Hydrogen and carbon nanostructure formation from methane cracking over iron and zeolite based catalysts

QD Chemistry

Alharthi, Abdulrahman ; Hargreaves, Justin

University:University of Glasgow

Department:School of Chemistry

关键词: methane,hydrogen, carbon filaments, iron-containing waste materials.;   

Others  :  http://theses.gla.ac.uk/5309/1/2014AlharthiPhd.pdf

来源: University of Glasgow

【 摘 要 】

The production of hydrogen by the catalytic cracking of methane was investigated. An extensive study was undertaken on two categories of materials, namely iron-containing wastes and prepared catalysts, which include palladium-based catalysts, nickel-based catalysts and a copper-based catalyst. Three types of iron-containing waste materials were examined as pre-catalysts. The iron waste samples comprised a biogenic sample from a local Landfill site; waste residue sample from an old local nail works site and Red Mud. The resulting waste iron catalysts are environmentally benign and may be “thrown away” following use. The biogenic sample presented an unusual tubular morphology resulting from its biogenesis. All these materials possessed significant peak activity for hydrogen production at 800 °C. Significant carbon deposition occurred on these samples. Calcination of biogenic and waste residue samples at 900 °C enhanced performance. Carbon was deposited in the form of carbon filaments on the waste residue sample. The addition of Pd promoted the biogenic sample’s activity but poisoned the waste residue sample. Cracking of methane over palladium-containing zeolite catalysts has also been studied. Pd/H-ZSM-5 exhibited the highest peak hydrogen formation rate at 750 °C and the highest amount of carbon was produced at 900 °C. The addition of Ni, Co, Cu and Fe dopants did not improve performance. The effect of support type (H-ZSM-5, -Al2O3 and SiO2) on the Pd catalyst performance was also investigated, with -Al2O3 producing the best activity. All post-reaction Pd catalysts showed the formation of carbon filaments. On comparing the catalytic activity of Pd/H-ZSM-5, Ni/H-ZSM-5 and Cu/H-ZSM-5, it was found that Pd/H-ZSM-5 catalyst possessed the highest activity, while Ni/H-ZSM-5 and Cu/H-ZSM-5 catalysts showed lower activity and similarity to each other in behaviour. Carbon filaments were formed over Pd/H-ZSM-5 and Cu/H-ZSM-5 but did not form over Ni/H-ZSM-5. It was observed that the carbon filaments only grow at higher Ni-loading on the zeolite. The catalytic activities of Ni on different supports were evaluated and SiO2 was found to be the most effective support.