Use of nanoporous ceramic membranes for carbon dioxide separation

Natural gas processes accounts for about 5.3 billion tonnes per year of carbon dioxide (CO2) emission to the atmosphere. At this rate of emission, the expectation will drastically rise if not curtailed. In order to achieve this, a cost-effective and environmental friendly technology is required. In recent times, membrane technology has been widely applied for CO2 removal from raw natural gas components. This article examines CO2 separation from natural gas, mainly methane (CH4), through a mesoporous composite membrane. A laboratory scale tubular silica membrane with a permeable length of 348 mm, I.D and O.D of 7 and 10 mm, respectively, was used in this experiment. Scanning electron microscopy (SEM) was used to analyze the morphology of the membrane. Single gas permeation of helium (He), CH4, nitrogen (N2), argon (Ar) and CO2 were determined at permeation temperature range between 25 and 100°C and feed gauge pressure of 0.05 to 5.0 barg. Before silica modification, He recorded the highest flow rate (0.3745 l/min) while CO2 recorded the least flow rate (0.1351 l/min) at 0.4 barg and 25°C. After silica modification, CO2 flow enhances significantly (3.1180 l/min at 1.0 barg) compared to CH4 (2.1200 l/min at the same gauge pressure) due to the influence of surface flow mechanism. Temperature variation described the applicability of Knudsen diffusion for He. A combination of viscous, surface and Knudsen diffusion transport mechanisms were obtained throughout the experiment. Membrane thickness was also calculated to be 2.5 × 10−4 m

Advanced membrane design for improved carbon dioxide capture.

A nano-structure tubular hybrid inorganic membrane capable of stripping carbon dioxide from flue gas stream was designed and tested at laboratory scale to improve compliance to various environmental regulations to cushion the effect of global warming. Single gas separation experiments using silica modified ceramic membrane was carried out to investigate individual gas permeation behaviors at different pressures and membrane eficiency after a dip coating method. Four gases; Nitrogen (N2), Carbon dioxide (CO2), Oxygen (O2) and Methane (CH4) were used. Plots of flowrate versus pressure were generated. Results show that the gas flow rate increases with pressure drop. However at above a pressure of 4bar, the flow rate of CO2 was much higher than the other gases, indicating dominance of a more selective adsorptive type transport mechanism

Advanced membrane design for improved carbon dioxide capture.

A nano-structure tubular hybrid inorganic membrane capable of stripping carbon dioxide from flue gas stream was designed and tested at laboratory scale to improve compliance to various environmental regulations to cushion the effect of global warming. Single gas separation experiments using silica modified ceramic membrane was carried out to investigate individual gas permeation behaviors at different pressures and membrane eficiency after a dip coating method. Four gases; Nitrogen (N2), Carbon dioxide (CO2), Oxygen (O2) and Methane (CH4) were used. Plots of flowrate versus pressure were generated. Results show that the gas flow rate increases with pressure drop. However at above a pressure of 4bar, the flow rate of CO2 was much higher than the other gases, indicating dominance of a more selective adsorptive type transport mechanism

Experimental study of gas flux characteristics in a CO2 selective silica based modified membrane.

The purpose of membrane gas separation for CO2 capture from flue gas process is to reduce greenhouse emissions as well as associated environmental challenges globally. This study looks at gas separation in a single gas permeation experiment using CO2, O2, CH4 and N2 gases by means of a highly selective and permeable inorganic ceramic membrane. A fresh ceramic membrane has been prepared by dip-coating technique through immersion in a silica-based precursor solution for pore size modification and used for gas purification purposes. Results obtained show excellent performance of the silica based membrane for CO2 recovery applications through adsorptive transport mechanism. Effect of pressure drop on gas flux showed a linear proportionality. The gas flux has high CO2 flux of 1.71mols-1m-2 at room temperature in comparison to that of other gases. Further results show that CO2 permselectivity to that of N2 supported the theoretical Knudsen with a high selectivity factor of 3.83 confirming a reasonable capture of CO2 to that of N2 as a major component of a flue gas stream.;\\$aCarbon capture; Composite membrane; Gas permeation; Gas flux; Perm selectivit

Purification of gases using nanoporous inorganic membranes.

The application of membranes has gained acceptance in the chemical and process industries for separation and purification for over three decades and is currently being practiced for natural gas processing, waste water treatment among others. A crack-free composite membrane was employed in this paper. Scanning electron microscopy (SEM) observation was carried out to characterize the membrane. The operational parameters such as feed flow rate, permeation pressure, permeation temperature, kinetic diameter and gas molecular characteristics are examined at 25C to 450C and 0.05 to 1.0 barg feed pressure. The performance of gas selectivity is also provided. Separation factor of 2.554 was obtained for H2/CO2 at 450C and 0.8 barg. Activation energies of 1.0 and 0.42 kJ/mol were also obtained for H2 and CO2/CO/H2 gas mixtures at 1.0 barg

Reservoir structural strategies on the integrity of gas mobility ratio.

