Steam reforming of glycerol for the co-production of carbon nanotubes and hydrogen using metal/stainless steel mesh catalyst

Dr. Chunfei WuSchool of Engineering, The University of Hull, UK, December 2014

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Contents1. Background

2. Possibility with Ni-Mg-Al catalyst

3. Stainless steel mesh as catalyst support

4. Influence of reforming temperature

5. Other works for CNTs/H2 production

Conclusions

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1. Background• The EU has a capacity of biodiesel production

• Problem of by-product of biodiesel production (10 wt.%)

• Substantially influences the biodiesel industry

• Making profit from biodiesel by-product-glycerol

Promising steam reforming of glycerol

a process to turn ‘negative’ coke deposition on catalysts to the ‘positive’ of carbon material production

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2. Preliminary study with Ni-Mg-Al

System

Gas

Analyser

Syringe Pump

Reforming

600 °C

Thermocouple

Catalyst

Condenser

Thermocouple

Glycerol/Water

Molar ratio

Preheating

250 °C

Nitrogen carrier gas

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(a) 500 ˚C + water; (b) 600 ˚C; (c) 600 ˚C + water; (d) 700 ˚C; (e 700 ˚C +water

High ratio of oxidation of filamentous carbons for 700 ˚C

DTG-TPO of reacted Ni-Mg-Al catalysts

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3. Stainless steel mesh as catalyst support

Another approach for CNTs and hydrogen production- Stainless steel mesh – based catalyst

• Easy simple and efficient configuration of catalyst system• Easy to separate carbon materials (only physical shaking)• Potentially increase the life-time of catalyst

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Metal addition to stainless steel mesh

Only stainless steel as catalyst is not working well for CNTs production

Previous work shows that mixture of SS mesh and Ni-catalyst is good for both H2 and CNTs production from gasification of waste plastics

Therefore, loading Metals on the surface of stainless steel mesh

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SEM of fresh metal/stainless steel mesh

Clear deposition of NiO nano-particles

Co/SS

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XRD of fresh metal/stainless steel mesh

• Identify NiO crystal phase

• Relative intensity of NiO is low for L-Ni/SS-500

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Results of catalytic steam reforming of glycerol with different catalysts

Reaction temperature: 600 °C; Glycerol (90 vol.%)

No SS SS Co/SS-500 M-Ni/SS-500 L-Ni/SS-500 H-Ni/SS-

500

M-Ni/SS-

900

Gas yield (wt.%) 15.07 18.54 53.38 73.61 37.18 42.41 63.75

H2 production(mmol g-1) 2.42 2.81 17.58 27.41 12.92 14.34 22.24

Mass balance (wt.%) 97.25 93.18 92.62 93.97 98.20 93.28 92.65

Gas concentration (Vol.%)

CO 46.90 47.47 38.08 36.23 41.99 38.42 36.62

H2 31.55 30.81 50.60 54.43 51.45 51.59 52.93

CO2 2.42 2.89 5.43 6.57 2.49 5.62 7.54

CH4 7.78 6.83 3.82 2.60 2.33 2.51 2.40

C2-C4 11.35 12.00 2.08 0.17 1.74 1.86 0.49

Carbon (wt.%) 5.63 5.94 2.77 5.52 8.41

• H2 production increased with Ni addition

• M-Ni/SS-500 generated the highest H2

• CO+H2 concentration more than 90 Vol.%

• M-Ni/SS-900 generated the highest carbon yield

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SEM analysis of reacted metal/stainless steel mesh

Reacted Co/SS Reacted Ni/SS

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TEM analysis of reacted M-Ni/SS-500

Metals within CNTs are Ni, not Fe; Thick wall of CNTs

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Temperature programme oxidation

• Similar pattern of carbon formation on reacted catalyst and carbon powder

• Presence of amorphous carbons

• Majority carbon oxidation after 550 oC• Different metal residue after TPO• Amorphous/filamentous carbon ratio

(900 oC < 500 oC calcine)

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XRD analysis of reacted catalysts

• Only SS, almost no carbon peak

• Clear diffraction of graphitic carbon for reacted Ni/SS

• NiO was reduced into Ni• FeNi/Ni intensity ratio

reduced with the increase of Ni loading

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Raman analysis of reacted catalysts (metal/mesh)

• Strong Raman spectra of disordered and graphitic carbons

• The lowest D/G ratio for M-Ni/SS-900 reacted mesh

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4. Influence of reforming temperatureReforming temperature (oC) 600 700 800 900

Gas/wood (wt. %) 44.5 86.7 96.6 97.0

Liquid yield (wt. %) 45.3 13.3 7.4 7.8

Carbon (wt.%) 2.9 2.1 0.1 -

Mass balance (wt. %) 92.7 102.1 104.1 104.8

H2 yield (mmol H2 g-1 sample) 16.5 23.0 26.6 26.0

Gas composition

( Vol.% N2 free)

CO 36.1 35.5 33.7 38.0

H2 51.2 44.4 44.8 43.4

CO2 0.0 7.6 8.3 5.9

CH4 8.7 9.5 12.0 12.5

C2-C4 2.7 1.9 0.6 0.2

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SEM/TEM of reacted Ni/SS after experiment

600 oC

700 oC 800 oC

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TPO of carbons obtained from the experiments

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5. Other works for CNTs/H2 production

• High temperature needed for carbon oxidation• KIT-6 support has higher carbon than SBA-15• Large Ni particles generate more carbon formation

Ni/porous catalyst

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Plasma treatment of fresh catalyst

• Carbon generation is significantly influenced by the plasma treatment of Ni/ZSM-5 catalyst

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Conclusions Simultaneously production of CNTs and hydrogen is possible and should be promising

The production is significantly influenced by process conditions, water content, reaction temperature

Catalyst and process condition e.g. temperature play important roles

Stainless steel mesh is a promising candidate for CNTs production due to the easy separation of CNTs and simply configuration of catalyst system

Porous materials can be finely manipulated to control the CNTs/H2 production

Further control the quality of CNTs

Application of CNTs

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AcknowledgementMany thanks to Colleague from the Leeds University: Prof. Paul T. Williams and

Sydney University Colleagues: Dr. Jun Huang and Miss Fangzhu Jin

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Thank you for your attention!

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