H2and CO Research Articles

Using a protrusion sapphire substrate to synthesize ZnO nanoflower arrays and application of Cu decorated ZnO nanoflower arrays as a H2and CO gas sensor

In this study, a straightforward method is proposed to grow ZnO nanoflower arrays, which will be utilized as gas sensors for detecting H2and CO gases. The process involves using the sol–gel method to create the ZnO thin films on a sapphire substrate with protrusion structure. These thin films are then annealed to serve as the seed layer for the subsequent growth of ZnO nanorods. For the synthesis of the ZnO nanorods, a 0.3[Formula: see text]M solution containing C6H12N4and Zn(CH3COO)2− 2H2O was employed as the precursor, and the hydrothermal method was used at 90∘C for a synthesis time of 60[Formula: see text]min. Due to the unique protrusion structure of the ZnO seed layer, the ZnO nanorods grew perpendicular to it, resulting in the formation of the ZnO nanoflowers. Furthermore, the ZnO seed layer’s matrix structure enables the growth of the ZnO nanoflowers in an orderly array pattern. For the further enhancement of the sensing properties of the gas sensor, a deposition method was used to decorate the Cu nanomaterials on the ZnO nanoflower arrays. The undecorated and Cu-decorated ZnO nanoflower arrays were proceeded to fabricate devices utilizing complemented by an interdigital upper electrode. Subsequently, the gas-sensing performance of both sensor types was compared concerning their ability to detect H2and CO gases. The findings in this research conclusively indicate that sensors fabricated using the Cu-decorated ZnO nanoflower arrays exhibited a remarkable enhancement in gas-sensing properties when compared to the device using the undecorated ZnO nanoflower arrays, particularly for detecting H2and CO gases. These results demonstrated that the Cu-decorated sensors had substantially higher response rates and faster response times during the gas-detecting processes.

Oxidation of iron by giant impact and its implication on the formation of reduced atmosphere in the early Earth

Giant impact–driven redox processes in the atmosphere and magma ocean played crucial roles in the evolution of Earth. However, because of the absence of rock records from that time, understanding these processes has proven challenging. Here, we present experimental results that simulate the giant impact–driven reactions between iron and volatiles (H 2 O and CO 2 ) using x-ray free electron laser (XFEL) as fast heat pump and structural probe. Under XFEL pump, iron is oxidized to wüstite (FeO), while volatiles are reduced to H 2 and CO. Furthermore, iron oxidation proceeds into formation of hydrides (γ-FeH x ) and siderite (FeCO 3 ), implying redox boundary near 300-km depth. Through quantitative analysis on reaction products, we estimate the volatile and FeO budgets in bulk silicate Earth, supporting the Theia hypothesis. Our findings shed light on the fast and short-lived process that led to reduced atmosphere, required for the emergence of prebiotic organic molecules in the early Earth.

CFD Simulation of Air-Piloted Downdraft Gasification Process: A Comparative Study Between Coal and Palm Kernel Shell as Feedstock

A fixed bed downdraft gasifier model based on computational fluid dynamic (CFD) framework was developed to investigate the influence of feedstock (palm kernel shell [PKS] and coal) on the quality of syngas produced via the gasification process. Euler–Euler approach was utilized in this study to describe the gas and solid phases. Realizable k-ε turbulence model was used to evaluate the constitutive properties of the dispersed phase and the gas phase behavior. This simulation model was validated by comparing the syngas composition of gasification simulation of coal with previous research, which yielded the overall accuracy result of 83.2%. This study also highlighted that PKS gasification produced 53.74% and 90.51% higher composition of H2and CO respectively as compared to coal gasification. Whereas coal gasification produced 81.35%, 71.31% and 52.29% higher composition of CH4, H2O and CO2respectively as compared to PKS gasification. Hence, PKS produced 66.2% higher combustible gas of H2and CO than coal. PKS is thus considered as a potential renewable feedstock for gasification process as an alternative to the non-renewable coal. In addition, PKS gasification produced 52.29% lesser composition of CO2as compared to coal gasification.

