Publications
206 results found
Bian H, Ai L, Heng JYY, et al., 2023, Effects of chemical potential differences on methane hydrate formation kinetics, Chemical Engineering Journal, Vol: 452, Pages: 1-11, ISSN: 1385-8947
To underpin the increasing interest in practical applications of gas hydrates, for gas storage and separation for instance, the formation and growth of hydrates at liquid-gas interfaces are of fundamental importance. Although the thermodynamics of hydrate formation has been widely studied and is well understood, the kinetics of these processes is not well characterised. In this work, a high-pressure, low-temperature stirred reactor was used to conduct hydrate formation kinetic studies in a temperature range from 276.5 to 283.5 K and a pressure range from 5 to 10.5 MPa, with a special focus on 1) the impact of agitation conditions on the available water-gas interfacial surface area for mass transfer and growth rate during hydrate formation, and 2) the effect of the chemical potential driving force on the formation rate. Five hydrate growth regimes were identified, with varying degrees of gas mass transfer control across the gas-water interface depending on the extent to which hydrate layers built up at this interface, gas needed to move through solid hydrate layers, and the extent to which the gas was entrained within the water phase. The formation rate in the initial linear growth regime, before the onset of solid hydrate gas mass transfer effects, was found to depend in an essentially exponential manner on the chemical potential difference from the equilibrium state. Semi-empirical models related to Arrhenius-type kinetic models were used to correlate the data, the best of which reproduced the formation rates from the chemical potential differences to within ± 5 %. The approach has general applicability to help determine the balance between kinetic and thermodynamic factors in identifying the optimum pressure-temperature conditions for processes for gas storage, gas separation and other hydrate applications.
Yusuf M, Beg M, Ubaidullah M, et al., 2022, Kinetic studies for DRM over high-performance Ni-W/Al2O3-MgO catalyst, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 47, Pages: 42150-42159, ISSN: 0360-3199
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- Citations: 15
Parkinson B, Balcombe P, Speirs JF, et al., 2022, Levelized cost of CO2 mitigation from hydrogen production routes (vol 12, pg 19, 2019), ENERGY & ENVIRONMENTAL SCIENCE, ISSN: 1754-5692
Schrecker L, Dickhaut J, Holtze C, et al., 2022, Discovery of unexpectedly complex reaction pathways for the Knorr pyrazole synthesis via transient flow, REACTION CHEMISTRY & ENGINEERING, Vol: 8, Pages: 41-46, ISSN: 2058-9883
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- Citations: 1
Chadha D, Hellgardt K, 2022, Flipping classrooms, sowing seeds, and developing confidence: teaching engineering judgement to undergraduate engineering students, American Society for Engineering Education Annual Meeting
Yusuf M, Farooqi AS, Alam MA, et al., 2022, Response surface optimization of syngas production from greenhouse gases via DRM over high performance Ni-W catalyst, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 47, Pages: 31058-31071, ISSN: 0360-3199
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- Citations: 8
Gan HS, Kanao S, Sato T, et al., 2022, Identifying marine debris source position using adjoint marginal sensitivity method and stranded beach litter data in Singapore, MARINE POLLUTION BULLETIN, Vol: 182, ISSN: 0025-326X
Stark RT, Pye D, Chen W, et al., 2022, Assessing a sustainable manufacturing route to lapatinib, Reaction Chemistry and Engineering, Vol: 7, Pages: 2420-2426, ISSN: 2058-9883
A synthetic route to an anti-cancer drug, lapatinib, was devised to support the development of a sustainable manufacturing process in South Africa. Quantitative metrics were employed to evaluate the sustainability of the key steps of the reaction.
Deadman BJ, Gian S, Lee VEY, et al., 2022, On-demand, in situ, generation of ammonium caroate (peroxymonosulfate) for the dihydroxylation of alkenes to vicinal diols, Green Chemistry, Vol: 24, Pages: 5570-5578, ISSN: 1463-9262
Using the dihydroxylation of alkenes as a benchmark, the reactivities of fresh and aged solutions of (NH4)2S2O8 (electrochemically generated) were compared to commercially-procured peroxydisulfate and Oxone®. The study revealed that peroxymonosulfate (Caro’s acid, PMS) is the active oxidant in such reactions. Using complementary redox colorimetry and in situ IR spectroscopy to monitor the oxidants, the competitive decomposition of peroxydisulfate in an acidic solution into PMS and H2O2 can be quantified for the first time. The new insight enabled the design and implementation of both batch and flow processes to maximise the concentration of active PMS oxidant. The utility of these oxidants for organic synthesis is demonstrated by the dihydroxylation of eight styrenes and seven alkyl alkenes, where the ammonium PMS solutions performed better than Oxone® (counterion effect). Last but not least, a non-chromatographic method for isolating and purifying the water-soluble diol product was developed.
