Thomas Dijkmans

Quantitative analysis of crude and stabilized bio-oils by comprehensive two-dimensional gas-chromatography.

Bio-oils produced by fast pyrolysis of lignocellulosic biomass have proven to be a promising, clean, and renewable energy source. To better assess the potential of using bio-oils for the production of chemicals and fuels a new comprehensive characterization method is developed. The combination of the analyical power of GC×GC-FID and GC×GC-TOF-MS allows to obtain an unseen level of detail for both crude and hydrotreated bio-oils originated from pine wood biomass. The use of GC×GC proves to be essential to capture the compositional differences between crude and stabilized bio-oils. Our method uses a flame ionization detector to quantify the composition, while GC×GC-TOF-MS is used for the qualitative analysis. This method allows quantification of around 150 tentatively identified compounds, describing approximately 80% of total peak volume. The number of quantified compounds in bio-oils is increased with a factor five compared to the present state-of-the-arte. The necessity of using multiple internal standards (dibutyl ether and fluoranthene) and a cold-on column injector is also verified.

Wood-derived olefins by steam cracking of hydrodeoxygenated tall oils

Tall oil fractions obtained from Norwegian spruce pulping were hydrodeoxygenated (HDO) at pilot scale using a commercial NiMo hydrotreating catalyst. Comprehensive two dimensional gas chromatography (GC×GC) showed that HDO of both tall oil fatty acids (TOFA) and distilled tall oil (DTO) produced highly paraffinic hydrocarbon liquids. The hydrotreated fractions also contained fatty acid methyl esters and norabietane and norabietatriene isomers. Steam cracking of HDO-TOFA in a pilot plant revealed that high light olefin yields can be obtained, with 35.4 wt.% of ethene and 18.2 wt.% of propene at a coil outlet pressure (COP) of 1.7 bara, a dilution of 0.45 kg(steam)/kg(HDO-TOFA) and a coil outlet temperature (COT) of 820 °C. A pilot plant coking experiment indicated that cracking of HDO-TOFA at a COT of 850 °C results in limited fouling in the reactor. Co-cracking of HDO tall oil fractions with a typical fossil-based naphtha showed improved selectivity to desired light olefins, further demonstrating the potential of large scale olefin production from hydrotreated tall oil fractions in conventional crackers.

Detailed compositional characterization of plastic waste pyrolysis oil by comprehensive two-dimensional gas-chromatography coupled to multiple detectors ☆

The detailed compositional characterization of plastic waste pyrolysis oil was performed with comprehensive two-dimensional GC (GC×GC) coupled to four different detectors: a flame ionization detector (FID), a sulfur chemiluminescence detector (SCD), a nitrogen chemiluminescence detector (NCD) and a time of flight mass spectrometer (TOF-MS). The performances of different column combinations were assessed in normal i.e. apolar/mid-polar and reversed configurations for the GC×GC-NCD and GC×GC-SCD analyses. The information obtained from the four detectors and the use of internal standards, i.e. 3-chlorothiophene for the FID and the SCD and 2-chloropyridine for the NCD analysis, enabled the identification and quantification of the pyrolysis oil in terms of both group type and carbon number: hydrocarbon groups (n-paraffins, iso-paraffins, olefins and naphthenes, monoaromatics, naphthenoaromatics, diaromatics, naphthenodiaromatics, triaromatics, naphthenotriaromatics and tetra-aromatics), nitrogen (nitriles, pyridines, quinolines, indole, caprolactam, etc.), sulfur (thiols/sulfides, thiophenes/disulfides, benzothiophenes, dibenzothiophenes, etc.) and oxygen containing compounds (ketones, phenols, aldehydes, ethers, etc.). Quantification of trace impurities is illustrated for indole and caprolactam. The analyzed pyrolysis oil included a significant amount of nitrogen containing compounds (6.4wt%) and to a lesser extent sulfur containing compounds (0.6wt%). These nitrogen and sulfur containing compounds described approximately 80% of the total peak volume for respectively the NCD and SCD analysis. TOF-MS indicated the presence of the oxygen containing compounds. However only a part of the oxygen containing compounds (2.5wt%) was identified because of their low concentrations and possible overlap with the complex hydrocarbon matrix as no selective detector or preparative separation for oxygen compounds was used.

GPU based simulation of reactive mixtures with detailed chemistry in combination with tabulation and an analytical Jacobian

Abstract Incorporating detailed chemistry in solvers still remains a daunting and intractable task due to the prohibitive computational cost. However the combination of advanced mathematical solution techniques such as tabulation and calculating the analytical Jacobian in combination with efficient computational techniques that use the graphical processing unit (GPU) to do calculations can drastically speedup the simulation. These techniques are not mutually exclusive as is demonstrated for an ordinary differential equation (ODE) problem describing the classical adiabatic, constant-volume ignition of an equimolar methane/air mixture. Acceleration with up to a factor 120 can be obtained with the new algorithm compared to the algorithm employed in the reference solver. Maximum speedup is obtained in the case where the analytical Jacobian and the rates are calculated using the GPU when using intrinsic compiler functions to calculate transcendental functions which are used to calculate thermodynamic and kinetic coefficients. This is because the GPU can calculate transcendental functions significantly more efficient than a CPU.