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Chemical recycling of poly(ethylene terephthalate) (PET) in supercritical ethanol has been investigated. In the presence of water, under supercritical conditions (temperature and pressure above 516 K and 6,384 kPa, respectively) excess ethanol reacts with PET to form diethyl terephthalate (DET) as the main product. A laboratory-made 0.1 l-batch reactor was used at 528 K under pressures from 7,600 and 11,600 kPa. After the required reaction times, the reaction products were analyzed by reverse phase high pressure liquid chromatography and nuclear magnetic resonance. It was found that PET is completely depolymerized into monomers in about 5 h. The influences of water, pressure, ethanol/PET weight ratio, PET sources, as well as depolymerization time were investigated. Maximum DET recovery yield was 98.5%.

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This chapter aims to explain how bio-ethanol has been drawn to become a successful alternative to partially replace petroleum as a source of liquid fuels in Brazil. A brief historical analysis about the production of bio-ethanol from sugarcane is presented. The motivation to start the production of the ethanol as biofuel in the 1970s and how the governmental policies have contributed to the ups and downs, successes, and failures of the sugarcane industry is shown. Then, the efficiency of the sector is addressed; firstly, the increasing efficiency of the agricultural sector is discussed, showing how the productivity per hectare has increased in the last decades and which improvements are further expected in a near future. Finally, the industrial process is discussed: the current efficiency in processing sugarcane to produce ethanol and the emerging technologies, not only to process sugarcane juice, but also to harness bagasse, vinasse, and sugarcane straw.fuel, high-energy density, and relatively safe handling) made it an important substitute for liquid fuel from petroleum in the Brazilian energetic matrix. In fact, the world overwhelming dominance of gasoline, diesel, and jet fuel for transportation clearly shows the preference for liquid fuels due to their high-energy density. Except for the ethanol, most of the liquid fuels in the world are petroleum based. As petroleum is not renewable, in the long term, it must be substituted by other kind of energy. Aside from that, the use of fossil energy results in the releasing of greenhouse gas emission, which contributes for global warming. Hence, society in general is looking for alternatives to avoid global warming and thus replace petroleum. Biomass, like the sugarcane, clearly represents a sustainable and low-cost resource that can be converted into liquid fuels on a large scale to have a meaningful impact on petroleum use. Why has bio-ethanol become a successful alternative to partially replace petroleum fuels? A short historyThe beginning of the development of the ethanol fuel in Brazil is related to the petroleum shortage in Brazilian territory and the worldwide oil crisis. Brazil had few oil wells in 1970s, and the country was extremely vulnerable to international oil crisis. In 1973, during the first oil crisis, prices increased by 400%, which greatly affected the Brazilian economy in this way, and the Brazilian government began to seek an alternative to reduce its international dependence on oil. At that time, anhydrous ethanol, produced from sugarcane, had already been mixed to gasoline at a ratio of 5%, since 1931. In 1975, government created the Brazilian ethanol program, Proálcool, which involved many economical sectors to develop bio-ethanol as fuel to replace gasoline [2]. This program had massive governmental funds to develop feedstock and industry. In 1979, during the second oil crisis, Brazil presented the first ethanol fuel-powered car. At that time, Brazil had active state intervention over the price and the production of ethanol [3], which dictate...

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