22 research outputs found
Carbon-neutral synthetic fuel production via CO2 methanation over supported Ni catalysts
Get PDFThe innovative Power-to-Gas concept is a promising solution for converting surplus energy into synthetic natural gas (SNG). Through catalytic CO2 methanation, renewable H2 and captured CO2 are converted to methane (CH4) or SNG, thereby offering a potent energy storage medium characterised by its elevated heating value. Intrinsic to the global push towards sustainable energy solutions, CO2 methanation stands as a mature reaction, perpetually demanding high-performing catalyst design and synthesis to enhance industrial process efficiency.
The main thesis goals come together along three crucial trajectories. First, it involves the synthesis of high-performance Ni-based catalysts, including YSZ, CeO2, Al2O3, and SBA-15, followed by their performance evaluation for CO2 methanation. Second, the investigation of the influence of distinct reactor conditions, encompassing temperature, H2/CO2 ratio, catalyst positioning, CH4 presence in feed, gas hourly space velocity (GHSV), pressure, and the effect of La-promoter on the yield and selectivity of the optimal catalyst. Finally, the third trajectory delves into the design and modification of monolithic and split reactors for CO2 methanation. This chapter encompasses an investigation into dual catalyst beds and the dynamic interplay of catalyst ratios within reactor subsections.
The thesis started with a background on the recent trend in energy demand, the impact of high fossil fuel dependency on climate change, and the transition from fossil fuel to renewable energy. The discussion also covered an overview of carbon capture technologies and the potential of CO2 methanation as a strategy for CO2 mitigation. The thermodynamics, reactor considerations, and intricate reaction mechanisms of CO2 methanation are discussed.
The catalysts were synthesised using the wetness impregnation technique, followed by comprehensive characterisation, including BET surface measurements, thermogravimetric analysis, scanning electron microscopy, and Raman spectroscopy, for the understanding of their physicochemical properties. The performance of the synthesised catalysts was studied in a continuous flow quartz tube fixed-bed reactor with an internal diameter of 5.5 mm and wall thickness of 2 mm at a temperature range of 473 to 823 K and pressure range of 0.5 to 3 bar depending on the test setup. The gaseous feed stream employed contains N2 (60 mL min-1), H2 (60 mL min-1) and CO2 (15 mL min-1) in the ratio of 4:4:1. Mears' and Weisz-Prater criteria obtained indicated negligible transport limitations.
Activity tests revealed Ni/YSZ as the optimal catalyst with a CO2 conversion rate of approximately 83%. The superior performance of Ni/YSZ is attributed to its distinctive properties, including high oxygen vacancies, augmented basic sites, and an intrinsic resilience to metal sintering, underscored by a low activation energy. The optimum temperature was between 633 and 643 K beyond which the catalyst activity declined. While an increase in the H2:CO2 ratio favoured both the CH4 yield and CO2 conversion, CH4 yield was found to decline at an H2:CO2 ratio beyond 4.
For the investigation of the effect of La-promoter on the performance of Ni/YSZ, a slight stability enhancement was observed, but the catalytic activity was largely unaltered. Notably, there was a structural change in Ni/YSZ as observed from the characterisation results upon La-promoter addition indicating its potential to positively influence catalyst performance in other reforming reactions.
For the reactor design, three distinctive configurations—the single reactor with one catalyst bed, the single reactor with dual catalyst beds, and a two-reactor series, were considered. In the latter configuration, the catalyst ratio within the reactors was varied from 20 to 80%. The outcome revealed that the series-connected two-reactor system with an installed water-removing device and catalyst of ratio of 30%:70% is the best, providing a CO2 conversion of approximately 99%.
