Catalytic conversion of biomass-derived oils to fuels and chemicals.

摘要

Experimental and kinetic modeling studies were conducted to determine the viability of upgrading a wood-oil to liquid hydrocarbon fuels and chemicals in a fixed bed micro-reactor using HZSM-5, silicalite, H-mordenite, H-Y and silica-alumina catalysts.;Characterization and stability studies on the wood-oil showed that it was a complex mixture of volatile acids, alcohols, aldehydes, ketones, esters, ethers, furans, phenols hydrocarbons and non-volatile compounds. The oil was unstable with time. However, its stability improved when mixed with tetralin.;Upgrading with HZSM-5 was conducted in the presence and absence of steam. 40 to 65 wt% of the oil was converted to a highly aromatic organic distillate containing 45 to 70 wt% hydrocarbons, most of which were gasoline range hydrocarbons. Benzene, toluene, xylene were the major components. Between 30 to 45% reduction in coke formation, 5 to 18 wt% increase in organic distillate and reduced hydrocarbon selectivity were obtained in the presence of steam.;The optimum yields and selectivities when upgrading with the other catalysts were 22 wt% and 0.29 for silicalite; 28 wt%, and 0.28 for H-mordenite; 21 wt% and 0.21 for H-Y; and 26.2 and 0.36 for silica-alumina. H-mordenite and H-Y showed high selectivity for kerosene range hydrocarbons and silicalite mostly for gasoline range hydrocarbons. The hydrocarbon fraction from silica-alumina did not show any defined distribution. The pore size, acidity and shape selectivity of the catalyst influenced the distribution of hydrocarbons. The overall performance followed the order: HZSM-5 ;Kinetic and mathematical modeling studies were also carried out. With the aid of model compound reactions, a reaction pathway was proposed for the conversion of the wood-oil. Cracking, deoxygenation, aromatization and polymerization reactions were identified as the main reactions leading to the formation of products. A mathematical based on the integral reactor design equation and power law rate model was derived. The model predicted the experimental results fairly accurately. Also, hydrocarbon selectivity models were derived. These models showed that lower temperatures and concentrations should be employed in order to achieve high hydrocarbon selectivity. However, this was at the expense of higher conversions.;Fuel range hydrocarbons and useful chemicals could be produced by catalytically upgrading wood-oils. The yields of these fractions could be predicted from models based on the integral reactor design equation and power law rate models.