paper52971 1

							 A Novel Solid Catalyst Process for
       Biodiesel Production



                  Dheeban Kannan
                   Jack V. Matson

                    June 25, 2008
12th Annual Green Chemistry and Engineering Conference
                    Washington, DC
                         Introduction
       Biodiesel – fatty acid (m)ethyl esters

       Importance – energy

                       environmental

                       economy


       Motivation          separation hassles
                               
                               
                               
                               
                               
                               
                               
                               
        • Soluble liquid catalysts --> Solid catalysts




2
                                                           Background
                                        1500
                                                      US Production
             Million Gallons per Year

                                        1200
                                                      EU Production

                                         900


                                         600


                                         300
                                                                                                  Source:
                                           0                                                      European Biodiesel Board
                                               2002                   2003   2004   2005   2006   National Biodiesel Board




       Current annual biodiesel potential of US: 280 million
        gallons
       Microalgae promises yields ~1000 times that of soybean
       Solid catalysts – Crucial for large scale commercial
        production
3
                                          Background
       Transesterification Reaction
               R-COOCH2                                                                        CH2OH
                    l                                     catalyst                             l
               R-COOCH              +     3 CH3OH            ̶ ̶ ̶>   3 R-COOCH3          +    CHOH
                    l                                                                          l
               R-COOCH2                                                                        CH2OH
                  triglyceride               methanol                     methyl esters        glycerol
              (vegetable oil)                                           (biodiesel)
                                 where R denotes a hydrocarbon chain of carbon number 12~16.


       Conventional Process Information
        •   Reactants immiscible – reaction at interface
        •   Liquid base catalysts used: 60˚C – 1.5 hr
        •   Separation of catalyst from product mixture poses
            problems – additional processing units
        •   Feedstock with high free fatty acid content require
            additional acid-catalyzed preceding step
        •   Wastewater
4
            Lead-up to Current Research

       Solid bases not effective for conventional reaction
        conditions

       Solid acids even behind in performance

       Supercritical process1
        •   No catalyst, 350˚C, 500 atm, 4 min
        •   40:1 Alcohol:Oil Molar ratio [conventional 6:1]
        •   Pressure too high, Thermal breakdown issues
        •   Critical Point: Methanol 240˚C, 80 atm,
                             Ethanol 247˚C, 65 atm
        •   With cosolvent2, 280˚C, 130 atm, 10 min
5                      [1]. Saka, S. and Kusdiana, D., Fuel (2001) 225
                       [2]. Cao et al., Fuel 84 (2005) 347
          Lead-up to Current Research
       Critical regime desired for better miscibility
         • Alcohol both as a reactant and as a cosolvent

       Could mild solid bases be effective near critical regime?

       Packed-Bed Reactor - High T okay for continuous
        process

       Suppes et al.3 tried calcium carbonate
         • 260˚C, 70 atm, residence time 18 min

         • 50% biodiesel as cosolvent, otherwise poor yield



6               [3]. Suppes et.al., J. Am. Oil Chem. Soc., (2001) 139
                          Batch Tests
       Batch reactors used initially to test and screen catalysts
       Various weak solid base salts and mild metal oxide bases
        were tested
       Analytical Procedures: Gas Chromatography (GC)
                               Thin Layer Chromatography (TLC)
       Certain metal oxides showed good results    (Patent Pending)
         • ~95% conversion in 18 min

       Free fatty acid conversion of 93% observed. Probably
        due to the amphoteric nature of metal oxides. Eliminates
        the need of a separate acid-catalyzed preceding step.

7
    Performance of Catalysts – Batch Tests

                               100

                                95
                                                                                    260 o C, 18 min
    Biodiesel Conversion (%)




                                90
                                                                                 40:1 Alcohol:Oil Molar ratio
                                85

                                80

                                75

                                70

                                65

                                60
                                     TiO   Ca Al oxide   MnO   CaTiO3    CuO      CaCO3           TiO2          no catalyst




8                                    * Catalysts tested at 220, 200, 175, 150 ˚C – similar trend
    Lab-Scale Packed-Bed Reactor




        Reactor Temperature 260˚C, Pressure ~70 atm

9
                                Lab-Scale Packed-Bed Reactor
                                100

                                 90
     Biodiesel Conversion (%)




                                 80

                                 70

                                 60
                                                                                  TiO
                                 50
                                                                                  CaTiO3
                                 40
                                                                                  MnO (20-35 mesh)
                                              40:1 Alcohol:Oil Molar ratio
                                 30                                               CaCO3
                                              260˚C, Pressure ~70 atm
                                 20
                                      0   5                10                15         20           25
                                                      Residence time (min)


10
                                             Activity Sustenance Tests
                                •    Performance of the catalysts checked for deterioration with time
                                •    No deterioration for 200 hours

                                100
                                    90
     Biodiesel Conversion (%)




                                    80
                                    70
                                    60
                                    50
                                    40
                                    30
                                    20                                                MnO (+200 mesh)
                                    10
                                                                                   Residence time = 5 min
                                    0
                                         0    20   40   60     80     100    120       140      160         180   200
                                                             Catalyst Run Time (hr)


11
                                                             Reaction Order
                                         Pseudo first order reaction  excess alcohol (40:1 ethanol:oil molar ratio)
                                          X = 1 – e-kt
                                   100                                                1

                                   90
     Biodiesel Conversion, X (%)




                                   80                                                0.8

                                   70

                                   60                                                0.6




                                                                               1-X
                                   50
                                   40                                                0.4
                                                                                                                        -0.2829 t
                                   30
                                                                                                              1-X = e
                                                                                                                   2
                                                                                                                  R = 0.9945

