Browsing by Author "Nabavi, Seyed Ali"
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Item Open Access Advances, challenges, and perspectives of biogas cleaning, upgrading, and utilisation(Elsevier, 2022-02-05) Golmakani, Ayub; Nabavi, Seyed Ali; Wadi, Basil; Manovic, VasilijeBiogas as a renewable energy resource can be broadly recognised as a carbon–neutral fuel which reduces anthropogenic greenhouse gas emissions, mitigates global warming, and diversifies energy supply. However, the biogas share in the global renewable energy supply chain and technology deployment and maturity are not commensurate with the potential. The first half of this study critically reviews state of the art developments in biogas cleaning and upgrading technologies by considering their present status, current challenges, and barriers associated with their future development. The second part of this paper aims to address critical gaps in converting biogas to biomethane, proposing required pre-treatment steps for different technologies. The third part focuses on current policies concerning the strict regulations implemented for flaring consent applications. In this section, biogas upgrading technologies were compared by estimating the global warming potential (GWP) resulting from waste gases (WG). It was observed that due to high methane losses, WGs from membrane technologies have the highest GWP, but with flaring have the lowest GWP. In the last part of this review, the recent applications of biogas in cogeneration (CHP), tri-generation (CCHP), quad-generation systems, heat, and vehicles are discussed. The use of biogas by different technologies, and their resulting efficiencies were analysed in CHP applications, including microturbines, micro humid air turbine (mHAT), solid oxide fuel cells (SOFC) and hybrid systems of SOFC-microturbines.Item Open Access Assessment of optimal conditions for the performance of greenhouse gas removal methods(Elsevier, 2021-06-18) Asibor, Jude Odianosen; Clough, Peter T.; Nabavi, Seyed Ali; Manovic, VasilijeIn this study, a comparative literature-based assessment of the impact of operational factors such as climatic condition, vegetation type, availability of land, water, energy and biomass, management practices, cost and soil characteristics was carried out on six greenhouse gas removal (GGR) methods. These methods which include forestation, enhanced weathering (EW), soil carbon sequestration (SCS), biochar, direct air capture with carbon storage (DACCS) and bioenergy with carbon capture and storage (BECCS) were accessed with the aim of identifying the conditions and requirements necessary for their optimum performance. The extent of influence of these factors on the performance of the various GGR methods was discussed and quantified on a scale of 0–5. The key conditions necessary for optimum performance were identified with forestation, EW, SCS and biochar found to be best deployed within the tropical and temperate climatic zones. The CCS technologies (BECCS and DACCS) which have been largely projected as major contributors to the attainment of the emission mitigation targets were found to have a larger locational flexibility. However, the need for cost optimal siting of the CCS plant is necessary and dependent on the presence of appropriate storage facilities, preferably geological. The need for global and regional cooperation as well as some current efforts at accelerating the development and deployment of these GGR methods were also highlighted.Item Open Access Beyond the triangle of renewable energy acceptance: The five dimensions of domestic hydrogen acceptance(Elsevier, 2022-08-07) Gordon, Joel A.; Balta-Ozkan, Nazmiye; Nabavi, Seyed AliThe ‘deep’ decarbonization of the residential sector is a priority for meeting national climate change targets, especially in countries such as the UK where natural gas has been the dominant fuel source for over half a century. Hydrogen blending and repurposing the national grid to supply low-carbon hydrogen gas may offer respective short- and long-term solutions to achieving emissions reduction across parts of the housing sector. Despite this imperative, the social acceptance of domestic hydrogen energy technologies remains underexplored by sustainability scholars, with limited insights regarding consumer perceptions and expectations of the transition. A knowledge deficit of this magnitude is likely to hinder effective policymaking and may result in sub-optimal rollout strategies that derail the trajectory of the net zero agenda. Addressing this knowledge gap, this study develops a conceptual framework for examining the consumer-facing side of the hydrogen transition. The