Imperial College London

Prof Klaus Hellgardt

Faculty of EngineeringDepartment of Chemical Engineering

Professor of Chemical Engineering
 
 
 
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Contact

 

+44 (0)20 7594 5577k.hellgardt

 
 
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Location

 

208ACE ExtensionSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

205 results found

Bian H, Ai L, Heng JYY, Maitland GC, Hellgardt Ket al., 2023, Effects of chemical potential differences on methane hydrate formation kinetics, Chemical Engineering Journal, Vol: 452, Pages: 139084-139084, ISSN: 1385-8947

Journal article

Schrecker L, Dickhaut J, Holtze C, Staehle P, Vranceanu M, Hellgardt K, Hii KKMet al., 2022, Discovery of unexpectedly complex reaction pathways for the Knorr pyrazole synthesis via transient flow, REACTION CHEMISTRY & ENGINEERING, ISSN: 2058-9883

Journal article

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

Conference paper

Gan HS, Kanao S, Sato T, Hellgardt K, Uchiyama Yet al., 2022, Identifying marine debris source position using adjoint marginal sensitivity method and stranded beach litter data in Singapore., Mar Pollut Bull, Vol: 182

Movement of marine debris is transboundary and complex, travelling vast distances and accumulating on shorelines. These marine debris wash ashore as stranded beach litter. The objective of this work is to identify release sources of marine debris accumulated along the Singapore coastlines collected by applying a time-backward adjoint marginal sensitivity method and citizen science data of stranded beach litter by a voluntary beach clean-up group. A popular tourist hotspot on the opposite shore was estimated as a possible release source contributing to the marine debris accumulation. This analytical result was validated by population density, industry types, rainfall, and inference from product packaging labels. The use of the citizen science data also illustrated potential as a data source for baseline monitoring and long-term cross-border research that influence policymaking. Future research can be conducted in an expanded domain, considering monsoon effects and instantaneous release events.

Journal article

Yusuf M, Farooqi AS, Alam MA, Keong LK, Hellgardt K, Abdullah Bet 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

Journal article

Stark RT, Pye D, Chen W, Newton OJ, Deadman BJ, Miller P, Panayides J-L, Riley DL, Hellgardt K, Hii KKMet 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.

Journal article

Deadman BJ, Gian S, Lee VEY, Adrio LA, Hellgardt K, Hii KKMet 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.

Journal article

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

Journal article

Chadha D, Campbell J, Maraj M, Brechtelsbauer C, Kogelbauer A, Shah U, Hale C, Hellgardt Ket 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.

Journal article

Yusuf M, Farooqi AS, Ying YX, Keong LK, Alam MA, Hellgardt K, Abdullah Bet 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

Journal article

Wang S, Panayides J-L, Riley D, Tighe CJ, Hellgardt K, Hii KKM, Miller PWet 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.

Journal article

Cardoso A, Pastor-Perez L, Reina TR, Suelves I, Luis Pinilla J, Hellgardt K, Millan Met 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

Journal article

Chadha D, Kogelbauer A, Campbell J, Hellgardt K, Maraj M, Shah U, Brechtelsbauer C, Hale Cet 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.

Journal article

Yusuf M, Farooqi AS, Al-Kahtani AA, Ubaidullah M, Alam MA, Keong LK, Hellgardt K, Abdullah Bet 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

Journal article

Yunus IS, Wang Z, Sattayawat P, Muller J, Zemichael FW, Hellgardt K, Jones PRet al., 2021, Improved Bioproduction of 1-Octanol Using Engineered Synechocystis sp. PCC 6803, ACS SYNTHETIC BIOLOGY, Vol: 10, Pages: 1417-1428, ISSN: 2161-5063

Journal article

Parkinson B, Patzschke CF, Nikolis D, Raman S, Hellgardt Ket 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

Journal article

Wichmann J, Lauersen KJ, Biondi N, Christensen M, Guerra T, Hellgardt K, Kuehner S, Kuronen M, Lindberg P, Roesch C, Yunus IS, Jones P, Lindblad P, Kruse Oet al., 2021, Engineering Biocatalytic Solar Fuel Production: The PHOTOFUEL Consortium, TRENDS IN BIOTECHNOLOGY, Vol: 39, Pages: 323-327, ISSN: 0167-7799

Journal article

Bian H, Ai L, Hellgardt K, Maitland GC, Heng JYYet 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.

