Protocol to develop component additivity models that predict oil yield from hydrothermal liquefaction.

Here, we describe steps for performing hydrothermal liquefaction (HTL) experiments and developing component additivity models that predict oil yields from HTL of mixtures with biomass and plastics. Such models could be developed for predicting outcomes from any thermochemical valorization process (e.g.

Hydrothermal liquefaction of polysaccharide feedstocks with heterogeneous catalysts.

Hydrothermal liquefaction (HTL) of starch, cellulose, pectin, and chitin with Pd/C, Co-Mo/γ-AlO, and zeolite was investigated at 320 °C for 30 min. Using Co-Mo/γ-AlO at 5 wt% loading led to the highest biocrude yields from starch (25 wt%) and cellulose (23 wt%). The yields from cellulose are more than twice those from noncatalytic HTL (11 wt%).

Component additivity model for plastics-biomass mixtures during hydrothermal liquefaction in sub-, near-, and supercritical water.

We produced oils via hydrothermal liquefaction (HTL) of binary mixtures of biomass components (e.g., lignin, cellulose, starch) with different plastics and binary mixtures of plastics themselves.

Hydrothermal carbonization of simulated food waste for recovery of fatty acids and nutrients.

We conducted Hydrothermal carbonization (HTC) of simulated food waste under different reaction conditions (180 to 220 °C, 15 and 30 min), with the aim of recovering both fatty acids from the hydrochar and nutrients from the aqueous-phase products. HTC of the simulated food waste produced hydrochar that retained up to 78% of the original fatty acids. These retained fatty acids were extracted from the hydrochar using ethanol, a food-grade solvent, and gave a net recovery of fatty acid of ∼ 50%.

Biodiversity Improves Life Cycle Sustainability Metrics in Algal Biofuel Production.

Algal biofuel has yet to realize its potential as a commercial and sustainable bioenergy source, largely due to the challenge of maximizing and sustaining biomass production with respect to energetic and material inputs in large-scale cultivation. Experimental studies have shown that multispecies algal polycultures can be designed to enhance biomass production, stability, and nutrient recycling compared to monocultures. Yet, it remains unclear whether these impacts of biodiversity make polycultures more sustainable than monocultures.

Supercritical water gasification of phenol over Ni-Ru bimetallic catalysts.

Incorporating Ru in a Ni catalyst for gasification of phenol in supercritical water at 450 °C and 30 min promoted formation of cyclohexanol via hydrogenation, which is a key step toward gasification. Both Ni and Ni-Ru catalysts were effective to reduce the formation of cyclohexanone and oligomerization products, compared with the case with no catalyst. H and CH yields increased as the Ru/Ni ratio increased, as did the carbon and hydrogen yields in the gas phase products.

Ecological Engineering Helps Maximize Function in Algal Oil Production.

Algal biofuels have the potential to curb the emissions of greenhouse gases from fossil fuels, but current growing methods fail to produce fuels that meet the multiple standards necessary for economical industrial use. For example, algae grown as monocultures for biofuel production have not simultaneously and economically achieved high yields of the high-quality lipid-rich biomass desired for the industrial-scale production of bio-oil. Decades of study in the field of ecology have demonstrated that simultaneous increases in multiple functions, such as the quantity and quality of biomass, can occur in natural ecosystems by increasing biological diversity.

Ecological Stoichiometry Meets Ecological Engineering: Using Polycultures to Enhance the Multifunctionality of Algal Biocrude Systems.

For algal biofuels to be economically sustainable and avoid exacerbating nutrient pollution, algal cultivation and processing must maximize rates of biofuel production while simultaneously minimizing the consumption of nitrogen (N) and phosphorus (P) fertilizers. We experimentally tested whether algal polycultures could be engineered to improve N and P nutrient-use efficiency compared to monocultures by balancing trade-offs in nutrient-use efficiency and biocrude production. We analyzed the flows of N and P through the processes of cultivation, biocrude production through hydrothermal liquefaction, and nutrient recycling in a laboratory-scale system.

Modeling the effects of microalga biochemical content on the kinetics and biocrude yields from hydrothermal liquefaction.

A kinetic model for the hydrothermal liquefaction (HTL) of microalgae was developed and its performance in predicting biocrude yields was tested. Kinetic interactions between algal proteins, carbohydrates, and lipids were also included for the first time. These interactions provided a better fit of the data used to determine model parameters, but the kinetics model lacking interactions provided a better prediction of published biocrude yields.

Effect of temperature, water loading, and Ru/C catalyst on water-insoluble and water-soluble biocrude fractions from hydrothermal liquefaction of algae.