Ibadurrohman M, Hellgardt K, 2022, Effects of PEG templating of spray-pyrolyzed TiO2 films on their nanoscale roughness and eventual photoelectrochemical properties, JOURNAL OF APPLIED ELECTROCHEMISTRY, Vol: 52, Pages: 929-940, ISSN: 0021-891X
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- Citations: 1
Chadha D, Campbell J, Maraj M, et al., 2022, Engaging students to shape their own learning: driving curriculum re-design using a Theory of Change approach, Education for Chemical Engineers, Vol: 38, Pages: 14-21, ISSN: 1749-7728
Curriculum review is challenging, although if carried out strategically can be less so. The adoption of a theory of change approach for reviewing a chemical engineering curriculum at a research-intensive university in the UK is discussed. The curriculum review was undertaken as part of an institutional drive to modularise the curricula and align the number of contact and independent study hours for all undergraduate students in the institution. At the heart of our curriculum review is the student experience, which is often ignored in favour of the views of institutional management. The curriculum has been redesigned using a theory of change approach, which has enabled us to establish short and long-term plans based on our efforts to create a less burdensome, student-centred curriculum that incorporates our institutional learning and teaching strategy. As part of the process, assumptions needed to be surfaced, meaningful evidence collated, and a central end-goal identified These plans are evidence-based and include: the provision of a departmental wellbeing advisor, the application and development of interactive pedagogies, appropriate mechanisms that support slow learning through formative assessment and less of an assessment burden, and nurturing links with industry-based partners ensuring a greater emphasis on students’ professional development and their exposure to chemical engineering industries.
Yusuf M, Farooqi AS, Ying YX, et al., 2021, Syngas production employing nickel on alumina-magnesia supported catalyst via dry methane reformingSynthesegasherstellung unter Verwendung von Nickel auf Aluminium-Magnesium unterstutztem Katalysator durch Trockenreformierung von Methan, MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Vol: 52, Pages: 1090-1100, ISSN: 0933-5137
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- Citations: 8
Wang S, Panayides J-L, Riley D, et al., 2021, Rapid formation of 2-lithio-1-(triphenylmethyl)imidazole and substitution reactions in flow, Reaction Chemistry and Engineering, Vol: 6, Pages: 2018-2023, ISSN: 2058-9883
The functionalisation of imidazoles is a necessary step in the formation of many active pharmaceutical intermediates. Herein, we report a flow chemistry approach for the rapid and efficient formation of 2-lithio-1-(triphenylmethyl)imidazole at ambient temperature and its reaction with a range of electrophiles, achieving modest to high yields (40–94%) in short reaction times (<1 min). The method is amenable to the scale-up of this highly reactive lithio-imidazole intermediate.
Cardoso A, Pastor-Perez L, Reina TR, et al., 2021, Lignin to Monoaromatics with a Carbon-Nanofiber-Supported Ni-CeO2-x Catalyst Synthesized in a One-Pot Hydrothermal Process, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 9, Pages: 12800-12812, ISSN: 2168-0485
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- Citations: 3
Chadha D, Kogelbauer A, Campbell J, et al., 2021, Are the kids alright? Exploring students’ experiences of support mechanisms to enhance wellbeing on an engineering programme in the UK, European Journal of Engineering Education, Vol: 46, Pages: 662-677, ISSN: 0304-3797
In this paper, we aim to explore students’ experiences of support mechanisms that support their wellbeing on an engineering degree programme at a research-intensive higher education institution and understand how theory relates to practice. This study was conducted using a mixed-methods approach involving student survey responses (N = 173), interviews with 16 students and focus groups. Kahu and Nelson’s conceptual framework was used as a lens through which to explore student support mechanisms. Preliminary data analysis indicates that the intense workload adversely affects students as do some of the interactions they have with personal tutors and their peers. Our findings suggest that workload needs to be reduced, personal tutors need to fill gaps in their skills set, especially associated with student support, and institutional and departmental protocols be continually updated to support student wellbeing. Additionally, student wellbeing officers and professional, dedicated wellbeing advisors could be part of a long-term solution.
