Lab-scale pyrolysis and hydrothermal carbonization of biomass digestate: Characterization of solid products

The aim of the present study is to investigate the production of biochar from anaerobic digestion (AD) digestate. Re-Cord selected digestate from real and representative (regarding the scale and the process technology) anaerobic digestion plant. Please click on the file below for full content of the abstract

Biochar from lab-scale pyrolysis: influence of feedstock and operational temperature

AbstractBiochar properties are highly dependent on the feedstock type and operational conditions during thermochemical processing, in particular slow pyrolysis. To clarify this aspect, nine biochars were produced by pyrolyzing in a macro TGA at 400, 550, and 650 °C three different decorticated and chopped biomasses. The studied biomasses are representative of conifer (black pine) and deciduous (poplar and willow) woods. Biochar surface area, size, and shape of pores were investigated by means of nitrogen adsorption isotherm, Hg porosimetry, and electron microscopy. The results indicate that biochars with high surface area can be obtained at high temperature, especially starting from pine feedstock. Regarding porosity, micro-pores (1–10 nm) are not remarkably affected by the starting feedstocks, while macro-pores (> 10 nm) are strictly connected with the morphology of the starting wood. More than the surface area, we found a strong correlation between the chemical composition (elemental composition and FTIR) of the biochars and their retention and release capacity of ions (cation exchange capacity, CEC). The trend in the CEC, determined via coupled approach by spectrophotometric and ion chromatography, reveals that the increase in the processing temperature has the effect of reducing the number of functional groups able of exchanging the cations with the equilibrium solution. This work represents a step forward in the characterization of the char produced by pyrolysis of biomass thanks to the development of a multi-technique approach allowing to obtain a structure-property correlation of the biochars. Our results and experimental approach can help in the optimization of the parameters used in the preparation of these materials.Graphical abstrac

Woody and herbaceous invasive alien plant species‐derived biochars are potentially optimal for soil amendment, soil remediation, and carbon storage

Invasive alien plant species (IAPS) are a global problem, representing a threat to ecosystem functioning, biodiversity, and human health. Legislation requires the management and eradication of IAPS populations; yet, management practices are costly, require several interventions, and produce large amounts of waste biomass. However, the biomass of eradicated IAPS can become a resource by being used as feedstock for biochar production and, at the same time, implementing the management of IAPS. Here we carried out an in-depth characterization of biochar produced at 550°C derived from 10 (five woody and five herbaceous) widespread IAPS in the central-southern lps region to determine their potential applications for soil amendment, soil remediation, and carbon storage. Biochar was produced at a laboratory scale, where its physicochemical characteristics, micromorphological features, and lead adsorption from aqueous solutions were measured. To investigate any possible trade-offs among the potential biochar applications, a principal component analysis was performed. IAPS-derived biochars exhibited relevant properties in different fields of application, suggesting that IAPS biomass can be exploited in a circular economy framework. We found coordinated variation and trade-offs from biochars with high stability to biochars with high soil amendment potential (PC1), while the biochar soil remediation potential represents an independent axis of variation (PC2). Specifically, IAPS-derived biochar had species-specific characteristics, with differences between the woody and herbaceous IAPS, the latter being more suitable for soil amendment due to their greater pH, macronutrient content, and macropore area. Biochar derived from woody IAPS showed a greater surface area, smaller pores, and had higher lead adsorption potentials from aqueous solutions, hinting at their higher potential for heavy metal pollution remediation. Moreover, biochar derived from woody IAPS had a higher fixed carbon content, indicating higher carbon stability, and suggesting that their biochar is preferable for carbon sequestration in the view of climate change mitigation

Chemoselective Aerobic Oxidation of Unproteced Diols Catalyzed by Pd-(NHC) (NHC = N-heterocyclic carbene) Complexes

[[abstract]]Neutral Pd(X)(η3-allyl) (X = Cl, OAc (acetate)) complexes bearing mono-coordinating NHC ligands have been synthesized, characterized and employed to catalyze the aerobic oxidation of unprotected 1,2- and 1,3-diols selectively to hydroxy ketones. A comparison of the catalytic performance of these precursors with a reference system has shown that the precursor with the ligands N,N′-bis(adamantyl)imidazol-2-ylidene and chloride is the most efficient for the chemoselective oxidation of 1,2-diols is concerned. High-pressure 1H NMR (HPNMR) experiments in combination with catalytic batch reactions have provided valuable information on the activation of the precursor as well as on the stability of the catalysts

Performance and emissions of liquefied wood as fuel for a small scale gas turbine