Fragmentation pathways of deprotonated ortho-hydroxybenzyl alcohol.

The ortho, meta, and para isomers of hydroxybenzyl alcohol can be unequivocally distinguished by the collision-induced dissociation mass spectra of their anions. The presence of a prominent peak at m/z 121 for an elimination of a dihydrogen molecule renders the ortho-isomer spectrum markedly different from those of its meta and para congeners. Investigations carried out with deuterium-labeled isotopologues of the ortho isomer verified that the labile hydrogen atom on the hydroxyl group and one of the benzylic hydrogen atoms are specifically removed in the formation of the m/z 121 ion. The ortho-isomer spectrum also showed a prominent peak at m/z 93. Experimental data indicated that the m/z 93 product ion originates either from a two-step H2and CO elimination mechanism or from a direct loss of a HCHO molecule from the precursor anion. The intensity ratio of the m/z 93 and 94 peaks in the spectrum recorded from the m/z 124 ion generated from a sample of o-hydroxybenzyl alcohol dissolved in D2O supported the notion that the direct HCHO loss is the more dominant pathway for the generation of the phenolate ion under low activation conditions. In contrast, the two-step mechanism becomes the more dominant pathway under high collisional activation conditions. The spectrum also showed a weak peak at m/z 105 for a water loss. Based on computational data, the m/z 105 ion generated in this way appears to be a composite generated from a common ion-neutral complex intermediate in which a hydroxyl anion is positioned equidistantly between one of the benzylic hydrogens and a nearby hydrogen atom of the benzene ring. Upon activation, the complex dissociates to form either a phenide or a quinone methide anion. The reaction forming a carbon dioxide adduct under ion-mobility conditions was used to support the proposed water-loss mechanism.

Process optimization and economic evaluation of air gasification of Saudi Arabian date palm fronds for H2-rich syngas using response surface methodology

The transition of energy extraction from the fossil fuel to renewable energy is a primary drive-in world. Saudi Arabia is one of the big producer of date fruit which generates an abundant amount of date palm wastes. There is no proper utilization of these wastes in Saudi Arabia. Conversion of date palm waste into energy is a major potential alternative source of bioenergy via gasification. In current study, process optimization and economic evaluation of air gasification of date palm fronds (DPF) has been performed in downdraft gasifier for energy conversion. The impact of three process parameters temperature, air flowrate, and feedstock particle size on gas composition were investigated. The response surface methodology (RSM) was adopted for experimental design, optimization, and individual and interactive effects of parameters on H2 and CO compositions to find their optimum values. Temperature is the most influencing factor for H2 composition and it varies from 6 vol% to 18 vol% which is higher compared to air flowrate and feedstock particle size. A similar pattern of influencing factors was observed for CO composition it varies from 8 vol% to 20 vol%. The enrichment of H2and CO is due to the activation of endothermic reactions at elevated temperature. On the other hand, factor influencing order for CO2composition as feedstock particle size > air flowrate > temperature. The optimum conditions were found 900℃ temperature, 1 l/min air flowrate, and 6 mm feedstock particle size to maximizing the H2 and CO compositions. Cost of syngas produced from air gasification of DPF was determined SAR 4.04/kg which can be minimized to scale-up the gasification system. DPF conversion into energy is environmentally friendly alternative source of renewable energy that will helps to reduce the dependency on fossil fuel.

Gas phasevs.liquid phase: monitoring H2and CO adsorption phenomena on Pt/Al2O3by IR spectroscopy

The adsorption of H2and CO over Pt/Al2O3was studied in gas and in liquid phase by FT-IR and ATR-IR spectroscopies under otherwise similar conditions. The solvent competes with hydrogen and CO for terrace and kink metal sites.

