. Mo)-1

(x10²¹)

Al₂O₃Surface Area=240m²g⁻¹

2 0.30 20.0 2.39

-do- 5 .75 61.0 2.92

-do- 10 1.50 130.0 3.10

-do- 15 2.25 155.0 2.47

-do- 20 3.0 170.0 2.03

-do- 30 4.5 140.0 1.15

-do- 40 6.0 120.0 0.72

CATALYST CHARACTERISTICS AND ACTIVITIES FOR HDS OF THIOPHENE AT 648K

Catalyst %MoO₃ Atoms of Mo ,nm⁻²

K(x10²) K (at. Mo)⁻¹(x10²¹)

SiO₂Surface Area=350m²g⁻¹

5 0.60 56.8 2.72

,, 10 1.20 130.8 3.10

,, 15 1.80 161.2 2.56

,, 20 2.40 179.0 2.14

,, 30 3.60 225.6 1.80

,, 40 4.80 192.4 1.14

CATALYST CHARACTERISTICS AND ACTIVITIES FOR HDS OF THIOPHENE AT 648K

Catalyst %MoO₃ Atoms of Mo ,nm⁻²

K(x10²) K (at. Mo)-1

(x10²¹)

TiO₂Surface Area=43m²g⁻¹

1 0.97 22.0 5.26

,, 3 2.92 52.0 4.14

,, 6 5.84 65.0 2.59

,, 10 9.73 46.0 1.09

CATALYST CHARACTERISTICS AND ACTIVITIES FOR HDS OF THIOPHENE AT 648K

Catalyst %MoO₃ Atoms of Mo ,nm⁻²

K(x10²) K (at. Mo)-1

(x10²¹)

ZrO2

Surface Area=18m²g⁻¹

1 2.33 15.0 3.58

,, 3 6.97 26.0 2.07

,, 6 13.98 27.0 1.08

,, 10 23.30 21.5 .51

SPECIFIC ACTIVITY OF Mo CATALYST

SPECIFIC ACTIVITY OF Mo CATALYST

Application of hydrodesulfuriztion for natural gas feed at IFFCO, Kalol• Sulphur compounds are removed from natural

gas 2-3 ppm to less than .1 ppm.• Desulfurizer operates at a pressure of 39

kg/cm²,temperature 30-35°C.• Catalyst life is 10 months,catalyst used is

activated carbon.• Natural gas flow : 20059 kg/hr• Catalyst volume is 28.3 m³

NEED FOR NEW AND EFFICIENT CATALYST

Allowable s in environment :1999 :500 ppm2001 : 50 ppm2003 ; 10 ppmFossil fuel resources are depleting fast.

Catalyst should have higher mechanical strength,higher activity,higher tolerance for contaminants,longer life.

THE NEW CATALYSTS TiO₂ - Al₂O₃ Composite supports instead of Al₂O₃

Supports, Al₂O₃ - MgO mixed supports.Au –Pd catalystsMoC catalystsUltrasonically controlled deposition precipitation:

Co–Mo HDS catalysts deposited on wide-pore ceramic material

Development of mesoporous molecular sieve materials

The above are indicative examples.

CONCLUSIONIn our study of the desulfuriztion of petroleum crudes we found that same catalyst behaves differently when placed on different base supports . So better catalysts can be developed not only by changing the catalyst material but also by designing better bed supports.

REFERENCES1. Perry’s Chemical Engineers Handbook.2. www.wikipedia.org3. www.sciencedirect.com4. Recent Trends in Chemical Reaction Engineering-Vol ii ,

Wiley Eastern Limited.5. Petroleum Refining Technology : Dr. Ram Prasad : Khanna

Publishers.6. Data provided by IFFCO , Kalol unit ,Gujarat and ONGC

Dehradun.7. Elements Of Chemical Reaction Engineering : H.S. Fogler.

THANK YOU!