Catalytic Upgrading Of Bio-oil: Catalysts Preparation And Processing Study

Derived from fast pyrolysis of biomass, bio-oil was been recognized as renewable feedstock for the production of transport fuels and chemicals. However, the composition of bio-oil was complex, containing a large number of oxygen functional groups, sequentially leading to instablity of bio-oil. Therefore, it was imperatively to upgrade bio-oil to make full use of it and replace the fossil fuels. The previous study has shown that thermostability of bio-oil was dependent on the catalytic action of organic acids and polymerization of sugars, aldehydes, ketones and furans. Main purpose of this study was improving the thermal stability of bio-oil through catalytic esterification, focus on conversion of unstable components, such as sugars, aldehydes, ketones and organic acids, then providing a theoretical basis for transport fuels and chemicals on further application. Carbon-based solid acid catalyst was prepared from wood meal and black liquor solids, and applied on catalytic esterification process. Then, sugars and sugar derivatives in water-like phase of bio-oil was converted into methyl levulinate by acid catalytic and solid fuels by hydrothermal carbonization. Finally, applied simultaneous esterification and alkylation reaction on upgrading of bio-oil and its model compounds, and implemented to convert the low molecular components of acids and aldehydes into high boiling point, long carbon chain and stable products.In the beginning, carbon-based solid acid catalyst was prepared from wood meal and black liquor solids, and applied on catalytic esterification process. The research discovered that, carbon-based solid acid catalyst has highly selective than commerce catalyst(Amberlyst-15 ion exchange resin) on preparation of 2-tert-butylhydroquinone. Under the condition of Amberlyst-15 catalyst, 1:1.5 oil/alcohol ratio, 12.5% catalyst dosage and temperature of 90 oC, the organic acid values were reduced 88.4%. Result from decomposition of acetal products, relative content of ethers reduced.Methyl levulinate was prepared from acid catalytic conversion of sugars and sugar derivatives in water-like phase of bio-oil. Under the condition of 5 alcohol/water ratio, 15% catalyst dosage, 3h reaction time, 160 oC reaction temperature, 98.1% conversion of levoglucosan and 72.6 selectivity of methyl levulinate was obtained. The transformation mechanism research has shown that, high alcohol/water ratio condition was advantageous on preparation of methyl levulinate. At the same times, hydrochars was also obtained from hydrothermal carbonization of sugars and sugar derivatives in water-like phase of bio-oil, and the liquid products was separated by ethyl acetate extraction.To resolve the problem of acetal product decomposion and its lower yields, applied simultaneous esterification and alkylation reaction on upgrading of bio-oil and its model compounds. The alkylation reaction not only effectively to suppressed the acetalization reaction, but also improved the yield alkylation products. The optimum conditions of simultaneous esterification and alkylation was 1:1 alcohol/water ratio, 3g 2-MF dosage, 10% catalyst dosage, 160 oC reaction temperature.Finally, the influence of alcohols on simultaneous esterification and alkylation has shown that the effect of alkylation reaction was better than esterification reaction in bio-oil upgrading. Among them, the optimum decrease effect of acid value and viscosity of bio-oil was simultaneous esterification and alkylation of methanol, and decreased 84.8%, 89.0%, respectively. The optimum alcohol on oil soluble and water unsoluble alcohol character of upgraded bio-oil was 1-butanol. The experiment with 90 oC distillation, vacuum distillation and extraction offered an effective way for separation of low molecular weight components, water phase composition, extraction phase and sugar phase of upgraded bio-oil. And obtained a high value chemical methyl-α-D-glucopyranoside.