| As a clean, renewable resource, biomass can not only reduce the dependence on fossil fuels, but also solve the problem of greenhouse gas emissions. Biomass can be converted to transportation fuels and high quality chemicals by various methods(pyrolysis, chemical catalysis, microbial fermentation, etc.). Lignocellulosic biomass can be used to produce platfrom compounds(5-hydroxymethyl furfuryl,furfural, furfuryl alcohol, etc.) through acid-catalyzed decomposition. Then C8~C20alkane is obtained by a series of chemical catalytic reaction.In this paper, the independent patent“a prepared C5~C25 alkanes from furfuryl alcohol method”was used as the technical route.It mainly studied the sulfuric acid catalytic furfuryl alcohol(FA) condensation in water. Throughqualitative and quantitative analysis of the FA condensation reaction products, the structure of the product information and the quantitative relationship between each product were obtained. And thefurfuryl alcohol condensationreaction kinetics was studied in this paper, which revealed distribution regularity of condensation products. On this basis,FA condensation reaction mechanism was discussed.First of all, FAcondensation reaction products were characterized.By infrared spectrum(IR), we found characteristic absorption peaks of the furan ring(the vC-H band of 2,5-disubstituted rings at 790 cm-1). It confirmed FAoccurred condensation reaction. By GC-MS and LC-MS, we separatedand detected condensation products of dimer to pentamer(carbon number distribution C9~C25), and determined the structure of dimer to pentamer.By further high gel liquid phase chromatography(GPC) in the detection, we found that the molecular weight of FA condensation reaction products was a multi-decentralized system. And when FA completely converted, the number average molecular weight of product fast increased with increasing reaction time. Its value was 4427 g/mol, corresponding to the condensation product of carbon chain length of more than 250.Next, we studied the reaction temperature, concentration of sulfuric acid, which had effect on the FA condensation reaction, and the reaction kinetics equation of FA and its parameters in waterwere obtained. FA reaction order is one, and the activation energy is 64.2 KJ/mol. According to product distribution of FA condensation reaction, there are likely two kinds of reaction mechanisms of the sulfuric acid catalytic FA condensation reaction in water, namely intermolecular step ploycondensation and FA cationic chain ploycondensation. On this basis, the reaction mechanism model of FAcondensation reaction wasestablished, FA condensation reaction product were simplified as B(C9~C25) and C(>C25), and the FA condensation reaction product of dynamics equation was deduced. The model we have establishedwas in good agreement with the experimental results which well explain the reaction temperature and reaction time had effect on distribution of A(FA), B and C. The content of A rapidly decreased with increasing reaction temperature and reaction time. The content of B firstly increased then decreased with increasing reaction temperature and reaction time, the extension of up to 30 wt%. The content of C increased with increasing of reaction temperature and reaction time, and the extension of up to 95 wt%.Finally,by the Response Surface Methodology(RSM) of Box-Behnken Design experiment Design method,we studied reaction temperature, reaction time,concentration of sulfuric acid and concentration of FA, which had effect on the FA condensation reaction product of carbon chain length of C9~C25 selective.From theexperiment and simulation date, we got the largest selectivity of B component was 38.3 mol% in aqueous solvent systemunder these conditions: reaction temperature of 59 ℃, sulfuric acid concentration is 0.98 wt%, FA concentration is31 wt%, reaction time of 51 min, 100 g of the mixture.In this condition, the experiment result was 36.1 mol%, which was in conformity with the RSM results. |
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