E-Thesis 532 views
Application of gas chromatography-mass spectrometry (GC-MS) in the quantitative analysis of organic analytes generated in gasification/pyrolysis coupled Fischer Tropsch (FT) reactor: syngas clean-up and hydrocarbon production / Geraint L. Sullivan
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DOI (Published version): 10.23889/Suthesis.50204
Abstract
The identification and quantitation of organic tars, often requires specialised sampling techniques, such as gas sampling tubes, headspace vials and thermal desorption kits, which all require additional modules for instrument interfacing and sample introduction. The gold standard analysis techniques...
| Published: |
2018
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa50204 |
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| Abstract: |
The identification and quantitation of organic tars, often requires specialised sampling techniques, such as gas sampling tubes, headspace vials and thermal desorption kits, which all require additional modules for instrument interfacing and sample introduction. The gold standard analysis techniques for these organic gaseous compounds is gas chromatography coupled to mass spectrometry (GC-MS) as it provides separation of complex samples and high mass selectivity of ions. A solvent trap method using acetone to capture organic tars that originate from thermochemical treatment of different feedstocks; pinewood, brownfield soil (contaminated with oily sludge) and secondary treated sludge cake. It was then possible to analyse tar compounds without the expense of additional instrumentation and user training. Compounds identified in the solvent traps varied according to the feedstock used. Pine wood was used as an operational standard and generated typical biomass tars from sugar and lignin breakdown. Brownfield soil contaminated with oily sludge generated a wide range of polyaromatic hydrocarbons (PAHs), typical with hydrocarbon waste and secondary sludge cake generated a mixture of biomass breakdown products and nitrogenous compounds. Acetone provided a dual role, not only as a sample preparation method but for syngas cleaning. Tandem acetone scrubbers removed the majority of tars (>90% efficiency) and also capable of removing troublesome volatile compounds, such as acetylene. Spent acetone scrubbers could easily be recycled using waste heat, with up to >90% of semi-volatile tars being recovered. Clean syngas was converted to hydrocarbons using the Fischer-Tropsch (FT) reaction where a novel low temperature Cobalt was used. This catalyst was prepared in a different method from conventional cobalt catalysts (energy intensive calcination 12h at 600 ⁰C in air). The novel catalyst (CAT-1) was prepared using chemical oxidation to generate a cheaper and environmentally friendlier FT catalyst. Initial test experiments, using simulated syngas (bottled carbon monoxide and hydrogen) showed the generation of hydrocarbon material, suggesting a successful catalytic reaction. Further to this a trial using real scrubbed syngas from a combined gasification/ FT system, generated trace hydrocarbons, with no contamination in the final product from the tars, suggesting progress with acetone scrubbers. To further the economic feasibility of pyrolysis/gasification-FT process a smaller investigation into possible use of the remaining biochar as a sorbent to treat contaminated water simulating aqueous scrubbers. Biochar derived from pine wood and uncharacterised sludge cake were activated and showed selectivity for volatile polyaromatic compounds and petroleum derived compounds. |
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| Item Description: |
Under embargo until 29/04/2024. |
| Keywords: |
Pyrolysis, gasification, Fisher-Tropsch, Gas chromatography-Mass spectrometery |
| College: |
Faculty of Medicine, Health and Life Sciences |