The synthetic evaluation of CuO-MnO x -modified pinecone biochar for simultaneous removal formaldehyde and elemental mercury from simulated flue gas.

A series of low-cost Cu-Mn-mixed oxides supported on biochar (CuMn/HBC) synthesized by an impregnation method were applied to study the simultaneous removal of formaldehyde (HCHO) and elemental mercury (Hg0 ) at 100-300° C from simulated flue gas. The metal loading value, Cu/Mn molar ratio, flue gas components, reaction mechanism, and interrelationship between HCHO removal and Hg0 removal were also investigated. Results suggested that 12%CuMn/HBC showed the highest removal efficiency of HCHO and Hg0 at 175° C corresponding to 89%and 83%, respectively. The addition of NO and SO2 exhibited inhibitive influence on HCHO removal. For the removal of Hg0 , NO showed slightly positive influence and SO2 had an inhibitive effect. Meanwhile, O2 had positive impact on the removal of HCHO and Hg0 . The samples were characterized by SEM, XRD, BET, XPS, ICP-AES, FTIR, and H2 -TPR. The sample characterization illustrated that CuMn/HBC possessed the high pore volume and specific surface area. The chemisorbed oxygen (Oβ ) and the lattice oxygen (Oα ) which took part in the removal reaction largely existed in CuMn/HBC. What is more, MnO2 and CuO (or Cu2 O) were highly dispersed on the CuMn/HBC surface. The strong synergistic effect between Cu-Mn mixed oxides was critical to the removal reaction of HCHO and Hg0 via the redox equilibrium of Mn4+ + Cu+ ↔ Mn3+ + Cu2+ .