Effect Of CH4 Research Articles

Effect of CH4 on plasma spheroidization of tantalum powder

In this work, hydrogenation-dehydrogenation tantalum powder was spheroidized by plasma spheroidization to prepare high purity spherical tantalum powder suitable for use in additive manufacturing. The effects of methane (CH4) in sheath gas on morphology, property and chemical composition of spheroidized tantalum powder were investigated. The spheroidized tantalum powder showed increased spheroidization ratios up to 99.9% by comparison to that of raw powder. Compared to spheroidized tantalum powder obtained in argon (Ar) or Ar + hydrogen atmosphere, a significant reduction in oxygen content from 600 ppm to less than 200 ppm was observed with the addition of CH4. Excessive CH4 addition of 1.5 L/min also caused a sharp increase in carbon content from 250 ppm to 3300 ppm. These findings indicate that the addition of CH4 in spheroidization is an effective way to reduce oxygen content of tantalum powder and expected to be applied to the spheroidization of other powders.

Effects of CH4 and CO on hydrogen embrittlement susceptibility of X80 pipeline steel in hydrogen blended natural gas

The slow strain rate tensile experiments are carried out to investigate the tensile properties of X80 pipeline steel in hydrogen blended natural gas environments with different H2/CH4/CO contents. Mechanical properties and fracture morphologies are further analyzed. The results show that the hydrogen embrittlement susceptibility of X80 steel can be inhibited by the presence of CH4/CO, and the inhibition mechanisms are discussed. When the CH4 contents increase above 20 vol%, the inhibition on hydrogen embrittlement of X80 steel is stabilized. By comparison, the inhibitory effect of CO is more significant.

Effect of CH4, H2, Ar, Carbon Additives and the Shape of a Reactor on the Porous Structure of Acetylene Black Formed During the Decomposition of Acetylene

Effect of CH4, H2, Ar, Carbon Additives and the Shape of a Reactor on the Porous Structure of Acetylene Black Formed During the Decomposition of Acetylene

Non-thermal plasma assisted catalytic thiophene removal from fuel under different atmospheres

Hydrodesulfurization is one of the most critical processes in the petroleum industry to increase the quality and economic value of crude oil. However, this process consumes a great amount of expensive hydrogen to convert sulfur-species to H2S, which causes a series of critical environmental issues. Herein, we report a novel method of non-thermal plasma assisted catalytic desulfurization of crude oil, while commonly used hydrogen is replaced with low-priced methane. As one of the most common sulfur-containing species in petroleum, thiophene is selected as the model compound in this study. It is proved that non-thermal plasma could effectively convert thiophene with a conversion higher than 90%, while thiophene is mostly converted into the solid deposit. Also, the H2S emission is well-controlled over a carefully designed Sn–Ga/SBA-15 catalyst. In a 12 h long-term experiment, the reactor still exhibits excellent desulfurization performance and low H2S emission during the whole test. Several control experiments are performed under N2 or H2 for comparison. Among all these atmospheres, N2 shows the best performance in terms of thiophene conversion and H2S emission minimization. The effect of CH4 and H2 incorporation is also investigated. As the product with the highest proportion, the composition of solid deposit is carefully analyzed, and a novel method of O2-plasma oxidation is tested to in-situ remove solid deposit over catalyst surface and reactor. In general, this research explores an economical and environmental-friendly alternative for the desulfurization of crude oil.

Feasible coupling of CH4/H2 mixtures to H2 storage in liquid organic hydrogen carrier systems

The cheap CH4-containing hydrogen mixtures are available in petrochemical industry and nevertheless, their usage is limited because of economic issue. We herein demonstrate the impacts of CH4 fraction (fCH4) in CH4/H2 mixtures on the essential steps for liquid organic hydrogen carrier (LOHC) systems. In the preparation of Ru/Al2O3 catalysts by thermolysis in CH4/H2 mixtures, the fCH4 affects the content of carbon formed by methane decomposition but not the size of Ru nanoparticles, indicating that it should be avoided to use a CH4/H2 mixture with the fCH4 of higher than 30%. When CH4/H2 mixtures are used for the hydrogenation of monobenzyltoluene, the higher fCH4 reduces the catalytic activity, particularly at high temperatures and H2 partial pressures because of competitive adsorption of CH4 and H2 on the Ru surface. Such an effect of CH4 is lessened under mild conditions, which is confirmed by the experiments using the same CH4/H2 mixture for both catalyst preparation and hydrogenation reaction. Therefore, it is feasible to use the CH4/H2 mixture of up to 30% fCH4 for the preparation of Ru/Al2O3 and for stable H2 storage performance at lower temperatures and H2 partial pressures, thus enabling to couple the CH4/H2 mixture to LOHC systems.