Journal article

Patzschke CF, Parkinson B, Willis JJ, Nandi P, Love AM, Raman S, Hellgardt Ket al., 2021, Co-Mn catalysts for H-2 production via methane pyrolysis in molten salts, CHEMICAL ENGINEERING JOURNAL, Vol: 414, ISSN: 1385-8947

Journal article

Parkinson B, Patzschke CF, Nikolis D, Raman S, Dankworth DC, Hellgardt Ket 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

Journal article

Yusuf M, Farooqi AS, Keong LK, Hellgardt K, Abdullah Bet al., 2021, Contemporary trends in composite Ni-based catalysts for CO2 reforming of methane, CHEMICAL ENGINEERING SCIENCE, Vol: 229, ISSN: 0009-2509

Journal article

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

Journal article

Yusuf M, Beg M, Ubaidullah M, Shaikh SF, Keong LK, Hellgardt K, Abdullah Bet al., 2021, Kinetic studies for DRM over high-performance Ni–W/Al<inf>2</inf>O<inf>3</inf>–MgO catalyst, International Journal of Hydrogen Energy, ISSN: 0360-3199

The reaction kinetics of DRM over high-performance Ni–W/Al2O3–MgO bimetallic catalyst is investigated in a fixed bed reactor. The variation of reaction rate is examined within the CH4 and CO2 partial pressure from 0.2 to 0.6 atm and the temperature range of 600oC–800 °C. It is found that the rate of reaction for DRM is more sensitive to CH4 partial pressure compared to CO2 partial pressures. At a constant partial pressure of CO2 and increasing the CH4 partial pressure, the increase in the reaction rate is more than reverse conditions. The activation energies of consumption of CH4 and CO2 were found to be 45.9 and 31.9 kJ/mol, respectively, showing a higher energy barrier for CH4 activation than CO2. Four typical kinetic models then fitted the experimental results obtained, i.e., Power Law, Langmuir- Hinshelwood and Eley-Rideal model I and II. The Langmuir-Hinshelwood model showed the best fitting between experimental and estimated reaction rates.

Journal article

Al-Qahtani A, Parkinson B, Hellgardt K, Shah N, Guillen-Gosalbez Get 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.

Journal article

Yusuf M, Bazli L, Alam MA, Masood F, Keong LK, Noor A, Hellgardt K, Abdullah Bet 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.

Conference paper

Daud ARM, Berrueco C, Hellgardt K, Millan M, Kandiyoti Ret 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.

Journal article

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

Journal article

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.

Journal article

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

Journal article

Feng Y, Morgan M, Fraser PD, Hellgardt K, Nixon PJet al., 2020, Crystal structure of geranylgeranyl pyrophosphate synthase (CrtE) involved in cyanobacterial terpenoid biosynthesis, Frontiers in Plant Science, Vol: 11, ISSN: 1664-462X

Cyanobacteria are photosynthetic prokaryotes that perform oxygenic photosynthesis. Due to their ability to use the photon energy of sunlight to fix carbon dioxide into biomass, cyanobacteria are promising hosts for the sustainable production of terpenoids, also known as isoprenoids, a diverse class of natural products with potential as advanced biofuels and high-value chemicals. However, the cyanobacterial enzymes involved in the biosynthesis of the terpene precursors needed to make more complicated terpenoids are poorly characterized. Here we show that the predicted type II prenyltransferase CrtE encoded by the model cyanobacterium Synechococcus sp. PCC 7002 is homodimeric and able to synthesize C20-geranylgeranyl pyrophosphate (GGPP) from C5-isopentenyl pyrophosphate (IPP) and C5-dimethylallyl pyrophosphate (DMAPP). The crystal structure of CrtE solved to a resolution of 2.7 Å revealed a strong structural similarity to the large subunit of the heterodimeric geranylgeranyl pyrophosphate synthase 1 from Arabidopsis thaliana with each subunit containing 14 helices. Using mutagenesis, we confirmed that the fourth and fifth amino acids (Met-87 and Ser-88) before the first conserved aspartate-rich motif (FARM) play important roles in controlling chain elongation. While the WT enzyme specifically produced GGPP, variants M87F and S88Y could only generate C15-farnesyl pyrophosphate (FPP), indicating that residues with large side chains obstruct product elongation. In contrast, replacement of M87 with the smaller Ala residue allowed the formation of the longer C25-geranylfarnesyl pyrophosphate (GFPP) product. Overall, our results provide new structural and functional information on the cyanobacterial CrtE enzyme that could lead to the development of improved cyanobacterial platforms for terpenoid production.

Journal article

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