Yusuf M, Farooqi AS, Al-Kahtani AA, et al., 2021, Syngas production from greenhouse gases using Ni-W bimetallic catalyst via dry methane reforming: Effect of W addition, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 46, Pages: 27044-27061, ISSN: 0360-3199
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- Citations: 21
Yunus IS, Wang Z, Sattayawat P, et al., 2021, Improved Bioproduction of 1-Octanol Using Engineered Synechocystis sp. PCC 6803, ACS SYNTHETIC BIOLOGY, Vol: 10, Pages: 1417-1428, ISSN: 2161-5063
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- Citations: 5
Parkinson B, Patzschke CF, Nikolis D, et al., 2021, Molten salt bubble columns for low-carbon hydrogen from CH4 pyrolysis: Mass transfer and carbon formation mechanisms, CHEMICAL ENGINEERING JOURNAL, Vol: 417, ISSN: 1385-8947
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- Citations: 6
Wichmann J, Lauersen KJ, Biondi N, et al., 2021, Engineering Biocatalytic Solar Fuel Production: The PHOTOFUEL Consortium, TRENDS IN BIOTECHNOLOGY, Vol: 39, Pages: 323-327, ISSN: 0167-7799
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- Citations: 7
Bian H, Ai L, Hellgardt K, et al., 2021, Phase behaviour of methane hydrates in confined media, Crystals, Vol: 11, Pages: 1-16, ISSN: 2073-4352
In a study designed to investigate the melting behaviour of natural gas hydrates which are usually formed in porous mineral sediments rather than in bulk, hydrate phase equilibria for binary methane and water mixtures were studied using high-pressure differential scanning calorimetry in mesoporous and macroporous silica particles having controlled pore sizes ranging from 8.5 nm to 195.7 nm. A dynamic oscillating temperature method was used to form methane hydrates reproducibly and then determine their decomposition behaviour—melting points and enthalpies of melting. Significant decreases in dissociation temperature were observed as the pore size decreased (over 6 K for 8.5 nm pores). This behaviour is consistent with the Gibbs–Thomson equation, which was used to determine hydrate–water interfacial energies. The melting data up to 50 MPa indicated a strong, essentially logarithmic, dependence on pressure, which here has been ascribed to the pressure dependence of the interfacial energy in the confined media. An empirical modification of the Gibbs–Thomson equation is proposed to include this effect.
Patzschke CF, Parkinson B, Willis JJ, et al., 2021, Co-Mn catalysts for H-2 production via methane pyrolysis in molten salts, CHEMICAL ENGINEERING JOURNAL, Vol: 414, ISSN: 1385-8947
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- Citations: 14
Parkinson B, Patzschke CF, Nikolis D, et al., 2021, Methane pyrolysis in monovalent alkali halide salts: Kinetics and pyrolytic carbon properties, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 46, Pages: 6225-6238, ISSN: 0360-3199
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- Citations: 15
Yusuf M, Farooqi AS, Keong LK, et al., 2021, Contemporary trends in composite Ni-based catalysts for CO2 reforming of methane, CHEMICAL ENGINEERING SCIENCE, Vol: 229, ISSN: 0009-2509
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- Citations: 58
Agbede OO, Kelsall GH, Hellgardt K, 2021, A novel molten tin reformer: Kinetics of oxygen dissolution in molten tin, CHEMICAL ENGINEERING SCIENCE, Vol: 231, ISSN: 0009-2509
Yusuf M, Bazli L, Alam MA, et al., 2021, Hydrogen production via natural gas reforming: A comparative study between DRM, SRM and BRM techniques, Pages: 155-158
The world population is escalating at a tremendous scale, and hence the global energy demands. The utilization of fossil fuels on a massive scale is not environmentally friendly and posing threats to global warming. CH4 and CO2 are the two major greenhouse gases (GHGs) that are mainly responsible for the greenhouse effect. Gas reforming techniques are promising alternatives to utilize the two GHGs and produce alternative sources of fuel such as syngas and hydrogen. Steam, dry and bireforming of methane are the three main gas reforming processes that can be used for hydrogen and syngas production. These gas reforming reactions are highly endothermic in nature; hence catalyst development is another aspect that is still persistent. The SRM reaction is an extensively used and accepted method for hydrogen production due to its comparatively lower activation energy requirement than BRM and DRM. However, DRM can be a promising technique to produce syngas, since the syngas produces is with H2: CO of unity. The syngas produced by DRM can be used directly in Fischer-Tropsch synthesis to produce higher hydrocarbons.