Methane-rich water induces bulblet formation of scale cuttings in Lilium davidii var. unicolor by regulating the signal transduction of phytohormones and their levels.

Previous studies have shown that methane (CH4 ) has promoting roles in the adventitious root (AR) and lateral root (LR) formation in plants. However, whether CH4 could trigger the bulblet formation in scale cutting of Lilium davidii var. unicolor has not been elucidated. To gain insight into the effect of CH4 on the bulblet formation, different concentrations (1, 10, 50, and 100%) of methane-rich water (MRW) and distilled water were applied to treat the scale cuttings of Lilium. We observed that treatment with 100% MRW obviously induced the bulblet formation in scale cuttings. To explore the mechanism of CH4 -induced bulblet formation, the transcriptome of scales was analyzed. A total of 2078 differentially expressed genes (DEGs) were identified. The DEGs were classified into different metabolic pathways, especially phenylpropanoid biosynthesis, starch and sucrose metabolism, and plant signal transduction. Of these, approximately 38 candidate DEGs involved in the plant signal transduction were further studied. In addition, the expression of AP2-ERF/ERF, WRKY, GRAS, ARF, and NAC transcription factors (TFs) was changed by MRW treatment, suggesting their potential involvement in bulblet formation. As for hormones, exogenous IAA, GA, and ABA could induce the bulblet formation. Additional experiments suggested that MRW could increase the endogenous IAA, GA, and JA levels, but decrease the levels of ABA during bulblet formation, which showed that higher IAA, GA, JA levels and lower ABA content might facilitate bulblet formation. In addition, the levels of endogenous hormones were consistent with the expression level of genes involved in phytohormone signal transduction. Overall, this study has revealed that CH4 might improve the bulblet formation of cutting scales in Lilium by regulating the expression of genes related to phytohormone signal transduction and TFs, as well as by changing the endogenous hormone levels.

Invited Review: Methane sources, quantification, and mitigation in grazing beef systems

ABSTRACT Purpose The purpose of the review was to examine enteric methane emissions, quantification methods, and mitigation strategies in grazing beef systems. Sources Peer-reviewed literature and conference abstracts were the main sources of information for this review. Synthesis Methane emissions (CH4) can be reduced by improving forage quality by including more cool-season forages and legumes and rotationally grazing animals. Including forages with beneficial secondary compounds such as condensed tannins and saponins also has CH4-mitigation potential. Providing nutritional supplements that improve the nutritional status of the animal and the efficiency of feed energy use has the potential to reduce CH4 emissions from grazing cattle. Genetic selection has shown some viability in reducing herd emissions, but heritability estimates are low for CH4 yield. More research is needed to understand the potential. Soil methanotrophy may partially offset CH4 emissions when animals are stocked moderately but soil CH4 uptake rates are relatively low in most grazing ecosystems. A new metric to quantify the global warming potential of CH4, GWP*, may allow future models to more appropriately consider the behavior and effects of CH4 in the atmosphere. Conclusions and Applications Methane mitigation strategies in grazing environments are limited, but producer decisions that improve the nutritional status of animals, the quality of the forage base, and supplementation of known CH4-mitigation compounds can reduce CH4 production. Now that less expensive, easier to use quantification tools exist, researchers need to conduct more long-term monitoring experiments and focus on reducing CH4 production of grazing animals where potential for reduction is largest.

