Axel Funke​

Karlsruhe Institute of Technology | KIT · Institute for Catalysis Research and Technology (IKFT)

In this study, fast pyrolysis of sundried sorghum straw (Sorghum bicolor, SS) and millet straws (Pennisetum glaucum (L). R. Brown, MS), was conducted in a 10 kg.h−1 pyrolysis pilot plant. The aim was to compare their pyrolytic products with products derived from other widely used straw biomasses. Gas chromatography with flame ionization detection (...

Wheat straw is a renewable agricultural by-product that is currently underutilized in the production of bioenergy and bioproducts due to its high ash content, as well as high transport costs due to its low volumetric energy density. The thermogravimetric analysis of this material produces derivative curves with a single broad peak, making it diffic...

Wheat straw is an untapped resource with great potential. However, its high ash content hinders its utilization. Thermogravimetric data, especially DTG profiles, feature a single degradation step, and conventional lignocellulosic analysis is not straightforward; DDTG minima and zeros can be used to identify relevant points. Isoconversional and curv...

Continuous fast pyrolysis is developed for in situ synthesis of ultra‐small metal oxide nanoparticles embedded into three‐dimensional macroporous carbon matrix as demonstrated by the TiO2/carbon nanohybrid. The TiO2 nanoparticles with the average size of 4.6 nm ± 0.6 nm are uniformly distributed in the in situ generated macroporous carbon matrix. W...

In this study, the fate of carbon and nutrient elements; nitrogen, phosphorus, and potassium was investigated during the hydrothermal carbonization (HTC) of three model solutions with different nutrient concentrations to mimic biogas residues from silage and cattle manure. The HTC was conducted at 180 °C, 220 °C, 240 °C, and 260 °C for 3 h reaction...

The large variations found in literature for the activation energy values of main biomass compounds (cellulose, hemicellulose and lignin) in pyrolysis TGA raise concerns regarding the reliability of both the experimental and the modelling side of the performed works. In this work, an international round robin has been conducted by 7 partners who pe...

Pyrolysis kinetics of Quercus cerris cork was investigated using thermogravimetric analysis with heating rates of 10, 20, 50, and 100 °C min−1. The activation energies and chemical compositions of cork components were determined by different model-fitting methods, isoconversional Kissinger-Akahira-Sunose (KAS) method, and Lorentzian multi-peak fitt...

A round robin study evaluating the analysis of biomass liquefaction oils (BLOs) from fast pyrolysis and hydrothermal liquefaction (HTL) was performed, involving fifteen laboratories in seven countries in order to assess the current status of analytical techniques for the determination of nitrogen, sulfur, and chlorine content in BLOs and evaluate p...

A round robin study evaluating the analysis of biomass liquefaction oils (BLOs) from fast pyrolysis and hydrothermal liquefaction (HTL) was performed, involving fifteen laboratories in seven countries in order to assess the current status of analytical techniques for the determination of nitrogen, sulfur, and chlorine content in BLOs and evaluate p...

Crude oil price volatility directly affects the worldwide fuels and chemicals markets, impacts food production costs, as well as it influences investments in alternative energy sources. Global warming is a consequence of greenhouse gases emissions, among which CO2 plays a crucial role. A circular economy appears to be a global consensus to limit th...

A holistic investigation considering the sugarcane bagasse characterization, fast pyrolysis and upgrading of bio-oil applying two nickel-based catalysts is presented. The bio-oil composition is correlated to the bagasse building blocks, and the hydrotreatment reaction pathways are identified. Despite the high ash content of 6.75 wt%, 60.1 wt% of bi...

Near Infrared (NIR) Spectroscopy is widely employed as a rapid technique for the evaluation of properties of biomass materials. Precision and accuracy of the instruments is an important aspect in order to minimize error in the determination of results. The objective of this publication is to determine scanning repeatability and reproducibility of t...

