Hydrogenation Of Carbon Monoxide Research Articles

Condensed Layer Deposition of Nanoscopic TiO2 Overlayers on High-Surface-Area Electrocatalysts.

Encapsulating an electrocatalytic material with a semipermeable, nanoscopic oxide overlayer offers a promising approach to enhancing its stability, activity, and/or selectivity compared to an unencapsulated electrocatalyst. However, applying nanoscopic oxide encapsulation layers to high-surface-area electrodes such as nanoparticle-supported porous electrodes is a challenging task. This study demonstrates that the recently developed condensed layer deposition (CLD) method can be used for depositing nanoscopic (sub-10 nm thick) titanium dioxide (TiO2) overlayers onto high-surface-area platinized carbon foam electrodes. Characterization of the overlayers by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) showed that the films are amorphous, while X-ray photoelectron spectroscopy confirmed that they exhibit TiO2 stoichiometry. Electrodes were also characterized by hydrogen underpotential deposition (Hupd) and carbon monoxide (CO) stripping, demonstrating that the Pt electrocatalysts remain electrochemically active after encapsulation. Additionally, copper underpotential deposition (Cuupd) measurements revealed that TiO2 overlayers are effective at blocking Cu2+ from reaching the TiO2/Pt buried interface and were used to estimate that between 43 and 98% of Pt surface sites were encapsulated. Overall, this study shows that CLD is a promising approach for depositing nanoscopic protective overlayers on high-surface-area electrodes.

A DFT Study of CO Hydrogenation on Graphene Oxide: Effects of Adding Mn on Fischer–Tropsch Synthesis

The hydrogenation of carbon monoxide (CO) offers a promising avenue for reducing air pollution and promoting a cleaner environment. Moreover, by using suitable catalysts, CO can be transformed into valuable hydrocarbons. In this study, we elucidate the mechanistic aspects of the catalytic conversion of CO to hydrocarbons on the surface of manganese-doped graphene oxide (Mn-doped GO), where the GO surface includes one OH group next to one Mn adatom. To gain insight into this process, we have employed calculations based on the density functional theory (DFT) to explore both the thermodynamic properties and reaction energy barriers. The Mn adatoms were found to significantly activate the catalyst surface by providing stronger adsorption geometries. Our study concentrated on two mechanisms for CO hydrogenation, resulting in either CH4 production via the reaction sequence CO → HCO → CH2O → CH2OH → CH2 → CH3 → CH4 or CH3OH formation through the CO → HCO → CH2O → CH2OH → CH3OH pathway. The results reveal that both products are likely to be formed on the Mn-doped GO surface on both thermodynamic grounds and considering the reaction energy barriers. Furthermore, the activation energies associated with each stage of the synthesis show that the conversion reactions of CH2 + OH → CH3 + O and CH2O + OH → CH2OH + O with energy barriers of 0.36 and 3.86 eV are the fastest and slowest reactions, respectively. The results also indicate that the reactions: CH2OH + OH → CH2 + O + H2O and CH2OH + OH → CH3OH + O are the most exothermic and endothermic reactions with reaction energies of −0.18 and 1.21 eV, respectively, in the catalytic pathways.

Multi-objective optimization of methanol reforming reactor performance based on response surface methodology and multi-objective particle swarm optimization coupling algorithm for on-line hydrogen production