Effect of Combustible Gas Components on SNCR Reaction with Reducing Agent in Ceramic Kiln

Selective non-catalytic reduction (SNCR) is a denitration method used in NOx process-control of ceramic kiln. In this study, the effect of combustion gas components (CO, H2, CH4) on NOx removal in the SNCR process was investigated, using ammonia and urea as reducing agent in a lab-scale experimental platform. The results showed that the addition of CO slightly promoted the NOx removal efficiency when ammonia was used as reducing agent, while when urea was used as reducing agent, the addition of CO inhibited the denitrification. The increase of H2 and CH4 addition ratio in the simulated flue gas reduced the de-NOx efficiency. With the same addition ratio, the effect of CH4 on the reduction of denitration efficiency was much more obvious than that of H2. When ammonia was used as reducing agent, the ammonia escape was much greater than that of urea.

Hydrogen peroxide is involved in methane-induced tomato lateral root formation.

Pharmacological and molecular evidence reveals a novel role of methane (CH4) gas in root organogenesis, the induction of lateral root (LR) formation, and this response might require hydrogen peroxide (H2O2) synthesis. Although plants can produce CH4 and release this to atmosphere, the beneficial role(s) of CH4 are not fully elucidated. In this study, the fumigation with CH4 not only increased NADPH oxidase activity and H2O2 production, but also induced tomato lateral root primordial formation and thereafter LR development. However, exogenously applied argon and nitrogen failed to influence LR formation. Above responses triggered by CH4 were sensitive to the removal of endogenous H2O2 with dimethylthiourea (DMTU; a membrane-permeable scavenger of H2O2), suggesting the hypothesis that CH4's effect on LR formation could be mediated by endogenous H2O2. Diphenylene iodonium (DPI) inhibition of the H2O2 generating enzyme NADPH oxidase attenuated H2O2 synthesis and impaired LR formation in response to CH4, confirming the requirement of NADPH oxidase-dependent H2O2. Meanwhile, the alterations of endogenous H2O2 concentrations failed to influence CH4 production in tomato seedlings. Molecular evidence revealed that CH4-induced SlCDKA1, SlCYCA2;1, and SlCYCA3;1 transcripts, and -decreased SlKRP2 mRNA were impaired by DMTU or DPI. Contrasting changes in LR formation-related miR390a and miR160 transcripts and their target genes, including SlARF4 and SlARF16, were observed. Together, our pharmacological and molecular evidence suggested the requirement of H2O2 synthesis in CH4-triggered tomato LR formation, partially via the regulation of cell cycle regulatory genes, miRNA-, and tasiRNA-modulated gene expression.

Unconventional Vegetable Oils for a Reduction of Methanogenesis and Modulation of Ruminal Fermentation

The objective of this study was to evaluate the use of vegetable oils from plants grown in Brazil, first using the in vitro batch culture, and then evaluating the oil with methane (CH4) reducing potential in an in vivo experiment. The in vitro experiment was conducted as a completely randomized design using the seven contrasting oils. Treatments consisted of a control and 3 increasing concentrations (0, 1, 2, and 5% v/v) of oil added to a tifton 85 hay samples. All vegetable oils linearly decreased (P < 0.01) gas production after 24 h of incubation, with the greatest reduction when 5% of oil was included into the diet. Açaí and buriti had no effect of CH4 (% or mL/g DM incubated) however carrot, macaúba, basil, passionflower, and pequi oil all linearly decreased (P < 0.01) CH4 production with increasing inclusion rate of oil. Pequi oil resulted in the largest decrease in CH4 production (mL/g DM incubated) after 24 h of in vitro incubation. The objective of the in vivo experiment was to evaluate the effects of pequi oil on nutrient digestibility, CH4 production, and rumen fermentation parameters in wethers fed a hay-based diet. The experiment was conducted as a 2 × 2 Latin Square design using 4 Dorper wethers (63.4 ± 1.46 kg body weight). There were 2 experimental periods of 21 d each, with d 1–14 used for diet adaptation and d 15–21 for measurements and collections. The treatments consisted of a control diet and pequi oil fed at 70 g per animal per day. The addition of pequi oil to the diet had no effect on feed intake or the digestibility of nutrients, however there was a numerical decrease in the population of cellulolytic bacteria. There was a tendency (P = 0.06) for pequi oil addition to decrease CH4 production (g/d) by 17.5%. From this study, we can conclude that pequi oil may be used as a suitable oil for reducing CH4 production from ruminants, with no negative effects on intake or digestibility.