Influence of Ce2O3 addition on the basicity of Ni/MgO and on its catalytic performance in dry reforming of methane (Turning CO2 to fuel)

The only way to stabilize the Earth’s climate is to stabilize the concentration of greenhousegases in the atmosphere. In this study, the conversion of methane and CO2 to synthesis gasusing dry reforming over catalysts Ni/Mg1-XCeXO (x= 0, 0.03, 0.07, 0.15; 1 wt% Ni each),dry reforming of methane was performed. The catalysts were prepared by K2CO3 coprecipitationfrom aqueous cerium nitrate hexahydrate and magnesium nitrate hexahydrate.Impregnation of nickel (II) acetylacetonate onto MgO-Ce2O3 was then conducted. TEM,XRD, FTIR, XRF, XPS, and BET characterizations of the catalysts were carried out.Results showed that the catalysts were reduced at 700 °C by H2 prior to each reaction. CH4and CO2 conversions at 900 °C of the catalysts after being tested for 200h decreased in theorder Ni/Mg0.85Ce0.15O, Ni/Mg0.93Ce0.07O, Ni/Mg0.97Ce0.03O, and Ni/MgO. The highest H2and CO selectivities, was observed at a 1:1 CH4:CO2 mole ratio. We further performed adry reforming in the presence of low-concentration oxygen flow (1.25 Vol %) and found anincreased CH4 conversion.

Gasification of Municipal Solid Waste Using Tyre Char as Catalyst

Gasification is raised as the most promising technologies of municipal solid waste (MSW) removal as well as energy recovery. The principal problem related with the gasification process is the high amount of tar released during the gasification process that causes environmental and operational problems. The purpose of this study is to investigate the performance of MSW gasification using tyre char as an alternative option for catalytic gasification to produce tar free clean gas. Catalytic performance of tyre char was compared with performance of MSW gasification alone without the tyre char in a bench scale downdraft reactor. The waste tyre char removed 80% of tars in syngas at 700 °C. Analysis of the syngas compositions indicated that concentration of H2 and CO were significantly increased. Therefore, it was concluded that chars especially tyre char can be an effective and inexpensive catalyst for tar removal and syngas production of MSW gasification.

H2chemistry in interstellar ices: the case of CO ice hydrogenation in UV irradiated CO:H2ice mixtures

Context.In dense clouds, hydrogenation reactions on icy dust grains are key in the formation of molecules, like formaldehyde, methanol, and complex organic molecules (COMs). These species form through the sequential hydrogenation of CO ice. Although molecular hydrogen (H2) abundances can be four orders of magnitude higher than those of free H-atoms in dense clouds, H2surface chemistry has been largely ignored; several laboratory studies show that H2does not actively participate in “non-energetic” ice chemistry because of the high activation energies required.Aims.For the example of CO ice hydrogenation, we experimentally investigated the potential role of H2molecules on the surface chemistry when energetic processing (i.e., UV photolysis) is involved. We test whether additional hydrogenation pathways become available upon UV irradiation of a CO:H2ice mixture and whether this reaction mechanism also applies to other chemical systems.Methods.Ultra-high vacuum (UHV) experiments were performed at 8–20 K. A pre-deposited solid mixture of CO:H2was irradiated with UV-photons. Reflection absorption infrared spectroscopy (RAIRS) was used as an in situ diagnostic tool. Single reaction steps and possible isotopic effects were studied by comparing results from CO:H2and CO:D2ice mixtures.Results.After UV-irradiation of a CO:H2ice mixture, two photon-induced products, HCO and H2CO, are unambiguously detected. The proposed reaction mechanism involves electronically excited CO in the following reaction steps: CO + hν→CO*, CO*+ H2→HCO + H where newly formed H-atoms are then available for further hydrogenation reactions. The HCO formation yields have a strong temperature dependence for the investigated regime, which is most likely linked to the H2sticking coefficient. Moreover, the derived formation cross section reflects a cumulative reaction rate that mainly determined by both the H-atom diffusion rate and initial concentration of H2at 8–20 K and that is largely determined by the H2sticking coefficient. Finally, the astronomical relevance of this photo-induced reaction channel is discussed.