The utilization of high-temperature exhaust to drive methanol steam reforming for on-line hydrogen production in engines is an effective approach to solving hydrogen storage and transportation challenges. In this work, the response surface methodology (RSM) is combined with the multi-objective particle swarm optimization (MOPSO) algorithm, and is first utilized for multi-objective optimization of the performance of a methanol reforming reactor. Regression models for optimization objectives are developed based on RSM, and the reliability and significance of regression models are determined through analysis of variance. The influence mechanism of the interaction between design variables on optimization objectives is elucidated by visual analysis of the response surface. A multi-objective optimization of reactor performance is performed utilizing the MOPSO algorithm, and the Pareto optimal solution is obtained from the Pareto optimal frontier based on the technique for order preference by similarity to ideal solution method. Optimization results demonstrate that the Pareto optimal solution is obtained at an exhaust temperature of 585.21 K, an exhaust flow rate of 0.0097 kg·s−1, a steam to methanol ratio of 1.48, and a weight hourly space velocity of 1.2. The hydrogen yield, methanol conversion and carbon monoxide selectivity corresponding to the Pareto optimal solution are 68.53 mol·h−1, 0.83 and 0.011, respectively. Under optimal operating parameters, the methanol reforming reactor achieves 21.92 % exhaust energy recovery.

Synergistic effect of Zr and K promoters on iron-based catalysts in CO hydrogenation reaction

There is a growing demand for decreasing fossil fuel usage. That being said, we should move toward renewable and sustainable energy sources. Iron-based catalysts are usually employed in this route. In this work, an incipient impregnation process was used for preparing four γ-Al2O3 supported iron-based catalysts with different weight percents including 20Fe/5Cu/γ-Al2O3, 20Fe/5Cu/2K/γ-Al2O3, 20Fe/5Cu/3Zr/γ-Al2O3 and 20Fe/5Cu/1.5Zr/1K/γ-Al2O3 under the pressure of 20 atm, the temperature of 285 °C, H2 to CO ratio of one, and a gas hourly space velocity of 2 NL/ (h. gCat). BET, FE-SEM, XRD, H2-TPR, ICP, and TEM techniques were used to determine the characteristics of the catalysts, while gas chromatography results were used to determine CO conversion and product selectivity. Due to the synergistic effect of the two promoters, the doubly-promoted catalyst exhibited a C5+ selectivity of 64.2 %, surpassing both the Fe/Cu/γ-Al2O3 catalyst and the singly-promoted catalysts. This result highlights the enhanced performance of the doubly-promoted catalyst. Compared to the other catalysts prepared, the doubly-promoted catalyst demonstrated a higher carbon monoxide (CO) conversion rate of 67.7 % and yield of 43.5 %. Moreover, The results demonstrate the significant impact of Zr and K promoters of the synthesized Fe-based catalysts on hydrocarbon product distribution.

Real-time experimental investigation of a multi-flow biomass gasifier by using various locally available wood biomass

Biomass gasification is one of the prominent technologies for thermal applications, electricity generation through engines. The present investigation was carried out to obtain behavior of multi-flow gasifier by using locally available wood biomass chips (i.e., Acacia Nilotica & Eucalyptus biomass). Experiments were conducted to examine the variation of gas composition, LHV, cold gasification efficiency, equivalence ratio at different flow rates, and pressure drop with the time in complete operation of gasifier. Result shows that producer gas obtained from this gasifier has maximum lower heating value of 4.39 MJ/kg with hydrogen gas (13.61% vol/vol) and carbon monoxide (15.61% vol/vol). The composition of CH4 in producer gas was less than 2%. The maximum cold gas efficiency of 72.2% was obtained at optimal equivalence ratio of 0.309 with gas flow rate of 5 g s−1 with moisture content of 7.51%. These locally available wood can be appropriate feedstock for gasifiers. The clean and cooled gas can be utilized in internal combustion engines or turbines for clean power production.