This study investigates for the first time the combustion in a micro gas turbine (MGT) of a new bioliquid, a viscous biocrude, which is a liquefied wood (LW) produced via solvolysis of lignocellulosic biomass in acidified glycols. The test rig includes a modified fuel injection line, a re-designed combustion chamber and revised fuel injection positions. The main novelties of this work are: (1) producing of liquefied wood with pure ethylene glycol as a solvent, and methanesulfonic acid as a catalyst, to obtain a bio-crude with lower viscosity and higher lignocellulosics content than previous tested formulations(2) upgrading raw liquefied wood by blending it with ethanol to further reduce the viscosity of the mixture(3) utilizing a commercially available MGT Auxiliary Power Unit (APU) of 25%kW electrical power output, with notably reduced extent of adaptations to use the newly obtained fuel mixture. Fuel properties, and their impact on combustion performance using liquefied wood, are investigated by analyzing MGT performance and emissions response at different load and blend ratios. Emissions revealed that the presence of LW in the blends significantly affects CO and NOX concentrations compared to conventional fuels. CO roughly increased from 600%ppm (pure ethanol as fuel) to 1500%ppm (at 20%kW electrical power). The experimental study reveals that it is possible to achieve efficient MGT operation while utilizing high biocrude to ethanol ratios, but a number of adaptations are necessary. The achieved maximum share of liquefied wood in the fuel blend is 47.2% at 25%kW power output. Main barriers to the use of higher share of liquefied wood in these type of systems are also summarized

Characterization of microalga Chlorella as a fuel and its thermogravimetric behavior

.Microalgae are photosynthetic microorganisms living in marine or freshwater environment. In this study, samples of Chlorella spp. and Nannochloropsis from two different origins were analysed to settle a preliminary characterization of these microorganisms as intermediate energy carriers and their properties compared to a conventional lignocellulosic feedstock (pine chips). Both microalgae samples were characterized in terms of elemental composition (CHONS and P) and thermogravimetric behavior. This was investigated through non-isothermal thermogravimetric analysis in nitrogen atmosphere at heating rate of 15 °C min−1 and temperature up to 800 °C. Solid residues produced at 300 °C and 800 °C from TGA were also analysed to determine the ultimate composition of chars. Activation energy, reaction order and pre-exponential factor were calculated for the single step conversion mechanism of 1 g of Chlorella spp. and compared to literature data on Chlorella protothecoides and Spirulina platensis. Calculated kinetic parameters, given as intervals of several determinations, resulted to be: pre-exponential factor (A) 1.47–1.62E6 min−1, activation energy (E) 7.13–7.92E4 J mol−1, reaction order (n) 1.69–2.41. 1.2 kg of Chlorella spp. was then processed in a newly designed batch pyrolysis pilot reactor, capable of converting up to 1.5 kg h−1 of material, and pyrolysis liquid collected, analysed and compared with a sample of fast pyrolysis from pine chips. This preliminary investigation aimed at carrying out a first characterization of algae oil and optimise the operational aspects of the reactor, tested with the first time with this unconventional feedstock. The algae pyrolysis oil exhibited superior properties as intermediate energy carrier compared to pyrolysis oil from fast pyrolysis of pine chips, in particular higher HHV and carbon content and lower oxygen and water content. These data can potentially be used in the design and modelling of thermochemical conversion processes of microalgae

Performance and emissions of liquefied wood as fuel for a small scale gas turbine

Test of modified MGT with crude oil derived from wood liquefation

Organic dye-sensitized solar cells containing alkaline iodide-based gel polymer electrolytes: Influence of cation size

The electrolyte used in dye-sensitized solar cells (DSSCs) plays a key role in the process of current generation, and hence the analysis of charge-transfer mechanisms both in its bulk and at its interfaces with other materials is of fundamental importance. Because of solvent confinement, gel polymer electrolytes are more practical and convenient to use with respect to liquid electrolytes, but in-depth studies are still necessary to optimize their performances. In this work, gel polymer electrolytes of general formulation polyacrylonitrile (PAN)/ethylene carbonate (EC)/propylene carbonate (PC)/MI, where M+is a cation in the alkaline series Li-Cs, were prepared and used in DSSCs. Their ionic conductivities were determined by impedance analysis, and their temperature dependence showed Arrhenius behavior within the experimental window. FT-IR studies of the electrolytes confirmed the prevalence of EC coordination around the cations. Photo-anodes were prepared by adsorbing organic sensitizer D35 on nanocrystalline TiO2thin films, and employed to build DSSCs with the gel electrolytes. Nanosecond transient spectroscopy results indicated a slightly faster dye regeneration process in the presence of large cations (Cs+, Rb+). Moreover, a negative shift of TiO2flat-band potential with the decreasing charge density of the cations (increasing size) was observed through Mott-Schottky analysis. In general, results indicate that cell efficiencies are mostly governed by photocurrent values, in turn depending on the conductivity increase with cation size. Accordingly, the best result was obtained with the Cs+-containing cell, although in this case a slight reduction of photovoltage compared to Rb+was observed