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Gases, Volume 3, Issue 4 (December 2023) – 5 articles

Cover Story (view full-size image): If ammonia, which is easy to liquefy and store, can be produced and used using nitrogen in the air in connection with the hydrogen value chain, it can be used as a carbon-neutral fuel for a power source of transportation. However, since ammonia has a slow combustion speed, there is a possibility of incomplete combustion and a resulting decrease in efficiency. In addition, nitrogen oxides in the exhaust gas may increase due to the nitrogen atoms contained in the fuel. There are still so many obstacles to overcoming this disadvantage. The use of hydrogen is encouraging with regard to extending the flammability limit of ammonia because hydrogen burns quickly and has a short quench distance. View this paper
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3 pages, 185 KiB  
Editorial
Helium: Sources, Applications, Supply, and Demand
by Juan Sebastian Serra Leal, Jimena Incer-Valverde and Tatiana Morosuk
Gases 2023, 3(4), 181-183; https://doi.org/10.3390/gases3040013 - 6 Dec 2023
Cited by 1 | Viewed by 3166
Abstract
Helium is an inert gas with no color or odor [...] Full article
16 pages, 3884 KiB  
Article
Greenhouse Gas Conversion into Hydrocarbons and Oxygenates Using Low Temperature Barrier Discharge Plasma Combined with Zeolite Catalysts
by Oleg V. Golubev, Dmitry E. Tsaplin and Anton L. Maximov
Gases 2023, 3(4), 165-180; https://doi.org/10.3390/gases3040012 - 5 Dec 2023
Viewed by 1278
Abstract
Global warming occurs as a result of the build-up of greenhouse gases in the atmosphere, causing an increase in Earth’s average temperature. Two major greenhouse gases (CH4 and CO2) can be simultaneously converted into value-added chemicals and fuels thereby decreasing [...] Read more.
Global warming occurs as a result of the build-up of greenhouse gases in the atmosphere, causing an increase in Earth’s average temperature. Two major greenhouse gases (CH4 and CO2) can be simultaneously converted into value-added chemicals and fuels thereby decreasing their negative impact on the climate. In the present work, we used a plasma-catalytic approach for the conversion of methane and carbon dioxide into syngas, hydrocarbons, and oxygenates. For this purpose, CuCe zeolite-containing catalysts were prepared and characterized (low-temperature N2 adsorption, XRF, XRD, CO2-TPD, NH3-TPD, TPR). The process of carbon dioxide methane reforming was conducted in a dielectric barrier discharge under atmospheric pressure and at low temperature (under 120 °C). It was found that under the studied conditions, the major byproducts of CH4 reforming are CO, H2, and C2H6 with the additional formation of methanol and acetone. The application of a ZSM-12 based catalyst was beneficial as the CH4 conversion increased and the total concentration of liquid products was the highest, which is related to the acidic properties of the catalyst. Full article
(This article belongs to the Section Gas Emissions)
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7 pages, 238 KiB  
Opinion
Alternative Gaseous Fuels for Marine Vessels towards Zero-Carbon Emissions
by Cherng-Yuan Lin, Pei-Chi Wu and Hsuan Yang
Gases 2023, 3(4), 158-164; https://doi.org/10.3390/gases3040011 - 17 Nov 2023
Viewed by 2007
Abstract
The maritime industry is recognized as a major pollution source to the environment. The use of low- or zero-carbon marine alternative fuel is a promising measure to reduce emissions of greenhouse gases and toxic pollutants, leading to net-zero carbon emissions by 2050. Hydrogen [...] Read more.