Large impacts of small methane fluxes on carbon isotope values of soil respiration

Carbon dioxide isotope (δ13C of CO2) analysis is increasingly used to address a broad range of questions involving soil C dynamics and respiration sources. However, attaining δ13C mass balance is critical for robust interpretation. Many ecosystems exhibit methane (CH4) fluxes that are small in the context of total C budgets, yet may significantly impact δ13C values of CO2 due to large kinetic fractionations during CH4 production. Thus, the δ13C values of CO2 do not directly reflect respiration C sources when co-occurring with CH4, but few studies of terrestrial soils have considered this phenomenon. To assess how CH4 altered the interpretation of δ13C values of CO2, we incubated a Mollisol and Oxisol amended with C4-derived plant litter for 90 days under two headspace treatments: a fluctuating anaerobic/aerobic treatment (four days of anaerobic conditions alternating with four days of aerobic conditions), and a static aerobic treatment (control). We measured δ13C values of CO2 and CH4 with a tunable diode laser absorption spectrometer, using a novel in-line combustion method for CH4. Cumulative δ13C of CO2 differed significantly between treatments in both soils. The δ13C values of CO2 were affected by relatively small CH4 fluxes in the fluctuating anaerobic/aerobic treatment. Effects of CH4 on δ13C values of CO2 were greater in the Oxisol due to its higher percent contribution of CH4 to total C mineralization (18%) than in the Mollisol (3%) during periods of elevated CH4 production. When CH4 accounted for just 2% of total C mineralization, the δ13C values of CO2 differed from total C mineralization by 0.3–1‰, and by 1.4–4.8‰ when CH4 was 10% of C mineralization. These differences are highly significant when interpreting natural abundance δ13C data. Small CH4 fluxes may strongly alter the δ13C values of CO2 relative to total mineralized C. A broad range of mineral and peatland soils can experience temporary oxygen deficits. In these dynamic redox environments, the δ13C values of CO2 should be interpreted with caution and ideally combined with δ13C of CH4 when partitioning sources and mechanisms of soil respiration.

The Effect of CH4 on NH3-SCR Over Metal-Promoted Zeolite Catalysts for Lean-Burn Natural Gas Vehicles

We present a systematic investigation of the deNOx activity of two commercial metal exchanged zeolite NH3-SCR catalysts, a Cu-SAPO and a Fe-BEA, in view of their application to the exhaust after-treatment systems of lean-burn natural gas vehicles. The catalytic activity data collected under realistic operating conditions, representative of the after-treatment system of lean-burn vehicles, were compared to those obtained adding methane to the gas feed stream in order to assess the impact of this hydrocarbon, which is usually emitted from natural gas engines, on the NH3-SCR catalytic chemistry. Our results indicate a negligible impact of methane on the SCR activity at all conditions, but in the presence of a large excess of NO2 at T > 400 °C due to methane oxidation by NO2. The data collected over the two individual metal-promoted zeolites were also compared with those obtained combining both catalysts in sequential arrangements, in order to take advantage of their complementary high activities in different temperature ranges. The Fe-zeolite + Cu-zeolite sequence outperformed the two individual components in terms of both overall deNOx efficiency and N2O selectivity, and was equally insensitive to methane.

Biogas steam reformer for hydrogen production: Evaluation of the reformer prototype and catalysts

This work aims to investigate a biogas steam reforming prototype performance for hydrogen production by mass spectrometry and gas chromatography analyses of catalysts and products of the reform. It was found that 7.4% Ni/NiAl2O4/γ-Al2O3 with aluminate layer and 3.1% Ru/γ-Al2O3 were effective as catalysts, given that they showed high CH4 conversion, CO and H2 selectivity, resistance to carbon deposition, and low activity loss. The effect of CH4:CO2 ratio revealed that both catalysts have the same behavior. An increase in CO2 concentration resulted in a decrease in H2/CO ratio from 2.9 to 2.4 for the Ni catalyst at 850 °C, and from 3 to 2.4 for the Ru catalyst at 700 °C. In conclusion, optimal performance has been achieved in a CH4:CO2 ratio of 1.5:1. H2 yield was 60% for both catalysts at their respective operating temperature. Prototype dimensions and catalysts preparation and characterization are also presented.

