ordered mesoporous materials - ugent · collaboration on acid catalysis (transesterification...

Ordered porous materials in liquid phase catalytic reactionsTowards zero leaching supports

Pascal Van Der Voort

Ghent UniversityCenter for Ordered Materials, Organometallics & Catalysis

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Multi-scale modeling and design of chemical reactions and reactors

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Evolving fromPerformance

analysisTo

Kinetics Based Design...

Methusalem – formal and informal

• Formal: 1 PhD student (+ benchfee)▫ Working on catalytic activity of MOFs

• Informal▫ Collaboration on acid catalysis (transesterification

reactions, modelling)▫ Use of infrastructure (GC-GC/MS, ammonia ads)▫ Preparing joint research projects (JT @ FWO;

possibly @IWT)▫ Copromotorships in PhDs & mastertheses

(starting 2010)

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COMOC – Center for Ordered Materials, Organometallics and Catalysis• Development of ordered porous materials▫ Synthesis and characterization▫ Applications in versatile fields

Low k-materials;Thin films

Adsorbents for heavy metals

Packing materialsfor HPLC

Zero leaching catalysts in liquid phase reactions

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Spray drying mesoporous particles

6Packing materials for HPLC

Spray drying is robust

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Varying spray dryerBuchi B290, two-fluid

nebulizerGEA Niro A/S Mobil Minor, rotary

nozzle

Packing materials for HPLC

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Results - Morphology700 eq 1400 eq 2800 eq 5600 eq 8400 eq

H2O concentration is the main factor

Spray drying is robust

Packing materials for HPLC

HPLC evaluation

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Results – Stability vs Packing and evaluation

Packing conditions:30 minutes at 900 bar

Measurement after 170chromatographic runs

Packing materials for HPLC

HPLC evaluation

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Results – Chromatographic performanceA, B: Analysis of a mixture containing uracil (1), 1-phenyl-1-ethanone (2), 1-

phenyl-1-butanone (3), 1-phenyl-1-pentanone (4), 1-phenyl-1-hexanone

(5), 1-phenyl-1-heptanone (6), 1-phenyl-1-octanone (7), 1-phenyl-1-

decanone (8) and 1-phenyl-1-dodecanone (9) (50 µg/mL each); C: Analysis of a mixture of uracil (1, 50

µg/mL), benzene (2, 80 µg/mL), naphthalene (3, 50 µg/mL), antracene

(4, 300 µg/mL), fluoranthene (5, 50 µg/mL), benzo[k]fluoranthene (6, 300

µg/mL); D: Analysis of a mixture containing uracil (1), methyl-4-hydroxybenzoate (2), ethyl-4-

hydroxybenzoate (3), propyl-4-hydroxybenzoate (4) and butyl-4-

hydroxybenzoate (5) (50 µg/mL each). The flow rate was 0.2 ml/min in A and

0.3 mL/min in B,C and D.

Packing materials for HPLC

Action points

• Back pressure is not reduced to the expected level

• Shift attention to▫ CEC (Capilary Electro Chromatography) -

Excellent preliminary results by coating open tubular columns with mesoporous layer;

▫ Spraydrying of hybrid materials (PMOs)▫ Lab on a chip – Collaboration VUB – Work in

Progress.

11Packing materials for HPLC

In microelectronics industry:Low-k materials are used as insulators of interconnect wiring in computerchips

Low-k materials:Low relative dielectric constant compared to SiO2 (k<4)

Low k-materials;Thin films

•Frederik Goethals, Benjamin Meeus, An Verberckmoes, Pascal Van Der Voort and Isabel Van Driessche, “Hydrophobic high quality ring PMOs with an extremely high stability”, Journal of Materials Chemistry, 2010, 20 (9), 1709‐1716.  

•Frederik Goethals,  Carl Vercaemst, Veerle Cloet, Serge Hoste, Pascal Van Der Voort and Isabel Van Driessche, “Comparative study of ethylene and ethenylene‐bridged periodic mesoporousorganosilicas”, Microporous and Mesoporous Materials, 2010, 131 (1­3), 68‐74.  DOI

New low-k materials:

• Low-k value (current value 2.3)

• Thin Films

• Porous

• Low polarisable

• Hydrophobic

•Mechanical stable

PMOs

Low k-materials;Thin films

PMO -- What is a PMO ?