MONITORING AND ANALYSING AIR POLLUTION IN RESIDENTIAL AREAS UNDER THE INFLUENCE OF VEHICLE AND METALLURGICAL PLANT EMISSIONS

Assessment of the level of air pollution in the residential areas of an urbanized city allows to determine the main pollutants contained in the air and allows to adjust or improve the cleaning equipment of emission sources. The purpose of the work: research of the general level of air pollution in the zone of influence of the central road with heavy traffic and an industrial facility on the air quality of residential areas of the city of Kamianske. Methodology. The work used air quality analyzers Benetech GM 8804, Wintact wt 8811, Benetech GM 8806 to determine the presence (concentration) of hydrogen sulfide, carbon monoxide, ammonia, formaldehyde, dust (PM 2.5), combustible gases (LEL). Sampling points were chosen in residential areas: indoors, on the adjacent territory and near the road. Scientific novelty. In the course of research, it was found that the residential area, which is located closer to the industrial facility and to the central part of the city with shopping centers, has relatively higher LEL indicators and lower indicators of oxygen content in the air. The dynamics of changes in air pollution over time are not high. Practical value. Monitoring and analysis of the level of air pollution contributes to the detection of dangerous chemicals in the air of a residential area, the patterns of decreasing oxygen content and the dynamics of changes in the content of combustible gases in the air over time and with a change in the distance to the source of pollution. Results. It was found that the air of residential areas does not contain compounds of hydrogen sulfide, carbon monoxide, ammonia, and formaldehyde sufficient for the measurement range of analytical devices. Traces of dust were detected. Recorded decrease in oxygen content indoors and in atmospheric air near roads. The content of combustible gases (LEL) in the studied premises in most samples is higher than outside.

Using CoCu2Ga/SiO2 to identify stability-issues in ethanol-selective Co-Cu alloyed catalysts in carbon monoxide hydrogenation

Hydrogenation of CO to higher alcohols such as ethanol is an attractive pathway for industrial production while avoiding competition with food crops. However, thermocatalytic ethanol production from syngas is currently hindered by the lack of selective catalysts. The structural integrity of ternary-alloyed CoCu2Ga nanoparticles supported on silica was studied during thermo-catalytic CO hydrogenation. Catalysts of four different CoCu2Ga weight-loadings were tested catalytically under differential conversion, showing their different intrinsic selectivity during CO hydrogenation towards ethanol, methanol, and hydrocarbons. CoCu2Ga catalysts with 3.5 wt% and 17.8 wt% proved most and least selective towards ethanol formation, respectively. These two were studied in depth using STEM-EDX of fresh and spent samples showing different size distributions of the nanoparticles for all samples, and a change in the Co/Cu distribution of the nanoparticles from fresh to spent samples. In situ characterization using XRD, XANES, and EXAFS during CO hydrogenation supported the findings of the STEM-EDX and elucidated that the fresh more homogenous catalyst consisting of ternary CoCu2Ga nanoparticles de-alloyed into Cu-rich and CoGa-rich nanoparticles. This de-alloying was possibly driven by two factors: the metastable phase of CoCu2Ga decreasing its free energy by separating Cu and Co; and the strong interaction between Co and CO further driving a segregation. From a theoretical standpoint, Cu-Co intermetallics present the most selective catalyst to form ethanol over methane and methanol. The experimental findings presented here support the theory, although further efforts are needed to improve structural stability during the catalytic reaction.

New insights on the Cu–Ce interaction in Cu/Ce catalysts based on ZSM-5 and Beta for the preferential oxidation of carbon monoxide in excess hydrogen

Cu-Ce-modified zeolites are shown to be effective in preferential CO oxidation (CO-PROX) in H2-rich stream. Catalysts containing copper and cerium based on zeolites ZSM-5 (Si/Al = 15, 28 and 40) and Beta (Si/Al = 19) are synthesized by sequential incipient wetness impregnation and tested in total (CO-TOX) and preferential oxidation of CO. The influence of zeolite framework type, Si/Al ratio, metal loading and order of metal introduction on the formation of active sites and their activity and selectivity are studied. Based on XRD, TEM, XPS, adsorbed CO DRIFTS and H2-TPR studies it is shown that of the key importance is synergistic interaction of copper and cerium not only on the surface, but in the zeolite channels. Cu+ incorporated in CeO2 and mixed copper-cerium oxo/hydroxocations can both be active sites in CO oxidation. Wider channels of Beta framework favor the penetration of metal cations, but not formation of necessary active sites. The presence of CuO phase in the catalysts negatively affects the stability and selectivity in CO-PROX. ZSM-5-based catalyst containing largest amount of oxocations (2.6 wt% Cu, 10 wt% Ce, Si/Al = 15) makes it possible to completely remove CO from H2-rich mixture in CO-PROX at 150–190 °C.

