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Direct formation of gasoline hydrocarbons from cellulose by hydrothermal conversion with in situ hydrogen

Yin, Sudong, Mehrotra, Anil Kumar, Tan, Zhongchao
Biomass and bioenergy 2012 v.47 pp. 228-239
alkanes, bioenergy, biomass, cellulose, fossils, furfural, gasoline, headspace analysis, hydrogen, hydrogenation, hydroxymethylfurfural, liquefaction, pH, pyrolysis, steam, temperature
A new process based on aqueous-phase dehydration/hydrogenation (APD/H) has been developed to directly produce liquid alkanes (C₇ – ₉), which are the main components of fossil gasoline, from cellulose in one single batch reactor without the consumption of external hydrogen (H₂). In this new process, part of the cellulose is first converted to in situ H₂ by steam reforming (SR) in the steam gas phase mainly; and, in the liquid water phase, cellulose is converted to an alkane precursor, such as 5-(hydroxymethyl)furfural (HMF). In the final reaction step, in situ H₂ reacts with HMF to form liquid alkanes through APD/H. Accordingly, this new process has been named SR(H₂)-APD/H. Experimental results show that the volumetric ratio of the reactor headspace to the reactor (H/R) and an initial weakly alkaline condition are the two key parameters for SR(H₂)-APD/H. With proper H/R ratios (e.g., 0.84) and initial weakly alkaline conditions (e.g., pH = 7.5), liquid alkanes are directly formed from the SR(H₂)-APD/H of cellulose using in situ H₂ instead of external H₂. In this study, compared with pyrolysis and hydrothermal liquefaction of cellulose at the same temperatures with same retetion time, SR(H₂)-APD/H greatly increased the liquid alkane yields, by approximately 700 times and 35 times, respectively. Based on this process, direct formation of fossil gasoline from renewable biomass resources without using external H₂ becomes possible.