Sorption-enhanced autothermal reforming of synthetic and real agro-industrial wastewaters

In this work, sorption-enhanced reforming (SER) and sorption-enhanced autothermal reforming (SE-ATR) were investigated for hydrogen production from synthetic and real olive mill wastewater (OMW) and real distillery wastewater (DW), for the first time; materials employed included a previously reported Ni–Rh catalyst supported on a hydrotalcite-derived material, promoted with La, and a commercial CaO as CO 2 -selective sorbent. Basic characterization of the catalyst revealed, through temperature-programmed reduction with H 2 (TPR – H 2 ), the reduction temperature of 750 °C. Sorption test results showed a CaO CO 2 sorption capacity of ∼2.0 mmol CO 2 ·g sorb -1 under dry conditions at 500 ℃ and p CO2 = 0.048 bar, increasing to ∼8.5 mmol CO 2 ·g sorb -1 in the presence of steam at 500 ℃ with p CO2 = 0.007 bar and p H 2 O = 0.855 bar. In the SER experiments at 500 °C, pre-breakthrough H 2 yields reached 10.85 mol H 2 ·mol OMW -1 with H 2 purities close to 99%, while the SE-ATR achieved lower yields (∼6.4 mol H 2 ·mol OMW -1 ) but improved thermal efficiency and reduced coke formation. Over four sorption-desorption cycles, sorbent capacity decreased to 58.6% of its initial value for the SE-ATR, which was attributed to sintering of the CaO sorbent. Tests with real OMW and DW achieved total organic carbon (TOC) and chemical oxygen demand (COD) removals above 98% and 99%, respectively, with total phenolic content (TPH) removal exceeding 95%. The reaction condensate of the real effluents, had a sufficiently low organic load to be discarded, according to EU regulation. These results demonstrated the potential of the SER and the SE-ATR for simultaneous renewable hydrogen production and wastewater treatment.