• Energy Research
• 6. Clean water close

The phenomena occurring during hydrothermal liquefaction (HTL) of algal biomass to form biocrude are not fully understood. It is still not clear which species are optimal for a microalgae biorefinery, as well as the influence of their composition on the biocrude oil molecular composition. Moreover, the molecular characterization itself of the HTL biocrude oils is troublesome because of the presence of a huge number of different molecular constituents. In this work, a stepwise Py-GC-MS procedure, originally developed to solve certain issues of conventional GC-MS analysis, was further improved using a non-negative matrix factorization (NNMF) assisted peak resolution. This procedure not only increased the speed of GC-MS interpretation and made it more objective, it also disclosed additional information on certain HTL biocrude constituents which are usually neglected by the manual data handling and it minimized the fraction of unidentified compounds. With this novel analysis strategy, the biocrude oils produced during a screening with 8 different microalgae strains at two different process conditions (250 and 375 °C, both for 5 min) were analyzed. Main chemical constituents produced by HTL were quantified, obtaining a satisfactory chemical description of this matrix. The results revealed that the influence of process conditions was more important than the difference in the strains applied. Moreover, even if different biocrude yields were observed, the chemical composition results were similar for the different algal strains when processed at the same temperature.

AbstractA thermocatalytic reforming (TCR®) unit patented by Fraunhofer UMSICHT was tested to convert lignocellulosic biomass and three organic wastes, digestate, paper sludge, and sewage sludge, into enhanced pyrolysis products. The TCR® reactor is an intermediate pyrolysis screw reactor connected to a reformer. hawse have explored the TCR® of four feedstocks in a 2 kg h−1 laboratory‐scale plant. The aim of the work was to compare the product yields and qualities (biochar, bio‐oil, and syngas) obtained by using TCR® under the same pyrolysis conditions (pyrolysis at 400 °C and postcatalytic reforming at 700 °C). Finally, paper sludge bio‐oil was distilled at several temperatures to obtain the oil fractions. High‐quality bio‐oil and syngas from four different kinds of biomass were obtained and compared to that from traditional intermediate pyrolysis and fast pyrolysis. The bio‐oil showed a high higher heating value (HHV) (35–38 MJ kg−1) independent of the kind of biomass used, and the total acid number was 1.8–5.4 mgKOH g−1. Fractional distillation led to a gasoline‐like light fraction and an overall distillation rate of 74 %.

Municipal Solid Waste (MSW) refers to a heterogeneous mixture composed of plastics, paper, metal, food and other miscellaneous items. Local authorities commonly dispose of this waste by either landfill or incineration which are both unsustainable practices. Disposing of organic wastes via these routes is also becoming increasingly expensive due to rising landfill taxes and transport costs. The Thermo-Catalytic Reforming (TCR®) process, is a proposed valorisation route to transform organic wastes and residues, such as MSW, into sustainable energy vectors including (H2 rich synthesis gas, liquid bio-oil and solid char). The aim herein, was to investigate the conversion of the organic fraction of MSW into fuels and chemicals utilising the TCR technology in a 2kg/h continuous pilot scale reactor. Findings show that MSW was successfully processed with the TCR after carrying out a feedstock pre-treatment step. Approximately, 25wt.% of the feedstock was converted into phase separated liquids, composed of 19wt.% aqueous phase and 6wt.% organic phase bio-oil. The analysis of the bio-oil fraction revealed physical and chemical fuel properties, higher heating value (HHV) of 38MJ/kg, oxygen content <7wt.% and water content <4wt.%. Due to the bio-oil's chemical and physical properties, the bio-oil was found to be directly miscible with fossil diesel when blended at a volume ratio of 50:50. The mass balance closure was 44wt.% synthesis gas, with a H2 content of 36vol% and HHV of 17.23MJ/Nm3, and 31 wt.% char with a HHV of 17MJ/kg. The production of high quantities of H2 gas and highly de-oxygenated organic liquids makes downstream hydrogen separation and subsequent hydro-deoxygenation of the produced bio-oil a promising upgrading step to achieve drop-in transportation fuels from MSW.

Abstract The upgrading of biomass pyrolysis vapors by zeolite cracking over H-ZSM5 (Si/Al 45, biomass:zeolite mass ratio 1:10) was investigated by analytical (Py–GC–MS) and preparative pyrolysis. Pine sawdust, the microalgae Spirulina platensis, seaweed (Ulva sp.), and marine fish discard were selected as representative biomass with different composition, in particular protein content (from 60%), followed by PAHs (mostly naphthalene). The relative abundance of N-CCs in catalytic bio-oil was lower in comparison to Py–GC–MS suggesting that a fraction was distributed into the aqueous phase. In general, HZSM-5 exhibited a significant dehydration, deoxygenation and denitrogenation effect favoring the formation of a “gasoline-like” bio-oil even from a highly proteinaceous biomass. However, it also induced the formation of nitrogen-containing polyaromatic compounds, like carbazoles.

The slow pyrolysis process of poultry litter was investigated using different experimental and analytical techniques. A fixed bed reactor was used for the simulation of the slow pyrolysis process up to a constant temperature (400–800 °C) under nitrogen flow. Yields of the different product fractions were determined. On-line FTIR techniques were used to detect the most significant compounds in the evolved gas (carbon dioxide, carbon monoxide and methane). GC–MS results allowed the identification of the more important categories of compounds in the liquid condensate (phenols, fatty acids, sterols, N-containing compounds). The fate of nitrogen and sulphur, present in relevant amounts in the original substrate, was investigated: sulphur remains mostly in char at any investigated temperature, while nitrogen is split among the different products, slightly increasing its transfer to the gas phase only at higher pyrolysis temperatures. The energy transfer from the original biomass substrate to the different product fractions was also investigated. The fraction of biomass energy transferred to non-condensable gases raises with pyrolysis temperature and was estimated to be able to thermally sustain the process at 550 °C. The results obtained shed some light on the potential use of the slow pyrolysis process for sanitation and waste-to-energy valorization of poultry litter.

The study evaluated the growth of Desmodesmus communis on column photobioreactor and its thermochemical treatment by catalytic pyrolysis using HZSM-5 zeolite. D. communis showed good results in terms of growth (0.05gL-1d-1). Analytical pyrolysis of original algae and derived bio-oil mixed with zeolite was used as a screening method in order to gather information on the cracking process. Preparative pyrolysis on bench scale reactor was performed on algae biomass over a zeolite bed at 1:10 ratio (wt/wt). Py-GC-MS of biomass/catalyst mixture showed that the denitrogenation/deoxygenation increased with increasing zeolite load from 1:5 to 1:20 ratio and became significant at 1:10 ratio. The composition observed by analytical pyrolysis was featured by the predominance of alkylated monoaromatic hydrocarbons. The scaling-up to bench scale confirmed the results obtained with analytical pyrolysis in terms of monoaromatic hydrocarbons. However, low yield of catalytic oil (8% by weight) was observed.