Limited commercial availability;« home made » precursors

Calcination not possible,important step

Functional groups in ENTIRE WALL

Low k-materials;Thin films

Carl Vercaemst, Matthias Ide, Bart Allaert, NeleLedoux, Francis Verpoort and Pascal Van Der

Voort, “Ultra-fast hydrothermal synthesis of diastereoselective pure ethenylene-bridged

periodic mesoporous organosilica”, Chemical Communications, 2007, 2261-2263.

PrecursorsLow k-materials;Thin films

Formation of porous material = surfactant removal

SEM HRTEM

Low k-materials;Thin films

Influence of porogen loading on porosity

Low k-materials;Thin films

Precursor Porosity k

58 1.96

55 1.8

Low k-materials;Thin films

PMOs still have silanol groups -> high affinity to water=> Removal of silanol groups:

=> Grafting with HMDS: 2SiOH + (CH3)3SiNHSi(CH3)3 ->2SiOSi(CH3)3 + NH3

Glass PMOs Hydrophobized PMOs

33°55° 85°

Low k-materials;Thin films

20Low k-materials;Thin films

Porosity k(RMPMO) k(EPMO)32% 2.28 2.4545% 1.95 2.12

Top contact: silver dotsBottom: Si sputtered with Pl/Ti

Summary

Finding optimum between k value and Young Modulus is crucial:

⇒HMDS treated PMOs have a high young modulus and low-k value

Close collaboration with IMEC for further implementation

Porosity (v%)

Low k-materials;Thin films

Solid acidcatalysis

Mercury(II) ion adsorption

Adsorbents for heavy metals

PMOs as adsorbents and as catalysts

Els De Canck, Linsey Lapeire, Jeriffa De Clerq, Francis Verpoort and Pascal Van Der Voort, "A new

Ultra Stable Mesoporous Adsorbent for the Removal of Mercury", Langmuir, 2010, 26(12), 10076-10083, DOI:

10.1021/la100204d

Thiol containing PMOs ‐ Synthesis

Bromination with Br2 (g)

Substitution with Cl‐Mg‐(CH2)3‐SH

•Els De Canck, Linsey Lapeire, Jeriffa De Clerq, Francis Verpoort and Pascal Van Der Voort, "A new Ultra Stable MesoporousAdsorbent for the Removal of Mercury", Langmuir, 2010, DOI: 10.1021/la100204d

Adsorbents for heavy metals

0 0.5 10

200

400

600

V a /c

m3 (S

TP) g

-1

p / p0

Mercury(II) ion adsorption• Other mesoporous silica adsorbents▫ One‐pot‐synthesis with –(CH2)3‐SH functionalities

• Using this material as anadsorbent results into:▫ Complete loss of mesoporousstructure

=> Hydrolysis of Si‐O‐Si bond

Before Hg2+ 

Adsorption

After Hg2+ 

Adsorption

Adsorbents for heavy metals

Mercury(II) ion adsorption• Other mesoporous silica adsorbents▫ SBA‐15 functionalized with –(CH2)3‐SH (post‐synthesis)

• Using this material as anadsorbent results into:▫ Loss of thiol functionalities

=> Hydrolysis of Si‐O‐Si bond

% SH/gram

Loss of 90%

Adsorbents for heavy metals

Mercury(II) ion adsorption• Structural stability: XRD and nitrogen adsorption measurement• Chemical stability: No loss of thiol groups=> Stable C‐C bond

