C02 emissions are one of the main causes of the greenhouse effect. Reactions between C02 and H2, such as methanol synthesis and methanation, could play an important role in reducing these emissions. The low methanol yield, both selectivity and conversion, is the main problem in the methanol synthesis. Methanation could be considered as another alternative process, because recent research showed that the yield in methanation'process is high, the conversion of C02 to C~ was nearly 100%. By using a combination of the Zero Emission Petrol Vehicle (ZEPV) concept, catalytic hydrogenation of CO2 and methanol to gasoline (MTG) process gasoline can be re-synthesised from recycle C02. The objectives of this thesis are to examine the methanol sY!lthesis behaviour in the lab scale tubular catalytic reactor, to investigate the effect of molecular Sieve 4A (MS 4A) on this synthesis and to analyse the feasibility study for a re-syn fuel refinery. First, methanol synthesis experiments were performed on a CuO/ZnO/AhOJ catalyst at 190- 2200 C, 1 bar, 3600 - 7200 h-I and H2/C02 = 3 - 4. The results indicated that methanol was produced from reaction between H2 and CO2 at those conditions. A maximum C02 conversion was reached at 1900 C, 1 bar, 3600 h-I and H2/C02 = 4. The numerical model results predicted that the initial rate of methanol synthesis increase sharply at pressures into 50 atm and is then relativ~ly constant at pressures above 50 atm. At 50 atm, the initial rate ratio is predicted to increase 35 - 45 times than the initial rate at 1 atm. The presence of water is one of the problems affecting the synthesis. Then to investigate the effect of adding a desiccant, methanol synthesis using a CuO/ZnO/AhOJ catalyst and a MS 4A were carried out at the conditions with the maximum CO2 conversion. The results showed that MS 4A adsorbed water hence the conversion of C02 increased from 1.13% to 2.12%. According to the numerical model, these conversions are predicted 35 - 45 times at pressure around 50 atm. Finally, material and energy balances were calculated for four possible chemical pathways for this re-synthesis (the direct CO2 hydrogenation, the Camere process, the methane to methanol process and the electrolysis process) to determine energy requirements in the re-syn fuel refineries. By using the ZEPV concept, some 70 MT/year of C02 from the combustion of about 22 MT/year of gasoline in around 30 million vehicles in UK can be liquefied at 70 bar and stored on board. This liquid C02 is available to be converted back to gasoline via methanol. The 30% conversion, which was obtained from combination of experiment and numerical model results, was applied for direct hydrogenation of CO2. For the other chemical pathways, the conversion used was based on previous studies. Carrying out this recycling in a set of geographically distributed 're-syn fuel' refineries using offshore wind energy has no further requirement for exploration of crude oil, no limitation of raw material and furthermore no cost penalty for the emitted carbon value. The economic analysis shows that the present (2008) forecourt price for the typical oil refinery (98 p/l) is lower than this forecourt price for the 're-syn fuel' refinery using the offshore wind energy (l09 p/l). By predicting that the wind energy cost will be reduced to as Iowa 2.5 plkWh in the future (2020), it is estimated that the forecourt price of gasoli~e from this futuristic sustainable resynthesis refinery would be decreased to 89 p/l. This forecourt price is cheaper than the current gasoline forecourt price from a typical conventional oil refinery. Based on this preliminary economic assessment, gasoline re-synthesis from recycled CO2 using offshore wind energy is both perfectly sustainable and almost competitive for today and will be cheaper than gasoline from crude oil in the future.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:505377 |
| Date | January 2009 |
| Creators | Musadi, Maya Ramadianti |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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