1,720,956 research outputs found
Catalytic hydrogenation of CO₂ for sustainable transport
No full textC02 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.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Carbon neutral gasoline re-synthesised from on-board sequestrated CO 2
No full textCO2emissions are one of the main causes of the greenhouse effect. Catalytic hydrogenation of CO2, such as methanol synthesis and methanation, could play an important role in reducing these emissions. 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 CO2. However the low methanol yields, both selectivity and conversion, is the main problem in the methanol synthesis. The objectives of research in the University of Manchester are to examine the methanol synthesis 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. The experimental results showed that a maximum CO2 conversion was reached at 190°, 1 bar, 3600 h1 and H2/CO 2=4 and MS 4A adsorbed water hence the conversion of CO2 increased from 1.13% to 2.12%. The numerical model results predicted that the initial rate of methanol synthesis increases sharply at pressures into 50 atm and is then relatively 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.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 CO2 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 CO2 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/1) is lower than this forecourt price for the "re-syn fuel" refinery using the offshore wind energy (109 p/1). By predicting that the wind energy cost will be reduced to as low as 2.5 p/kWh in the future (2020), it is estimated that the forecourt price of gasoline from this futuristic sustainable re-synthesis refinery would be decreased to 89 p/1. ©2011, AIDIC Servizi S.r.l
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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