The maritime industry is recognized as a major pollution source to the environment. The use of low- or zero-carbon marine alternative fuel is a promising measure to reduce emissions of greenhouse gases and toxic pollutants, leading to net-zero carbon emissions by 2050. Hydrogen (H2), fuel cells particularly proton exchange membrane fuel cell (PEMFC), and ammonia (NH3) are screened out to be the feasible marine gaseous alternative fuels. Green hydrogen can reduce the highest carbon emission, which might amount to 100% among those 5 types of hydrogen. The main hurdles to the development of H2 as a marine alternative fuel include its robust and energy-consuming cryogenic storage system, highly explosive characteristics, economic transportation issues, etc. It is anticipated that fossil fuel used for 35% of vehicles such as marine vessels, automobiles, or airplanes will be replaced with hydrogen fuel in Europe by 2040. Combustible NH3 can be either burned directly or blended with H2 or CH4 to form fuel mixtures. In addition, ammonia is an excellent H2 carrier to facilitate its production, storage, transportation, and usage. The replacement of promising alternative fuels can move the marine industry toward decarbonization emissions by 2050. Full article
14 pages, 6985 KiB  
Article
Influence of Hydrogen on the Performance and Emissions Characteristics of a Spark Ignition Ammonia Direct Injection Engine
by Cheolwoong Park, Yonghun Jang, Seonyeob Kim, Yongrae Kim and Young Choi
Gases 2023, 3(4), 144-157; https://doi.org/10.3390/gases3040010 - 16 Oct 2023
Cited by 7 | Viewed by 1788
Abstract
Because ammonia is easier to store and transport over long distances than hydrogen, it is a promising research direction as a potential carrier for hydrogen. However, its low ignition and combustion rates pose challenges for running conventional ignition engines solely on ammonia fuel [...] Read more.
Because ammonia is easier to store and transport over long distances than hydrogen, it is a promising research direction as a potential carrier for hydrogen. However, its low ignition and combustion rates pose challenges for running conventional ignition engines solely on ammonia fuel over the entire operational range. In this study, we attempted to identify a stable engine combustion zone using a high-pressure direct injection of ammonia fuel into a 2.5 L spark ignition engine and examined the potential for extending the operational range by adding hydrogen. As it is difficult to secure combustion stability in a low-temperature atmosphere, the experiment was conducted in a sufficiently-warmed atmosphere (90 ± 2.5 °C), and the combustion, emission, and efficiency results under each operating condition were experimentally compared. At 1500 rpm, the addition of 10% hydrogen resulted in a notable 20.26% surge in the maximum torque, reaching 263.5 Nm, in contrast with the case where only ammonia fuel was used. Furthermore, combustion stability was ensured at a torque of 140 Nm by reducing the fuel and air flow rates. Full article
(This article belongs to the Special Issue Gas Emissions from Combustion Sources)
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8 pages, 2041 KiB  
Communication
Effect of Mixing Technique on Physico-Chemical Characteristics of Blended Membranes for Gas Separation
by Danial Qadir, Humbul Suleman and Faizan Ahmad
Gases 2023, 3(4), 136-143; https://doi.org/10.3390/gases3040009 - 26 Sep 2023
Viewed by 1273
Abstract
Polymer blending has attracted considerable attention because of its ability to overcome the permeability–selectivity trade-off in gas separation applications. In this study, polysulfone (PSU)-modified cellulose acetate (CA) membranes were prepared using N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF) using a dry–wet phase inversion technique. [...] Read more.
Polymer blending has attracted considerable attention because of its ability to overcome the permeability–selectivity trade-off in gas separation applications. In this study, polysulfone (PSU)-modified cellulose acetate (CA) membranes were prepared using N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF) using a dry–wet phase inversion technique. The membranes were characterized using scanning electron microscopy (SEM) for morphological analysis, thermogravimetric analysis (TGA) for thermal stability, and Fourier transform infrared spectroscopy (FTIR) to identify the chemical changes on the surface of the membranes. Our analyses confirmed that the mixing method (the route chosen for preparing the casting solution for the blended membranes) significantly influences the morphological and thermal properties of the resultant membranes. The blended membranes exhibited a transition from a finger-like pore structure to a dense substructure in the presence of macrovoids. Similarly, thermal analysis confirmed the improved residual weight (up to 7%) and higher onset degradation temperature (up to 10 °C) of the synthesized membranes. Finally, spectral analysis confirmed that the blending of both polymers was physical only. Full article
(This article belongs to the Special Issue Membrane Processes for Decarbonisation)
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