Renewable feedstocks carbohydrates

Oxidative Conversion of Renewable Feedstock Carbohydrate Oxidation... 

Propylene oxide is one of the top 50 chemicals. More than 4 million t/a are produced worldwide. It is reacted via polyetherpolyols to form polyurethanes and via propylene glycol to form polyesters 15). Obviously, the polyol and diol functionalities are used to form with diisocyanates derived from diamino compounds polyurethanes and with diacids polyesters, respectively. These functionalities are available from renewable feedstocks carbohydrates, oils and fats, proteins and lignins. 

The biorefinery scheme was developed initially for carbohydrate-containing feedstocks. Large biorefineries are currently operating in the USA (e.g., Cargill at Blair, Nebraska) and in Europe (e.g., Roquette Frs. at Lestrem, France). The concept can be extended to produce chemicals from other renewable feedstocks. An integrated production of oleochemicals and biofuels can be achieved in biorefineries using vegetables oils as main feedstock to produce versatile platform mole-... 

Converting renewable feedstocks into a mixture of products that can be used as such in the synthesis or formulation of end-products. This approach is widely used in food and feed industries where there is no requirement to prepare specific molecules from bio-resources but rather mixtures of triglycerides, carbohydrates and proteins. 

Special attention is given to the integration of biocatalysis with chemocatalysis, i.e., the combined use of enzymatic with homogeneous and/or heterogeneous catalysis in cascade conversions. The complementary strength of these forms of catalysis offers novel opportunities for multi-step conversions in concert for the production of speciality chemicals and food ingredients. In particular, multi-catalytic process options for the conversion of renewable feedstock into chemicals will be discussed on the basis of several carbohydrate cascade processes that are beneficial for the environment. 

Although the focus here is on the integration of biocatalysis with chemocataly-sis (bio-chemo cascades) for carbohydrates as renewable feedstocks, some representative examples (from laboratory to industrial scale) of both bio-bio and chemo-chemo cascades are also given below for comparison of their relative scope and limitations. 

Another important goal of green chemistry is the utilisation of renewable raw materials, i.e. derived from biomass, rather than crude oil. Here again, the processes used for the conversion of renewable feedstocks - mainly carbohydrates but also triglycerides and terpenes - should produce minimal waste, i.e. they should preferably be catalytic. 

In our opinion, this development was facilitated mainly by two key factors the technical progress of all analytical methods, particularly in the fields of NMR spectroscopy and X-ray diffractometry, and the plenty of structural data meanwhile available for metal complexes of model compounds of carbohydrates. The basic research on the structural chemistry of the latter complexes followed by a transfer of the thereby gained knowledge in stability and regioselectivity of metal coordination into reducing carbohydrates has proved to be very successful. By this way, the improvement of existing and the development of new applications of metal complexes of carbohydrates, which provide a cheap and renewable feedstock, is merely a matter of time. 

Carbohydrates are the most abundant resource for the conversion of renewable feedstocks in useful chemicals and energy. Approximately 180 billion tons of biomass is produced from photosynthesis each year, including about 180 million tons of edible sugars [1] and more than 1 billion tons of starch from grains [2]. 

The symposium on which this book is based is certainly not the first to describe the concept of using renewables as chemical feedstocks. Well into the 20th century, renewable feedstocks supplied a significant portion of the nation s chemical needs. The chemurgy movement of the 1930s, led by such notables as William Hale and Henry Ford, promoted the use of farm products as a source of chemicals, with the belief that anything that can be made from a hydrocarbon could be made from a carbohydrate" (I).li is only in the period of time between 1920 and 1950 that we have witnessed the transition to a nonrenewables based economy (2). 

This process for ethyl lactate is carbohydrate-based, rather than petrochemical-based, using com, for example. It therefore demonstrates Principle 7, Renewable Feedstocks. 

Separation greatly reduces the complexity of the starting biomass by converting an extensive range of inputs to a much smaller number of monomers and polymers. Depending on the feedstock, carbohydrates can make up 75% or more of the starting biomass and are therefore of particular interest as renewable raw materials. 

Consideration of renewable feedstocks as petrochemical substitutes also leads one immediately to the problem of manipulating oxidation levels, but in a different sense. Carbohydrates are die most common primary class of compounds available from renewable biomass (S), yet these compounds are... 

Virtually all pseudo commodity and commodity chemicals as well as most fine chemicals are synthesized from petroleum feedstocks. It has been estimated that 98% of all chemicals produced in the United States in excess of 2 x 10 kg are synthesized from petroleum and natural gas. By contrast, chemicals isolated as natural products from plants or produced by microbes from carbohydrate feedstocks are typically restricted to ultrafme chemicals and a relatively few fine chemicals. The goal of our research effort is to ascertain how the widest possible spectrum of commodity, pseudo commodity, fine, and ultrafine chemicals can be synthesized from polyol starting materials such as d-glucose, d-xylose, 1-arabinose, and glycerol. These starting materials, in turn, are derived from renewable feedstocks derived from plants such as starch, hemicellulose, cellulose, and oils. A key feature of these conversions is the use of recombinant microbes as synthetic catalysts. 

Graphical representation of the atom economy vs. F C for common carbohydrates and their derivatives. Graph and data are reproduced with permission of Springer (Based on DusseHer M, Mascal M, Sels B. In Nicholas KM, editor. Selective catalysis for renewable feedstocks and chemicals, vol. 353. Springer... 

This chapter explores the sources of renewable feedstocks, in particular, carbohydrates, lignin, lipid oils, and proteins, followed by the production of chemicals from renewable resources, and finally some current applications of renewable materials. 

Using renewable and sustainable materials instead of non-renewables. For example, shifting from hydrocarbon to carbohydrate feedstocks. 

---