Fuels systems, cellulose-based

An overview of cellulose-based chemicals and fuels systems is presented in Figure 1. In this cyclic system, demand for fuels and chemicals leads to the organization of factors of production (land, labor, capital, etc.) for the generation of biomass for use as a renewable resource. The plant culture activity is called silviculture if trees are the desired biomass or agriculture if herbaceous plants are grown... 

Figure 1. Overview of cellulose-based chemicals and fuels systems...

Among the additives which may be used as substitutes for these systems, intumescent additives seems to be particularly attractive. Fire protection of flammable materials (in particular, paints, varnishes and cellulose-based materials) by an intumescence process has been known for several years [1]. Intumescent technology has more recently found a place in polymer science as a method of providing flame retardancy to polymer formulations, especially polypropylene (PP) formulations [2]. These systems interrupt the self-sustained combustion of the polymer at its earliest stage, i.e. the thermal degradation with evolution of the gaseous fuels. 

Phosphoric acid-based systems, for cellulosics, 11 488 Phosphoric acid esters, 24 159 Phosphoric acid fuel cells (PAFC), 13 858— 860 12 203-204, 216-219 19 626 effects of carbon monoxide and sulfur in, 12 219... 

According to a recent conference given by Prof. Kita [162], the classical synthesis method currently used by Mitsui allows to produce about 250 zeolite membranes per day. Both the LTA and T types (Na K) membranes are now commercial and more than 80 pervaporation and vapor permeation plants are operating in Japan for the dehydration of organic liquids [163]. A typical pervaporation system, similar to the one described in [8], is shown in Fig. 11. One of the most recent applications concerns the production of fuel ethanol from cellulosic biomass by a vapour permeation/ pervaporation combined process. The required heat is only 1 200 kcal per liter of product, i.e. half of that of the classical process. Mitsui has recently installed a bio-ethanol pilot plant based on tubular LTA membranes in Brazil (3 000 liters/day) and a plant with 30 000 liters/day has been erected in India. The operating temperature is 130 °C, the feed is 93 % ethanol, the permeate is water and the membrane selectivity is 10 000. 

It is seen that metal and metal oxide catalysts have significant roles in the catalyHc process for the production of fuels and chemicals. There are several catalysts that are used commercially in the biorefinery system to produce fuels and chemicals. Metal oxides are composed of cations possessing Lewis acid sites and anions wifh Br0nsted base sites. They are classified into single metal oxides and mixed metal oxides. Transition metal oxides have catalytic activity for cellulose hydrolysis, and when used as solid acid catalysts, they are reusable and thus may be easily separated from the reaction mixture. 

A variety of catalytic routes have been described in recent years for the chemical transformation of carbohydrates into hydrocarbon liquid fuels and oxygenated biofuels which wiU be discussed in this chapter. Special focus will be brought to the recent progress of integrated processes based on the use of multifunctional catalytic systems without isolation of the platform intermediates. Fig. 13.1 summarizes the main chemical routes for the conversion of cellulosic platform molecules into high-energy-density biofuels. 

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