Exploring Large Pore Size Alumina and Silica-Alumina Based Catalysts for Decomposition of Lignin

Evaluation of copper doped silica-alumina and γ-alumina catalysts for lignin decomposition was conducted using a suite of chemical analysis protocols that enabled a comprehensive characterization of the reaction product. X-ray diffraction analysis was used to verify the concentration of doped copper on catalyst supports. Then, batch experiments were performed to study the significance of catalyst support type, catalyst dopant concentration, lignin concentration, catalyst-to-lignin ratio, reactor stirring rate and reaction time. Aqueous products were extracted with dichloromethane and analyzed using a detailed gas chromatography-mass spectrophotometry analytical protocol, allowing for quantification of over 20 compounds. Solid residues were analyzed by thermogravimetric analysis and scanning electron microscopy. The highest yield of monomeric products from these screening experiments occurred with 5 wt% Cu on silica-alumina with a 1:1 w/w ratio of catalyst to lignin. A second set of experiments were conducted at these conditions to evaluate the effect of varying the reaction temperature between 300 and 350 ºC. Lower reaction temperatures (300 ºC) resulted in more unreacted lignin while higher temperatures (\u3e350 ºC) led to an increased formation of liquid phase products, but also increased char formation. While the total amount of liquid phase products increased, the combined yield of monomer phenolic products was only 5–7 wt% of the liquid extracted product and statistically independent of temperature and other operational parameters, although the yields of different chemicals varied with temperature. Unlike most pyrolytic processes, the concentration of gas phase products gradually decreased with increasing reaction temperature and became negligible at 400 ºC, while the formation of coke increased with temperature. This seemingly contradictory result is likely due to increased product polymerization occurring at higher temperatures

Comparative scoping study report for the extraction of microalgae oils from two subspecies of Chlorella vulgaris

The production of microalgae as a fatty acid oil resource for use in biofuels production is a widespread research topic at the lab scale. Microalgae contain a higher lipid content on a dry-weight basis compared to oilseeds such as soybeans. Additionally, the growth and cultivation cycle of microalgae is 15 days, in comparison to soybeans, for which the cycle occurs once or twice annually. However, to date, it has been uneconomical to produce microalgae oils in a world-scale facility due to limitations in cultivating microalgae at commercial scales. Recent developments suggest that the use of heterotrophic microalgae may be economically feasible for large-scale oil production. To assess this feasibility, a comparative scoping study was performed analysing the feasibility of an industrial-scale process plant for the growth and extraction of oil from microalgae. Processes were developed at the preliminary design level using heterotrophic subspecies and autotrophic subspecies of Chlorella vulgaris. AACE Class 4 cost estimates and economic analyses were performed. This study concludes that processes based on heterotrophic microalgae are more likely to reach economic feasibility than processes using autotrophic microalgae. However, a few barriers still remain to achieving free-market economic viability

Exploring large pore size alumina and silica-alumina based catalysts for decomposition of lignin

Evaluation of copper doped silica-alumina and γ-alumina catalysts for lignin decomposition was conducted using a suite of chemical analysis protocols that enabled a comprehensive characterization of the reaction product. X-ray diffraction analysis was used to verify the concentration of doped copper on catalyst supports. Then, batch experiments were performed to study the significance of catalyst support type, catalyst dopant concentration, lignin concentration, catalyst-to-lignin ratio, reactor stirring rate and reaction time. Aqueous products were extracted with dichloromethane and analyzed using a detailed gas chromatography-mass spectrophotometry analytical protocol, allowing for quantification of over 20 compounds. Solid residues were analyzed by thermogravimetric analysis and scanning electron microscopy. The highest yield of monomeric products from these screening experiments occurred with 5 wt% Cu on silica-alumina with a 1:1 w/w ratio of catalyst to lignin. A second set of experiments were conducted at these conditions to evaluate the effect of varying the reaction temperature between 300 and 350 ºC. Lower reaction temperatures (300 ºC) resulted in more unreacted lignin while higher temperatures (>350 ºC) led to an increased formation of liquid phase products, but also increased char formation. While the total amount of liquid phase products increased, the combined yield of monomer phenolic products was only 5–7 wt% of the liquid extracted product and statistically independent of temperature and other operational parameters, although the yields of different chemicals varied with temperature. Unlike most pyrolytic processes, the concentration of gas phase products gradually decreased with increasing reaction temperature and became negligible at 400 ºC, while the formation of coke increased with temperature. This seemingly contradictory result is likely due to increased product polymerization occurring at higher temperatures

Thermal Carbon Analysis Enabling Comprehensive Characterization of Lignin and Its Degradation Products

We have developed a novel thermal carbon analysis (TCA) method that provides both carbon mass balance and thermal fractionation profiles. Though not providing chemical structural information, this method enables a comprehensive characterization of both lignin and its degradation products, potential renewable and sustainable feedstocks. TCA is essential as a complement to a qualitative chemical speciation by thermal desorption–pyrolysis gas chromatography–mass spectrometry (TD–Py–GC–MS). Mono- and diaromatic oxygenated compounds were used as model compounds to optimize the method. The influence of various parameters such as solvents, amounts of sample loaded, and temperature ramp configuration, were investigated. A multistep temperature program with TD and pyrolytic temperatures with and without oxygen was employed for analysis of untreated lignin, where up to 55 wt % evolved in the presence of oxygen only, this fraction being unaccounted for by currently used methods. The TCA results were supported by thermogravimetric analysis with a matching heating ramp resulting in a similar mass distribution; however, TCA has the advantage of being selective for carbon. For lignin degradation products, the TD steps of TCA yielded similar recoveries as a solvent extraction followed by GC–MS. Thus, TCA may be used for screening significant product fractions to quantify the previously uncharacterized oligomer/polymer and char fractions