In this study, four commonly injected EOR gases, CH4, N2, Air, and CO2, have been simultaneously investigated through an experimental method to determine the effect and correlational relevance of 28 structural and 22 fluid quantities to mobility ratio integrity. An experimental method involving five analogous structural strategies has been conducted. A total of 1,920 experimental runs were executed, and 15,360 data points were generated. The results revealed that the mobility ratio is significantly affected by the structural and fluid realities of the EOR process. The mobility integrity for the four gases were correlated to Reservoir Quality and Transmissibility variations the most. Overall the mobilities of the four gases experienced correlational variations for 12 structural parameters. Fourteen of the fluid properties have correlational relevance to CH4 mobility. N2 and CO2 have 11, and Air has 10. The findings from this study can be directly applied in selecting suitable injection gas and screening reservoirs so that the correlational dynamics are favourable to mobility objective and integrity, thereby optimising oil recovery in hetrogeneous reservoirs

Experimental determination of carbon capture and sequestration response to reservoir quantities.

Reservoir entities can be classified into geological, geometrical and fluidic. To complicate matters, reservoirs are usually set in geological layers, such that each layer interacts with injected and resident fluids differently. Carbon dioxide (CO2) is one of the fluids injected in reservoirs. This injection process achieves both economic and environmental benefits. On the one hand, the CO2 injection increases oil production in a process called CO2 Enhanced Oil Recovery (CO2 EOR). On the other hand, it engenders the storage of CO2 in subsurface geological sites to reduce greenhouse gas and mitigate global warming in a process called Carbon Capture and Sequestration (CCS). Consequently, CO2 injection has to effectively couple with these reservoirs entities individually and collectively to achieve CO2 EOR and sequestration optimisations. Other investigators have not properly documented the CO2 sequestration optimisation subject area in light of its response to reservoirs entities. Hence the purpose of this study is to offer information on this area. Rigorous data mining and experimental methods have been applied to characterise and determine CCS response to the petrophysical quantities of reservoirs. The data mining analysis phase indicate that reservoirs’ suitability to CO2 EOR application can be characterised by reservoir petrophysical quantities, such as permeability, porosity, oil viscosity and API gravity. In the experimental phase, five analogous core samples with varying structural quantities were used. The empirical analysis investigated the response of CCS to 20 reservoir quantities. Reservoirs are natural replicas of industrial materials such as nano, ceramics and silicate materials. Although reservoirs are made of sedimentations of sandstones, shale and carbonate, they however, significantly share similar physical property characteristics with the aforementioned industry material. The characterisation of reservoir rock pores size includes nanopores in shale and microspores in sandstone rocks. Similarly, authors characterisation of permeability in reservoir rocks is similar to that of industrial materials such as ceramic membranes. Consequently, these materials can be aptly used to study the carbon capture and sequestration CCS in reservoir rock to a significant degree of accuracy. The series of graphs generated in the course of the investigation show that the relationship between CCS and the petrophysical quantities ranges from linear to higher-order polynomial. The results demonstrated that CCS directly responds to pore size and gas density. CSS inversely responds to the aspect ratio, pore density, specific surface area, and displacement pressure. Furthermore, CCS is found to be responsive to porosity, tortuosity and permeability in the third-order polynomial. The research outcome provides a deeper understanding of CCS optimisation in structurally complicated multilayer reservoirs. The result also provides utility in investigating CCS response to the variability encountered in reservoir systems

Hydrogen transport through dense and porous membranes for fuel cell applications.

In this work the design of a nano structured ceramic membrane is carried out for fuel cell applications. However the innovation is that a membrane porous network is modified through its immersion in silica based solution and in a palladium solution to form composite membrane. Subsequently, the development of hybrid ceramic gas separation membrane elaborates on the recovery of hydrogen from fuel reforming unit for use in fuel cell applications. To enhance the efficiency of the fuel cell, clean hydrogen using membranes with a high permeability and selectivity for H2 over N2 and CO2 are a necessity

Cross-national trends in adolescents psychological and somatic complaints before and after the onset of COVID-19 pandemic

Purpose Building on research suggesting that the COVID-19 pandemic may have led to an exacerbation of deteriorating trends in mental health among adolescents, this paper examined trends in adolescents' psychological and somatic complaints across 35 countries from 2010 to 2022, and tested trends in sociodemographic inequalities in these outcomes between 2018 and 2022. Methods Using data from 792,606 adolescents from 35 countries (51% girls; mean age = 13.5; standard deviation 1.6) across four Health Behaviour in School-aged Children surveys (2010, 2014, 2018, 2022), hierarchical multilevel models estimated cross-national trends in adolescent psychological and somatic complaints. We tested whether observed values in 2022 were in line with predicted values based on 2010–2018 linear trends. Finally, moderation effects of age, family affluence, and family structures on the outcomes were tested (2018–2022). Results Both girls and boys showed substantially higher levels of psychological complaints in 2022 compared with the predicted values. For somatic complaints, higher levels than predicted in 2022 were observed only in girls. Moderation analyses revealed an increase from 2018 to 2022 in age gaps and a narrowing in the socioeconomic gap for both outcomes. Also, there was a widening gap between adolescents living with 2 parents and those living in a single parent household in 2022 compared to 2018. Discussion Cross-national increases in adolescent psychological and somatic complaints were higher than expected in 2022, based on previous trends. Magnitudes of change varied across different sociodemographics groups, with implications for pre-existing mental health inequalities