Hydrothermal stability of a new hybrid membrane in dehydration applications Jaap Vente
Approach Four way competences: Materials research System development Process design Implementation facilitation Five different lines of applications Pervaporation NH 3 separation Oxygen production Hydrocarbons separations Hydrogen purification
Why dehydration with membranes? By 2015 potential energy savings: NL: 7 PJ/yr (2% of industrial energy consumption) World: 240 PJ/yr Production of e.g. Esters and resins Methyl ethyl ketone (MEK) Ethanol Ureum Acrylic acid
Industrial performance demands Standard ECN tests: 5 wt.% water in butanol Fluxes 5 kg/m 2 h Selectivity > 220 Longevity 2-3 years Conditions: Various ph Temperatures up to 150 C
Tubular microporous membranes 1000 nm Pores < 1nm ZrO2 /TiO 2 4 nm pores 120 nm pores
Materials covered Previous developments: SiO 2 Methylated SiO 2 New leads: TiO 2 ZrO 2 Hybrid silica, organic bridges (Ceramic supported polymers)
SiO 2 Me-SiO 2 pervaporation results (95ºC) J H2O /kg h -1 m -2 8 6 4 2 0 10 4 10 3 10 2 10 1 0 100 100 SiO 2 1 step Me-SiO 2 10% MTES 30% MTES 200 200 300 t/d 300 t/d 400 400 500 500 5 wt.% H 2 O in BuOH, 10 mbar Addition of MTES gives better performance with time Constant performance possible for over 18 months! Published data Chem.Comm.2004, 834-835
SiO 2 Me-SiO 2 pervaporation up to 165ºC J H2O / kg h -1 m -2 ) 16 12 8 4 115 C 135 C 165 C single step Me-SiO 2 2.5 wt.% H 2 O in BuOH, 10 mbar Failure within weeks No clear relation with temperature 0 10 20 t/d 30 40 J BuOH / kg h -1 m -2 ) 4 3 2 1 0 10 20 t / d 30 40
Membrane surface after testing (Me-SiO 2 ) Severely damaged Dense white particles Many pinholes Illustrative example (Me-SiO 2, 135 C, 7 days)
Pore size distribution new membranes Permporometry with H 2 O Suitable for thin toplayers All membranes similar N 2 and mercury adsorption methods are for bulk material, not for thin layers! Normalised permeance 1.0 0.8 0.6 0.4 0.2 0.0 0 1 2 Kelvin diameter (nm) Methylated Silica Bridged Silica Zirconia Titania 3 4
Pervaporation with zirconia membrane J H2 O (kg.m-2.h -2 ) 5 4 3 2 1 0 100 90 80 70 Water content permeate (%) 0 20 40 60 80 Time (days) 95 C, n-butanol/h 2 O (95/5%) Flux decline, but stable after 20 days Operating for at least 120 days 100 120
Hybrid membranes from bisfunctional silica precursors replacing Si O Si bonds by Si C C Si bonds (OC 2 H 5 ) 3 Si CH 2 CH 2 Si (OC 2 H 5 ) 3 (bis(triethoxysilyl)ethane, BTESE) Patented in collaboration with Univ. of Twente and Univ. of Amsterdam (Ashima Sah, Andre ten Elshof, Hessel Castricum, Marjo Mittelmeijer)
New membrane materials: Hybrid membranes BTESE Water, HNO 3, EtOH Reflux at 60ºC, 3 hrs Mix Coating and calcination Mix in EtOH MTES
Performance hybrid membranes (1) (150ºC) Water flux (kg/m 2 h) 25 20 15 10 5 0 0 200 400 600 Time on stream (d) Watercontent in the permeate (%) 100 95 90 85 80 75 70 0 200 400 600 Time on stream (d) Me-SiO 2 stability Feed: 5% H 2 O in BuOH T = 150 C
Hydrothermal stability at 150ºC Time 2y <2d 2w Si CH 3 -Si -Si-CH 2 CH 2 -Si
Performance hybrid membranes (2) (190ºC) Feed: 2,5% H 2 O in BuOH T = 190 C Water flux (kg/m 2 h) 12 11 10 9 8 7 6 5 0 5 10 15 20 25 Time on stream (d) 30 35 100 98 96 94 92 90 Waterconcentrate in the permeate (%)
Performance hybrid membranes (3) 10000 8000 Water flux and conc. in perm in different solvents Water flux Water conc. in permeate 100 80 Flux (g/m 2 h) 6000 4000 2000 0 MeOH EtOH PrOH BuOH MEK THF AcNi NMP Solvents 60 40 20 0 Water in perm. (wt.%) Feed = 5 wt.% water in solvent
Origins of stability More stable bonds Higher crack propagation energy Lower surface diffusion coefficient Lower solubility
Hybrid membrane in the press Over 1700 hits on Chem Commun in February 2008 alone! NRC Chem Engineering MIT Tech Review Chem Processing Control & Automation Magazine Chem Tech C2W Tech Weekblad Petrochem
Next steps FOCUS: IMPLEMENTATION State of the art membrane Determine application window ph, H 2 O content, solvents Create consortium for commercialisation: end user(s), membrane producer(s), system integrator(s), supplier(s) enabling parts. Definition launching application(s). Further development: Reduce pore size: H 2 O-EtOH, and hydrogen separation Increase pore size: nanofiltration
Next step: 1m 2 field test
Acknowledgements The MST group at ECN Universities of Twente and Amsterdam: Hessel Castricum, Andre ten Elshof, Ashima Sah, Marjo Mittelmeijer- Hazeleger Financial support: STW, SenterNovem
Thank you for your attention For more information please contact me: vente@ecn.nl +31 224 56 4916
Chem. Commun., 2008, 1103-5, DOI: 10.1039/b718082a J. Mater. Chem., 2008, 18, 2150-8, DOI: 10.1039/b801972j J. Sol-Gel Sci Techn, 2008, DOI: 10.1007/s10971-008-1742-z J. Mem. Sci, 2008, in preparation PLUS MORE TO COME! Patent: WO2007081212