paper affirms that the spatiotemporal patterns of renewable energy adoption are shaped by a range of interacting scales, dimensions, and factors. The UK’s emerging hydrogen landscape and its actor-network is characterized as a heterogenous system, composed of dynamic relationships and interdependencies. Future studies should engage with domestic hydrogen acceptance as a co-evolving, multi-scalar phenomenon rooted in the interplay of five distinct dimensions: attitudinal, sociopolitical, community, market, and behavioral acceptance. If arrived to, behavioral acceptance helps realize the domestication of hydrogen heating and cooking, established on grounds on cognitive, sociopolitical, and sociocultural legitimacy. The research community should internalize the complexity and richness of consumer attitudes and responses, through a more critical and reflexive approach to the study of social acceptance.Item Open Access Carbon emissions and decarbonisation: the role and relevance of fermentation industry in chemical sector(Elsevier, 2023-10-07) Agrawal, Deepti; Awani, Kelvin; Nabavi, Seyed Ali; Balan, Venkatesh; Jin, Mingjie; Aminabhavi, Tejraj M.; Dubey, Kashyap Kumar; Kumar, VinodFermentation industry is emerging as sustainable technological alternative to cater the production of various chemical building blocks which are commercially manufactured by petrochemical route. The primary reason for this major transition is global commitment towards decarbonisation of chemical sector, as their conventional fossil-based routes pose serious environmental threat. For instance, in 2022, the direct carbon dioxide (CO2) emission during synthesis of primary chemicals accounted for ∼ 920 Mt. CO2 is one of the prominent greenhouse gases (GHG’s), contributing majorly towards global warming effect and drastic climate change. Fermentation industry largely thrives on exploiting fermentable and organic carbon derived from edible and/or non-edible biomass and transforming them to valorised products using microbial cell factories. Therefore, the production of bio-based chemicals via this route is often associated with low or zero-carbon footprint, resulting in either carbon neutral or carbon negative products. This review focuses on different types of fermentative processes and their impact on carbon release and decarbonisation. It further discusses the relevance and contribution of fermentation industry as well as biological processes to provide a sustainable solution towards decarbonisation of chemical sector. Further, it showcases the advantages of some commercial proven and/or pipeline bio-based products over their conventional competitor fossil-based products, especially from an environmental viewpoint. Finally, advantages of biogenic CO2 from fermentation industry over other sources and CO2 removal from fermentation as a platform for carbon offsetting are covered.Item Open Access Carbonation of lime-based materials under ambient conditions for direct air capture(Elsevier, 2019-09-07) Erans, María; Nabavi, Seyed Ali; Manovic, VasilijeCarbonation of lime-based materials at high temperatures has been extensively explored in the processes for decarbonisation of the power and industrial sectors. However, their capability to capture carbon dioxide from air at realistic ambient conditions in direct air capture technologies is less explored. In this work, lime and hydrated lime samples are exposed to ambient air for prolonged durations, as well as to calcination/ambient-carbonation cycles, to assess their carbonation performance. It is shown that the humidity plays a key role in carbonation of lime under ambient conditions. Furthermore, faster weathering and higher conversions are demonstrated by hydrated lime, showing a carbonation conversion of 70% after 300 h. Importantly, it was found that there was a negligible difference in the carbonation conversions during five calcination/ambient-carbonation cycles, which can be explained by simultaneous reactivation of cycled material by moist air. These findings indicated that lime-based materials are suitable for carbon dioxide capture from ambient air employing cyclic processes, in a practical time-scale, and that humidity of air plays a key role.Item Open Access Comparative analysis of ammonia combustion for domestic applications(Elsevier, 2022-12-02) Bazooyar, Bahamin; Coomson, George; Manovic, Vasilije; Nabavi, Seyed AliThis article explores whether ammonia is a reliable fuel for heat and electricity generation in domestic applications. First, the ammonia combustion characteristics, including adiabatic flame temperature, ignition delay time, and laminar flame speed are analysed and compared with the