Activated Biochar-Based Metal Catalysts for Steam Reforming of Pyrolysis Bio-Oil Model Compound

In the last years, a growing interest in using biochar as catalyst or catalyst support has arisen due to its relatively low cost and easy functionalization. Even though pristine biochar does not have a well-developed specific surface area and pore size distribution, which are essential features for a catalyst, they can be easily improved by means of further procedures. Among all the biochar upgrading procedures, CO₂ controlled gasification is one of the most promising since it is possible to obtain activated carbons with high surface area and expanded pore size distribution. One of the most interesting field of application of the biochar-based catalysts is the upgrading of pyrolysis vapors through the conversion of the condensable products (bio-oil) into permanent gases via catalytic steam reforming. The specific aim of this work is to produce biochar-based catalyst for pyrolysis vapors upgrading starting from binder-free wheat straw pellets. For this purpose, the selected biomass was first pyrolyzed under N₂ atmosphere and then activated with CO2 at 700°C and 1.0 MPa. These activated biochars were then loaded with different percentages of Fe, Co, Ce and Ni in order to produce mono and bi-metallic catalysts to be tested for mid-temperature (400–600 °C) steam reforming of a pyrolysis bio-oil model compound. The samples which showed the most promising results in terms of selectivity, conversion and stability were finally tested for steam reforming of the aqueous phase of a real bio-oil.