                                   20                     +200 mesh MnO              0.2

                                   10

                                    0                                                 0
                                         0    3       6       9      12   15               0   3      6       9        12           15

                                               Residence time, t (min)                         Residence time, t (min)




12
                                                         Molar Ratio Tests
                                Optimal  Molar-Ratio
                                     •Balance the better medium of interaction provided by the excess
                                     alcohol with reaction space
                           80                                                                   0.25                                             10

                           70
Biodiesel Conversion (%)




                                                                                                 0.2                                                 8
                           60




                                                                             Rate constant, k
                           50                                                                                                                        6
                                                                                                0.15
                           40




                                                                                                                                                         WHSV
                                                                                                                           rate constant
                           30                                                                    0.1                                                 4
                                                                                                                           WHSV
                           20
                                                    MnO (+200 mesh)                             0.05                                                 2
                           10
                                               Residence time = 5 min
                           0                                                                      0                                                  0
                                0      10      20        30        40   50                             0     10       20         30        40   50
                                    Ethanol:Vegetable Oil Molar Ratio                                      Ethanol:Vegetable Oil Molar Ratio



            13
                                                          Pressure Effect


                            80                                                                           0.3

                            70
 Biodiesel Conversion (%)




                                                                                                        0.24
                            60




                                                                                     Rate constant, k
                            50                                                                          0.18
                            40
                                                                                                        0.12
                            30

                            20                    MnO (+200 mesh)                                       0.06
                            10
                                                  Residence time = 5 min
                            0                                                                             0
                                 0   250    500     750      1000      1250   1500                             0   250     500    750    1000    1250   1500

                                           Outlet Pressure (psi)                                                         Outlet Pressure (psi)




14
                                                  Near-Critical Regime

                           80                                                     0.0
                                                                                   1.75E-03   1.90E-03      2.05E-03        2.20E-03      2.35E-03        2.50E-03
                           70        ~ 1070 psi                                   -1.0
Biodiesel Conversion (%)




                                                                                                 260° C
                           60        ~ sat. vapour P
                                                                                                          240° C
                                                                                  -2.0
                           50                                                                                      220° C
                                                                                                                                       40:1 Molar ratio
                                    MnO (+200 mesh),
                                  Residence time = 5 min




                                                                           ln k
                                                                                                                            200° C
                           40                                                     -3.0
                                                                                                                                     175° C
                           30
                                                                                  -4.0
                           20
                                                                                                ~ 1070 psi
                                                                                  -5.0                                                              150° C
                           10
                                                                                                ~ sat. vapour P
                           0                                                      -6.0
                            100       150              200     250   300
                                                                                                3        1/T (1/K)
                                             Temperature (C)                                    Linear (
                                                                                                3)


15
                      Related Studies
        NiO, VO, FeO, ZnO and CoO tested in packed-bed
         reactor. Only FeO gives similar results

        Free fatty acid tested in packed-bed reactor show 97 %
         conversion in 7.5 minutes – conversion rate even faster




16
                                               Water Tests
       • Water present in cheap feedstock                                         • Water formed during reaction with high
       • 95% Ethanol with water considerably cheaper                                FFA content waste oil, animal tallow
        80                                                                         0.3

        70
                                                                                  0.24
        60
                         Free acid content




                                                               Rate constant, k
        50
                                                                                  0.18
                         Biodiesel conversion
 (%)




        40
                 Residence time = 5 min, + 200 mesh MnO                           0.12
        30

        20
                                                                                  0.06
        10

        0                                                                           0
             0             3            6             9   12                             0        3       6        9     12

                        Water wt. % in ethanol                                                  Water wt. % in ethanol
   Ethanol:Oil                                                                    Ethanol:Oil
17 30:1 Molar ratio                                                               30:1 Molar ratio
   1.58:1 Mass ratio                                                              1.58:1 Mass ratio
   Alcohol
 (Methanol)
                Mixing
                                                 Process Simplification
                Tank
     Catalyst
     (NaOH)


                                      Methanol
                Transesterfication
                                      Recovery
                    Reaction

                                      Product        Water   Product    Adsorption
                                     Separation      Wash    Drying      Polishing


  Various                            Glycerol
                  Free Fatty Acid
    Oil                              Distillation
                   Pretreatment
 Feedstock


                                     High Quality    Waste             High Quality
                                       Glycerol      Water              Biodiesel




18
                                   Conventional              Proposed
                                     Process                  Process
         Process Type                   Batch                Continuous
          Catalyst Life         Very Short (consumed)           Long
       Conversion Time              ~90 minutes            10~20 minutes

                                Catalyst, soap, water,
      Impurities (ASTM)                                  Glycerol, glycerides
                                 glycerol, glycerides

     Pretreatment of Free
                                         Yes                     No
          Fatty Acids
      Catalyst Mixing Unit               Yes                     No
     Distillation of Glycerol            Yes                     No
 Washing & Wastewater                    Yes                     No
        Product Drying                   Yes                     No
19
                 Acknowledgements
     •   Shaun Pardi
     •   Brian Dempsey
     •   Penn State Institutes of Energy and Environment
     •   Larry Duda and Ronald Danner
     •   Joe Perez and Wallis Lloyd
     •   CSPS Personnel – Adam Jones, Marc Russel, Ida
         Balashova, Lourdes Serna, Roman Galdamez
     •   Chris Torres and Brian Plunkett
     •   Restek




20
         Thank You!

                   Questions ?
Our Team: Dheeban Kannan, Kevin Gombotz, Frank Higdon and Jack Matson