A method for identifying coalbed methane co-production interference based on production characteristic curves: A case study of the Zhijin block, western Guizhou, China

Efficient detection of coalbed methane(CBM) co-production interference is the key to timely adjusting the development plan and improving the co-production efficiency. Based on production data of six typical CBM co-production wells in the Zhijin block of western Guizhou Province, China, the production characteristic curves, including production indication curve, curve of daily water production per unit drawdown of producing fluid level with time, and curve of water production per unit differential pressure with time have been analyzed to explore the response characteristics of co-production interference on the production characteristic curves. Based on the unit water inflow data of pumping test in coal measures, the critical value of in-situ water production of the CBM wells is 2 m^(3)/(d·m). The form and the slope of the initial linear section of the production indication curves have clear responses to the interference, which can be used to discriminate internal water source from external water source based on the critical slope value of 200 m^(3)/MPa in the initial linear section of the production indication curve. The time variation curves of water production per unit differential pressure can be divided into two morphological types: up-concave curve and down-concave curve. The former is represented by producing internal water with average daily gas production greater than 800 m^(3)/d, and the latter produces external water with average daily gas production smaller than 400 m^(3)/d. The method and critical indexes for recognition of CBM co-production interference based on the production characteristic curve are constructed. A template for discriminating interference of CBM co-production was constructed combined with the gas production efficiency analysis, which can provide reference for optimizing co-production engineering design and exploring economic and efficient co-production mode.

Catalytic carbon dioxide hydrogenation to methane: A review of recent studies

Recently, various efforts have been put forward on the development of technologies for the synthesis of methane from CO2 and H-2, since it can offer a solution for renewable H-2 storage and transportation. In parallel, this reaction is considered to be a critical step in reclaiming oxygen within a closed cycle. Over the years, extensive fundamental research works on CO2 methanation have been investigated and reported in the literatures. In this updated review, we present a comprehensive overview of recent publications during the last 3 years. Various aspects on this reaction system are described in detail, such as thermodynamic considerations, catalyst innovations, the influence of reaction conditions, overall catalytic performance, and reaction mechanism. Finally, the future development of CO2 methanation is discussed. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Pretreatment of Rice Straw by Hydrogen Peroxide for Enhanced Methane Yield

A pretreatment process for hydrogen peroxide （H2O2） was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time （PT）, H2O2 concentration （HC）, and substrate to inoculum ratio （S/I） on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC （w/w total solid）, and 1.08 S/I; these conditions result in a methane yield of 288 mL g-1 volatile solids （VS）. A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g-1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.

Intensification of methane and hydrogen storage inclathrate hydrate and future prospect

Gas hydrate is a new technology for energy gas（methane/hydrogen）storage due to its large capacity of gas storage and safe.But industrial application of hydrate storage process was hindered by someproblems.For methane,the main problems are low formation rateand storage capacity,which can be solved by strengthening mass andheat transfer,such as adding additives,stirring,bubbling,etc.Onekind of additives can change the equilibrium curve to reduce the formation pressure of methane hydrate,and the other kind of additivesis surfactant,which can form micelle with water and increase the interface of water-gas.Dry water has the similar effects on the methanehydrate as surfactant.Additionally,stirring,bubbling,and sprayingcan increase formation rate and storage capacity due to mass transferstrengthened.Inserting internal or external heat exchange also canimprove formation rate because of good heat transfer.For hydrogen,the main difficulties are very high pressure for hydrate formed.Tetrahydrofuran（THF）,tetrabutylammonium bromide（TBAB） andtetrabutylammonium fluoride（TBAF） have been proved to be able todecrease the hydrogen hydrate formation pressure significantly.

Hydrogen and syngas production from two-step steam reforming of methane using CeO_2 as oxygen carrier

CeO2 oxygen carrier was prepared by precipitation method and tested by two-step steam reforming of methane （SRM）. Two-step SRM for hydrogen and syngas generation is investigated in a fixed-bed reactor. Methane is directly converted to syngas at a H2/CO ratio close to 2 ： 1 at a high temperature （above 750 °C） by the lattice oxygen of CeO2; methane cracking is found when the reduction degree of CeO2 was above 5.0% at 850 °C in methane isothermal reaction. CeO2？δ obtained from methane isothermal reaction can split water to generate CO-free hydrogen and renew its lattice oxygen at 700 °C; simultaneously, deposited carbon is selectively oxidized to CO2 by steam following the reaction （C＋2H2O→CO2＋2H2）. Slight deactivation in terms of amounts of desired products （syngas and hydrogen） is observed in ten repetitive two-step SRM process due to the carbon deposition on CeO2 surface as well as sintering of CeO2.