In a previous study, a near infrared (NIR) spectroscopy model was developed using a spectra of ground bamboo samples. Although the previous report on ground bamboo described a good performance, operation in the power plant was found to be inconvenient due to preparation costs and labour required for the necessary preparation of ground samples. Thus...

Fast pyrolysis processes immediately produce two phases: a gas and a solid. Volatiles present in this gas condense into a "bio-oil" comprised of several hundred compounds and a relevant amount of water. To facilitate its use and downstream upgrading, the control of parameters such as water content is important. Fractional condensation is a feasible...

Properties of pyrolysis bio-oils greatly depend on the condensation and storage strategies employed. Bio-oil specifications can be manipulated by using multiple condensers in series - fractional condensation. Pyrolysis bio-oils are a largely unknown and complex mixture, and the modeling of liquid-vapor equilibria depends on two main factors: employ...

Fast pyrolysis trials of wheat straw were performed in a pilot plant featuring a screw reactor and two stage condensation system. Trials differed in the moisture content of the used biomass (1.2%, 9.2%, and 23.6%) and the sweeping gas flowrate. Higher moisture feedstock seems to lead to higher bio-oil production but the largest organic liquid yield...

This poster reflects the effect of the moisture content of lignocellulosic feedstock on the fast pyrolysis process. This effect is reflected primarily on the product distribution of the process, the water content of the derivate bio-oil, and on the heat demand of the reactor. To supply the latter, pyrolysis gas was considered as a fuel due to its l...

Fast pyrolysis is an option to convert lignocellulosic biomass into a large fraction of liquid bio-oil besides some char/ash and non-condensable gas. When ash-rich material is used, this usually results in a higher water content of the pyrolysis oil and a possible phase separation. To avoid phase separation, fractional condensation systems have bee...

Simulations of auger type reactors are conducted with the aim of assessing the rate of heat transfer between heat carrier and biomass particles to achieve fast pyrolysis conditions. It is shown that the heat transfer coefficient can be comparably high as in fluidized bed reactors due to the dense packing of particles that is kept by mechanical agit...

The impact of conversion process parameters in pyrolysis (maximum temperature, inert gas flow rate) and hydrothermal carbonization (maximum temperature, residence time and post-washing) on biochar and hydrochar properties is investigated. Pine wood (PW) and corn digestate (CD), with low and high inorganic species content respectively, are used as f...

The feasibility of applying char obtained from wheat straw fast pyrolysis as charge carbon in an electric arc furnace (EAF) for the production of steel was investigated. Fast pyrolysis char represents a by-product which could be made available at reasonable cost. It is characterized by higher volatile content than slow pyrolysis char. Prior to appl...

Sugarcane (Saccharum spp.), one of the most important crops in the world, is used forethanol and sugar production at Brazilian sugarcane biorefineries. The residues, sugarcane bagasse (SCB) and sugarcane straw (SCS), known as Lignocellulosic Biomass (LCB) are usually used as fuel for Combined Heat and Power (CHP) in the First-Generation biorefineri...

Comparison of different literature results for fast pyrolysis of biomass is difficult due to the variety in feedstock, process conditions, analyses, and detail of the provided data. The presented experiments represent a concerted effort to directly compare two bench scale units (10 kg h⁻¹) for fast and intermediate pyrolysis on the basis of the sam...

Fast pyrolysis is being increasingly applied in commercial plants worldwide. They run exclusively on woody biomass, which has favorable properties for conversion with fast pyrolysis. In order to increase the synergies of food production and the energetic and/or material use of biomass, it is desirable to utilize residues from agricultural productio...

Modeling of fast pyrolysis reactors is challenging, even with state of the art computational tools and design, because rules to scale up well-running fast pyrolysis reactors are missing. Dimensional analysis is a classical tool to evaluate complex processes on a scientific basis and its application to fast pyrolysis is presented herein. Using the e...