0 0.5 10

150

300

450

V a /c

m3 (S

TP) g

-1

p / p0

SH‐(CH2)3‐PMO

After Hg2+ 

Adsorption

PMO

SH‐(CH2)3‐PMO

After Hg2+ 

Adsorption

Adsorbents for heavy metals

Mercury(II) ion adsorption• Experiments show a1:1 ratio Hg2+/SH

10 ppm

100 ppm

Adsorbents for heavy metals

Sulfonic functionalizedperiodic mesoporous organosilicas

28Zero leaching catalysts in liquid phase reactions

Sulfonation

E-ePMO

E-ePMO

SO3H-E-ePMO

SO3H-E-ePMOAfter catalysis

After catalysis

Acidity 1.19 mmol H+/g

+ 400

+ 600

29Zero leaching catalysts in liquid phase reactions

SULFONATED PMO

Acidic (trans)esterification

Homogeneous versus heterogeneous catalyst

- Propanol and acetic acid- 90°C- 3 hours

=> Conversion of propanol ~ 93%

30Zero leaching catalysts in liquid phase reactions

SULFONATED PMO

I Pore size and pore structure engineering

Swellingagent

N2-Physisorption

Zero leaching catalysts in liquid phase reactions

ETHENE PMO

Carl Vercaemst, Bart Goderis, Petra E. de Jongh, Johannes D. Meeldijk, Francis Verpoort and Pascal Van Der Voort, Ethenylene-bridged periodic mesoporous organosilica foams with ultra-large mesopores, Chemical Communication, 2009, 4052-4054

II Controlling the pore channel length and pore connectivity

Zero leaching catalysts in liquid phase reactions

ETHENE PMO

•Carl Vercaemst, Heiner Friedrich, Petra de Jongh, Alexander Neimark, Bart Goderis, Francis Verpoort, Pascal Van Der Voort, Periodic mesoporous organosilicas consisting of 3D hexagonally ordered interconnected globular pores”, Journal of Physical Chemistry C, 2009, 113, 5556‐5562.

II Controlling the pore channel length and pore connectivity

Zero leaching catalysts in liquid phase reactions

ETHENE PMO

III Controlling the morphology

Ethanol Pentanol Butanol (medium)

Butanol (high)Butanol (low)Propanol

Zero leaching catalysts in liquid phase reactions

ETHENE PMO•Carl Vercaemst, Matthias Ide, Heiner Friedrich, Krijn P.  de Jong, Francis Verpoort and Pascal Van Der Voort, “Isomeric periodic mesoporousorganosilicas with controllable properties”, Journal of Materials Chemistry, 2009,  19, 8839‐8845.  

Action points• Leaching stability of sulfonated groups must improve;• Sulfonation mechanism of ethene functions not clear; • Other functionalities; great prospects by a recent silyl

ester method this Columbian PhD student comes to COMOC in September:

• @ LCT: Use different porosities, plugs, ... to study diffusion effects in a profound way (proven concept with nanoparticles VS-1 INSIDE SBA-15) & Recent interest in “nanoMOFs” New PhD project ? FWO project ?

• Study “added value” reaction to compete with acid resins. Introduce chirality, size exclusion.

35Zero leaching catalysts in liquid phase reactions

ETHENE PMO

Supports: inorganic & organic

Periodicmesoporousorganosilica

Metal organicframeworks

Porous carbon(starbons)Macroporous

metallic scaffolds Phenolic resins

Redox catalysts Acid catalysts

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SBA-15

Zero leaching catalysts in liquid phase reactions

Mesoporous titania on macroporoustitanium scaffolds

Macroporoustitanium Scaffold

Mesoporoustitanialayer

1) EISA processtitanium precursor

2) Calcination

37Zero leaching catalysts in liquid phase reactionsMESOPOROUS TITANIA

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Titanium scaffolds

3DFD

PU replica

Foaming technique

Zero leaching catalysts in liquid phase reactionsMESOPOROUS TITANIA

Synthesis optimization• Variation of synthesis conditions (solvent, Ti-precursor,

template …)• e.g. template variation:▫ CTAB : (C16H33)N(CH3)3Br▫ P123 : EO20PO70EO20

▫ F127 : EO97PO69EO297

Type Template SBET

(m²/g)Pore volume

(cc/g)Pore size

(nm)

A CTAB 185 0,26 2,41

C P123 232 0,50 3,55

D F127 168 0,35 4,05

0

50

100

150

200

250

300

350

0 0,2 0,4 0,6 0,8 1

Volume adsorbed nitrogen (cc/g)

Relative pressure  (p/p0)

A C D

39Zero leaching catalysts in liquid phase reactionsMESOPOROUS TITANIA

Action points

• Catalysts do not work well in olefinic epoxidations, basically form peroxide adducts;

• Test catalysts in water phase total oxidation of phenol; they could be very suited for gas phase reactions as well. (@ LCT ?)

