Title : Fe-containing composite for decomposition of methane into COx-free hydrogen and nano-carbon
Abstract:
Thermal catalytic decomposition (TCD) of methane is an efficient hydrogen production technology with the lowest carbon oxide emissions. TCD methane is an endothermic one-step reaction, which is essential for the following reasons: firstly, the large number of natural reserves of methane, besides leading known reserves of natural gas are increased so using methane economically reliable; secondly, decomposition of methane takes place without the participation of oxygen that does not result in the formation of CO or CO2, which is an advantage as compared with steam reforming of methane.
In the present work, an iron-containing catalyst was synthesized electrochemically by cycling the potential on the nickel foam surface. The resulting catalysts were studied in the reaction of methane decomposition to hydrogen and carbon in the temperature range of 650-850°C. The cycle of iron deposition on nickel was studied, as well as the stability of the obtained composites in the decomposition of methane. A set of methods (SEM, TPR-H2, BET, etc.) investigated the physicochemical characteristics.
It was determined that the highest catalytic activity is observed for the composite, where the cycle of iron deposition on nickel foam is 150 minutes to 98.6%, and was stable for 540 minutes. In the temperature range of 650-850°C, only hydrogen is formed in the gas reaction products, the presence of carbon oxides, ethylene and ethane was not observed. With an increase in the conversion of methane on Ni-Fe150, the yield of hydrogen in the reaction products increased, the initial yield of hydrogen was 71%, which increased from 60 minutes to 74% and from 180 minutes to 76%. According to the results of TGA/DTA and Raman spectroscopy, it was determined that graphite-like carbon is formed on all composites, the largest amount (32%) is formed on Ni-Fe150. According to the results of BET, TPR-H2, an increase in the activity of Ni-Fe composites in the decomposition of methane compared to Ni-foam is associated with an increase in the textural characteristics of the composite, as well as the formation of a Ni-Fe alloy. An increase in the activity of Ni-Fe150 in comparison with Ni-Fe75 and Ni-Fe250 - with an increase in the reducibility of iron cations in the composition of the nickel-iron alloy, which ensures an increase in the concentration of metal particles - active centers.
