formation of carbon nanomaterials by the catalytic

Formation of carbon nanomaterials by the catalytic cracking of methane Rahi Varsani, Andrew Cornejo, Weike Zhang, Swaminatha Iyer, Lizhen Gao, Colin Raston, Hui Tong Chua and Martin Saunders The University of Western Australia, Perth, Australia What form of carbon is produced? Conclusions Clean process for hydrogen production developed by catalytic cracking of methane. Carbon is captured in form of nanostructures, predominantly nano-onions. For more information see: Cornejo, A., Gao, L., Zhang, W., Varsani, R.R., Saunders, M., Iyer, K.S., Francis, R., Raston, C.L. and Chua, H.T. (2011) Methane to zero emission hydrogen with carbon captured as pure spheroidal nanomaterials, Chemistry: A European Journal 17, 9188-9192. High resolution TEM shows carbon is graphitic for all shapes of nanostructure. This is confirmed on bulk scale by Raman Scattering (below right), which gives reproducible graphite peaks. Catalyst composition: EELS and EFTEM EELS/EFTEM cannot confirm if core is metal or metal carbide due to presence of graphitic coating. High resolution TEM used to confirm core phase: • Structure matches that of cementite – Fe 3 C • Combined with EELS data, the majority of the cores are confirmed to be Fe 2 CrC Electron energy-loss spectroscopy confirms two dominant core compositions: • Fe and Cr with trace Mn (dominant composition) • Fe and Ni with trace Co Carbon nanomaterials Catalytic cracking of methane Goal: To develop a clean method to produce hydrogen without the emission of greenhouse gases. Solution: Create an efficient catalytic process to convert methane (CH 4 ) into hydrogen while capturing the carbon in the form of nanomaterials. Catalyst: Stainless steel mesh loaded with additional metal oxides and calcined. Catalyst structure: HRTEM Resulting material comprised of metal-rich particles encased in carbon. Variety of shapes formed with three morphologies observed most frequently: • Onions – spherical nanostructures 100-200nm in diameter (dominant structure) • Tubes – Cylindrical nanostructures 100-200nm in diameter and microns in length • Chains – Interconnected, looped nanostructures 100-200nm in diameter Energy-filtered TEM shows no clear correlation between the core composition and the shape of the nanomaterial formed. Key: Green – Carbon; Red – Fe/Cr; Blue – Fe/Ni SEM (left) shows a coating of carbon nanomaterials on the surface of the steel mesh while TEM (right) reveals the variety of nanostructures formed. 20μm 200nm 200nm 200nm 200nm 20nm 10nm 100nm 100nm 100nm

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Page 1: Formation of carbon nanomaterials by the catalytic

Formation of carbon nanomaterials by the catalytic cracking of methane

Rahi Varsani, Andrew Cornejo, Weike Zhang, Swaminatha Iyer, Lizhen Gao, Colin Raston, Hui Tong Chua and Martin Saunders

The University of Western Australia, Perth, Australia

What form of carbon is produced? Conclusions

Clean process for hydrogen production developed by catalytic cracking of methane.

Carbon is captured in form of nanostructures, predominantly nano-onions.

For more information see: Cornejo, A., Gao, L., Zhang, W., Varsani, R.R., Saunders, M., Iyer, K.S., Francis, R., Raston, C.L. and Chua, H.T. (2011) Methane to zero emission hydrogen with carbon captured as pure spheroidal nanomaterials, Chemistry: A European Journal 17, 9188-9192.

High resolution TEM shows carbon is graphitic for all shapes of nanostructure.

This is confirmed on bulk scale by Raman Scattering (below right), which gives reproducible graphite peaks.

Catalyst composition: EELS and EFTEM

EELS/EFTEM cannot confirm if core is metal or metal carbide due to presence of graphitic coating. High resolution TEM used to confirm core phase:

•  Structure matches that of cementite – Fe3C •  Combined with EELS data, the majority of the cores

are confirmed to be Fe2CrC

Electron energy-loss spectroscopy confirms two dominant core compositions:

•  Fe and Cr with trace Mn (dominant composition) •  Fe and Ni with trace Co

Carbon nanomaterials

Catalytic cracking of methane!

Goal: To develop a clean method to produce hydrogen without the emission of greenhouse gases. Solution: Create an efficient catalytic process to convert methane (CH4) into hydrogen while capturing the carbon in the form of nanomaterials. Catalyst: Stainless steel mesh loaded with additional metal oxides and calcined.

Catalyst structure: HRTEM

Resulting material comprised of metal-rich particles encased in carbon.

Variety of shapes formed with three morphologies observed most frequently:

•  Onions – spherical nanostructures 100-200nm in diameter (dominant structure)

•  Tubes – Cylindrical nanostructures 100-200nm in diameter and microns in length

•  Chains – Interconnected, looped nanostructures 100-200nm in diameter

Energy-filtered TEM shows no clear correlation between the core composition and the shape of the nanomaterial formed.

Key: Green – Carbon; Red – Fe/Cr; Blue – Fe/Ni "

SEM (left) shows a coating of carbon nanomaterials on the surface of the steel mesh while TEM (right) reveals the variety of nanostructures formed."

20µm 200nm

200nm 200nm

200nm