Renewable feedstocks biomass

The use of renewable resources for manufacturing specific performance and speciality chemicals, and for fibres to replace synthetic ones, is growing. The driver for this is improved cost/performance. In order to have a major impact on the amount of oil and gas used there is a need to convert biomass into new, large-scale basic feedstocks such as synthesis gas or methanol. Many technical developments in separation science as well as improvements in the overall yield of chemicals are required before renewable feedstocks can compete effectively with oil and gas, but the gap will continue to narrow. 

Biomass can be a renewable feedstock for methane. Biomass feedstocks for methane production include crop residues, municipal solid waste (MSW), and wood resources. Biomass resources for the production of alcohol fuels are estimated at about 5 million dry tons per day which could provide 500 million gallons of methanol per day. 

The pyrolysis-based technology, in particular, because of the co-products opportunity, has the most favorable economics. An added advantage of biomass as a renewable feedstock is that it is not intermittent, but can be used to produce hydrogen as and when required. With scientific and engineering advancements, biomass can be viewed as a key and economically viable component to a renewable-based hydrogen economy. Economic viability of different types of energy generation processes is summarized in Table 8.1 (Bockris, 1981 Tanisho, 1996 Benemann, 1997). 

Approximately 89 million metric t of organic chemicals and lubricants, the majority of which are fossil based, are produced annually in the United States. The development of new industrial bioproducts, for production in standalone facilities or biorefineries, has the potential to reduce our dependence on imported oil and improve energy security. Advances in biotechnology are enabling the optimization of feedstock composition and agronomic characteristics and the development of new and improved fermentation organisms for conversion of biomass to new end products or intermediates. This article reviews recent biotechnology efforts to develop new industrial bioproducts and improve renewable feedstocks and key market opportunities. 

The use of organometallic rhenium complexes has found a very broad scope as oxidation catalysts as described in the previous section, making MTO the catalyst of choice for many oxidation reactions of olefins. Interestingly, MTO and related rhenium compounds have also found application in the reverse reaction, the deoxygenation of alcohols and diols. Especially in recent years, this reaction has attracted much attention due to the increased interest in the use of biomass as feedstock for the chemical industry. This section provides an overview of the use of rhenium-based catalysts in the deoxygenation reaction of renewables. 

As Table 2.2.1 demonstrates, the chemical industry step by step has reached a point where fine chemicals are produced from biomass, especially by means of biotechnology. Beginning with the production of bulk chemicals, not only biotechnology but also chemocatalysis is needed to convert renewable feedstock into products in the high quantities characteristic of bulk chemicals. 

The development of biobased products is part of the current initiative to support the sustainable agriculture movement and to replace petrochemical substrates with renewable feedstocks. These activities provide the incentive to convert or incorporate agricultural biomass, co-products, and similar low-value materials into more valuable materials that benefit both growers and consumers. Glycerin obtained from the production of biodiesel presents a versatile substrate for the development of new products, and complements the biobased initiative. 

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. 

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]. 

Bioconversion of renewable feedstocks to industrial chemicals has been described. In this chapter, we have illustrated technology that Genencor International has developed to harness biomass as carbon feedstocks for conversion to industrial products and to make available its bioengineered enzymes to convert biomass into fermentable sugars. This research effort provides a means for the production of desired bioproducts by enzymatic conversion of biomass-based feedstock substrates. This concept of using cellulosic biomass for manufacturing industrial chemicals has several incentives that can be explored and implemented. 

Straw and Other Crop Residues Crop residues are another source of renewable feedstock that do not find their way into milling processes, especially the residues which are already separated from the crop during or directly after harvesting. For most cereals and oil crops, this Hgnocellulosic biomass is called straw, for example, wheat straw, rice straw, or barley straw. The crop residues of maize are known as corn stover. 

Renewable is defined by the Oxford English Dictionary as not depleted by its utilization .What feedstocks do we have that are really renewable Those that immediately come to mind are biomass, waste CO2 and waste plastics. While traditional discussions of renewable feedstocks exclude the wastes, they are eminently renewable (they are being renewed whether we like it or not) and are available in much larger quantities than biomass (Figure 8). 

Renewable materials may be, in many cases, green and sustainable, but we should not make the mistake of assuming that this is always the case. The environmental effects of large scale use of biomass for production of materials and (especially) fuels can be quite detrimental this is an area requiring much more research. However, renewable feedstocks have the possibility of being sustainable, whereas non-renewable feedstocks can never, regardless of the circumstances, be sustainable. 

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