In a broader perspective, the findings from this work can help in advancing the research on the seamless and efficient integration of a methanation reactor with a solid oxide electrolyser, considering that the best performance was achieved at reaction conditions such as relatively elevated temperatures and low pressures, which are similar to the operating conditions of a solid oxide electrolyser
Synthesis and characterization of La-promoted Ni/SBA-15 catalysts for methane dry reforming
Get PDFMethane dry reforming (MDR) is one of the practicable ways of synchronously converting two greenhouse gases (CO2 and CH4) into syngas which is a valuable feedstock for chemical processes such as Fischer–Tropsch synthesis, but the process suffers from catalyst deactivation caused by active metal sintering and carbon formation. Thus, this research investigated the influence of operating parameters including reactant partial pressure and temperature on the activity of 10%Ni/SBA-15 catalyst in MDR reaction. Additionally, the effect of La-promoter on the performance of 10%Ni/SBA-15 catalyst for MDR was studied. Both the 10%Ni/SBA-15 and 3%La-10%Ni/SBA-15 catalysts were synthesised by the incipient wetness impregnation method and characterised using BET surface area, XRD, FESEM, TEM, FTIR, EDX, H2-TPR, NH3-TPD, and Raman analyses. Subsequently, the synthesised catalysts were tested for MDR in a quartz fixed-bed tubular reactor under atmospheric pressure at varying CO2 and CH4 partial pressure of 20–60 kPa, and a reaction temperature of 923-1023 K. Both the unpromoted and La-promoted catalysts exhibited high BET surface area in the range of 303-445 m2 g-1. FESEM and TEM results revealed that the Ni particles were well distributed in the La-promoted catalyst while some clusters were formed on the unpromoted 10%Ni/SBA-15 catalyst. Evaluation of the catalytic activity of the 10%Ni/SBA-15 catalyst in MDR at 923 K gave CH4 and CO2 conversions of 65.3% and 70.3%, which declined within 4 h on-stream at percentage deviations of 26.1% and 17.6%, respectively. The observed deactivation of the unpromoted catalyst with time-on-stream was attributed to favoured Boudouard reaction leading to carbon formation. However, the 10%Ni/SBA-15 catalyst activity improved with appreciable stability as reaction temperature increased from 923 K to 1023 K at percentage increment of 47.5% and 39.6% in CH4 and CO2 conversions, respectively. The improvement in activity of 10%Ni/SBA-15 catalyst at high temperature was ascribed to the endothermicity of MDR reaction and the suppression of Boudouard reaction. Furthermore, CH4 conversion of the 10%Ni/SBA-15 catalyst increased from 91.1% to 98.8% as the CO2 partial pressure
Global Trends in Heavy Oil and Bitumen Recovery and In-Situ Upgrading:A Bibliometric Analysis During 1900-2020 and Future Outlook
No full textBitumen and heavy oil are energy resources with high viscosities, high densities, and high metals and heteroatoms content. This paper reports a bibliometric survey to investigate the historic trends and the future pattern of heavy oil and bitumen recovery and upgrading worldwide. It evaluates research outputs and their impact on the topic from 1900 to 2020. Data were extracted from Web of Science (WoS), vetted using Microsoft Excel, and visualized using VOSViewer. Globally, the study identified 8248 publications. Canada had the highest research output and was also widely cited, and the highest-productive countries are the United States from 1900 to 1970, Canada from 1971 to 2000, Canada from 2001 to 2010, and China from 2011 to 2020. The keywords frequency suggests that most research on heavy oil and bitumen focuses more on viscosity reduction, rheology, asphaltenes, enhanced oil recovery methods, and upgrading. These are the top five most productive institutions in the field: University of Calgary > China University of Petroleum > University of Alberta > Russian Academy of Sciences > China National Petroleum Corporation. The Universities of Calgary and Alberta are, however, the most frequently cited and most impactful, with respective citations and h-indexes of 10367 (50 h-index) and 8556 (47h-index). The future of heavy oil and bitumen depends on crude oil price, the economics of transportation alternatives, climate change policies and technologies, while the design of robust and low-cost catalysts would guide in-situ catalytic upgrading.</p
Exergy Analysis and Evaluation of the Different Flowsheeting Configurations for CO2 Capture Plant Using 2-Amino-2-Methyl-1-Propanol (AMP)
