Biomass Conversion to Chemicals

In the earliest years of humankind, those auxiliaries today known as chemicals could only be obtained from nature. This may have included the use of native coal, gas, or oil, but heavy exploitation may not have occurred. Since industrialization, the use of coal (since the nineteenth century), acetylene (1930-1950), and finally oil and gas (since the 1950s) served as a base for fuels and chemicals as well. 

In Europe, approximately 69 million tons of oil was used as the raw material for the chemical industry in 2008 [1], The total oil demand in Europe was 703 million tons in that year [2], In contrast, only approximately 5% of all industry feedstock is of renewable origin [3], Most of this reflects direct use of natural products like cotton for textiles, wood pulp for papermaking, or different oils for special applications and for oleochemistry in general (detergents, lubricants, etc.) [3], 

In Germany, approximately 4.1% of all fossil raw materials and 14% of the crude oil demand were used in 2008 as feedstock for material use in the chemical industry, together 17 million t [4], In contrast, the total energy demand in Germany was 224 million t [5]. 

Therefore, the ecological and environmental effects of switching the base of chemicals to renewable sources will be diminished as long as fuels are produced from crude oil. Conversely, the relatively low amount of crude oil needed for the chemical industry will be accessible for a rather long period of time at moderate expenditures and exploitation cost. 

Another point in terms of CO2 reduction is the fact that binding carbon from biomass into chemicals is a more sustainable approach than converting CO2 to fuel which is burnt afterward - or capturing CO2 into subterranean caverns. 

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Processes for depolymerization of the biopotymer, sqiaration of the various chemical types, and aqueous phase processing all must be established for biomass conversion to chemical products to become widespread. 

A Chemist s View of the Selection of Viable Target Molecules and Their Formation in Cellulosic Biomass Conversion to Chemicals... 

Fig. 33.24. Biomass deconstruction is a Key step in its conversion to chemical products and fuels.

Genencor s proprietary concept of continuous biocatalytic systems using sequential enzyme reactions for processing the cellulosic component of biomass to biochemicals minimizes these problems. This concept addresses issues related to i) substrate inhibition, ii) enzyme inactivation, Hi) cofactor instability, iv) intermediate inhibition, and v) mass transfer limitations and thus overcomes key existing limitations for biomass conversion to industrial chemicals. ... 

Taaming E, Osmundsen CM, Yang X, Voss B, Andersen SI, Christensen CH (2011) Zeolite-catalyzed biomass conversion to fuels and chemicals. Energy Environ Sci 4(3) 793-804... 

Figure 4.7 Biomass conversion to oil. Reproduced from Ref. 22a with permission from The American Chemical Society...

Therefore the demand for land and other agricultural resources required to support biobased industrial products is probably not a factor for chemicals and materials, but will be an issue for biobased fuels. The demand for land to supply liquid fuels depends on the yields of biomass from the land, the yield of fuel from the biomass and the miles traveled per unit of fuel. All three factors are important and must be considered in conjunction. Increasing the efficiency (yield) of each step will increase the overall system efficiency. In particular, biomass conversion to fuel ethanol must be highly efficient and low cost if the product is to compete with petroleum-derived fuels. 

Biomass is a renewable resource from which various useful chemicals and fuels can be produced. Glycerol, obtained as a co-product of the transesterification of vegetable oils to produce biodiesel, is a potential building block to be processed in biorefineries (1,2). Attention has been recently paid to the conversion of glycerol to chemicals, such as propanediols (3, 4), acrolein (5, 6), or glyceric acid (7, 8). 

The economics of biomass conversion needs to be considered as well, for the production costs of biofuels typically amount to 60-120 per barrel of oil equivalent. Influential factors include the cost of the biomass at the plant gate, the conversion efficiency, the scale of the process and the value of the product (e.g., fuel, electricity or chemicals). 

Chemical intermediates are produced at a scale that is close to that of biomass conversion plants, e.g., between 100 kt a-1 (e.g., for acrylic acid) to 800 kt a-1 (e.g., for ethene diol). This has to be compared with the 20 Mt a-1 scale of a major oil refinery. 

However, most of these routes are still economically unattractive and the possibility of creating an equivalent petrochemistry based on biomass, which depends on raising the conversion efficiency and establishing cascades in which the residues of one product serve as inputs for another, still suffers from the relatively unattractive products derived from hemicellulose and lignin. Therefore, to bring back biomass into the chemical business , the utilization of biomass must be enhanced by integrating it into biorefinery (Fig. 2). 

The valorization of by-products in biomass conversion is a key factor for introducing a biomass based energy and chemistry. There is the need to develop new (catalytic) solutions for the utilization of plant and biomass fractions that are residual after the production of bioethanol and other biofuels or production chains. Valorization, retreatment or disposal of co-products and wastes from a biorefinery is also an important consideration in the overall bioreftnery system, because, for example, the production of waste water will be much larger than in oil-based refineries. A typical oil-based refinery treats about 25 000 t d-1 and produces about 15 000 t d 1 of waste water. The relative amount of waste water may increase by a factor 10 or more, depending on the type of feed and production, in a biorefinery. Evidently, new solutions are needed, including improved catalytic methods to eliminate some of the toxic chemicals present in the waste water (e.g., phenols). 

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