An Improved Manganese Pincer Catalyst for low Temperature Hydrogenation of Carbon Monoxide to Methanol

AbstractA manganese pincer complex Mn‐2 for the homogeneously catalysed conversion of CO/H2 to methanol was developed using a novel PNP ligand design. Compared to the previous state‐of‐the‐art catalyst system Mn‐1, the presented Mn‐2 with different substituents at the P‐atoms led to a significant increase of the reaction rate (TOF up to >1600 h−1).

Analysis of Student Responses to Downstream of the Inquiry Learning Model Integrated Ethno-STEM for Aroma Compounds from Indonesian Herbal Tea to Give a Conservation Character

This research is related to downstream research from an innovative learning model. This research aims to (a) downstream the Ethno-STEM integrated inquiry learning model, (b) analyze the profile of aroma compounds from herbal tea extracts in Indonesia, and (c) analyze student responses to the downstream of the Ethnoscience and STEM (Ethno-STEM) integrated inquiry learning model. STEM). Research was conducted at the Faculty of Mathematics and Natural Sciences. The research subjects were students of chemistry education at UNNES for the 2022/2023 academic year. The research instruments consisted of questionnaires, questionnaires, and observation sheets from the test results of Indonesian herbal tea aroma compounds. In this research the trapping of tea aroma compounds uses Arduino sensors. Data obtained from questionnaires and data on Indonesian herbal tea aroma compounds were analyzed descriptively qualitatively and quantitatively. The results of the research concluded that (a) the integrated Ethno-STEM inquiry learning model that was down streamed was the Sudarmin syntactic model, (b) Indonesian herbal tea aroma compounds consisted of hydrogen compounds, propane, carbon monoxide (CO), alcohol, carbon dioxide (CO2), toluene, ammonia, acetone, heptane, and sulfuric acid gas, and (c). students respond well to the integrated Ethno-STEM inquiry learning model that was developed, and this model is able to increase the Conservation character.

Solvation Shell Anatomy of H2S and CO Dissolved in Reline and Ethaline Deep Eutectic Solvents.

Rising atmospheric concentrations of anthropogenic hydrogen sulfide (H2S) and carbon monoxide (CO) as a result of industrialization have encouraged researchers to explore innovative technologies for capturing these gases. Deep eutectic solvents (DESs) are an alternative media for mitigating H2S and CO emissions. Herein, we have employed ab initio molecular dynamics simulations to investigate the structures of the nearest-neighbor solvation shells surrounding H2S and CO when they are dissolved in reline and ethaline DESs. We aim to delineate the structural arrangement responsible for favorable H2S and CO capture by analyzing the key interactions between H2S and CO solutes with various components of the DESs. We observe that in the reline-H2S system, chloride and carbonyl oxygen of urea are found to have the closest distance interaction with hydrogen atoms of the H2S solute. The sulfur atom of H2S is found to be predominantly solvated by hydrogen and oxygen atoms of urea molecules and the hydroxyl hydrogen of choline cations. The chloride ions and ethylene glycol molecules predominantly govern the solvation of H2S in the ethaline-H2S system. In both the DESs, H2S is solvated by the hydroxyl group of the choline cations rather than by their ammonium group. In the reline-CO system, all the atoms of urea along with chloride dominate the immediate solvation shell around CO. In the ethaline-CO system, hydroxyl oxygen and hydrogen atoms of ethylene glycol are found in the nearest solvation structure around CO. Both the DESs exhibit a stronger solvent-solute charge-transfer tendency toward the H2S solute compared to CO.