Get PDFThis paper presents steady-state simulation and exergy analysis of the 2-amino-2-methyl-1-propanol (AMP)-based post-combustion capture (PCC) plant. Exergy analysis provides the identification of the location, sources of thermodynamic inefficiencies, and magnitude in a thermal system. Furthermore, thermodynamic analysis of different configurations of the process helps to identify opportunities for reducing the steam requirements for each of the configurations. Exergy analysis performed for the AMP-based plant and the different configurations revealed that the rich split with intercooling configuration gave the highest exergy efficiency of 73.6%, while that of the intercooling and the reference AMP-based plant were 57.3% and 55.8% respectively. Thus, exergy analysis of flowsheeting configurations can lead to significant improvements in plant performance and lead to cost reduction for amine-based CO2 capture technologies
Latent heat thermal energy storage: A bibliometric analysis explicating the paradigm from 2000–2019
No full textLatent heat thermal energy storage is one of the most efficient ways of storing thermal energy through which the disparity between energy production or availability and consumption can be corrected, thus avoiding wastage and increasing the process efficiency. In the present study, a novel combination of clusters, networks, and bibliometric analyses are applied on an extensive dataset of publications to represent the overall structure and present interests of the field of latent heat thermal energy storage research. Data was collated for research trends for a 19–year period, between the years of 2000–2019, via the Web of Science database. It was observed that there was a slow rise in publications in this field from 2000–2010, but during the last decade there has been a surge of publications from 2011–2019. Around the time of the increase in interest, various legislations regarding energy conservation were passed. China, U.S.A and Germany lead in terms of total publications (5474, 2843 and 1169 respectively), however, Turkey leads in terms of average citation per document (35.70). In terms of authorship, L.F. Cabeza has the highest output of papers in this category (263 publications and average citations per document of 52.15) however, A. Sari has the highest average citations per document with a value of 72.25. Other observations include current patterns in the overall publications, the contribution of countries and regions, key institutions, authorship networks and collaborations, and most prominent journal. Overall results indicate the influence of government funding to specific areas of research, and how foreign policy may also affect research outputs of certain regions, countries and institutions.</p
Carbon capture technologies for climate change mitigation:a bibliometric analysis of the scientific discourse during 1998–2018
Get PDFThere are four strategies to combating global warming, namely by directly reducing greenhouse gas emissions, or indirectly through expanding renewable energy employment, more efficient use of energy, or a wide range of climate policies. This study reports a bibliometric analysis of direct carbon dioxide emission reduction through carbon capture. The research trend in carbon capture within the three main types of technologies, namely pre-combustion, post-combustion and oxy-fuel combustion, was investigated using publications from 1998 to 2018 retrieved from the Web of Science database. It was found that from 1998-2007 there was little or no research output on carbon capture, until 2008, when legislation on climate change abatement was introduced and public and industry awareness of clean fossil energy options grew. With these motivating factors, 55 countries engaged in carbon capture technologies and related research in which the United States has the most research output followed by the UK and, China. Among the carbon capture technologies commonly studied, the bibliometric analysis based on a keywords network map showed that post-combustion capture is the most referenced carbon capture technology with about 80.9% of total publications retrieved. Oxy-fuel combustion had the lowest number of publications (3.4%)
Corrigendum to “Carbon capture technologies for climate change mitigation: A bibliometric analysis of the scientific discourse during 1998–2018” [Energy Reports 6 (2020) 1200-1212]
