Integrated biorefinery conversion

Kleff S. The integrated biorefinery conversion of com fiber to value-added chemicals. Lansing, Michigan MBl International 2007. 

A biorefinery is a facility that integrates biomass conversion processes and eqtrip-ment to produce fuels, power, and value-added chemicals from biomass. Biorefinery is the co-production of a spectram of bio-based products and energy from biomass. The biorefinery concept is analogous to today s crude oil refinery. Biorefinery is a relatively new term referring to the conversion of biomass feedstock into a host of valuable chemicals and energy with minimal waste and emissions. 

To evaluate the sustainability concerning economic, environmental, and social aspects the Department of Energy (DOE) is funding integrated biorefinery projects in pilot, demonstration, and commercial scale. The importance of biochemical conversion is underlined by the fact that four out of five commercial scale plants funded by the DOE are based on biochemical conversion (Department of Energy, 2012). 

A biorefinery is a facility that integrates biomass conversion processes and equipment to produce the fuel, power, heat, and value-added chemicals from biomass.By producing multiple products, a biorefinery takes advantage of the various components in biomass, maximizing its value. As stated above single-cell biorefinery is a single-cell factory that can produce multiple products from biomass, or its derived components (Figure 9.1). 

Figure 11.6 illustrates a general superstructure of an integrated biorefinery with biomass feedstock b converted through pathways q to produce intermediates s and further processed via pathways q to produce products s. The mathematical model which relates the flow of biomass through different conversion pathways to produce the products is explained and discussed as follows. 

Once the optimal product is designed, the optimal conversion pathways that convert biomass into the bio-based fuel are identified in the second stage of the methodology. In this case study, palm-based biomass known as empty fruit bunches (EFB) is chosen as feedstock of the integrated biorefinery. The lignocellulosic composition of the EFB is shown in Table 11.9. 

Study. Figure 11.7 presents a superstructure developed based on the conversion pathways in Table 11.10. It is noted that the developed superstructure can be revised to include more conversion pathways and technologies in synthesising an integrated biorefinery. 

From Figure 11.8, it can be seen that Alkane, is produced from biomass in the conversion pathway sequence of pyrolysis and Fischer-Tropsch processes 1 and 2 followed by fractional distillation of alkanes, which are all thermochemical pathways. It is worth pointing out that specific separation processes that suit the identified product can be chosen and included in the integrated biorefinery to refine and separate the final product from by-products. Hence, separation processes for alkanes are chosen based on the results of the product design identified in stage 1 of the methodology. The performance of the separation processes is then taken into consideration in identifying the product yield and economic potential of the overall conversion pathway. 

This chapter surveys different process options to convert terpenes, plant oils, carbohydrates and lignocellulosic materials into valuable chemicals and polymers. Three different strategies of conversion processes integrated in a biorefinery scheme are proposed from biomass to bioproducts via degraded molecules , from platform molecules to bioproducts , and from biomass to bioproducts via new synthesis routes . Selected examples representative of the three options are given. Attention is focused on conversions based on one-pot reactions involving one or several catalytic steps that could be used to replace conventional synthetic routes developed for hydrocarbons. 

The present chapter focuses on process options integrated in a biorefinery scheme that should yield bio-products at a more competitive market price and quality. Although bioconversions are essential steps to derive the platform molecules that are used subsequently for catalytic transformations, only chemo-catalytic process will be examined. Selected examples of catalytic conversions illustrating different process options will be given. 

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 concept biorefinery is discussed in the US National Research Council Report Biobased Industrial Products [4] and by Lynd et al. [7] in much detail. The basic idea is the processing of multiple renewable resources and the production of multiple products in a production complex. Another characteristic of biorefinery is the integration of thermal, chemical, biological and/or cataly-tical processes for an efficient and optimal processing and utilization of the raw materials. Technological, ecological and economic analysis and system design should be implemented to ensure an overall optimization of raw material conversion and product formation in a similar way as for oil refineries. 

A biorefinery is the integral upstream, midstream, and downstream processing of biomass into a range of produas. In the classification system lEA Bioenergy Task 42 (described in the next chapter) has differentiated between mechanical pretreatments (extraction, fractionation, separation), thermochemical conversions, chemical conversions, enzymatic conversions, and microbial (fermentation both aerobic, anaerobic) conversions. 

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