Enhancement of higher alcohols selectivity in Fischer-Tropsch synthesis using Walnut and Almond shell derived biochars as Copper/Cobalt catalyst support

The production of higher alcohols from synthesis gas using biochar-supported copper-cobalt catalysts is investigated. Biochars were prepared via pyrolysis of Walnut shells and Almond shells and were subsequently activated through physical and chemical methods. A 15 wt% Copper and 5 wt% Cobalt was loaded on the activated biochars via the impregnation technique. The chemical and physical properties of the catalysts were studied using various methods. The catalytic performance of the catalysts was assessed in a fixed-bed microreactor at 20 bars, 320 °C, and, an H2/CO ratio of 2, and the results were compared with the γ-Alumina supported catalyst. Strong interaction between cobalt and copper particles and the formation of bimetallic CuCo2O4 species were observed. The catalysts' reducibility was enhanced by a factor of 1.42. The catalytic studies revealed a significant enhancement in the rate of carbon monoxide hydrogenation. The catalyst supported on low-cost Almond shell-derived biochar demonstrated the best performance. The total alcohol selectivity increased from 22.2 wt% to 34.2 wt%, and the C2+ alcohol selectivity rose from 78.3 wt% to 91.1 wt%, as compared to the industrial catalyst supported on alumina. However, the selectivity for C5+ liquid hydrocarbons decreased to 16.8 wt%. Notably, biochar-supported catalysts also exhibited good stability.

Edge-rich molybdenum disulfide tailors carbon-chain growth for selective hydrogenation of carbon monoxide to higher alcohols

Selective hydrogenation of carbon monoxide (CO) to higher alcohols (C2+OH) is a promising non-petroleum route for producing high-value chemicals, in which precise regulations of both C-O cleavage and C-C coupling are highly essential but remain great challenges. Herein, we report that highly selective CO hydrogenation to C2-4OH is achieved over a potassium-modified edge-rich molybdenum disulfide (MoS2) catalyst, which delivers a high CO conversion of 17% with a superior C2-4OH selectivity of 45.2% in hydrogenated products at 240 °C and 50 bar, outperforming previously reported non-noble metal-based catalysts under similar conditions. By regulating the relative abundance of edge to basal plane, C2-4OH to methanol selectivity ratio can be overturned from 0.4 to 2.2. Mechanistic studies reveal that sulfur vacancies at MoS2 edges boost carbon-chain growth by facilitating not only C-O cleavage but also C-C coupling, while potassium promotes the desorption of alcohols via electrostatic interaction with hydroxyls, thereby enabling preferential formation of C2-4OH.

Engineered Catalyst Based on MIL-68(Al) with High Stability for Hydrogenation of Carbon Dioxide and Carbon Monoxide at Low Temperature.

Today, the importance of decreasing and converting COx gases from the atmosphere into value-added chemicals by catalytic hydrogenation reactions has become one crucial challenge. In the current work, to facilitate the hydrogenation of COx, several mesoporous alumina catalysts with high efficiency and stability were synthesized using the MIL-68(Al) platform, a nanoporous MOF with a high surface area as a precatalyst, encapsulating nickel or nickel-iron nanoparticles (NPs). After removing the organic linker of MIL-68(Al) by calcination in air, two types of catalysts, promoted and unpromoted, were obtained with various loads of nickel and iron. A set of analyses (PXRD, BET-N2, TEM, FE-SEM, ICP-OES, EDX-map, CO2-TPD, H2-TPR, and H2-TPD) were performed to evaluate the physicochemical properties of catalysts. Based on the analysis results, the promoted catalyst had smaller particles and pores due to the effective and uniform distribution of nickel NPs. Also, H2-TPR and CO2-TPD results in samples containing Fe promoter demonstrated the facilitation of the reduction process and the adsorption and activation of CO2, respectively. The results of CO2 methanation indicated an improved catalytic performance for promoted samples, especially at low temperatures (200-300 °C), compared to unpromoted catalysts. 5Fe·15Ni@Al2O3MIL-68(Al) catalyst displayed the best performance compared to other catalysts, with a conversion of 92.4% and selectivity of 99.6% at 350 °C and GHSV = 2500 h-1. Moreover, the 5Fe·15Ni@Al2O3MIL-68(Al) catalyst facilitated the CO2 methanation reaction by reducing the activation energy to 42.5 kJ mol-1 compared with other reported catalysts. Both types of catalysts performed 100% hydrogenation of CO to CH4 with full selectivity at 250 °C and exhibited high stability for at least 100 h at 300 °C. Notably, such high significant catalytic performance is only achieved by the usage of the "MOFs templating strategy" due to the high surface area for the effective distribution of NPs, the strong metal-support interaction, and the formation of nickel aluminate species, preventing the sintering of NPs.

