The upgrading of biogas by pressure swing adsorption (PSA) was studied. Simulations of a process for binary separation of CH 4 -CO 2 using zeolite 13X as selective adsorbent were carried out at 323 K. The results obtained with a two-column PSA process using a six-step cycle (pressurization, feed, depressurization, blowdown, purge, and pressure equalization) were compared with initial estimates by simulating the behavior of only one column. The recycle of highly contaminated streams was quantitatively evaluated in this paper. When recycled streams have purity lower than 99%, there is a significant decrease in the overall purity of biomethane. According to the simulations performed for a stream of biogas of 500 N m 3 /day, it is possible to obtain biomethane with a purity higher than 99% with a recovery of 85% and a power consumption of 0.12 kW/mol of produced methane.

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Pressure swing adsorption (PSA) is one of the industrial separation processes for biogas upgrading to produce biomethane. Biogas generated from biological feedstocks can have strong variations in composition and flow rate. To tackle these variations while maximizing the performance of a PSA process, an advanced control strategy should be developed. In order to develop an advanced control system that maximizes performance of the biogas upgrading PSA under the presence of severe feed disturbances, a perturbation analysis has been performed. Zeolite 13X was used as selective adsorbent for CH 4 −CO 2 separation and binary breakthrough curves, and single-column PSA experiments were performed.Step-function perturbations of 5% in inlet flow rate and CO 2 composition were introduced in the PSA. The PSA experiments have demonstrated that a change in flow rate or in CO 2 composition leads to a variation less than 2% in the temperature at the top of the column. The gas composition, at the column outlet, in the adsorption step, increases as the position of the CO 2 concentration front propagates further. This work shows that temperature variations inside the column can be used as observers to monitor the location of the CO 2 concentration wave and, therefore, to be able to take decisions on the PSA step times. These observers (thermocouples) should be implemented in the top of column where the variation is more pronounced.

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Carbon capture and storage will play a crucial role in industrial decarbonisation. However, the current literature presents a large variability in the techno-economic feasibility of CO2 capture technologies. Consequently, reliable pathways for carbon capture deployment in energy-intensive industries are still missing. This work provides a comprehensive review of the state-of-the-art CO2 capture technologies for decarbonisation of the iron and steel, cement, petroleum refining, and pulp and paper industries. Amine scrubbing was shown to be the least feasible option, resulting in the average avoided CO2 cost of between $$62.7\;\mathrm{C}\!\!\!\!{\scriptstyle{{}^=}\,} \cdot {\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ for the pulp and paper and $$104.6\;\mathrm{C}\!\!\!\!{\scriptstyle{{}^=}\,} \cdot {\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ for the iron and steel industry. Its average equivalent energy requirement varied between 2.7 (iron and steel) and $$5.1\;\;{\rm{M}}{{\rm{J}}_{{\rm{th}}}} \cdot {\rm{kg}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ (cement). Retrofits of emerging calcium looping were shown to improve the overall viability of CO2 capture for industrial decarbonisation. Calcium looping was shown to result in the average avoided CO2 cost of between 32.7 (iron and steel) and $$42.9\;\mathrm{C}\!\!\!\!{\scriptstyle{{}^=}\,} \cdot {\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ (cement). Its average equivalent energy requirement varied between 2.0 (iron and steel) and $$3.7\;\;{\rm{M}}{{\rm{J}}_{{\rm{th}}}} \cdot {\rm{kg}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ (pulp and paper). Such performance demonstrated the superiority of calcium looping for industrial decarbonisation. Further work should focus on standardising the techno-economic assessment of technologies for industrial decarbonisation.