3 research outputs found
On-Line Process Analysis of Biomass Flash Pyrolysis Gases Enabled by Soft Photoionization Mass Spectrometry
In the current discussion about future energy and fuel
supply based on regenerative energy sources, the so-called second-generation
biofuels represent a vitally important contribution for the provision
of carbon-based fuels. In this framework, at the Karlsruhe Institute
of Technology (KIT), the bioliq process has been developed, by which
biomass is flash-pyrolyzed at 500 °C for the production of so-called
biosyncrude, a suspension of the pyrolysis liquids and the remaining
biochar. However, little is known about the composition of the pyrolysis
gases in this process with regard to different biomass feedstock and
process conditions, and the influence on the subsequent steps, namely,
the gasification and subsequent production of biofuels or base materials.
Time-of-flight mass spectrometry (TOFMS) with two soft (i.e., fragmentation
free) photoionization techniques was for the first time applied for
on-line monitoring of the signature organic compounds in highly complex
pyrolysis gases at a technical pyrolysis pilot plant at the KIT. Resonance-enhanced
multiphoton ionization with TOFMS using UV laser pulses was used for
selective and sensitive detection of aromatic species. Furthermore,
single-photon ionization using VUV light supplied by an electron beam-pumped
excimer light source was used to comprehensively ionize (nearly) all
organic molecules. For the miscellaneous biomass feeds used, distinguishable
mass spectra with specific patterns could be obtained, mainly exhibiting
typical pyrolytic decomposition products of (hemi)cellulose and lignin
(phenol derivatives), and nitrogen-containing compounds in some cases.
Certain biomasses are differentiated by their ratios of specific groups
of phenolic decomposition products. Therefore, principal component
and cluster analysis describes the varied pyrolysis gas composition
for temperature variations and particularly for different biomass
species. The results can be integrated in the optimization of the
bioliq process
Single Photon Ionization Orthogonal Acceleration Time-of-Flight Mass Spectrometry and Resonance Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry for Evolved Gas Analysis in Thermogravimetry: Comparative Analysis of Crude Oils
Coupling thermal analysis (TA) with a subsequent analytical method in order to investigate evolved gaseous products from the thermal analysis is a well established method. A popular practice to analyze the gaseous products evolving from thermal analysis is mass spectrometry using electron impact ionization (EI).(1-4) As the kinetic energy of the electrons thereby is typically far beyond the ionization energies of the assayed samples, the electron impact effects fragmentation particularly of organic compounds, hampering the correlation of the ion signals to the gaseous compounds. This applies for complex mixtures in particular. Fragmentation can be reduced using so-called soft ionization techniques. In the course of the presented setup, single photon ionization (SPI) using electron beam pumped excimer lamps (EBEL) emitting vacuum ultraviolet (VUV) light (lambda = 126 nm) is employed. For the instrumentation, a TA system has been coupled to an EBEL-SPI-oaTOFMS (oaTOFMS: orthogonal acceleration time-of-flight mass spectrometry) system using a heated transfer capillary in order to detect semivolatile organic substances from the gas flow of a thermobalance with high temporal resolution. Presented measurements focus on crude oils of different origins. In-depth analysis demonstrates that it is possible to tell apart different crude oil samples on the basis of temperature resolved mass spectra gained from the described setup. TA allows for the assay of crude oils without sample preparation via a distillation process which precedes the thermal decomposition of nonvolatile oil components, i.e., resins and asphaltenes. The gases that evolve during thermal analysis are a complex mixture of organic compounds. These can be analyzed without losing molecular information using mass spectrometry with a soft ionization technique, such as SPI