Effect of CH4 on the CO2 breakthrough pressure and permeability of partially saturated low-permeability sandstone in the Ordos Basin, China

The behavior of CO2 that coexists with CH4 and the effect of CH4 on the CO2 stream need to be deeply analyzed and studied, especially in the presence of water. Our previous studies investigated the breakthrough pressure and permeability of pure CO2 in five partially saturated low-permeability sandstone core samples from the Ordos Basin, and we concluded that rocks with a small pore size and low permeability show considerable sealing capacity even under unsaturated conditions. In this paper, we selected three of these samples for CO2-CH4 gas-mixture breakthrough experiments under various degrees of water saturation. The breakthrough experiments were performed by increasing the gas pressure step by step until breakthrough occurred. Then, the effluent gas mixture was collected for chromatographic partitioning analysis. The results indicate that CH4 significantly affects the breakthrough pressure and permeability of CO2. The presence of CH4 in the gas mixture increases the interfacial tension and, thus, the breakthrough pressure. Therefore, the injected gas mixture that contains the highest (lowest) mole fraction of CH4 results in the largest (smallest) breakthrough pressure. The permeability of the gas mixture is greater than that for pure CO2 because of CH4, and the effective permeability decreases with increased breakthrough pressure. Chromatographic partitioning of the effluent mixture gases indicates that CH4 breaks through ahead of CO2 as a result of its weaker solubility in water. Correlations are established between (1) the breakthrough pressure and water saturation, (2) the effective permeability and water saturation, (3) the breakthrough pressure and effective permeability, and (4) the mole fraction of CO2/CH4 in the effluent mixture gases and water saturation. These results deepen our understanding of the multi-phase flow behavior in the porous media under unsaturated conditions, which have implications for formulating emergency response plans for gas leakage into unsaturated zones. Finally, knowing the flow characteristic of gas mixture can guide CO2 storage, CO2-EOR and CO2-ECBM projects. Future studies should pay attention to the effects of saline water with different salt types and concentrations on the multi-phase flow behavior with applications to geological CO2 storage and energy storage using CH4.

The Effect of CH4 on Life Span and Nosema Infection Rate in Honeybees, Apis mellifera L.

Greenhouse gas (GHG), as a cause of climate change, is considered as one of the biggest problems society is currently facing. We carried out the effect of CH4 on the llife span of adult honeybee, Apis mellifera, and Nosema ceranae infection. Adult worker bees exposed at CH4 2ppm, 20ppm, 200ppm. Survival rates was significantly decreased after 10days and worker bees survived for 31days. Nosema infection rate of bees and mortality are independent of each other. No significant differences found in infection rate between CH4 concentrations. Interaction between a variety of climate change factor and diseases should be needed a wide rage of research.

Quantitative LIF measurements and kinetics assessment of NO formation in H2/CO syngas–air counterflow diffusion flames

Quantitative non-intrusive measurements of NO species using the Laser Induced Fluorescence technique are reported in laminar counterflow syngas–air diffusion flames for a wide range of strain rates and as a function of fuel composition (i.e. H2/CO ratio). The local strain rate of the flames was varied from 35s−1 to 750s−1 for three compositions of syngas (1:4, 1:1 and 4:1 H2/CO ratio). Numerical simulations corresponding to the experimental conditions were conducted using OPPDIF with six H2/CO chemical kinetic mechanisms from the literature. The peak [NO] predictions by mechanism M3 (GRIMech. 3.0) were found to be closest to measurements at low strain rates, while predictions using M1 (partial C1 mechanism by Li et al.) and M4 (full C1 mechanism by Li et al.) mechanisms improved at higher strain rates. A Quantitative Reaction Path Diagram (QRPD) analysis showed that mechanism M3 (GRIMech 3.0) predicted a shift from the NNH (dinitrogen monohydride) and prompt NO pathways towards NNH pathway contributing to NO formation with increasing strain rates. Mechanism M6 (Konnov 0.6) predicted significant prompt-NO contributions via an alternate CNN pathway in addition to the NNH pathway at low as well as high strain rates. Unlike M3 and M6, the M1 mechanism consistently predicted the NNH pathway to be the sole major route for NO formation across all strain rates. The N2O intermediate pathway was found to be insignificant for most of the flames. The sensitivity analysis concerning the effect of CH4 on NO formation routes indicated the need to include CH chemistry in the mechanisms, so as to model the NO formation accurately for H2/CO mixtures containing even trace amounts of hydrocarbons. Lastly, the NO emission indices (EINO) are reported as a function of strain rates for the three compositions of syngas showing 32%H2:8%CO case resulting in the lowest NO emissions and fuel consumption per unit power output.

