Agglomeration of Biochar and Iron(III)-hydroxide to Composite Agglomerates for Use as Filter Material for Biogas Purification

The use of biochar in biogas processes is frequently investigated in recent studies. To enhance the performance, biochar can be combined with iron(III)-hydroxide. For better physical properties and handling it is necessary to combine these two components into a homogeneous product. The addition of a binder enables to agglomerate these two components into pellets or granules that demonstrate good mechanical properties, albeit with a drastic reduction in BET-surface area. A crucial step before the composite pelleting is the conditioning, due to the contradictory properties of biochar and iron(III)-hydroxide. Granulation is less critical in terms of the contradictory properties of the raw materials and achieves a larger BET-surface is. However, the mechanical durability of the granules decreases with increasing batch and biochar particle size.