Analysis and optimization of low-emission technologies: the cases of chemical looping dry reforming and adsorptive vapor recovery

Hydrogen and syngas demand has seen a dramatic rise in the last years, but their conventional fossil-based production processes are associated with high CO2 emissions. As such, new approaches are needed to achieve greater process sustainability. Current and novel production technologies are here extensively reviewed, with greater focus on the chemical looping reforming technology using CeO2 based carriers. The experimental evaluation of four different oxygen carriers for methane reforming is here presented: a natural chromite mineral, pure CeO2, a 50% mol CeO2-CuO mixture and 30% w Al2O3-CeO2 mixture. The Al2O3-CeO2 carrier showed enhanced performance compared to the pure CeO2 carrier when regenerated in either 3%vol O2 or 15%vol CO2 flows, with H2 and CO yields of 2.9±0.5 and 1.5±0.3 mmol/gCeO₂ and 41±6% CH4 conversion in the former condition, and H2 and CO yields of 2.80±0.01 and 1.35±0.04 mmol/gCeO₂, and 31.6±0.3% CH4 conversion in the latter. A first attempt at modeling the process for CeO2 carrier was carried out using Aspen AdsorptionTM software. Toxic emissions are also a critical concern for process sustainability, with volatile organic compounds being persistent and highly toxic environmental pollutants. Fugitive emissions from storage tanks are a severe source of risk for the workers, the population and the environment around such plants, as well as a significant loss of valuable products. In the second part of the present elaborate, the main technologies available for abatement of volatile organic compounds are discussed, with a greater focus on adsorption. An extensive review of data for adsorption of hydrocarbons is performed for zeolite, activated carbon and silica adsorbents. An Aspen AdsorptionTM simulation is performed to assess the behavior of activated carbon multicomponent adsorption columns. Bed height and diameter play the greatest role in determining column performance (power law relationship) while regeneration pressure and purge flowrate have a more limited effect.