查看更多>>摘要：An efficient hydrogenolysis for organosolv lignin was proposed by using Co/C coupled with NaOH catalyst in this work. A boosted aromatic monomer yield was achieved, which was superior to the noble metal-based catalysts. The optimal 15%Co/C catalyst coupled with NaOH exhibited the best hydrogenolysis performance, with lignin conversion of 94.5 % and aromatic monomers yield of 43.4 %. Wherein, the product of benzyl alcohols showed the highest yield 23.5 %. The recycling performance of 15%Co/C catalyst was outstanding, with lignin conversion above 92.8 % after three runs and the yield of aromatic monomer slightly dropped to 38 %. The hydrogenolysis reaction pathway was also investigated based on the beta-O-4 dimer model compound study. 2-(2methoxyphenoxy)-1-phenyl ethanol was selected as lignin beta-O-4 dimer model compound, and the hydrogenolysis reaction was conducted efficiently at 160 degrees C under the synergistic catalysis effect of metal sites and base sites. NaOH promoted the initial depolymerization of lignin through protonation, which improved the accessibility of lignin product to Co/C catalyst, and thus enhanced the reactivity of catalytic hydrogenolysis. NaOH also facilitated the etherification of intermediate products with solvents. And the presence of Co metal site stabilized free radicals and inhibited monomer product etherification. This catalytic system provides a potential strategy for the large-scale lignin utilization, with the advantage of high efficiency and handleability.
Santos, Patricia Leonidia dosLima, Michael Douglas RoqueBufalino, LinaHein, Paulo Ricardo Gherardi...
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查看更多>>摘要：The literature lacks information on how the final slow pyrolysis temperature and Amazonian Forest wood species impact charcoal's physical, chemical, and energetical properties. Thus, this study aimed to evaluate the effect of wood species and final slow pyrolysis temperatures on the charcoal quality for the Brazilian steelmaking industry. Wood wastes were sampled from the branches of six tropical hardwoods (Dinizia excelsa, Manikara elata, Caryocar villosum, Couratari oblongifolia, Anacardium giganteum, and Parkia gigantocarpa). Laboratory-scale slow pyrolysis was performed at 400, 500, 600, and 700 degrees C. The variations were significant for wood basic density (0.420-0.990 g cm(-3)), lignin content (22.78-40.68 %, based on dry mass - db), and total extractives' content (2.45-12.01 % db). Furthermore, a significant effect of the pyrolysis temperature and wood species on the gravimetric yield of charcoals (31.66-39.41 % db) was confirmed. The greatest higher heating values for charcoal (>31.00 MJ kg(-1)) were observed for pyrolysis performed above 600 degrees C for all species, except P. gigantocarpa, which provided charcoal with 31.90 MJ kg(-1) at 500 degrees C. Balancing all variables studied, temperatures between 400 and 500 degrees C were optimal for charcoal production. For such species, the effect of the raw wood properties overcame the impact of slow pyrolysis temperature.
NETL
NSTL
Elsevier