To meet these challenges, mono- and bifunctional catalysts should be investigated, such as zeolites, mesoporous materials with uniform pore size distribution (MCM-41,MSU, SBA-15), micro/mesoporous hybrid materials doped with noble and transition metals, and base catalysts. These catalysts should be able selectively favor the decarboxylation reactions, producing high-quality bio-oil with low amounts of oxygen and water. A lower degree of formation of undesirable
oxygenated compounds, such as alcohols, ketones, acids, and carbonyl compounds, is envisaged, as these compounds are known to be detrimental for the direct use or further coprocessing of bio-oil. The application of catalysts doped with noble metals would promote reactions of bio-oil involving oxygen removal and ring-opening, and at the same time minimize the consumption of hydrogen.