Biomethanol

The alcohols that can be used for motor fuels are methanol (CH3OH), ethanol (C2H5OH), propanol (C3H7OH), and butanol (C4H,OH). However only the first two of the alcohols are technically and economically suitable as fuels for internal combustion engines (ICEs). Main conunercial bioalcohols from renewable feedstocks are bioethanol and biomethanol in the world s energy market. 

Table 3.5 Main produetion faeilities of methanol and biomethanol ...

In fact, the use of methanol as additive for gasoline has attracted interest over a number of years diuing times of critical shortage. However, much more attention is paid to the use of ethanol obtained from com and sugar cane which, for instance, satisfy a small part of the transportatiOTi fuel requirements in United States and Brazil. The fundamental difference between the production of bioethanol and biomethanol is that the latter does not rely on agriculture or on diminishing fossil fuels [6]. 

In the short term the choice of ethanol instead of methanol is obvious as bioethanol is available on a large scale today while there is hardly any production of biomethanol. Another advantage is that the composition of the crude ethylene flow from the reactor is much simpler than that obtained by dehydration of methanol. Mainly it contains water and ethylene with some nonreacted ethanol and minor traces of other substances. Consequently, there is no need for distillation equipment leading to a lower investment. Table 6.1 gives the composition of the crude ethylene stream from the reactor and the composition after water washing, compression and cooling as stated in Table II in the Braskem patent [29], The ethylene to be sent for flnal purification is approximately 99.4%, with ethane (0.15%) and butene-1 (0.27%) as the most abundant by-products. 

Other biofuels with less significant impact and diffusion include biogas, other bioalcohols (eg, biomethanol, biobutanol, etc.), firewood, vegetable oil, bioethers, dried manure, and agricultural waste (Guo et al., 2015). 

Nakagawa, H., Harada, T., Ichinose, T., Takeno, K., Matsumoto, S., Kobayashi, M., Sakai, M., 2007. Biomethanol production and CO2 emission reduction from forage grasses, trees, and crop residues. Japan Agricultural Research Quarterly 41 (2), 173—180. 

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