Luisa Calvo

The results demonstrate that aqueous NH ₃ can be thermocatalytically decomposed to H ₂ and N ₂ at these comparatively mild temperatures.

The concept of NH₄ ⁺/NH₃ production from wastewater treatment for subsequent recovery and reuse has gained much attention in the past few years. The conversion of NO₃ ^– present in wastewater into NH₄ ⁺/NH₃ through catalytic reduction is a sustainable approach for resource utilization from wastewater. In the present work, the application of this technique to industrial wastewater with a high NO₃ ^– concentration is proposed. A good activity of Pd–Cu catalysts supported on carbon black was observed at high NO₃ ^– concentrations. Complete NO₃ ^– conversion was achieved in water with an initial concentration of 1000 mg/L and a catalyst concentration of 0.93 g/L in a stirred reactor. Furthermore, an improvement in catalytic activity was obtained when the reactor was operated without pH control, resulting in an increase in NH₄ ⁺ formation to 184 mg/L. Additionally, in successive 8-h reaction cycles with a reaction medium equivalent to that of industrial wastewater, a progressive decrease in catalytic activity was observed, which may be associated with a noticeable decrease in the Pd⁰/Pdⁿ⁺ species ratio.

Aqueous-phase reforming has been revealed as a novel, interesting and efficient process for the treatment of wastewater containing organic pollutants. However, due to the relatively severe operating conditions (above 15 bar and 200 °C), this process could become economically competitive if any solution for energy or material valorization is implemented. Most research has been devoted to direct the process to H₂ production as an alternative to reach economic sustainability, but the results obtained were not competitive in the current market of hydrogen and syngas. In this work, a preliminary simulation study (using Aspen HYSYS software) of the process heat balance in different conditions was implemented to induce a heat integration that would allow the auto-sustainability of the process, even generating in some cases an excess of energy that could constitute an opportunity for a positive economic balance. The results showed that this approach would only be possible by maximizing the methane production to the detriment of hydrogen production.