Methane, Volume 1, Issue 3 (September 2022) – 7 articles

The search for alternatives for converting methane into value-added products has been of great interest to scientific, technological, and industrial society. An alternative to this could be the use of copper-doped palladium catalysts with different proportions supported on metal oxides, such as Sb₂O₅.SnO₂ (ATO) catalysts. These combinations were employed to convert the methane-to-methanol in mild condition using a fuel cell polymer electrolyte reactor. The catalysts prepared presents Pd, CuO, and Sb₂O₅.SnO₂ phases with a mean particle size of about 9 nm. In activity experiments, the Pd₈₀Cu₂₀/ATO indicated maximum power density and maximum rate reaction for methanol production when compared to other PdCu/ATO materials. The use of ATO as a support favored the production of methanol from methane, while PdCu with high copper content demonstrated the production of more oxidized compounds, such as carbonate and formate. Full article

Livestock systems based on subtropical and tropical pastures are characterized by the low productivity of livestock due to the poor nutritional value of the forage (low nitrogen concentration and digestibility, and high fiber and lignin concentrations). These conditions lead to low productivity and, consequently, high absolute emissions of methane (CH₄) per unit of product. Dry distilled grains with solubles (DDGS) are the main by-product resulting from ethanol production, and they are characterized by their high-energy fibrous and protein content, thus becoming an option for the supplementation of low-quality forage. This research investigated the effects of dietary DDGS inclusion on dry matter digestibility (DMD) and enteric CH₄ emission. Eight adult sheep of 64 ± 8 kg live weight were used. The duration of the study was 54 days, divided into two periods (changeover design), which comprised a 17-day pre-experimental period and 10 days for experimental data collection. Animals were allocated to one of two treatments used: hay (H) as a control treatment, where animals were fed with Rhodes grass hay alone; and H + DDGS, where animals were fed with H supplemented with DDGS. CH₄ emissions were estimated using the sulfur hexafluoride (SF₆) tracer technique. Diets containing DDGS increased DMI by 22% (p < 0.05) and reduced daily CH₄ emissions by 24% (g/d), the CH₄ yield by 35% (g/kg DMI), and the average value of CH₄ energy per gross energy intake (Ym) by 44%, compared to the control treatment (p < 0.05). The experiment demonstrated that supplementation with DDGS in low-quality roughage reduced daily CH₄ emissions, yields, and Ym. Full article

Natural gas is a promising future source for the increasing energy demand. It is partially clean energy with fewer environmental impacts, and it is necessary to develop technologies to cater to the supply chain. Due to their inherent structural properties, gas hydrates or clathrate hydrates are promising materials for capturing and storing methane gas. In the present study, the experimental investigations were performed to assess the utilization of soybean powder (SBP) as a promoting additive compared to sodium dodecyl sulfate (SDS) for methane hydrate formation. The methane hydrate formation temperature and pressure with SBP are 277.8 ± 3.2 K, 7050.9 ± 76.2 kPa, similar to SDS 277.2 ± 0.3 K, 7446.3 ± 5.7 kPa in the non-stirred system. The gas uptake capacity is about 94.2 ± 4.5 v/v and 92.4 ± 4.6 v/v with SBP and SDS, which is ~60% of the practical, achievable limit. The time for the 90% of hydrate conversion is ~4.6 times higher for SBP than SDS. The more prolonged kinetics is ascribed to the complex constituents in the SBP. In contrast to the SDS solution, no foam was produced in the sample of the SBP solution. The current studies demonstrate that SBP can be utilized to develop cleaner and more effective promoters for methane hydrate formation without foam creation. Full article

Sugarcane bagasse (SCB) is the main residue obtained from sugarcane processing, and it has been widely investigated as a strategic renewable energy source. The typical recalcitrant characteristic of SCB requires the use of pretreatments (e.g., chemicals) to increase methane production through anaerobic digestion, which is normally reported to generate toxic effluents and increase operational costs. Based on this, the present study evaluated the efficiency of an inexpensive, alternative, and more sustainable method to improve the biodegradability of SCB and increase methane production by pre-storing it with acidic organic biowastes, such as cheese whey (CW) and fruit and vegetable waste (FVW). Different fresh weight-based proportions of FVW (5:95, 10:90, and 15:85) and CW (10:90, 20:80, and 25:75) were soaked with SBC for 7 days at 25 °C. These treatments were compared with traditional alkaline pretreatment using NaOH at concentrations of 1%, 5%, and 10% (w/v). The best result was obtained with SCB + FVW (5:95), being 520 ± 7 NL CH₄ kg VS⁻¹ (27.6% higher than the control) with degradation time (T₉₀) reduced from 13 to 7 days. Pretreatment with SBC + CW resulted in antagonistic effects due to process inhibition, while alkaline pretreatment with NaOH at concentrations of 5% and 10% similarly increased methane yield by 21.2% and 34.1%, respectively. Therefore, pre-storage of SBC with FVW proved to be the best strategy to increase methane production from SCB, while simultaneously avoiding the use of chemical reagents that result in toxic effluents. Full article

This study presents a new method to remove lignin from wheat straw (lignocellulosic) using the ozonation technique. Lignocellulosic material is a complex biopolymer composed of cellulose, hemicellulose and lignin. Apart from lignin, which acts as a chemical resistant, lignocellulosic is the main resource of cellulose and hemicellulose sugars. The ozonation reaction takes place in a two-phase solid–gas fluidization stainless steel reactor. The focus of this paper is to investigate the kinetics that govern lignin removal from lignocellulosic material after ozonation treatment. The kinetics of lignin removal did not agree with the experimental data until the suggested model is modified to a pseudo-second-order. The results showed that at a higher ozone supply of 150 mg min⁻¹, the surface reaction and intra-particular diffusion were the most significant factors to remove the lignin. Moreover, at a lower ozone supply of 30 mg min⁻¹, the intra-particular diffusion was the only contributor towards lignin removal. Full article

In this paper, a predictive combustion model is developed and implemented in GT-Power. The model consists of a detailed physically/chemically based ignition delay model, including a 1D spray model. The spray model results at the start of combustion are used to initialize the combustion model. The spray zone and the homogenous natural gas/air mixture are burned with different combustion models, to account for the effect of the inhomogeneous fuel distribution. NOx-emissions are modelled using a standard Extended Zeldovich Mechanism, and for the HC-emissions, two flame quenching models are included and extended with an empirical correlation. The models are calibrated with measurement data from a single cylinder engine, except for the ignition delay model which needs no calibration. The start of combustion and the combustion parameters are predicted well for a wide range of injection timings and operation conditions. Furthermore, considering unburned fuel, the engine operation parameters BSFC and IMEP are also predicted satisfactory. Due to the detailed description of the different combustion phases, the influence of the injection timing on the NOx-emission is captured satisfactorily, with the standard NOx-model. Finally, the knock limited MFB50 is also predicted within an acceptable range. Full article

Syngas generated from the catalytic dry reforming of methane (DRM) enables the downstream production of H₂ fuel and value-added chemicals. Ni-based catalysts with metal oxides, as both supports and promoters, are widely applied in the DRM reaction. In this review, four types of metal oxides with support confinement effect, metal-support interaction, oxygen defects, and surface acidity/basicity are introduced based on their impacts on the activity, selectivity, and stability of the Ni-based catalyst. Moreover, the structure–performance relationships are discussed in-depth. Finally, conclusive remarks and prospects are proposed. Full article