conventional fuels such as natural gas, dimethyl ether, hydrogen, and syngas, under 12 kWe turbine and 45kWth boiler conditions. Furthermore, the combustion of ammonia at a conventional boiler and turbine combustor was numerically modelled, analysed, and compared with the available fuels. The finding demonstrates that ammonia provides inferior combustion characteristics in combustion heat releases, stability region, and ignition characteristics. The ammonia combustion characteristics including, laminar flame speed and ignition delay time, were comparable to those of methane. The flame temperature and exhaust gas composition of ammonia are rather different than those of methane which may vary the heat transfer during the operation of gas turbines and boilers. The combustion of ammonia in boilers may produce the required heat for heating purposes; however, it needs further modification to achieve better NOX control. In a gas turbine, on the other hand, combustion ammonia leads to remarkably higher temperatures if the same turbine inlet temperature is needed compared to other fuels, however, at the cost of significant NOX formation, which may go beyond 100 ppm with thermal NO formation on par of fuel NO.Item Open Access Comparative evaluation of PSA, PVSA, and twin PSA processes for biogas upgrading: the purity, recovery, and energy consumption dilemma(MDPI, 2023-09-27) Golmakani, Ayub; Wadi, Basil; Manovic, Vasilije; Nabavi, Seyed AliThe current challenges of commercial cyclic adsorption processes for biogas upgrading are associated with either high energy consumption or low recovery. To address these challenges, this work evaluates the performance of a range of configurations for biogas separations, including pressure swing adsorption (PSA), pressure vacuum swing adsorption (PVSA), and twin double-bed PSA, by dynamic modelling. Moreover, a sensitivity analysis was performed to explore the effect of various operating conditions, including adsorption time, purge-to-feed ratio, biogas feed temperature, and vacuum level, on recovery and energy consumption. It was found that the required energy for a twin double-bed PSA to produce biomethane with 87% purity is 903 kJ/kg CH4 with 90% recovery, compared to 961 kJ/kg CH4 and 76% recovery for a PVSA process. With respect to minimum purity requirements, increasing product purity from 95.35 to 99.96% resulted in a 32% increase in energy demand and a 23% drop in recovery, illustrating the degree of loss in process efficiency and the costly trade-off to produce ultra-high-purity biomethane. It was concluded that in processes with moderate vacuum requirements (>0.5 bar), a PVSA should be utilised when a high purity biomethane product is desirable. On the other hand, to minimise CH4 loss and enhance recovery, a twin double-bed PSA should be employed.Item Open Access A country-level assessment of the deployment potential of greenhouse gas removal technologies(Elsevier, 2022-09-13) Asibor, Jude Odianosen; Clough, Peter T.; Nabavi, Seyed Ali; Manovic, VasilijeThe deployment of greenhouse gas removal (GGR) technologies has been identified as an indispensable option in limiting global warming to 1.5 °C by the end of the century. Despite this, many countries are yet to include and promote this option in their long-term plans owing to factors such as uncertainty in technical potential, deployment feasibility and economic impact. This work presents a country-level assessment of the deployment potential of five GGR technologies, including forestation, enhanced weathering (EW), direct air carbon capture and storage (DACCS), bioenergy with carbon capture and storage (BECCS) and biochar. Using a multi criteria decision analysis (MCDA) approach consisting of bio-geophysical and techno-economic factors, priority regions for the deployment of these GGR technologies were identified. The extent of carbon dioxide removable by 2100 via these technologies was also estimated for each of the 182 countries considered. While the obtained results indicate the need for regional cooperation among countries, it also provides useful evidence on the need for countries to include and prioritise GGR technologies in their revised nationally determined contributions (NDCs).Item Open Access Demonstration of a kW-scale solid oxide fuel cell-calciner for power generation and production of calcined materials(Elsevier, 2019-08-27) Nabavi, Seyed Ali; Erans, María; Manovic, VasilijeCarbonate looping (CaL) has been shown to be less energy-intensive when compared to mature carbon capture technologies. Further reduction in the efficiency penalties can be achieved by employing a more efficient source of heat for the calcination process, instead