Hydrothermal liquefaction (HTL) converts algal biomass into a crude bio-oil (biocrude) and aqueous-phase products. The effect of temperature, water loading, and added H and/or Ru/C catalyst on the properties of the biocrude that spontaneously separates from the aqueous phase post reaction and also the biocrude that is extractable from the aqueous phase by dichloromethane is explored herein. This report is the first to elucidate how the yields, compositions, heating values, and energy recoveries of the two biocrudes vary with the processing conditions above.

Hydrothermal liquefaction of sewage sludge under isothermal and fast conditions.

We investigated the effects of water loading, sludge moisture content, recovery solvent, and additives on the product yields and compositions from isothermal (673K, 60min) and fast (773K, 1min) hydrothermal liquefaction (HTL) of sewage sludge. The water loading (which affects pressure within the reactor) plays a small role in product yields. The sludge moisture content had a larger effect with the highest biocrude yields (26.

Power of Plankton: Effects of Algal Biodiversity on Biocrude Production and Stability.

Algae-derived biocrude oil is a possible renewable energy alternative to fossil fuel based crude oil. Outdoor cultivation in raceway ponds is estimated to provide a better return on energy invested than closed photobioreactor systems. However, in these open systems, algal crops are subjected to environmental variation in temperature and irradiance, as well as biotic invasions which can cause costly crop instabilities.

Algal polycultures enhance coproduct recycling from hydrothermal liquefaction.

The aim of this study was to determine if polycultures of algae could enhance tolerance to aqueous-phase coproduct (ACP) from hydrothermal liquefaction (HTL) of algal biomass to produce biocrude. The growth of algal monocultures and polycultures was characterized across a range ACP concentrations and sources. All of the monocultures were either killed or inhibited by 2% ACP, but polycultures of the same species were viable at up to 10%.

A quantitative kinetic model for the fast and isothermal hydrothermal liquefaction of Nannochloropsis sp.

Hydrothermal liquefaction (HTL) is a technology for converting algal biomass into biocrude oil and high-value products. To elucidate the underlying kinetics for this process, we conducted isothermal and non-isothermal reactions over a broad range of holding times (10s-60min), temperatures (100-400°C), and average heating rates (110-350°Cmin(-1)). Biocrude reached high yields (⩾37wt%) within 2min for heat-source set-point temperatures of 350°C or higher.

Near- and supercritical ethanol treatment of biocrude from hydrothermal liquefaction of microalgae.

Biocrude produced from algae by hydrothermal liquefaction was treated with near- and supercritical ethanol and ethanol-water mixtures at 210-290°C for 0.5-4h. Longer reaction times and higher temperatures better promoted esterification reactions.

Effects of processing conditions on biocrude yields from fast hydrothermal liquefaction of microalgae.

This study investigated the effects of algae species, reaction time, and reactor loading on the biocrude yield from fast hydrothermal liquefaction (HTL) of microalgae. Fast HTL reaction times were always less than 2 min and employed rapid heating and nonisothermal conditions. The highest biocrude yield obtained was 67±5 wt.

Trash to Treasure: From Harmful Algal Blooms to High-Performance Electrodes for Sodium-Ion Batteries.

Harmful algal blooms (HABs) are frequently reported around the globe. HABs are typically caused by the so-called blue-green algae in eutrophic waters. These fast-growing HABs could be a good source for biomass.

A general kinetic model for the hydrothermal liquefaction of microalgae.

We developed a general kinetic model for hydrothermal liquefaction (HTL) of microalgae. The model, which allows the protein, lipid, and carbohydrate fractions of the cell to react at different rates, successfully correlated experimental data for the hydrothermal liquefaction of Chlorella protothecoides, Scenedesmus sp., and Nannochloropsis sp.

Process improvements for the supercritical in situ transesterification of carbonized algal biomass.

This work focuses on the production of biodiesel from wet, lipid-rich algal biomass using a two-step process involving hydrothermal carbonization (HTC) and supercritical in situ transesterification (SC-IST). Algal hydrochars produced by HTC were reacted in supercritical ethanol to determine the effects of reaction temperature, time, ethanol loading, water content, and pressure on the yield of fatty acid ethyl esters (FAEE). Reaction temperatures above 275 °C resulted in substantial thermal decomposition of unsaturated FAEE, thereby reducing yields.

Anisole hydrolysis in high temperature water.

We investigated the hydrolysis of anisole to phenol in high-temperature water with and without water-tolerant Lewis acid catalysis. With no catalyst present, anisole hydrolyzes to phenol in 97% yield after 24 hours at 365 °C, our experimentally determined optimal temperature and time. Experiments with varied water density and analysis of comparable literature data suggest that anisole hydrolysis is almost third order in water, when the S(N)2 mechanism dominates.