Fuel Composition in Pressurized SOFCs

Introduction Pressurized SOFC system combined with gas and steam turbine will achieve high power generation efficiency approaching 70% as the triple combined cycle power generation system. It has been reported that operating SOFCs under high pressure can make cell power output higher (1,2). However, there are only a limited number of studies available on the fuel composition for pressurized SOFCs. In general, fuel gas consists of carbon, hydrogen and oxygen, so that the C-H-O equilibrium composition determines anode performance. In this study, fuel gas composition on the anode side of pressurized SOCFs was derived by thermochemical equilibrium calculation for considering various operating conditions in terms of carbon deposition and each gas molar fraction affecting power generation characteristics, all described in the C-H-O diagrams. Calculation Procedure We calculated carbon deposition region and each gas molar fraction under various equilibrium conditions upon suppling fuels composed of carbon, hydrogen and oxygen. Thermochemical calculations were carried out using three approaches: (i) calculation with equilibrium constants, using (ii) HSC Chemistry (Version 9.0.5, Outotec Research Oy, Finland) and (iii) FactSage (Version 6.3.1, Thermfact Ltd., Canada). As the first approach, we defined main reactions within the fuel and solved the system of equations using relational expression of equilibrium constants and elements ratios by Mathematica (Version 10.4.1, Hulinks Inc., Japan). HSC Chemistry and FactSage are both thermochemical equilibrium calculation software based on Gibbs free energy minimization, containing various databases. It has been known that the major constituents of equilibrium products are H2(g), H2O(g), CO(g), CO2(g), CH4(g), and C(s) (graphite) (3). The line specifying the carbon deposition region means the equilibrium concentration of C(s) equal to 10-6 of the initial carbon content in the fuel. The C-H-O diagrams are described in such a way between 100 and 1000oC, and between 1 and 30 bar. Results and discussion Comparing Fig. 1 with Fig. 2, carbon deposition region boundaries vary with respect to temperature and pressure. The C-H-O diagrams clearly show that carbon deposition region expands on the oxygen-rich side and contracts on the hydrogen-rich side with decreasing temperature and/or increasing total pressure. It can be explained by the chemical equilibrium reactions (I) and (II): CH4↔C(s)+2H2 (I) 2CO↔C(s)+CO2 (II) Reaction (I) is an endothermal reaction; on the hydrogen-rich side, equilibrium reaction (I) shifts to the left side, preventing carbon deposition at lower temperatures. With increasing total pressure, the equilibrium also shifts to the left side due to the decrease in the number of molecules. In the same way, Reaction (II) is an exothermal reaction and the number of molecules is lower on the right side, so that the equilibrium reaction shifts to the right side to promote carbon deposition. The C-H-O diagrams of various gases and the corresponding theoretical open circuit voltage are also calculated. These results suggest, for example, a decrease in the fraction of H2and CO under higher total pressure.

XAFCA: a new XAFS beamline for catalysis research.

A new X-ray absorption fine-structure (XAFS) spectroscopy beamline for fundamental and applied catalysis research, called XAFCA, has been built by the Institute of Chemical and Engineering Sciences, and the Singapore Synchrotron Light Source. XAFCA covers the photon energy range from 1.2 to 12.8 keV, making use of two sets of monochromator crystals, an Si (111) crystal for the range from 2.1 to 12.8 keV and a KTiOPO4 crystal [KTP (011)] for the range between 1.2 and 2.8 keV. Experiments can be carried out in the temperature range from 4.2 to 1000 K and pressures up to 30 bar for catalysis research. A safety system has been incorporated, allowing the use of flammable and toxic gases such as H2 and CO.

