Off-gas 10% of total Carbon AHTL Oil 72% of total Carbon (77% algal carbon recovery) Natural Gas 3.5% of total Carbon in Water & Solids Recycle to Ponds 8% of total Carbon as dissolved CO2 (9% of algal carbon) Reformer & Heater Exhaust 23% of total Carbon (Includes 21% of algal carbon) Natural Gas Drier & Exhaust 3.5% of total Carbon in
Wet algae slurries can be converted into an upgradeable biocrude by hydrothermal liquefaction (HTL). High levels of carbon conversion to gravity separable biocrude product were accomplished at relatively low temperature (350°C) in a continuous-flow, pressurized (sub-critical liquid water) environment (20 MPa). As opposed to earlier work in batch reactors reported by others, direct oil recovery was achieved without the use of a solvent and biomass trace components were removed by processing steps so that they did not cause process difficulties. High conversions were obtained even with high slurry concentrations of up to 35 wt.% of dry solids. Catalytic hydrotreating was effectively applied for hydrodeoxygenation, hydrodenitrogenation, and hydrodesulfurization of the biocrude to form liquid hydrocarbon fuel. Catalytic hydrothermal gasification was effectively applied for HTL byproduct water cleanup and fuel gas production from water soluble organics, allowing the water to be considered for recycle of nutrients to the algae growth ponds. As a result, high conversion of algae to liquid hydrocarbon and gas products was found with low levels of organic contamination in the byproduct water. All three process steps were accomplished in bench-scale, continuous-flow reactor systems such that design data for process scale-up was generated.
Arsenic contamination of groundwater has recently commanded widespread public attention. Under many conditions, arsenic, and certain other environmentally relevant toxic metals such as chromium, exist in nature as oxyanions. Selective binding of anions is one of the most challenging problems in chemistry, biology, and materials and environmental science. In this paper we report the synthesis and use of metal-chelated ligands immobilized on mesoporous silica as novel anion binding materials. Nearly complete removal of arsenate and chromate has been achieved in the presence of competing anions for solutions containing more than 100 mg/L (ppm) toxic metal anions under a variety of conditions. Anion loading of more than 120 mg (anion)/g of adsorption materials is observed. A binding mechanism is also proposed on the basis of computer modeling. First, Cu(II) ions are bonded to ethylenediamine (EDA) ligands to form octahedral complexes on the surface of the mesoporous silica. This gives rise to positively charged hosts with 3-fold symmetry that match the geometry of tetrahedral anions. The anion binding involves initial electrosteric coordination, followed by displacement of one ligand and direct binding with the Cu(II) center.
5-Hydroxymethylfurfural (HMF) was catalytically converted in a bench-scale flow reactor to the oxidized derivatives 2,5-furandicarboxylic acid (FDCA), 5-formyl-2-furancarboxylic acid (FFCA), and 2,5-diformylfuran (DFF). Conversions and selectivities to these products depended on oxidant, pH, catalyst, and reactor operating conditions. The feasibility of producing these species in a flow reactor was demonstrated.
We provide a direct
and detailed comparison of the chemical composition
of petroleum crude oil (from the Gulf of Mexico), shale oil, and three
biocrudes (i.e., clean pine, microalgae Chlorella sp., and sewage sludge feedstocks) generated by hydrothermal liquefaction
(HTL). Ultrahigh resolution Fourier transform ion cyclotron resonance
mass spectrometry (FT-ICR MS) reveals that HTL biocrudes are compositionally
more similar to shale oil than petroleum crude oil and that only a
few heteroatom classes (e.g., N1, N2, N1O1, and O1) are common to organic sediment-
and biomass-derived oils. All HTL biocrudes contain a diverse range
of oxygen-containing compounds when compared to either petroleum crude
or shale oil. Overall, petroleum crude and shale oil are compositionally
dissimilar to HTL oils, and >85% of the elemental compositions
identified
within the positive-ion electrospray (ESI) mass spectra of the HTL
biocrudes were not present in either the petroleum crude or shale
oil (>43% for negative-ion ESI). Direct comparison of the heteroatom
classes that are common to both organic sediment- and biomass-derived
oils shows that HTL biocrudes generally contain species with both
smaller core structures and a lower degree of alkylation relative
to either the petroleum crude or the shale oil. Three-dimensional
plots of carbon number versus molecular double bond equivalents (with
observed abundance as the third dimension) for abundant molecular
classes reveal the specific relationship of the composition of HTL
biocrudes to petroleum and shale oils to inform the possible incorporation
of these oils into refinery operations as a partial amendment to conventional
petroleum feeds.
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