of oxy-fuel combustion. In this study, a kW-scale solid oxide fuel cell (SOFC)-integrated calciner was designed and developed to evaluate the technical feasibility of simultaneously generating power and driving the calcination process using the high-grade heat of the anode off-gas. Such a system can be integrated with CaL systems, or employed as a negative-emission technology, where the calcines are used to capture CO2 from the atmosphere. The demonstration unit consisted of a planar SOFC stack, operating at 750 °C, and a combined afterburner/calciner to combust hydrogen slip from the anode off-gas, and thermally decompose magnesite, dolomite, and limestone. The demonstrator generated up to 2 kWel,DC power, achieved a temperature in the range of 530–550 °C at the inlet of the afterburner, and up to 678 °C in the calciner, which was sufficient to demonstrate full calcination of magnesite, and partial calcination of dolomite. However, in order to achieve the temperature required for calcination of limestone, further scale-up and heat integration are needed. These results confirmed technical feasibility of the SOFC-calciner concept for production of calcined materials either for the market or for direct air capture (DAC).Item Open Access Design and performance testing of a monolithic nickel-based SiC catalyst for steam methane reforming(Elsevier, 2023-12-13) Shen, Ziqi; Nabavi, Seyed Ali; Clough, Peter T.Hydrogen is a highly promoted carbon-free energy carrier that has drawn significant attention recently due to its potential to decarbonise energy sector. More than three-quarters of hydrogen is currently produced via steam methane reforming (SMR), and nickel-based catalysts are used in most applications. Structured catalysts have been reported to be able to further improve catalyst performance as they can optimise heat and mass transfer, as well as prevent coke formation with its structural and textural proprieties. Silicon carbide (SiC) has excellent hardness, thermal conductivity, and chemical inertness, therefore is a promising material to develop structured nickel-based monolithic SiC catalysts for SMR. In this work, a structured monolithic catalyst support has been formed by a modified freeze-gelation method, initially starting from SiC powder, and nickel has been distributed to form a monolithic nickel-based catalyst by wet impregnation. The results showed that the catalysts can achieve thermodynamic equilibrium at 600 °C with a gas hourly space velocity (GHSV) of 10,000 h−1, while reaching a high methane conversion of 86% at 800 °C and GHSV value of 20,000 h−1 during the performance tests using low feeding concentration and low pressure. This is the first time SiC catalytic materials have had their performance demonstrated for SMR under realistic operating conditions.Item Open Access Direct numerical simulation of packed and monolith syngas catalytic combustors for micro electrical mechanical systems(Elsevier, 2023-08-19) Bazooyar, Bahamin; Zhu, Mingming; Manovic, Vasilije; Nabavi, Seyed AliIn this work, a catalytic combustor for micro electrical mechanical system for syngas was designed and analysed using Direct Numerical Simulation (DNS) in conjunction with finite rate chemistry. The effect of catalyst (platinum (Pt), palladium (Pd), palladium oxide (PdO), and rhodium (Rh)), bed type (packed with twelve catalyst shapes and four catalyst monolith), shapes (packed: cylinder, hollow cylinder, four cylinder, single cylinder, single cylinder, cross-webb, grooved, pall-ring, hexagonal, berl-saddle, cube, intalox-saddle, and sphere, monolith: triangular, rectangular, hexagonal, and circular), and operating conditions (inlet temperature and velocity, fuel/air ratio, different concentrations CH4-H2-CO) on combustion efficiency and pressure drop were studied using different parameters (combustion efficiency (η), pressure drop, effectiveness factor (Ψ), and fuel conversions (H2 and CH4 conversions)). Analysis under different operating conditions reveals that the designed combustor can operate effectively with syngas of varying compositions with a high combustion efficiency of over 85%. Combustion mainly takes place on the surface of the catalyst without gas phase reaction with pressure drops between 18 Pa and 155 Pa. The intalox saddle shape catalysts resulted in the bed effectiveness factor 0.93.1 The Damköhler for hydroxyl radicals (OH) over the entire length of the reactor is uniformly distributed and well below 3, suggesting uniform combustion.Item Open Access Divergent consumer preferences and visions for cooking and heating technologies in the United Kingdom: make our homes clean, safe, warm and smart!