Direct Conversion of Glycerol into 1,3Propanediol over CuH4SiW12O40SiO2 in Vapor Phase

1
Direct Conversion of Glycerol into
1,3-Propanediolover Cu-H4SiW12O40/SiO2 in Vapor
Phase
V.Anandha Kiruba 16-05-09

• L. Huang et al.,Catalysis Letters, 2009

2
Introduction

• 1,3-Propanediol (1,3-PD) is a large-scale
  material for polymer, prepared by hydration of
  acrolein or by hydroformylation of ethylene
  oxide.

The reaction scheme of glycerol hydrogenolysis to
1,3-PD
3

• Tsukuda et al. proved that the SiO2 supported
  H4SiW12O40 (STA/SiO2) be active and selective for
  glycerol to acrolein at 275 C. STA/SiO2 is
  selected as active composition for glycerol
  dehydration.
• Copper is a potential catalyst for aldehyde
  hydrogenation. copper has poor activity towards
  CC cleavage, so few degradation products are
  formed over Cu-based catalysts. copper can act as
  active composition for 3-hydroxypropanal
  hydrogenation.
• SiO2 supported STA and copper is used as
  bifunctional catalyst to produce 1,3-PD in vapor
  phase process.

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Catalyst preparation-Impregnation method
Aq. H4SiW12O40
SiO2
Dried at 120ºC
Calcined at 350ºC
STA/SiO2
Aq.Cu(NO3)2.3H2O
Dried at 120ºC
Calcined at 350ºC
xCu-ySTA/SiO2
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The Reaction pathways of 1,3-PD and 1,2-PD
formation and their dehydration reactions over
Cu-STA/SiO2
6
Formation of Cyclic Acetals

• Cyclic acetals were deduced to form between
  glycerol and acrolein/3-hydroxypropanal on acid
  catalysts.

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The Condensation products from 1,3-Propanediol

• The condensation reactions between glycerol and
  aldehyde/ketone were easily accessible over solid
  acid catalysts.
• More kinds of byproducts can be supposed to form
  from condensation reactions
• between glycerol and acetaldehyde or
  formaldehyde,
• between diols and aldehyde,
• between glycerol and ketone
• between diols and ketone.
• The cyclic acetal is one of most important
  byproducts in the vapor phase hydrogenolysis of
  glycerol over metalacid bifunctional catalysts.

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Results and Discussion
Glycerol hydrogenolysis on 10Cu-20STA/SiO2,
10Cu/SiO2 and 30STA/SiO2 in vapor phase
Reaction conditions pressure 0.36 MPa,
H2/glycerol 1401(molar ratio) and WHSV 0.08
h-1

• Copper is unable to promote glycerol
  dehydration to 3-hydroxypropanal.
• Acrolein was the dominative product on
  30STA/SiO2, but 1,3-PD was not detected.
• Acrolein is the only dehydration product of
  3-hydroxypropanal, thus glycerol dehydration to
  3-hydroxypropanal should proceed mainly on
  supported STA rather than copper metal ,but
  supported STA is unable to catalyze
  3-hydroxypropanal hydrogenation to 1,3-PD.

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TPSR of glycerol dehydration on 15STA/SiO2 and
10Cu-15STA/SiO2

• No desorption peak of 3-hydroxypropanal based
  on its fragment ions (m/e 74 and 45). (highly
  reactive 3- hydroxypropanal further dehydrated to
  acrolein at the desorption temperature)
• The TPSR of 15STA/SiO2 showed only one acrolein
  desorption peak with a maximum at 190 ºC.
• After 10 wt copper was loaded onto 15STA/SiO2,
  no new peak of acrolein desorption was observed,
  which proves that the copper metal did not
  catalyze glycerol dehydration to
  3-hydroxypropanal.
• The supported copper also had little promotive
  or inhibitive effect on the glycerol dehydration
  to 3-hydroxypropanal over supported STA.
• Supported STA is unable to catalyze 3-
  hydroxypropanal hydrogenation, while copper metal
  is active for this reaction

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Effect of WHSV on the glycerol hydrogenolysis
over 10Cu-15STA/SiO2
Reaction conditions Pressure 0.36MPa. H2/glycerol
1401

• As the conversion increased with decreasing
  WHSV, the selectivities of 1,2-PD and 1,3-PD
  decreased.
• 1,2-PD and 1,3-PD were mainly converted to
  propanal and allyl alcohol over acid catalysts.
• The cyclic acetals were formed from the
  condensation reactions of diols and aldehyde.
• The selectivities of 1,2-PD and 1,3-PD
  decreased at lower WHSV owing to long residence
  time, in which the excessive reactions of 1,2-PD
  and 1,3-PD take place.

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Effect of temperature on the Glycerol
hydrogenolysis over 10Cu-15STA/SiO2

• On increasing the temperature from 180 to 210º
  C, the conversion increased from 73.2 to be
  complete, whereas the selectivities of 1,3-PD and
  1,2-PD decreased over 10Cu-20STA/SiO2.

Reaction conditions 0.36 MPa and H2/glycerol
1401(molar ratio), WHSV 0.08
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Effect of pressure on the glycerol hydrogenolysis
over 10Cu-15STA/SiO2
Reaction conditions H2/glycerol 1401 WHSV
0.1 h-1

• The selectivities to 1,3-PD and 1,2-PD increased
  when the pressure increased from 0.1 to 0.54 MPa.
  
• At 210º C and 0.54 MPa, the selectivity of
  1,3-PD was up to 32.1 with the conversion of
  83.4.

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The Equilibrium constants for the reactions
involving in vapor-phase glycerol hydrogenolysis
at 190º C
14
Effect of initial water content on the glycerol
hydrogenolysisover 10Cu-15STA/SiO2
Reaction conditions Temperature 210 ºC,
Pressure 0.36 MPa, WHSV 0.12 h-1, H2/glycerol
1401

• The reaction is favorable at lower water
  content.
• The selectivity of acrolein and allyl alcohol
  did not decrease and even increased slightly
• which implies that water is unable to restrain
  the excessive dehydration reactions e.g., 1,2-PD
  to propanal and dehydration of 1,3-PD to allyl
  alcohol.
• These side reactions are thermodynamically
  favorable and water has little effect on the
• dehydration reaction from thermodynamic
  consideration.

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Conclusion

• The formation of 1,3-PD proceeds through the
  designed bifunctional route
• (i) dehydration of glycerol to
  3-hydroxypropanal on the acid sites of STA
• (ii) hydrogenation of 3-hydroxypropanal to
  1,3-PD on copper metal.
• Several kinds of cyclic acetals are identified
  via GCMS, proving the condensation reactions
• as important side reaction in glycerol
  hydrogenolysis over the metalacid bifunctional
  catalyst.
• A 32.1 selectivity of 1,3-PD, with a 54.3
  combined selectivity to 1,3-PD and 1,2-PD was
• achieved at 83.4 conversion at 210º C, 0.54 MPa.
• The selectivity of 1,3-PD can be possibly further
  improved with further the optimization of
  catalyst such as copper loading and metal
  promoter addition.