The oscillating Fischer-Tropsch reaction.

The mechanistic steps that underlie the formation of higher hydrocarbons in catalytic carbon monoxide (CO) hydrogenation at atmospheric pressure over cobalt-based catalysts (Fischer-Tropsch synthesis) have remained poorly understood. We reveal nonisothermal rate-and-selectivity oscillations that are self-sustained over extended periods of time (>24 hours) for a cobalt/cerium oxide catalyst with an atomic ratio of cobalt to cerium of 2:1 (Co2Ce1) at 220°C and equal partial pressures of the reactants. A microkinetic mechanism was used to generate rate-and-selectivity oscillations through forced temperature oscillations. Experimental and theoretical oscillations were in good agreement over an extended range of reactant pressure ratios. Additionally, phase portraits for hydrocarbon production were constructed that support the thermokinetic origin of our rate-and-selectivity oscillations.

Low-cost mobile air quality monitoring based on internet of things for factory area

The most significant effect of industrialization is air pollution. Air pollution monitoring has become an important requirement in affected areas. With the advancement of electronic sensor technology and the Internet of Things (IoT), there are plenty of remote ambient air quality monitoring systems have been developed by measuring the levels of major air pollutants such as Sulfur Dioxide, (SO2), Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Ozone (O3), and Particulate Matter (PM). However, other hazardous gases such as Hydrogen Sulfide (H2S), Carbon Monoxide (CO), and Ammonia (NH3) also have the potential to appear in factory areas, especially factory areas located in rural areas. Therefore, this study proposes a low-cost mobile ambient air quality monitoring system by measuring CO, H2S, and NH3 gas levels that are easy to implement. The proposed system has been tested in factory areas and rural areas where factory pollutants can be mixed with agricultural pollutants. The test results show that the proposed system can detect CO, H2S, and NH3 gas levels. The levels of CO, H2S, and NH3 gases at the test site were still at a safe level. A mobile remote monitoring scheme by utilizing thinger.io as an IoT platform also works very well.

A Review of Theoretical Studies on Carbon Monoxide Hydrogenation via Fischer-Tropsch Synthesis over Transition Metals.

The increasing demand for clean fuels and sustainable products has attracted much interest in the development of active and selective catalysts for CO conversion to desirable products. This review maps the theoretical progress of the different facets of most commercial catalysts, including Co, Fe, Ni, Rh, and Ru. All relevant elementary steps involving CO dissociation and hydrogenation and their dependence on surface structure, surface coverage, temperature, and pressure are considered. The dominant Fischer-Tropsch synthesis mechanism is also explored, including the sensitivity to the structure of H-assisted CO dissociation and direct CO dissociation. Low-coordinated step sites are shown to enhance catalytic activity and suppress methane formation. The hydrogen adsorption and CO dissociation mechanisms are highly dependent on the surface coverage, in which hydrogen adsorption increases, and the CO insertion mechanism becomes more favorable at high coverages. It is revealed that the chain-growth probability and product selectivity are affected by the type of catalyst and its structure as well as the applied temperature and pressure.