(Elsevier, 2023-08-12) Gordon, Joel A.; Balta-Ozkan, Nazmiye; Nabavi, Seyed AliDecarbonising the global housing stock is imperative for reaching climate change targets. In the United Kingdom, hydrogen is currently being tested as a replacement fuel for natural gas, which could be used to supply low-carbon energy to parts of the country. Transitioning the residential sector towards a net-zero future will call for an inclusive understanding of consumer preferences for emerging technologies. In response, this paper explores consumer attitudes towards domestic cooking and heating technologies, and energy appliances of the future, which could include a role for hydrogen hobs and boilers in UK homes. To access qualitative evidence on this topic, we conducted ten online focus groups (N = 58) with members of the UK public between February and April 2022. The study finds that existing gas users wish to preserve the best features of gas cooking, such as speed, responsiveness and controllability, but also desire the potential safety and aesthetic benefits of electric systems, principally induction hobs. Meanwhile, future heating systems should ensure thermal comfort, ease of use, energy efficiency and smart performance, while providing space savings and noise reduction, alongside demonstrable green benefits. Mixed-methods multigroup analysis suggests divergence between support levels for hydrogen homes, which implies a degree of consumer heterogeneity. Foremost, we find that domestic hydrogen acceptance is positively associated with interest and engagement with renewable energy and fuel poverty pressures. We conclude that internalising the perspectives of consumers is critical to enabling constructive socio-technical imaginaries for low-carbon domestic energy futures.Item Open Access Double emulsion production in glass capillary microfluidic device: parametric investigation of droplet generation behaviour(Elsevier, 2015-03-20) Nabavi, Seyed Ali; Vladisavljević, G. T.; Gu, Sai; Ekanem, E. E.A three-phase axisymmetric numerical model based on Volume of Fluid–Continuum Surface Force (VOF–CSF) model was developed to perform parametric analysis of compound droplet production in three-phase glass capillary devices that combine co-flow and countercurrent flow focusing. The model predicted successfully generation of core–shell and multi-cored double emulsion droplets in dripping and jetting (narrowing and widening) regime and was used to investigate the effects of phase flow rates, fluid properties, and geometry on the size, morphology, and production rate of droplets. As the outer fluid flow rate increased, the size of compound droplets was reduced until a dripping-to-jetting transition occurred. By increasing the middle fluid flow rate, the size of compound droplets increased, which led to a widening jetting regime. The jetting was supressed by increasing the orifice size in the collection capillary or increasing the interfacial tension at the outer interface up to 0.06 N/m. The experimental and simulation results can be used to encapsulate CO2 solvents within gas-permeable microcapsules.Item Open Access Dynamics of double emulsion break-up in three phase glass capillary microfluidic devices(Elsevier, 2015-03-13) Nabavi, Seyed Ali; Gu, Sai; Vladisavljević, G. T.; Ekanem, E. E.Pinch-off of a compound jet in 3D glass capillary microfluidic device, which combines co-flowing and countercurrent flow focusing geometries, was investigated using an incompressible three-phase axisymmetric Volume of Fluid–Continuum Surface Force (VOF–CSF) numerical model. The model showed good agreement with the experimental drop generation and was capable of predicting formation of core/shell droplets in dripping, narrowing jetting and widening jetting regimes. In dripping and widening jetting regimes, the presence of a vortex flow around the upstream end of the necking thread facilitates the jet break-up. No vortex flow was observed in narrowing jetting regime and pinch-off occurred due to higher velocity at the downstream end of the coaxial thread compared to that at the upstream end. In all regimes, the inner jet ruptured before the outer jet, preventing a leakage of the inner drop into the outer fluid. The necking region moves at the maximum speed in the narrowing jetting regime, due to the highest level of shear at the outer surface of the thread. However, in widening jetting regime, the neck travels the longest distance downstream before it breaks.Item Open Access Eco-friendly fabrication of highly selective amide-based polymer for CO2 capture(American Chemical Society, 2019-09-05) Fayemiwo, Kehinde; Chiarasumran, Nutchapon; Nabavi, Seyed Ali; Loponov, Konstantin