No full textThe authors regret to report that there were errors in the published article. The errors appeared in abstract, results and discussion (subheadings 3.2 and 3.5) and in the conclusion. In results and discussion under subheading 3.2 (countries/region participation), the publication details of U.K. were mistakenly split into four namely, England, Scotland, Wales, and Northern Ireland with each constituent analysed as a country. This significantly affected the productivity of U.K. In results and discussion under subheading 3.5 (Participating authors), the errors were due to arrangements and abbreviations of authors names retrieved from the Web of Science. The corrections made are given below. Abstract, line 9–11 With these motivating factors, 49 countries engaged in carbon capture technologies and related research in which the United Kingdom had the most research output followed by the United States, and China. Results and discussion 3.2 Countries/regions participation, first paragraph: A total of 49 countries were involved in research related to CCT all over the world. Among these countries, only 24 countries have a minimum of 10 publications (see Fig. 4) with most publications on post-combustion capture followed by pre-combustion capture (see Table 1). Oxy-fuel combustion had the least number of publication. In terms of total number of publications (TP), the U.K. topped the table (total publications 171) followed by the U.S.A. (total publications of 146) and China (total publications 120). The research output suggested that these countries were leading the research on carbon capture and storage for greenhouse gas emissions abatement. This was not unexpected since the U.S.A. and China are the top two emitters of CO2 worldwide (“Climate change report card: These countries are reaching targets”, 2019) and the campaign for net-zero emission has been intensified in the U.K. in recent times. Conversely, the countries with the least publications on CCT related research were Bangladesh, Colombia, the Czech Republic, Estonia, Hungary, Indonesia, Kazakhstan, Tunisia, Turkey and Vietnam with only one publication each. In terms of total number of citations (TC), the U.S.A. had the highest citations. The top ten countries in order of citation were the U.S.A. (4416 citations) > U.K. (3607 citations) > Germany (2505 citations) > Netherlands (1971 citations) > Norway (1911 citations) > Australia (1888 citations) > China (1876 citations) > France (1795 citations) > Canada (1367 citations) > Spain (1161 citations). Continentally, Europe was the most active continent (53.86% of the total publications) and the second highest percentage came from Asia (20.68%), while Africa and South America were the least active continents (0.68% publications) (see Fig. 5). 3.5 Participating Authors 3.5.1 Co-authorship of authors, first paragraph An author's number of publications and citations are an indication of experts in a given field as well as the visibility of their research output. Among the authors retrieved, Paul Feron affiliated with CSIRO was the most published author (33 publications) followed by Meihong Wang affiliated with the University of Sheffield (28 publications), Paitoon Tontiwachwuthikul affiliated with the University of Regina (21 publications), Eric Favre affiliated with University of Lorraine (20 publications), Raphael Idem affiliated with University of Regina (20 publications) and Mathieu Lucquiaud affiliated with the University of Edinburgh (20 publications) (see Fig. 9). Interestingly, Jeffrey R. Long affiliated with the University of California, Berkeley and with only 4 publications was the most cited author (1151 citations) followed by Meihong Wang (1096 citations), Praveen Linga affiliated with the National University of Singapore (936 citations), Adekola Lawal affiliated with the Process System Enterprise (907 citations), Zoey R. Herm affiliated with the University of California, Berkeley (840 citations) and Rajamani Krishna affiliated with the University of Amsterdam (840 citations). It is worth noting that the authors Richard Baker, Haiqing Lin, Tim C. Merkel and Xiaotong Wei affiliated with Membrane Technology and Research (MTR), Inc. who had only one topical publication received 680 citations each. Conclusions and future outlook In this study, we conducted a bibliometric analysis of publications on CCT related research in the past 20 years (1998–2018) in order to show the status and trends in the application of the three main technologies, namely pre-combustion capture, post-combustion capture and oxy-fuel combustion. The findings from this work include the following: • A total of 1020 publications including articles and proceedings papers with the keywords “post-combustion”, “pre-combustion” and “oxy-fuel combustion” were retrieved from WoS database for the period 1998 to 2018. • 49 countries actively participated in CCT related research where the United Kingdom was the most productive country followed by the United States, and China based on criteria for number of publications and citations. • In terms of continents, Europe had the greatest productivity, followed by Asia. The least productive continents were South America and Africa. • CSIRO was the most