Evaluating quantitative determination of levoglucosan and hydroxyacetaldehyde in bio-oils by gas and liquid chromatography

This communication evaluates the suitability of gas and liquid chromatography for the quantification of levoglucosan and hydroxyacetaldehyde in bio-oils. It was found that both techniques can principally determine levoglucosan quantitatively in cellulose/biomass derived bio-oils. However, it is also shown that oligo-anhydrosugars present in the bio-oils undergo depolymerisation to levoglucosan during gas chromatography, resulting in an overestimation of the concentration of levoglucosan. Hydroxyacetaldehyde can only be determined quantitatively by liquid chromatography. Presented experimental evidence shows that the high temperature (200–320 °C) of injection in gas chromatography is a key factor causing oligo-anhydrosugars and hydroxyacetaldehyde to react during analysis, which may lead to flawed results

Effect of char on the combustion process of multicomponent bio-fuel

Combustion of pyrolysis oil has attracted many attention in recent years as a renewable and environmental friendly fuel. However, pyrolysis oil as an multi-component fuel has some differences compared to conventional fossil fuels. One of the main differences is the formation of solid char in the droplet during evaporation. The goal of this work is to study the effect of the solid char on the combustion characteristics of multi-component fuel. An Euler-Lagrange model of three phase gas/liquid/solid combustion is developed to study the detailed information about every phenomena in the process such as: heat, mass and momentum transfer between droplet and gas phase, droplet evaporation, homogeneous and heterogeneous reactions. The results indicate that the presence of the solid char and consequently its combustion elongates significantly the combustion region in a typical spray injection chamber/burner. Moreover, the gas phase reaches higher temperatures as a result of char combustion that creates more heat by heterogeneous oxidation as a kind of afterburner

Economic comparison of reactive distillation (RD) to a benchmark conventional flowsheet:Regions of RD applicability and trends in column design

A novel methodology for the techno-economic assessment of Reactive Distillation (RD) is presented. The developed methodology benchmarks reactive distillation (RD) to a conventional reactor + distillation train flowsheet (R+D) on a cost-optimized basis, with the optimization being performed on the process unit level (reactor sizing, number of stages, feed point(s)) and the internals level (reactive tray design). This methodology is applied to the ideal quaternary system A+B↔C+D with the conventional boiling point order of TC &lt; TA &lt; TB &lt; TD (αAD = 4, αBD = 2, αCD = 8). From this pool of data, a regime map of RD vs. R+D is established in which the attractive regions of either flowsheet option are identified in terms of the chemical reaction rate and chemical equilibrium. It is found that RD can arise as the cost optimal option for a large range of residence time requirements by virtue of overcoming the external recycle requirements of R+D. This is achieved through optimized reactive tray design. Contrary to conventional distillation design practices, it was found that the preferred use of bubble-cap trays over sieve trays to allow elevated weir heights and designing the column diameter below 80% of flooding become relevant design choices when accommodating high liquid holdup.</p

Recent developments in fast pyrolysis of ligno-cellulosic materials

Pyrolysis is a thermochemical process to convert ligno-cellulosic materials into bio-char and pyrolysis oil. This oil can be further upgraded or refined for electricity, transportation fuels and chemicals production. At the time of writing, several demonstration factories are considered worldwide aiming at maturing the technology. Research is focusing on understanding the underlying processes at all relevant scales, ranging from the chemistry of cell wall deconstruction to optimization of pyrolysis factories, in order to produce better quality oils for targeted uses. Among the several bio-oil applications that are currently investigated the production and fermentation of pyrolytic sugars explores the promising interface between thermochemistry and biotechnology

Hydrothermal gasification of sucrose

The earlier proposed two-step process, consisting of hydrogenation followed by hydrothermal gasification, for the conversion of carbohydrates is further developed by increasing its productivity, through the use of Pt and Ru catalysts in series. Aqueous sucrose is used as a model system to represent carbohydrate-rich waste water streams. In the first step, stabilisation, sucrose in a mass fraction of 10% in water is treated in a 45 cm 3 batch autoclave reactor with H 2 and is fully converted to sorbitol and mannitol at 413 K using a Ru catalyst with a 5% metal loading on a carbon support. A pseudo-first order kinetic model is developed and parameterised to support process development. In the second step, the stabilised mixture is gasified at 573 K using Pt and Ru catalysts with mass fractions of 5% on γ-Al 2 O 3 and carbon supports respectively. The novel sequential combination of these two catalysts for gasification provides high H 2 yields as well as high carbon to gas conversion (X CG ). The carbon based weight hour space velocity (WHSV c ) is increased from ca. 0.04 h −1 in previous work to 1 h −1 in this work. An energy balance shows that the ratio of the useable energy to the energy import, also termed ‘Energy Return On Energy Investment’ (EROEI) is ca. 5. This process provides an opportunity to simultaneously obtain clean water (TOC ∼ 4.7 g m −3 ) and produce valuable fuels (H 2 and CH 4 ) from carbohydrate-rich waste streams such as wastewaters from potato processing, fruit and vegetable processing industries

Deactivation of iron oxide used in the steam-iron process to produce hydrogen

In the steam-iron process pure hydrogen can be produced from any hydrocarbon feedstock by using a redox cycle of iron oxide. One of the main problems connected to the use of the iron oxide is the inherent structural changes that take place during oxygen loading and unloading leading to severe deactivation. This deactivation reduces the capability of the material for uptake and release of oxygen, basically due to loss of specific surface area. In this paper a simplified (reactive) sintering model is used to derive a relation for the loss in surface area of the material in the first redox cycles. This model is based on the relative conversion and the resulting swelling of the material during oxidation. Furthermore the grainy pellet model is used to describe the increase in grain size and increase in solid fraction in a particle due to the subsequent cycling of the iron oxide in the redox process. Model predictions are compared with redox experiments of H2/H2O–Fe/Fe3O4 at 800 °C. Grain growth over subsequent cycles could explain the observed deactivation over about 20 cycles satisfactorily

Recycling phosphorus by fast pyrolysis of pig manure: concentration and extraction of phosphorus combined with formation of value-added pyrolysis products

In order to recycle phosphorus from the livestock chain back to the land, fast pyrolysis of concentrated pig manure at different temperatures (400 °C, 500 °C, 600 °C), was undertaken to concentrate the phosphorus in the char fraction for recovery. Results show that 92%–97% of the phosphorus present in the pyrolysis feedstock ends up in the char fraction, while 60%–75% of that can be directly leached as ortho-phosphate, and 90% as total phosphorus. After char combustion, 100% of the phosphorus present can be leached as ortho-phosphate from the ash. Yields, heating values, and properties of the pyrolysis products have been analyzed. Expressed per tonne of fresh pig manure, the char phosphorus value is estimated at 0.81 € t−1–0.86 € t−1, energy application value at 2.4 € t−1–3.6 € t−1 (liquid organic phase) and 0.5 € t−1–0.7 € t−1 (char), and the fertilizer value of the aqueous phase at 0.10 € t−1–0.18 € t−1. Including costs for energy requirement, solid–liquid separation, and drying, pyrolysis costs are estimated around 0.4 € t−1–4.4 € t−1 for pig manure. It is concluded that pyrolysis costs compare positively with pig manure transportation costs of 0.06 € t−1 km−1, while it also offsets phosphorus extraction from the rapidly depleting phosphate rock