Nonpremixed and Premixed Combustion of Mixtures of Producer Gas and Methane

Abstract Experimental and kinetic modeling studies are carried out to characterize nonpremixed and premixed combustion of producer gas and mixtures of producer gas and methane. The producer gas, employed in the study, is made up of 55.00% carbon monoxide, 2.34% hydrogen, 12.72% methane, 5.24% ethene, and 24.7% carbon dioxide by mass. The primary focus is on characterizing the chemical influence of addition of producer gas on combustion of methane. The kinetic modeling studies are carried out employing a detailed chemical-kinetic mechanism, called the San Diego Mechanism, a skeletal mechanism, and a reduced mechanism made up of five global steps. Experiments on nonpremixed combustion are carried out employing the counterflow configuration. Critical conditions of extinction are measured for producer gas, methane, and mixtures of producer gas and methane. They are compared with predictions obtained using the detailed, skeletal, and reduced mechanism. Critical conditions of autoignition are measured for producer gas and compared with the predictions obtained employing the detailed mechanism. Experimental data and predictions show that with increasing amounts of producer gas in the mixture, the flame is more difficult to extinguish. Flame structures show that at a fixed value of the strain rate, leakage of oxygen from the reaction zone decreases with increasing amounts of producer gas in the combustible mixture. This is attributed to enhanced consumption of oxygen in an overall chain branching step that consumes hydrogen. Thus, the increase in the overall reactivity of the combustible mixture is attributed to presence of hydrogen in producer gas. Computations are performed, using the detailed mechanism and the skeletal mechanism, to investigate aspects of premixed combustion of stoichiometric mixtures of producer gas, methane, oxygen, and nitrogen at fixed values of adiabatic temperature. Burning velocities are calculated. They are found to be less sensitive to the amount of producer gas in the mixture. This is qualitatively different from that observed for nonpremixed combustion. It is attributed to complete consumption of all reactants including oxygen and combined influences of H2 and CO in producer gas on overall combustion of methane. A third set of computations was performed on strained premixed flames stabilized in counterflow between a stream of a stoichiometric mixture of producer gas, methane, oxygen, and nitrogen, and a stream of nitrogen at fixed adiabatic temperature. Critical conditions of extinction were obtained. The strain rate at extinction increased with increasing amounts of producer gas. The increase was comparable to that observed for nonpremixed combustion of these fuels.

Research on Acetylene Sensing Properties and Mechanism of SnO2Based Chemical Gas Sensor Decorated with Sm2O3

Acetylene C2H2gas is one of the most important fault characteristic hydrocarbon gases dissolved in oil immersed power transformer oil. This paper reports the successful preparation and characterization of samarium oxide Sm2O3decorated tin oxide SnO2based sensors with hierarchical rod structure for C2H2gas detection. Pure and Sm2O3decorated SnO2sensing structures were synthesized by a facile hydrothermal method and characterized by XRD, FESEM, TEM, EDS, and XPS measurements, respectively. Planar chemical gas sensors with the synthesis samples were fabricated, and their sensing performances to C2H2gas were systematically performed and automatically recorded by a CGS-1 TP intelligent gas sensing analysis system. The optimum operating temperature of the Sm2O3decorated SnO2based sensor towards 50 μL/L of C2H2is 260°C, and its corresponding response value is 38.12, which is 6 times larger than the pure one. Its response time is about 8–10 s and 10–13 s for recovery time. Meanwhile good stability and reproducibility of the decorated sensor to C2H2gas are also obtained. Furthermore, the proposed sensor exhibits excellent C2H2selectivity among some potential interface gases, like H2and CO gas. All sensing results indicate the sensor fabricated with oxide Sm2O3decorated SnO2nanorods might be a promising candidate for C2H2detection in practice.

Simple Synthesis of Mesoporous SnO<sub>2</sub> Microspheres and their Gas Sensing Properties

In this work, uniform mesoporous SnO2microspheres have been prepared via a facile and scalable method using tin tetrachloride pentahydrate (SnCl4·5H2O) and resorcinol-formaldehyde gel (RF gel) as starting materials. Furthermore, the structure and morphology of the as-prepared product were characterized by scanning electron microscope (SEM), Transmission electron microscope (TEM) and X-ray diffractometer (XRD). The results revealed that as-synthesized microspheres were around 500 nm in size and composed of large amount of SnO2nanoparticles with diameters of 10-20 nm. Gas sensors based on mesoporous SnO2microspheres were fabricated, and their gas sensing properties were tested for response to methane, butane, H2and CO gas. The sensor exhibited better sensitivity and selectivity to H2vapors at 300 °C than that of the conventional SnO2materials. The enhancement in gas sensing properties was attributed to their unique nanostructures.