Al-Qahtani A, Parkinson B, Hellgardt K, et al., 2021, Uncovering the true cost of hydrogen production routes using life cycle monetisation, Applied Energy, Vol: 281, Pages: 115958-115958, ISSN: 0306-2619
Hydrogen has been identified as a potential energy vector to decarbonise the transport and chemical sectors and achieve global greenhouse gas reduction targets. Despite ongoing efforts, hydrogen technologies are often assessed focusing on their global warming potential while overlooking other impacts, or at most including additional metrics that are not easily interpretable. Herein, a wide range of alternative technologies have been assessed to determine the total cost of hydrogen production by coupling life-cycle assessments with an economic evaluation of the environmental externalities of production. By including monetised values of environmental impacts on human health, ecosystem quality, and resources on top of the levelised cost of hydrogen production, an estimation of the “real” total cost of hydrogen was obtained to transparently rank the alternative technologies. The study herein covers steam methane reforming (SMR), coal and biomass gasification, methane pyrolysis, and electrolysis from renewable and nuclear technologies. Monetised externalities are found to represent a significant percentage of the total cost, ultimately altering the standard ranking of technologies. SMR coupled with carbon capture and storage emerges as the cheapest option, followed by methane pyrolysis, and water electrolysis from wind and nuclear. The obtained results identify the “real” ranges for the cost of hydrogen compared to SMR (business as usual) by including environmental externalities, thereby helping to pinpoint critical barriers for emerging and competing technologies to SMR.
Daud ARM, Berrueco C, Hellgardt K, et al., 2021, Oxidative cracking of three to five-member ring polycyclic aromatic hydrocarbons in subcritical and supercritical water, The Journal of Supercritical Fluids, Vol: 167, Pages: 105050-105050, ISSN: 0896-8446
Polycyclic aromatic hydrocarbons (PAH) are refractory structures common in heavy hydrocarbons. Thermal cracking in supercritical water (SCW) is limited but PAH can be completely oxidised if an oxidant is added. By restricting oxidant supply to substoichiometric amounts, this study aims to achieve partial oxidation as a route to useful chemicals, such as mono- and bi-aromatics. Oxidative cracking reactions of anthracene, pyrene and benzo[a]pyrene in subcritical and SCW were studied. PAH conversions well above 90 % were achieved along a fast heating ramp in a batch reactor. This quick initial oxidation took place predominantly in inner rings, weakening the aromatic structure and increasing cracking reactivity. This oxidation-cracking pathway became dominant in the SCW region, producing mostly oxygenated compounds with fewer aromatic rings. On the other hand, competing reactions leading to polymerization were favoured in the subcritical water region. PAH reactivity was found to follow the order anthracene > benzo[a]pyrene > pyrene.
Agbede OO, Kelsall GH, Hellgardt K, 2020, A solid oxide fuel cell with molten tin anode for electricity generation and methane reforming, JOURNAL OF POWER SOURCES, Vol: 474, ISSN: 0378-7753
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- Citations: 1
Ibadurrohman M, Hellgardt K, 2020, Importance of surface roughness of TiO<inf>2</inf> photoanodes in promoting photoelectrochemical activities with and without sacrificial agent, Thin Solid Films, Vol: 705, ISSN: 0040-6090
This paper is intended to highlight the importance of surface roughness of TiO2 photoanodes in a photoelectrochemical (PEC) cell with and without sacrificial agents. TiO2 films were synthesized via a spray pyrolysis method in the presence of PEG200 as a surface-roughening agent. The rough-surface photoanode led to excellent photo-voltammetric output by doubling the limiting photocurrent of its smooth-surface counterpart (from 0.11 mA/cm2 to 0.23 mA/cm2 at 0.8 V vs HgO|Hg). The function of glycerol as an anodic sacrificial agent is also exploited more effectively in the use of rough-surface TiO2. When the smooth-surface TiO2 is used, the presence of glycerol promotes additional photocurrent densities of as low as 0.037 mA/cm2 and 0.043 mA/cm2 at −0.7 V vs HgO|Hg and at 0.8 V vs HgO|Hg, respectively. At the same respective potentials, the use of rough-surface TiO2 gives rise to remarkably higher additional photocurrent density of 0.16 mA/cm2 and 0.11 mA/cm2 – favoring less anodic potential, that is. Hence, we conclude that surface roughening of the photoanode is an effective, albeit simple, strategy to significantly improve PEC responses and make the most use of anodic sacrificial agents.
Agbede OO, Hellgardt K, Kelsall GH, 2020, Electrical conductivities and microstructures of LSM, LSM-YSZ and LSM-YSZ/LSM cathodes fabricated on YSZ electrolyte hollow fibres by dip-coating, MATERIALS TODAY CHEMISTRY, Vol: 16, ISSN: 2468-5194
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- Citations: 7
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