• Graft V-complexes on TiO2 surface, using the silyl ester method.

• Graft Ti-complexes on SiO2 surfaces.

40Zero leaching catalysts in liquid phase reactionsMESOPOROUS TITANIA

Metal Organic Frameworks (MOFs)

• Metal ions are linked by organic ligands

• 3 dimensional network

• Microporosity

• High metal content

• Rigid structure

• Ligand coordinationinfluences electronic properties

41Zero leaching catalysts in liquid phase reactions

MOF

MOFs Metal ions Linkers

Cu2+

V4+

Zn2+

Co2+

Ni2+

Ag+

Cd2+

Cr3+

42Zero leaching catalysts in liquid phase reactions

MOF

V-MOF : synthesis• Simple synthesis: VCl3/ terephthalic acid/ H2O

4 days, 200°C (autoclave)Calcination: 22h30 min, 300°C

• Formula: VIVO{O2C-C6H4-CO2}

43Zero leaching catalysts in liquid phase reactions

MOF

Catalytic performance (MIL-47)

Oxidans: TBHP in H2OSolvent: ChloroformTemperature: 50°C

VO(acac)2

MIL-47

VOx/SiO2

VAPO-5

ChloroformTBHP, 50°C

44Zero leaching catalysts in liquid phase reactions

MOF

•Karen Leus, Ilke Muylaert, Matthias Vandichel, Guy B Marin, Michel Waroquier, Veronique Van Speybroeck and Pascal Van Der Voort, “The remarkable catalytic activity of the Saturated Metal Organic Framework V‐MIL‐47 in the cyclohexene oxidation”, Chemical Communications, 2010, DOI:10.1039/C0CC01506G.

Reaction mechanismVO(acac)2 V-MOF (MIL-47)

45Zero leaching catalysts in liquid phase reactions

MOF

Regenerability : V-MOF

46Zero leaching catalysts in liquid phase reactions

MOF

Action points• V-MOF synthesis from vanadium(III)-oxo acetic

clusters; avoid decavanadates ! (bottom up)• V-ZIF(zeolitic imidazolate framework) synthesis• Chiral, enantioselective catalysis: oxidation of

sulfides to sulfoxides.

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N NT Tβ (T-Imidazole-T) ~147 ˚

Zero leaching catalysts in liquid phase reactions

MOF

Mesoporous resins

48P/F resins ALD depositions

•Ilke Muylaert, Marijke Borgers, Els Bruneel, Joseph Schaubroeck, Francis Verpoort and Pascal Van Der Voort, “Ultra stable ordered mesoporous phenol/formaldehyde polymers as a heterogeneous support for vanadium oxide”, Chemical Communications, 2008, 4475‐4477

Controlling the porosityA B C D

49P/F resins ALD depositions

Leaching behaviour

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• Comparison of leaching behaviour ofVOx/SiO vs VOx/Resin

• Stirring in water at 80°C

• Stirring in 2.5M H2SO4 at 80°C

• VOx/resins are currentlyunder investigation for theircatalytic activity

P/F resins ALD depositions

Supported TiO2/SBA-15: synthesis

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Atomic layer deposition:

- sequential exposure to avolatile metal precursorand a reactive gas

- self-limitingly

- controlled deposition

- uniform layers

P/F resins ALD depositions

Rotatable powder reactor

52P/F resins ALD depositions

Actions points

• Cheap, easy producable, highly stable bakelite resins as catalytic support

• But... Only low to moderate activity of supported TiOx and VOx layers !

• Controlled ALD of resin-V-O-Ti-O-V...• Alternative activation of the resins:▫ Sulfonation – catalytic tests in progress▫ Metal complexes ?▫ Noble metals ? Reduction reactions.

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General remarks• Some nice materials, generally appreciated and COMOC is starting

to become known as center of expertise in synthesis of “new” porous materials (COMOC is founded in 2007)

• Our materials also used in collaboration in ▫ Dentistry (University Hospital)▫ Pesticides (bio-engineers – adsorption and controlled release)

• Need to adapt processes to cost and advanced level of the materials themselves▫ High end reactions, selectivity, chirality▫ Sensors, catalysts▫ Stability can compensate for cost

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COMOC -- April 2010

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