N.; Manovic, Vasilije; Benyahia, Brahim; Vladisavljevic, Goran T.Porous polymeric adsorbents for CO2 capture (HCP-MAAMs) were fabricated by co-polymerisation of methacrylamide (MAAM) and ethylene glycol dimethacrylate (EGDMA) using acetonitrile and azobisisobutyronitrile as a porogen and initiator, respectively. The X-ray photoelectron and Fourier transform infrared spectra revealed a high density of amide groups in the polymer matrix of HCP-MAAMs, which enabled high selectivity to CO2. The polymers BET surface area and total pore volume was up to 277 m2 g-1 and 0.91 cm3 g-1, respectively. The highest CO2 uptake at 273 K and 1 bar CO2 pressure was 1.45 mmol g-1 and the heat of adsorption was 27-35 kJ mol-1. The polymer with the lowest crosslinking density exhibited unprecedented CO2/N2 selectivity of 394 at 273 K. Life cycle assessment revealed a lower environmental impact of HCP-MAAMs compared to molecularly imprinted polymers. HCP-MAAMs are eco-friendly CO2 adsorbents owing to their low regeneration energy, environmentally benign fabrication process, and high selectivity.Item Open Access Effect of combined primary and secondary amine loadings on the adsorption mechanism of CO2 and CH4 in biogas(Elsevier, 2021-05-12) Wadi, Basil; Golmakani, Ayub; Manovic, Vasilije; Nabavi, Seyed AliBiomethane, produced by biogas upgrading, is a promising energy source that can play a key role towards net-zero emissions targets. The incorporation of amine functionalities into adsorbents for biogas upgrading can facilitate the selective adsorption of CO2, but their effect has not been comprehensively studied within the context of CH4 mixtures. In this work, the effectiveness of amine functionalities in selectively separating CO2 from biogas, is investigated. Primary, diamine, and triamine organo-silanes grafted at various loadings on SBA-15 were used to study the adsorption mechanisms associated with amine functionalities for CO2:CH4 gas mixtures. The successful incorporation of amines was confirmed with thermogravimetric analysis (TGA), Fourier Transform Infrared (FTIR), and elemental analysis (EA). The different amine reagents and loadings resulted in an alteration of adsorption mechanism that provided key information on the developing relationship between adsorption capacity, selectivity, and energy efficiency. Diamine with an amine loading of 2.5 mmol/g and a moderate silane coverage of 1.54 molecules/nm2 was found to provide the best balance of an enhanced CO2 adsorption capacity (1.12 mmol/g), a superior selectivity to densely grafted primary amines, and the lowest isosteric heat of adsorption of ∼25 kJ/mol at 1.12 mmol/g compared to ∼41 kJ/mol for primary and triamine materials. Amongst all the samples, a lower amine loading on the bare adsorbent enhanced CO2 adsorption capacity and selectivity while minimising the heat duty associated with adsorbent regeneration. Moreover, under isothermal desorption conditions at 25 °C, some samples achieved working capacities comparable to higher amine loaded materialsItem Open Access Effect of impurities on ultra-pure hydrogen production by pressure vacuum swing adsorption(Elsevier, 2019-10-29) Golmakani, Ayub; Nabavi, Seyed Ali; Manovic, VasilijeThe most viable technology for production of ultra-pure hydrogen (>99.99%), required for fuel cells, is steam methane reforming (SMR) coupled with pressure vacuum swing adsorption (PVSA). A PVSA process with a two-layer bed of activated carbon (AC)/zeolite 5A for ultra-pure hydrogen production from syngas was developed and simulated with the aim of exploring the effect of impurities on energy intensity of the process. The simulated concentration profiles showed that CH4 was removed by first half of the AC layer, CO2 and CO were mostly removed by the end of that layer, but zeolite 5A (the second layer) could not completely remove the remaining N2. Further, the effect of the N2 on performance of the PVSA process was demonstrated by simulating purification of two feeds with 3.1 and 1.1 vol% N2, respectively. The 2% drop in N2 concentration in the syngas feed resulted in decreased energy consumption of the PVSA process from 940 kJ/kg to 430 kJ/kg H2, while H2 recovery increased from 47% to 55%. Therefore, the presence of N2 has a very large impact on recovery and energy intensity of the ultra-pure hydrogen production process, and development of adsorbents with better N2 removal performances is required.Item Open Access Evaluation of moderately grafted primary, diamine, and triamine sorbents for CO2 adsorption from ambient air: balancing kinetics and capacity under humid conditions(American Chemical Society, 2021-08-30) Wadi, Basil; Golmakani, Ayub; Manovic, Vasilije; Nabavi, Seyed