1. CARBON NANOFIBRE GROWTH FROM LOW TEMPERATURE METHANE DECOMPOSITION OVER SKELETAL TRANSITION METAL CATALYSTS James Highfield 1, Yook Si Loo 1, Ziyi Zhong 1, Ruijiang Li 1 & Benjamin Grushko 2 1 Applied Catalysis Technology, Institute of Chemical & Engineering Sciences, 1 Pesek Road, Jurong Island, SINGAPORE S627833. 2 Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 GERMANY CH 4 C + 2 H 2  H 298 K = + 74.5 kJ mol -1 A.Direct eco-friendly route to “CO-free” H 2 and speciality carbons. B.Single-metal & multinary (alloy ?) skeletal catalysts from quasicrystals (QC) Route: Al 65-75 (TM/Cu) 35-25 arc melt/anneal XRD ideally single-phase QC [Selective leach of Al 5 M NaOH under N 2 ] In-situ washed, dried, “passivated” catalyst custom leaching rig characterization TEMXRD XRFBET catalytic testing [TG-FTIR/MS] TEM micrograph of fresh skeletal Co (ex Al 13 Co 4 ) Typical TG curve for CH4 decompositon (skeletal Co) 1. abrupt onset of weight gain (blue curve) above 350  C; 2. rapid establishment of fixed rate (10% per h @ 400  C) 250  C 300  C 350  C 400  C TEM micrographs of carbon nanofibres on skeletal cobalt deposited at 400  C (up to  50 wt. % as carbon) TG% 0.0 1.0 2.0 3.0 Time/h 1.0 2.03.04.0 on carburization Co “needles” broken into fine “teardrops” metal dusting corrosion? more proof of irreversible change new activity below 300  C ! 330  C 300  C 280  C 250  C Oven Temp. (  C) Rate of wt. gain (%) per hour in CH 4 /H 2 flow ‡ Ni ex Al 2 Ni GF Ni 9 Cu ex Al 22 Ni 9 Cu Ni/SA (65% Ni) Aldrich Fe 21 Cu 5 ex Al 74 Fe 21 Cu 5 Fe ex Al 5 Fe 2 Co 20 Cu 14 ex Al 67 Co 20 Cu 14 Co ex Al 13 Co 4 Ru 22 Cu 7 ex Al 71 Ru 22 Cu 7 Ru ex Al 76 Ru 24 2500.01 0.030.08--0.003 0.050.0050.001 280 0.28 3000.060.0170.0800.350.0040.02 0.82 330 1.4 2.50 3500.150.0300.065  zero 0.350.070.02 1.7 3.300.02 360 2.6 - 380 5.3 - 4008.802.200.0011.5 4.40.57 8.1 10.6 11.250.800.07 TG analysis of CH 4 decomposition: in-situ pre-reduced samples & controls ‡ CH 4 + 2 % H 2 [12 ml/min; 1:1 N 2 ] Red: start at 400  C, then T [new low-T activity] Blue: as for Red, then switch to CH 4 /N 2 at 250  C & T [dramatic inhibition by H 2 !] Green: mean of increasing rate (Fe-containing samples) [long induction phase?] Stoichiometry H 2 : C = 2.15 : 1 1.6 ml min -1 H 2  71  mol. min -1  0.40 mg min -1 C or 33  g at. min -1 E app = 129 +/- 6 kJ mol -1 Surface area = 30–160 m 2 g -1 Al = 5-10 wt.% Na < 1 wt.% Amorphous (except Ni) Proof of unimolecular decompn: CH 4 C + 2 H 2 Rate of C deposition vs. H 2 level [T = 450  C; cat. Fe 19 Ni 9 ; CH 4 : 80 ml min -1 ] Summary 1. Skeletal metals made from quasicrystalline precursors are “triggered” into CH 4 conversion at T > 350 C, yielding nanofibrous carbons & H 2 in the ratio C:H 2 = 1:2; 2. Pre-carburization leads to irreversible metal decrepitation, akin to “metal dusting corrosion”, creating particles in the range 20-50 nm well suited for filament growth; 3. 1st-row TMs Co, Ni, Fe, & their combinations most active, while Cu moderates activity; 4. Despite remarkable low-T activity, CH 4 conversion is still quite low (< 2% at 400 C); 5. Process operation would need high recycle ratios and rapid (in-situ?) removal of product H 2, a powerful inhibitor.