CO2 as Carbon Source for Fuel Synthesis

Abstract The growing use of fossil fuels (solid, liquid and gas) as the main primary energy sources, inevitably leads to an increasing amount of carbon dioxide released into the atmosphere. On the other hand, the increasing CO2 concentration in the atmosphere is indicated as the main cause of the greenhouse effect on the planet with consequent climate change. These reasons motivated in recent years growing efforts, from both technical-scientific and political communities, to control the accumulation of the atmospheric CO2. Carbon capture technologies are a well stabilized route to reduce the concentration of the greenhouse gas (CO2) from the atmosphere. However, the introduction of these capture processes always requires additional costs regardless of the adopted technology (post-combustion capture, pre-combustion capture or oxy-combustion). Despite higher costs, the adoption of efficient technologies for capturing CO2 is essential for the preservation of the environment. Besides the capture of CO2, its final sequestration in geologically stable sites is currently proposed for storing enormous quantities of gas involved. However, the geological storage of a given amount of CO2 avoids the possible use of C for about 27% wt. Therefore it seems reasonable to question if we can take advantage of this huge amount of carbon. As a matter of fact, the CO2 could become an important source of carbon for the synthesis of organic and inorganic compounds. In particular, there is a growing interest around the possibility to treat the CO2 in a reducing environment to convert it to methanol or methane. This option is an alternative to the well documented reduction of CO2 to carbon monoxide. Our interest is focused on the conversion to methane by hydrogen reduction. When the hydrogen is obtained by renewable energy, the method is a good way to store the electricity generated from renewable sources such as chemical energy; it is easily accessible and transportable thanks to the widespread presence of methane distribution network. We investigate the hydrogenation of CO2 on various Ni based catalysts. The conversion yield, the time stability and the poison sensitivity has been studied up to the temperature of 723 K and at atmospheric pressure.