Hydrothermal conversion of lipid-extracted microalgae hydrolysate in the presence of isopropanol and steel furnace residues

Purpose Microalgae have a high potential as a feedstock for the production of biofuels, either indirectly, through the extraction of lipids, which can be transformed into biodiesel, or directly via whole cell conversion using hydrothermal liquefaction (HTL). Both approaches have disadvantages, due to the high cost of cultivating microalgae with sufficient lipid content (>40%), while the whole cell conversion produces low quality oils, which require significant further upgrading. This work investigated the possibility of realising the benefits of both processes, by studying the liquefaction reaction of a lipid-extracted algae hydrolysate. Methods In order to enhance oil yields, the reaction was conducted in the presence of varying loadings of iso-propyl alcohol (IPA) and applied two waste steel furnace residues as potential liquefaction catalysts. Results Primarily, The lipid extraction process needs to be optimized to reduce the amount of acid contaminant within the liquefaction medium. For the HTL process, the addition of 50 vol% IPA resulted in remarkably high oil yields of up to 60.2 wt% on an organic basis, whereas the two furnace residues had no positive effect on the product distribution, and instead favoured the formation of solid reaction products. Nevertheless, the results suggested that the presence of iron potentially reduced the nitrogen and oxygen content of the bio-oil. Conclusions As such, HTL is a suitable method for valorising lipid-extracted algal biomass, where the bio-oil yields can be enhanced substantially by using IPA in conjunction with the water

Using supercritical CO2 in the preparation of metal-organic frameworks: Investigating effects on crystallisation

In this report, we explore the use of supercritical CO2 (scCO2) in the synthesis of well-known metal-organic frameworks (MOFs) including Zn-MOF-74 and UiO-66, as well as on the preparation of [Cu24(OH-mBDC)24]n metal-organic polyhedra (MOPs) and two new MOF structures {[Zn2(L1)(DPE)]∙4H2O}n and {[Zn3(L1)3(4,4’-azopy)]∙7.5H2O}n, where BTC = benzene-1,3,5-tricarboxylate, BDC = benzene-1,4-dicarboxylate, L1 = 4-carboxy-phenylene- methyleneamino-4-benzoate, DPE = 1,2-di(4-pyridyl)ethylene, 4.4’-azopy = 4,4’- azopyridine, and compare the results versus traditional solvothermal preparations at low temperatures (i.e., 40 °Ϲ). The objective of the work was to see if the same or different products would result from the ssCO2 route versus the solvothermal method. We were interested to see which method produced the highest yield, the cleanest product and what types of morphology resulted. While there was no evidence of additional meso- or macroporosity in these MOFs/MOPs nor any significant improvements in product yields through the addition of scCO2 to these systems, it was shown that the use of scCO2 can have an effect on crystallinity, crystal size and morphology

Zeolite Y supported nickel phosphide catalysts for the hydrodenitrogenation of quinoline as a proxy for crude bio-oils from hydrothermal liquefaction of microalgae

This work demonstrates the potential of zeolite Y supported nickel phosphide materials as highly active catalysts for the upgrading of bio-oil as improved alternative to noble metal and transition metal sulphide systems. Our systematic work studied the effect of using different counterions (NH4 + , H+ , K+ and Na+ ) and Si/Al ratios (2.56 and 15) of the zeolite Y. It demonstrates that whilst the zeolite counterion itself has little impact on the catalytic activity of the bare Y-zeolite, it has a strong influence on the activity of the resulting nickel phosphide catalysts. This effect is related to the nature of the nickel phases formed during the synthesis process Zeolites containing K+ and Na+ favour the formation of a mixed Ni12P5/Ni2P phase, H+ Y produces both Ni2P and metallic Ni, whereas NH4 + Y produces pure Ni2P, which can be attributed to the strength of the phosphorus-aluminium interaction and the metal reduction temperature. Using quinoline as a model for the nitrogen-containing compounds in bio-oils, it is shown that the hydrodenitrogenation activity increases in the order Ni2P > Ni0 > Ni12P5. While significant research has been dedicated to the development of bio-oils produced by thermal liquefaction of biomass, surprisingly little work has been conducted on the subsequent catalytic upgrading of these oils to reduce their heteroatom content and enable processing in conventional petrochemical refineries. This work provides important insights for the design and deployment of novel active transition metal catalysts to enable the incorporation of bio-oils into refineries

The kinetics of bulk hydration of the disaccharides alpha-lactose and trehalose by in situ neutron powder diffraction

The kinetics of bulk hydration of the disaccharides alpha-lactose and trehalose by in situ neutron powder diffractio