AliSuccessful deployment of direct air capture (DAC) to mitigate the consequences of climate change depends on many factors, one of which is the development of kinetically efficient CO2 sorbents with a high sorption capacity, at ultralow CO2 concentrations. This work evaluated CO2 adsorption performance of primary-, diamine-, and triamine-grafted SBA-15 at pressures below 5 kPa for DAC applications, measured through volumetric sorption, followed by humid air (23% RH) adsorption by gravimetric analysis. Under humid air flow, triamines at an amine loading of 4.6 mmol/g showed the highest enhancement in adsorption, with an uptake of 26 mg/g, but the slowest average adsorption rate of 216 μg/g/min. Diamine at an amine loading of 2.78 mmol/g had an adsorption rate of 295 μg/g/min but demonstrated the lowest uptake of 13 mg/g. In comparison, primary amines at a loading of 2.6 mmol/g reached an equilibrium uptake of 22 mg/g, with a higher adsorption rate of 354 μg/g/min. Triamine grafted at 3.5 mmol/g had the fastest kinetics of all samples, reaching 525 μg/g/min. Results indicated that primary amines and moderate-to-high density triamine reagents incorporated into mesoporous media can offer a superior adsorption rate that can make up for lower adsorption capacities, by optimizing cyclic performance, and should be considered when designing for continuous DAC processes.Item Open Access Exploring the contours of consumer heterogeneity: towards a typology of domestic hydrogen acceptance(Elsevier, 2024-01-11) Gordon, Joel A.; Balta-Ozkan, Nazmiye; Nabavi, Seyed AliHydrogen energy technologies are anticipated to play a fundamental role in securing a decarbonised energy future. While the deployment of low-carbon hydrogen energy systems remains nascent and is subject to a range of techno-economic constraints, potential scalability will also hinge on social acceptance. In response, this study draws on extensive national survey data to derive a comprehensive typology of domestic acceptance, which reflects multiple factors influencing consumer attitudes towards low-carbon hydrogen heating and cooking appliances. The proposed typology is developed through rigorous coding of over 1000 qualitative statements, leading to 12 core acceptance factors composed of a mix of positive, neutral, and negative sub-factors. The study finds that eight primary sub-factors account for close to 60 % of identified codes, with knowledge deficit (negative), environmental benefits (positive), and financial risks (negative) ranking highest. Critically, these three sub-factors are also the most statistically significant predictors of consumer heterogeneity. At the sub-group level, the analysis shows that engagement with renewable energy technology and climate change is associated with stronger perceptions of environmental benefits and lower financial concerns. By contrast, perceived financial risks and concerns over energy injustice constrain acceptance levels among fuel stressed respondents. Through mixed-methods analysis, the study transmits the value of advancing acceptance typologies as a critical mechanism for enacting a ‘just’ hydrogen economy. The analysis supports developing strategic measures which account for consumer heterogeneity to better support socially acceptable pathways for residential decarbonisation.Item Open Access Formulation, adsorption performance, and mechanical integrity of triamine grafted binder-based mesoporous silica pellets for CO2 capture(Elsevier, 2021-07-16) Wadi, Basil; Mahomed, Anisa; Bai, Yang; Osatiashtiani, Amin; Manovic, Vasilije; Nabavi, Seyed AliThis work explored formulation of mesoporous silicas pellets using a range of bentonite and colloidal silica (LUDOX), aiming to optimise the binder composition that minimises any deteriorating effects on adsorption performance, while provides an adequate mechanical integrity. Thermogravimetric analysis, scanning electron microscopy, and dynamic mechanical analysis were used to structurally characterise the pellets. Furtherer, CO2 adsorption isotherms of synthesised pellets, pre and post triamine grafting, were measured. Bentonite was found to be an effective single binder that forms mechanically strong pellets and retains up to 85% of CO2 capacity of the base adsorbent. At the presence of LUDOX, hardness of the pellets was lower, caused the largest decrease in CO2 capacity. Formulation with 25% bentonite was found to provide pellets with post triamine functionalisation CO2 capacity equivalent to powder SBA-15, at an amine efficiency of 0.41 mol CO2/mol, while minimising pore blockage and maintaining a compressive strength of 1.5 MPa.
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