Giulia Bozzano

Biogas has emerged as a valid feedstock for biomethanol production from steam reforming. This study investigates an alternative layout based on an auto-thermal electrified reforming assuming a 1 MW equivalent anaerobic digestion plant as a source for methanol synthesis. The process considers an oxy-steam combustion of biogas and direct carbon sequestration with the presence of a reverse water–gas shift reactor to convert CO₂ and H₂ produced by a solid oxide electrolyzer cell to syngas. Thermal auto-sufficiency is ensured for the reverse water–gas shift reaction through the biogas oxy-combustion, and steam production is met with the integration of heat network recovery, with an overall process total electrical demand. This work compares the proposed process of electrification with standard biogas reforming and data available from the literature. To compare the results, some key performance indicators have been introduced, showing a carbon impact of only 0.04 kgCO₂/kgMeOH for the electrified process compared to 1.38 kgCO₂/kgMeOH in the case of biogas reforming technology. The auto-thermal electrified design allows for the recovery of 66.32% of the carbon available in the biogas, while a similar electrified process for syngas production reported in literature reaches only 15.34%. The overall energy impact of the simulated scenarios shows 94% of the total energy demand for the auto-thermal scenario associated with the electrolyzer. Finally, the introduction of the new layout is taken into consideration based on the country’s carbon intensity, proving carbon neutrality for values lower than 75 gCO₂/kWh and demonstrating the role of renewable energies in the industrial application of the process.

Hydrogen sulfide is a highly toxic by-product in the refineries. Traditional sulfur recovery units are already used, but optimization studies on them are still limited. The proposed process evaluates the possibility of a new frontier for sulfur recovery and carbon dioxide emissions reduction in refineries. The technological kernel is the regenerative thermal reactor which allows to convert hydrogen sulfide with another challenging emission, carbon dioxide, to valuable products (syngas) and harmless compound as elemental sulfur and water. The work has compared the effectiveness of the proposed technology with the traditional sulphur recovery units in terms of techno-economics and environmental impacts by proposing several sensitivity analyses on the main process parameters. Results state that it greatly improves the sustainability of the process in terms of quality of syngas produced while limiting the emissions. The economic analysis results look to be very promising for a pilot plant setup.