Mechanism of Methanol Synthesis from CO2 Hydrogenation over Cu/γ-Al2O3 Interface: Influences of Surface Hydroxylation

The adsorption and hydrogenation of carbon dioxide on γ-Al2O3(110) surface-supported copper clusters of different sizes are investigated using density functional theory calculations. Our results show that the activation of CO2 is most obvious at the Cu/γ-Al2O3 interface containing the size-selected Cu4 cluster. It is interesting that the CO2 activation is more pronounced at the partially hydroxyl-covered interface. The catalytic mechanisms of CO2 conversion to methanol at the dry and hydroxylated Cu4/γ-Al2O3 interfaces via the formate route and the pathway initiated through the hydrogenation of carbon monoxide produced by the reverse water–gas shift reaction are further explored. On both interfaces, the formate pathway is identified as the preferred reaction pathway, in which the hydrogenation of HCOO to H2COO is the rate-limiting step (RLS). However, since the surface OH group can act as a hydrogen source in some elementary reactions, unlike the dry surface, the production of H2COOH species along the formate pathway is found at the hydroxylated interface. In addition, the introduction of OH at the interface leads to an increase in the kinetic barrier of the RLS, indicating that surface hydroxylation has a negative effect on the catalytic activity of CO2 conversion to CH3OH at the Cu/γ-Al2O3 interface.

Research progress on gas signal molecular therapy for Parkinson's disease.

The pathogenesis of Parkinson's disease (PD) remains unclear. Among the pathological manifestations is the progressive degeneration of the nigrostriatal dopaminergic pathway, leading to massive loss of neurons in the substantia nigra pars compacta and dopamine (DA) depletion. Therefore, the current drug treatment is primarily based on DA supplementation and delaying the progression of the disease. However, as patients' symptoms continue to worsen, the drug effect will gradually decrease or even disappear, thereby further aggravating clinical symptoms. Gas signaling molecules, such as hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and hydrogen (H2), exhibit pleiotropic biological functions and play crucial roles in physiological and pathological effects. In common neurodegenerative diseases including Alzheimer's disease and PD, gas signal molecules can prevent or delay disease occurrence via the primary mechanisms of antioxidation, anti-inflammatory response, and antiapoptosis. This article reviews the therapeutic progress of gas signaling molecules in PD models and discusses the possibility of their clinical applications.

Performance and sensitivity analysis of raw biogas combustion under homogenous charge compression ignition conditions

This study aims to investigate the feasibility of using raw biogas as the main fuel in homogeneous charge compression ignition (HCCI) engines and to identify the effects of different trace elements found in biogas on engine performance and emissions. This study was conducted using many models that simulate the operation of HCCI process. These models include the chemical kinetics, combustion model, and the heat transfer models. Raw biogas composition was selected based on the most available traces. The traces that were studied are Hydrogen Sulfide (H2S), Ammonia (NH3), Carbon monoxide (CO), Nitrogen (N2), Oxygen (O2), and Water vapor (H2O). Other parameters like the equivalence ratio, intake temperature, and pressure were also studied. It was found that raw biogas mixtures could produce higher power outputs in the presence of H2S and NH3. However, H2S and NH3 were found to increase the SOx and NOx percentages owing to their higher in-cylinder temperatures. Other traces such as CO and H2O can reduce the power output, but at the same time, they can reduce the engine NOx emissions but not the CO emissions. Engine performance was positively affected by increasing the intake pressure and equivalence ratio within the studied ranges. However, higher intake temperatures and reduce the engine efficiency and increase the engine emissions. On the other hand increasing the compression ratio (CR) increase the system efficiency but up to a certain limit. Considering the exhaust gas residual (EGR), this parameter reduce system performance but at the same time lower the NOx emissions significantly. A sensitivity analysis for the mentioned parameters indicates that EGR is the most effective parameter while CR are the least significant one.