This work focuses on the study of a pressure swing adsorption (PSA) process for biogas upgrading using a carbon molecular sieve adsorbent. Adsorption equilibrium and diffusion data of pure components were used to predict the multicomponent behavior. To validate the prediction of multicomponent adsorption at different concentrations, breakthrough curve experiments were performed for a gas mixture at different pressures (0.25, 0.5, 1, and 5 bar). Based on basic information, a model was used to predict the performance of a two-column PSA unit. The mixture used as feed was 60% CH 4 and 40% CO 2 with pressure swings between 5 bar in adsorption mode to 0.1 bar in blowdown. Experimental data demonstrated that the model could describe the PSA performance with good accuracy. We have evaluated the influence of different feed times in the biomethane recovery and purity. Biomethane purity higher than 97.5% with recovery higher than 90% was obtained.

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In coal-based chemical looping combustion (CLC) technology, relatively cheap metal oxides, referred to as oxygen carrier materials (OCMs), are required because some of the OCMs will be removed together with the residual ashes after combustion. CLC technology will have an estimated loss in efficiency of around 2% compared to standard combustion technology without capture if a proper OCM is found that can give full combustion, removing the need of an air separation unit (ASU). Materials with a chemical looping oxygen uncoupling (CLOU) effect will even give further benefits in faster gasification and combustion of the fuel. One can already find produced materials that can give such a desirable effect, but fabrication and material cost are still an issue in these cases. If such a material can be delivered by the mining industry, cost savings and plant efficiency will be high. Before selection of the natural minerals with strong inert inherent support that contain Fe and Mn, the need for a better understanding of the Fe−Mn system is needed. This pre-study combined with other literature findings of the Fe−Mn system shows that a Mn content of up to 25−33% will increase the CLOU effect, increase the conversion of CH 4 , and give possibilities for full combustion in a CLC plant.

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