The success of the chemical industry in biomass conversion to chemical products is highly dependent on the development of new catalysts. Since the original molecular structure of bio­mass components is supposed to be preserved, the focus of catalysis research will have to shift from building functional structures out of simple building blocks to the re-functionalization of complex molecular structures (Marquardt et al., 2010). A crucial role is played by the next research achievements for basic chemical reactions like dehydration, condensation, hydrogenation, and so on, which require high selectivity to be implemented at commercial scale. Enzymatic or whole-cell biocatalysts are often high-performance alternatives resulting in high selectivity and yield (Stephanopoulos, 2007). Hybrid catalysts, combining enzymes with chemocatalysts in a complex molecular or nanoparticulate structure, constitute even more sophisticated options (Marquardt et al., 2010). In particular, the specific developments needed in the main conversion reactions are:

• Hydrogenation/reduction: this reaction is generally used to add hydrogen, e. g. to an acid functional group to form alcohols. Research developments should ensure the possibility to operate at milder conditions (pressure, temperature, etc.) giving high selectivity, by means of the improvements in catalyst performances. Catalysts should also improve their tolerance to inhibitory compounds and lifetime.

• Oxidation: this reaction oxidizes carbon and converts alcohols into acid functional groups. In future biorefineries, mineral oxidants like sulfuric acid and nitric acid should be replaced by air, molecular oxygen, dilute hydrogen peroxide, and others. Tolerance to inhibitory components of biomass processing streams should also be enhanced.

• Dehydration: this reaction removes oxygen from the substrate and it is fundamental for biomass processing. It requires improvements in the selectivity, needed to avoid side reactions. New heterogeneous catalysts (solid acid catalysts) are preferred over liquid catalysts.

• Fermentation: fermentation processes convert sugars into valuable products. In general, an improvement of microbial biocatalysts to reduce acetic acid coproducts and increase yields is needed. Lower costs to recover the products are necessary to scale-up.

• Polymerization: it is usually done through esterification to produce innovative polymers, whose applications need to be tested. Issues of selectivity and control of molecular weight and properties are still open.

The combination of new catalysts and new substrates offers innovative and largely unex­plored opportunities to establish novel production pathways and novel innovative products with particular properties which must be still explored (Vennestr0m et al., 2010). The flexi­bility in tailoring the value chain, from feedstocks to the desired products (or vice versa), com­bined with the several possible uses of side streams, may lead to different options. These options must be systematically evaluated and screened to identify those with the best performances, including carbon efficiency, energy consumption, environmental impacts, and production cost. Ideally, such an evaluation should precede laboratory experiments in catalysis and production processes, in order to specifically focus research activities on the most promising alternatives.