Carbohydrates to Chemicals and Fuel Additives over ModifiedPolyoxometalate Catalysts

The quest to produce chemicals and transportation fuels from sources other than conventional non-renewable fossil resources has shifted the focus and direction of research activities towards the utilization of cleaner renewable feedstock. Renewable resources like biomass are ever-abundant and also have an added advantage of being carbon rich that can be leveraged for the production of various chemicals. Biomass is the source of carbohydrates which are the major precursor to produce fine chemicals and fuel additives. The catalytic conversion of biomass-derived carbohydrates to chemicals and fuel additives has been an extensive topic of research lately. Among various fine chemicals derived from biomass, 5-hydroxymethylfurfurl, 5-ethoxymethylfurfurl, alkyl levulinates and gamma valerolactone are some value-added chemicals with immense potential. The preparation of these chemicals derived from biomass requires catalysts with specific active sites with desirable acid/base properties. A majority of these chemicals can be formed by acid catalysis of carbohydrates. This chapter mainly focuses on the conversion of carbohydrates to value-added chemicals over modified heteropoly acid catalysts with sufficient Bronsted/Lewis acidity. Supported and metal-exchanged heteropoly molybdate and tungstate catalysts are synthesized and utilized for the conversion of biomass-derived carbohydrates to chemicals. The activity of these catalysts is discussed on the basis of their acidic sites, surface properties and structural features. Operating conditions such as reaction temperature, reaction time, feed concentration, catalysts concentration, solvent volume and the type of reactor used are also briefly discussed in this chapter.