Essay --

It should be necessary to provide hydrogen in an enormous amount at a great price. However, it is possible to accept if hydrogen is produced without CO2 emission because CO2 elimination is energy demanding and costly process related with environment problem, such as greenhouse effect. Unfortunately, currently conventional process of hydrogen production is the steam reforming process which has highly CO2 emission. Currently, approximately 48 % of hydrogen derives from natural gas by steam reforming process, 30 % from oil reforming in the chemical manufacturing and 18 % from coal gasification.3 It replies that 96 % of the hydrogen production derives from fossil associated with a huge amount of CO2 emission. Only 4 % of hydrogen production is come from water electrolysis.4 It also expected that hydrogen production without CO2 technologies are the great wish for the future of a sustainable hydrogen economy. Zero CO2 emissions are possible when the raw materials are from renewable source such as bio-gas. For instance, water electrolysis with renewable electricity and thermo-chemical cycle processes using renewable heat are the representative hydrogen production without CO2 emission.5, 6 However, the cost of hydrogen production using renewable processes is currently prohibitive cost. Thus, a changeover to a hydrogen economy would probably start with hydrogen produced from fossil fuels, especially natural gas (NG). Steam reforming of natural gas process is the most efficient and generally used process for the hydrogen production in commercial field.7 Steam reforming process is basically the transformation of methane and water to hydrogen gas and carbon oxides, and has two main reactions, as shown in Fig. X:7 Synthesis gas genera... ...ches have a catalyst deactivation problem related with the carbon, which come from methane decomposition, can be covered on the catalyst surface. Therefore, it needs the burning process17 or gasifying with steam18 for removing carbon on the catalyst surface. However, gasification or combustion of carbon residues on the catalyst surface causes to produce a huge amount of CO2 as byproduct. So, there have been researched the concurrent production of hydrogen and nanostructured carbon by Ni-and Fe- catalyst for decomposition of methane.19, 20 Also, another group reported the possibility of using carbon materials as catalyst for thermal decomposition.21, 22 They reported carbon catalyst is an environment-friendly method to the production of hydrogen and carbon. Carbon is precious byproduct of the thermal-catalytic process. It could reduce the cost of hydrogen production.