Peroviskites Synthesis to SOFC Anodes

The traditional Ni-based anodes are capable of providing a good power output using H2and CO fuels, but sulfur contamination in any hydrocarbon fuel is a problem. Thus, perovskite structure materials containing lanthanum have been widely studied as electrodes for solid oxide fuel cells (SOFCs), due to its electrical properties. In this work was investigated the obtain of the perovskite structure LaCr0.5Ni0.5O3, by Pechini method, and its suitability as SOFC anode. The choice of this composition was based on the stability provided by chromium and the catalytic properties of nickel. After preparing the resins, the samples were calcined at 300oC, 600oC, 700oC and 850oC. The resulting powders were characterized by X-ray, X-ray fluorescence spectroscopy, He pycnometry, specific surface area by BET isotherm and scanning electronic microscopy. The obtaining of the powders of LaCr0.5Ni0.5O3through the Pechini method proved to be effective for temperatures above 850oC.

Comparison of Oxidation Behaviors Between Ash Free Coal and Carbon in a Coin Type Direct Carbon Fuel Cell

Ash free coal extracted from a bituminous coal and carbon made from Oak were served as fuels in a direct carbon fuel cell and their oxidation behaviors were compared in terms of temperature, coal to carbonate ratio, and gas compositions in the cell. The ash free coal had much higher OCV and voltage at polarization states than carbon fuel at 650oC. Dominant product gases from the coal were H2and CO, while carbon had carbon monoxide in the tested range. Therefore difference in the oxidation process would be existed between the two fuels.Coal is relatively abundant energy source compared with other fossil fuels. Regardless of its abundance and long history of usage, inconvenience of its use reduces coal consumption at present. Coal as a solid fuel has a big problem of remaining ash in its use. Ash free coal has been attempted to overcome the problem. So far, ash free coal can be produced by two ways; one is removing ash compounds with acids and alkalines in the coal, calling UCC(Ultra Clean Coal), and another one is extracting organic compounds from the coal with organic solvents, named by ash free coal.In this work, ash free coal was produced by a micro-wave method with a polar solvent of NMP. For the comparison of oxidation behavior, carbon made from Oak was employed in this work. The electrochemical oxidation behaviors of coal and carbon were investigated with respect to temperature, coal to carbonate ratio, and gas compositions in a coin type direct carbon fuel cell (DCFC).The raw coal used in this work was Berau bituminous supplied by KEPRI in Korea. Carbon was made in-house, for 2 hrs at 400oC under N2 environment. A coin type direct carbon fuel cell was fabricated by molten carbonate fuel cell technology. The diameter of electrodes was about 3 cm. The anode was porous Ni-Al alloy, and the cathode was porous Ni. The matrix was made of LiAlO2. The long alumina tube at the upside of the cell was installed for the coal supply to the anode. A mixture of 62 mol% Li2CO3 and 38 mol% K2CO3 was served as electrolyte. The cathode gas was 70 % air and 30 % CO2. More details of the DCFC operation was described in a previous work [1]. The normal H2 fuel for the anode was H2:CO2 = 0.125 L/min: 0.025 L/min with ca. 5 % of H2O. Temperature ranged from 923K to 1123K. Coal to carbonate ratios were 3g to 3g, 3g to 1g, and 1g to 3g. Gas compositions in the cell were analyzed with a gas chromatography (HP 5890II).Figures 1 and 2 show OCV behaviors of fuel change from the normal H2 fuel to carbon fuel and ash free coal, respectively at 650oC, 750oC, and 850oC. The carbon fuel was a mixture of 3 g of carbon and 3 g of Li-K carbonates, while the ash free coal was a mixture of 3 g coal and 3 g of Li-K carbonates. Before 0 s the OCV was determined by the H2 fuel. After 0 s the carbon fuel shows only one minimum in the OCV whereas the coal does two minimums. The difference was attributed to the different gas species that carbon produced mostly CO species, while the coal gave H2 and CO as dominant gas species. In particular, very low OCV is observed at carbon fuel of 650oC, which indicates that very small reaction species in the condition. Very low gasification of carbon is the reason at the condition. On the other hand, coal fuel shows much higher OCV at 650oC. Rather easy gasification of ash free coal can be the reason. The main gas species of coal were CO and H2 because the hydrocarbon species in the coal is readily gasified even at 650oC. Similar amounts of CO and H2 were measured at the coal fuel in the anode chamber. The H2gas is generally more active than CO gas in the oxidation. Then the difference in the oxidation process between coal and carbon can be existed. ACKNOWLEDGEMENT This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0009748).

