Gas processing is a wide field with many application. FcLab is active on three main threads, namely reforming, adsorptive and carbon capture processes. Reforming a and adsorptive clean-up are often symbiotic with the investigation on fuel cells, being these technologies part of a fuel cell system. However, they exhibit a high interdisciplinary character and can be applied in other industrial fields. Moreover, catalytic and adsoptive processes embed a CC function.

 

Catalytic Processes

 DRY REFORMING – Dry reforming is a thermochemical process involving methane and carbon dioxide, leading to the formation of a syngas composed of hydrogen and carbon monoxide in a 1:1 ratio.This reaction is employed in industrial processes as a source of syngas for Fischer-Tropsch synthesis, because it yields the ideal ratio of reagents. The advantages of dry reforming over other reforming reactions (i.e. steam reforming or partial oxidation) consist in a lower energy demand and a higher fuel concentration in the produced syngas, in addition to the valorization of CO2 as a reforming agent. The main drawbacks of this process are the high temperatures (950-1000C°) necessary in order to avoid carbon deposition that leads to catalyst deactivation.
The research is currently investigating new catalysts to obtain high methane conversion rates and stable working conditions over time at lower temperatures (700-800°C), with the aim to couple a dry reformer to high-temperature fuel cell systems and to have access to a wider range of more common and less expensive materials for the components of the plant.

SORPTION ENHANCED STEAM REFORMING – Sorption enhanced steam methane reforming is an evolution of the well-known process of steam reforming that allows the generation of a hydrogen-rich syngas. The peculiar change in the system is the introduction of a CO2 sorbent material that absorbs part of the CO2 produced by the reforming process, thus shifting the chemical equilibrium towards the products. This allows to lower the process temperatures of SMR reaction and obtain the same value of methane conversion, overcoming the thermodynamical limit of the equilibrium reaction. The captured CO2 is then released in the regeneration phase of the sorbent and can be used for other processes or sequestered in tanks, avoiding its emission in the atmosphere.

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Gas Clean-up

High temperature fuel cells exhibit strict requirements in term of gas quality to prevent catalysts degradation and to preserve system lifetime. Therefore, a critical step of the fuel processing is the gas clean-up section, necessary to remove fuel pollutants as sulfur compounds (H2S, mercaptans, tiophenes, COS, CS2), halogens, siloxanes, tars and so on. Among the available methods for pollutants removal (wet, dry and membrane processes), adsorption technologies using porous materials have been identified as the most performing solutions, particularly fit for small-scale applications.

Experimental activities regard pollutants removal through adsorption processes, testing different commercial and innovative materials as activated carbons, zeolites and metal oxides. Experimental trials are carried out in a fixed bed reactor and allow finding sorbents adsorption capacity varying the operative conditions of the system: space velocity, reactor temperature, filter geometry, humidity content, gas composition and pollutants concentration. New materials as Metal Organic Frameworks (MOFs) and biochar materials residual of gasification plants are currently under investigation.

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Carbon Capture and Storage – CCS

The climate change caused by greenhouses gases (GHG) emissions has produced international and national legislation and policies dedicated to carbon dioxide emission reduction. All the measures introduced after the Kyoto Protocol and the recent European Directives bind the signatory countries to follow a roadmap which includes the exploitation of renewable energy sources, energy saving and greenhouse gas emission reduction.
 

In the energy sector it is possible to reduce CO2 emissions by three main strategies:

  • Improvement of the energy conversion efficiency of the power generation systems
  • Increase the energy production from renewable energy sources
  • Carbon Capture and Storage (CCS) from power generation technologies.

MCFC (Molten carbonate fuel cells) are a natural CO2 separation system because carbon dioxide is transported from the cathodic to the anodic side by its oxidation and the CO3= ion transit through the electrolyte. Supplying their cathode with a power plant exhaust gas, MCFCs separate CO2 by concentrating it in the anodic off-gas. MCFCs may operate as CO2 separators and concentrators while generating electric power, being thus a very interesting candidate to be used as carbon capture systems in fossil fired power plants.

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