Home >Documents >CRE L19 Catalyst Deactivation

CRE L19 Catalyst Deactivation

Date post:03-Jun-2018
Category:
View:215 times
Download:0 times
Share this document with a friend
Transcript:
  • 8/13/2019 CRE L19 Catalyst Deactivation

    1/18

    L -18 Catalyst Deactivation

    Prof. K. K.Pant

    Department of Chemical EngineeringIIT Delhi.

    [email protected]

    mailto:[email protected]:[email protected]
  • 8/13/2019 CRE L19 Catalyst Deactivation

    2/18

    Slow decay : Temperature time trajectory

    Moderate decay: Moving bed reactorsRapid Decay: Straight through transport reactors

    For and nthorder activity decay

    and mthorder gas phase

    Coupled differential eqns to be solved are

    (MBR)

  • 8/13/2019 CRE L19 Catalyst Deactivation

    3/18

    Moving bed reactors

  • 8/13/2019 CRE L19 Catalyst Deactivation

    4/18

    Thermofer Catalytic crackin unit (Used for reactions with moderate decay)

  • 8/13/2019 CRE L19 Catalyst Deactivation

    5/18

    Combining activity equation with the mole balance equation:

  • 8/13/2019 CRE L19 Catalyst Deactivation

    6/18

  • 8/13/2019 CRE L19 Catalyst Deactivation

    7/18

    For a first order Decay

  • 8/13/2019 CRE L19 Catalyst Deactivation

    8/18

    Straight through Transport

    Reactor (Circulating fludized bedreactor)

    Used when deactivation is rapid.Used for production of gasoline

    Catalyst pellet and feed enter

    together and transported rapidly.Bulk density of the catalyst is low

    compared to Moving bed.

  • 8/13/2019 CRE L19 Catalyst Deactivation

    9/18

    STTR : Used when coking is rapid.

  • 8/13/2019 CRE L19 Catalyst Deactivation

    10/18

    Mole balance

    rA= brA

    Or

    Z= Height ,and U is velocity of catalyst

  • 8/13/2019 CRE L19 Catalyst Deactivation

    11/18

    Reading Assignment: Examples : 10.5 ,10.7, 10.8 Fogler

  • 8/13/2019 CRE L19 Catalyst Deactivation

    12/18

  • 8/13/2019 CRE L19 Catalyst Deactivation

    13/18

  • 8/13/2019 CRE L19 Catalyst Deactivation

    14/18

    a

    1 R 1= ln +

    T E Ta o

    Temperature/Time Trajectories A control strategy involves maintaining a

    constant conversion with catalyst decay byincreasing operating temperature.

    develop a temperature/time trajectory to find Tt

    relationship:

    -rA (t=0,T0) = -rA (t= t,T) = a(t ,T)[-rA (t=0,T) ]

    (For First order reaction ) k T a T,t = ko

    E 1 1a -R T To

    k e a = ko o

  • 8/13/2019 CRE L19 Catalyst Deactivation

    15/18

    Temperature/Time Trajectories

    a

    E1 1d -

    R T Tda o n

    r = - = k ed ddt

    decay law is:

    a

    Ed- lnaE

    da a n- = k e

    ddt o

    a

    E

    dn-Ea

    = kdo

    a

    1 R 1= ln +

    T E Ta o

  • 8/13/2019 CRE L19 Catalyst Deactivation

    16/18

    Temperature/Time Trajectories

    1- n+ E Ead1-a

    t =

    k 1-n+ E Ead do

    a

    1 R 1= ln +T E T

    a o

    E 1 1a -R T T

    oa = e

    E -n E +Ea a 1 1d -

    R T To1-e

    =E

    dk 1-n+d Eo a

    a

    a

    Ed-n+E

    a tda = -k dt1 0d

    o

    Ed-n 1

    Ea

  • 8/13/2019 CRE L19 Catalyst Deactivation

    17/18

  • 8/13/2019 CRE L19 Catalyst Deactivation

    18/18

    THANK YOU

Embed Size (px)
Recommended