Effects of CH4 and CO2 on the sulfidization of goethite and magnetite: an in situ Raman spectroscopic study in high-pressure capillary optical cells at room temperature

Reactions of goethite and magnetite with sulfide solutions under CH4 and/or CO2 atmospheres were monitored in situ with Raman spectroscopy in the high-pressure capillary optical cells (HPOCs) at room temperature. Isolated systems were created in the enclosed HPOCs for the study of the mineral-solution interactions to prevent oxidation during the experiments. We observed that iron (oxyhydr)oxide minerals were inert to sulfide solution under CH4 atmosphere, and that the addition of CO2 to this system triggered the sulfidization reactions and produced iron monosulfide; mackinawite was identified in the solid phase immersed in the solution after six hours and pyrrhotite in the solid phase exposed to the vapor phase after 5 days. Mackinawite formed in the aqueous phase was metastable, and dissolved after about 10 days. The observed sulfidization of iron (oxyhydr)oxide minerals was through a replacement reaction rather than a dissolution-precipitation process.

Higher Hydrocarbon Production through Oxidative Coupling of Methane Combined with Hydrogenation of Carbon Oxides

AbstractIn the production of higher hydrocarbons, combining oxidative coupling of methane (OCM) with hydrogenation of the formed carbon oxides in a separate reactor provides an alternative to the currently applied methane conversion to syngas followed by Fischer‐Tropsch synthesis. The effects of CH4:O2 feed ratio in the OCM reactor and partial pressures of H2 or/and H2O in the hydrogenation reactor were analyzed to maximize production of C2+ hydrocarbons and reduce COx formation. The highest C2+ yield was achieved with low CH4:O2 feed ratio for OCM and removal of the formed water before entering the hydrogenation reactor.

Effects of CH4, H2 and CO2 Mixtures on SI Gas Engine

Performance of a four-stroke spark ignition gas engine operated on mixtures of CH4, H2 and CO2 was studied. Experiments were carried out at a constant engine speed of 2,000rpm and throttle opening of 14% with various equivalence ratios. The results showed that the highest brake power output of 12.5kW and 35% thermal efficiency were achieved when operated with the mixture of 69.70% CH4, 9.95% H2 and 20.45% CO2 and the equivalence ratios between 1.0 and 0.82.

CH4 and CO2 partial pressures influence and deactivation study on the Catalytic Decomposition of Biogas over a Ni catalyst

A conceptually similar approach to dry reforming of CH4 (DRM) called Catalytic Decomposition of Biogas (CDB) is proposed. CDB is based on the direct decomposition of CH4 and CO2, which are the most abundant components in biogas (typically with CH4:CO2 molar ratios higher than 1). The main difference between DRM and CDB lies in the desired products obtained in each process. While in DRM carbon formation is not desired and thus avoided, in CDB carbon accumulation in form of filamentous structures is promoted. In this work, the effect of CH4 and CO2 partial pressures on the initial reaction rates of CDB was studied using a Ni/Al2O3 catalyst. Furthermore, a deactivation study was carried out in order to determine the experimental conditions (CH4 and CO2 partial pressures and temperature) at which carbon formation did not deactivate the catalyst. It was proved that after a certain time on stream, CDB can reach the steady state even though the CH4:CO2 molar ratio is higher than one (typical biogas conditions). In addition, temperature increased reaction rates since CDB is an endothermic process, but it had no effect on catalyst deactivation.