active institution (based on number of publications) while SINTEF was the most cited institution. • A total of 202 journals participated in the publications of the articles and proceedings papers considered in this study. Among these journals, International Journal of Greenhouse Gas Control has the greatest productivity in terms of both number of publication and citations. The high productivity by International Journal of Greenhouse Gas Control was ascribed to its more specialised aim of publishing work relating to greenhouse gas emissions and climate change mitigation via carbon dioxide capture, transport and storage as compared to other journals that are majorly multidisciplinary. • Paul Feron was the most productive author in terms of publication, followed by Meihong Wang. In terms of citation number, Jeffrey R. Long was the most influential author followed by Meihong Wang, and Praveen Linga. • Post-combustion capture was the most covered CCT with over 80.9% of the 1020 publications retrieved, whilst oxy-fuel combustion was the least covered with 3.4% of the total publications. The authors would like to apologise for errors that appeared in the published article and for any inconvenience caused. The authors also appreciate the opportunity to correct the scientific record.</p
Influence of Lanthanide Promoters on Ni/SBA-15 Catalysts for Syngas Production by Methane Dry Reforming
Get PDFAbstractThe catalytic performance of Ce- and La-promoted Ni/SBA-15 catalysts for syngas production from CO2 reforming of methane has been investigated in a fixed-bed reactor at stoichiometric feed composition. Both promoted and unpromoted catalysts possessed high BET surface area of 303-445 m2 g-1. Additionally, SBA-15 support had a relatively uniform rod-like shape with a diameter of about 0.55μm and a reduction in the crystallite size of NiO phase from 27.0 to 19.1nm was observed with promoter addition reasonably due to the strong interaction between promoter and NiO particles. CeO2 and La2O3 dopants were finely dispersed on catalyst surface. Temperature-programmed oxidation of spent catalysts showed that coke-resistance was improved significantly with promoter modification and 3%La-10%Ni/SBA-15 catalyst was the most resistant to carbonaceous deposition rationally due to the least NiO crystallite size hindering the nucleation and growth of graphitic carbon. Hence, La-promoted catalyst appeared to be the optimum catalyst in terms of reactant conversion, H2 yield and stability whilst a gradual decline in both reactant conversion and H2 yield was experienced with unpromoted and Ce-doped catalysts. Regardless of catalyst types, the ratio of H2 to CO was always less than unity preferred for Fischer-Tropsch synthesis
Exergy Analysis and Evaluation of the Different Flowsheeting Configurations for CO2 Capture Plant Using 2-Amino-2-Methyl-1-Propanol (AMP)
No full textThis paper presents steady-state simulation and exergy analysis of the 2-amino-2-methyl-1-propanol (AMP)-based post-combustion capture (PCC) plant. Exergy analysis provides the identification of the location, sources of thermodynamic inefficiencies, and magnitude in a thermal system. Furthermore, thermodynamic analysis of different configurations of the process helps to identify opportunities for reducing the steam requirements for each of the configurations. Exergy analysis performed for the AMP-based plant and the different configurations revealed that the rich split with intercooling configuration gave the highest exergy efficiency of 73.6%, while that of the intercooling and the reference AMP-based plant were 57.3% and 55.8% respectively. Thus, exergy analysis of flowsheeting configurations can lead to significant improvements in plant performance and lead to cost reduction for amine-based CO2 capture technologies.</p
A Short Review on Mesoporous Silica-Supported Catalysts for Methane Dry Reforming
Get PDFThe aim of this review is to gain a better insight in to the recent developments made in mesoporous silica molecular sieves, such as MCM-41, SBA-15, and SBA-16, as supports for dry reforming of methane. It further explored how different constraints such as the synthesis method for the mesoporous materials and techniques for metal loading on the mesoporous materials influence the dry reforming reactions and products yields. The high surface area and 2D hexagonal arrays of MCM-41 and SBA-15, 3D cage like structure of SBA-16 allow for good dispersion of metals inside their channels, which in turn, facilitates high catalytic activity and less catalyst deactivation. In this review, attention will be given to different strategies for enhancing catalytic activities, and the effect of metal dispersion on mesoporous silica supports