Deep Removal of Methyl Mercaptan in Biogas

For a distributed PEMFC power station utilizing biogas as a source to produce hydrogen, deep desulfurization of the biogas is important. ZnO/γ-Al2O3 and CuO/γ-Al2O3 were prepared by an impregnation method, and their performances on CH3SH removal in the biogas have been studied. Results showed that CuO/γ-Al2O3 is able to remove CH3SH to below 10 ppb at 250-400 °C and has a sulfur capacity of 0.056 mmol g-1 at 300 °C. Regarding to the desulfurization mechanism, it has been confirmed that the removal of CH3SH with CuO/γ-Al2O3 is based on chemical adsorption. In the desulfurization, CH4s dry reforming took place at above 250 °C, and the generated H2 and CO reduced CuO to Cu2O and Cu. Further, it was supposed that H2S generates through the hydrogenation of CH3SH at the presence of H2.

Experimental Investigation of Biogas Reforming in Gliding Arc Plasma Reactors

Biogas is an important renewable energy source. Its utilization is restricted to vicinity of farm areas, unless pipeline networks or compression facilities are established. Alternatively, biogas may be upgraded into synthetic gas via reforming reaction. In this work, plasma assisted reforming of biogas was investigated. A laboratory gliding arc plasma setup was developed. Effects of CH4/CO2ratio (1, 2.33, 9), feed flow rate (16.67–83.33 cm3/s), power input (100–600 W), number of reactor, and air addition (0–60% v/v) on process performances in terms of yield, selectivity, conversion, and energy consumption were investigated. High power inputs and long reaction time from low flow rates, or use of two cascade reactors were found to promote dry reforming of biogas. High H2and CO yields can be obtained at low energy consumption. Presence of air enabled partial oxidation reforming that produced higher CH4conversion, compared to purely dry CO2reforming process.

Element Transformation and Gaseous Products Distribution for Lignite Gasification in Supercritical Water

Effects of factors on efficiencies of elements (C/H/N/S) and gaseous products were studied for lignite gasification in supercritical water. CO2, CH4and H2are main gaseous products. Temperature plays the most important role. With higher temperature, total efficiencies of lignite and elements have linear increasement, and yields of CO2, CH4and H2rise significantly while CO stays constant almostly. With pressure increasing, total efficiencies of lignite and elements are enhanced, and yields of CO2and CH4rise while change of H2and CO is small. With increasing of equivalence ratio of oxygen, efficiencies of C/H/N and lignite, yields of CO2and H2rise, but yield of CH4reduces. Increasing equivalence ratio of oxygen plays positive role in fixation of S on residues.

Hydrogen-Rich Gas Formation Characteristics under Microwave Catalytic Pyrolysis of Sewage Sludge

Microwave catalytic pyrolysis of sewage sludge were conducted on a single mode microwave reactor. The effects of CaO and steam on hydrogen-rich gas formation characteristics were analyzed. The results indicated that the CaO can improve the formation of H2and CO. When CaO in sewage sludge increased from 0 to 0.75 g/(g dried sludge), the H2and CO concentration increased from 62 vol.% to 77 vol.%, while CH4and CO2concentrations decreased from 28 vol.% to 9 vol.%. The steam can also improve the formation of H2and CO, with 1.59 g/min of the steam flowrate, the H2and CO concentration increased to the maximum of 81 vol.%, and the CH4and CO2concentration decreased to the minimum of 16 vol.%. When the steam gasification was coupled with the CaO catalyzing, the H2concentration can reach to 61 vol.%, which was 79.3% higher than the experimental conditions absent of steam and CaO.