Biochars have been found to enhance soil properties and to reduce atmospheric greenhouse gases due to their stable carbon fractions. It is known that stable carbon fractions of pyrolysis-derived biochars usually exhibit mean residence times (MRTs) of at least several hundred years. However, only a few studies exist on the stability of hydrochars, w...

From the very beginning, nature used hydrothermal processes to create fuels during various geological and biological eras involved in the formation of our planet. We then intensively used such fuels for societal development. Like any inheritance, we have the responsibility to pass them on to further generations. However, the rate at which we have u...

Fast pyrolysis is a thermochemical conversion process for the production of liquid substances from solid organic fuels, be it a blend for energetic use (liquid fuel) or more specific chemical substances for material use. However, complete liquefaction of the biomass cannot be achieved and there is always a solid byproduct, i.e. char. In most indust...

Experiments with a process development unit for fast pyrolysis of biomass residues of 10kgh(-1) have been performed to quantify the impact of two different product recovery options. Wheat straw, miscanthus and scrap wood have been used as feedstock. A separate recovery of char increases the organic oil yield as compared to a combined recovery of ch...

Products from the hydrothermal carbonization of two digestates have been analyzed in order to investigate the fate of nitrogen, phosphorus, and potassium in specific plant available speciations. The availability of phosphate and potassium ions was significantly increased due to hydrothermal carbonization of a nutrient-rich digestate. In contrast, t...

The difference between hydrothermal carbonization and vapothermal carbonization for the densification of the energy content of biomass has been investigated systematically for the first time. Vapothermal carbonization allows for higher solid content (solid biomass mass (dry basis) per totalmass of feedstock) in the reactor because the biomass is su...

The increasing interest in biogas production has brought notable attention to lignocellu-losic wastes as a promising and yet unexploited feedstock. As these materials are usually highly recalcitrant the energetic efficiency of biogas production, however, is comparatively low. With the aim to overcome this drawback, a novel cascaded approach was inv...

Available biomass, preferentially residues, can be divided in two groups: biomass with a high or natural water content ('wet' or 'green' biomass) and biomass with low water content such as wood and straw. In 'dry' biomass gasification processes, originating in most coal processing technologies, biomass of low water content is necessary to avoid the...

ZUSAMMENFASSUNG Hydrothermale Verfahren vermeiden eine energieintensive Trocknung von Biomasse und können dadurch Stoffströme mit einem hohen Wasseranteil für eine energetische Nutzung erschließen. Durch das Zusammentragen aktueller Daten wird deutlich, dass eine Effizienzsteigerung in der energetischen Verwertungskette fallabhängig ist. Grundsätzl...

This work provides a basis for the eneregtic assessment of hydrothermal carbonization for the conversion of biomass to produce an energy carrier with improved characteristics as a fuel. The heat of reaction of hydrothermal carbonization has been determined experimentally and the state of knowledge of this reaction is summarized for the first time....

Results from the measurement of the heat of reaction of hydrothermal carbonization by power compensated differential scanning calorimetry exhibited a comparably high experimental standard deviation of around 10–20%. The reasons for this standard deviation have been investigated and are being presented in this article. The zeroline deviation and it...

This paper presents a set of calorimetric measurements with the aim of better understanding the calorific nature of hydrothermal carbonization. Presented values so far show an inadequately high scatter to do so, preventing a well funded assessment of the energetic feasibility of this process. The heat released during hydrothermal carbonization at 2...

The carbonization of biomass residuals to char has strong potential to become an environmentally sound conversion process for the production of a wide variety of products. In addition to its traditional use for the production of charcoal and other energy vectors, pyrolysis can produce products for environmental, catalytic, electronic and agricultur...

Hydrothermal carbonization can be defined as combined dehydration and decarboxy lation of a fuel to raise its carbon content with the aim of achieving a higher calorific value. It is realized by applying elevated temperatures (180–220°C) to biomass in a suspension with water under saturated pressure for several hours. With this conversion process,...