Conversion of Methane to C_2 Hydrocarbons and Hydrogen Using a Gliding Arc Reactor

Methane conversion has been studied using gliding arc plasma in the presence of argon.The process was conducted at atmospheric pressure and ambient temperature.The focus of this research was to develop a process of converting methane to C2 hydrocarbons and hydrogen. The main parameters,including the CH4/Ar mole ratio,the CH4 flow rate,the input voltage,and the minimum electrode gap,were varied to investigate their effects on methane conversion rate, product distribution,energy consumption,carbon deposit,and reaction stability.The specific energy requirement（SER） was used to express the energy utilization efficiency of the process and provided a practical guidance for optimizing reaction conditions for improving energy efficiency. It was found that the carbon deposition was not conducive to methane conversion,and the gliding arc plasma discharge reached a stable state twelve minutes later.Optimum conditions for methane conversion were suggested.The maximum methane conversion rate of 43.39%was obtained under the optimum conditions.Also,C2 hydrocarbons selectivity,C2 hydrocarbons yield,H2 selectivity, H2 yield and SER were 87.20%,37.83%,81.28%,35.27%,and 2.09 MJ/mol,respectively.

Catalytic decomposition of methane to produce hydrogen:A review

The increasing demands of hydrogen and the recent discovery of large reserves of methane have prompted the conversion of methane to hydrogen.The challenges raised by intensive CO_(2) emission from the traditional conversion of methane have provoked emission-free hydrogen production from methane.The catalytic decomposition of methane(CDM) to produce hydrogen and advanced carbon hence comes into consideration due to the short process and environmental benignity.Although many researchers have made considerable progress in CDM research on the laboratory scale,CDM is still in its infancy in industrialization.The history of its development,fundamental mechanisms,and recent research progress in catalysts and catalytic systems are herein highlighted.The problems of catalytic interface degradation are reviewed,focusing on deactivation from coke deposition in the CDM process.The introduction of a liquid phase interface which can in-situ remove carbon products provides a new strategy for this process.Furthermore,the challenges and prospects for future research into novel CDM catalysts or catalyst systems are included.

CO_x-Free Hydrogen and Carbon Nanofibers Produced from Direct Decomposition of Methane on Nickel-Based Catalysts

Direct decomposition of methane was carried out using a fixed-bed reactor at 700 ℃ for the production of COx-free hydrogen and carbon nanofibers. The catalytic performance of NiO-M/SiO2 catalysts （where M=AgO, CoO, CuO, FeO, MnOx and MoO） in methane decomposition was investigated. The experimental results indicate that among the tested catalysts, NiO/SiO2 promoted with CuO give the highest hydrogen yield. In addition, the examination of the most suitable catalyst support, including Al2O3, CeO2, La2O3, SiO2, and TiO2, shows that the decomposition of methane over NiO-CuO favors SiOx support. Furthermore, the optimum ratio of NiO to CuO on SiO2 support for methane decomposition was determined. The experimental results show that the optimum weight ratio of NiO to CuO fell at 8：2 （w/w） since the highest yield of hydrogen was obtained over this catalyst.

Perovskite-type oxygen-permeable membrane BaCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) for partial oxidation of methane in coke oven gas to hydrogen

Perovskite-type oxygen-permeable membrane reactors of BaCo0.7Fe0.2Nb0.1O3-δ （BCFNO） packed with Ru-based catalyst had high oxygen permeability and could be used for hydrogen production by partial oxidation of methane in coke oven gas （COG）. At 1173 K, 94% of methane conversion, 85% of H2 selectivity, 107% of CO selectivity, and as high as 15.4 mL·cm^-2·min^-1 of oxygen permeation flux were obtained. The BCFNO membrane itself had poor catalytic activity to partial oxidation of CH4 in COG. During continuous operation for 70 h at 1173 K, no degradation of the membrane reaction performance was observed. XRD and SEM characterization also demonstrated that the BCFNO membrane reactor exhibited good stability in partial oxidation of methane in COG.

Catalytic performances of Ni/mesoporous SiO_2 catalysts for dry reforming of methane to hydrogen

Several mesoporous silicas with different morphologies were controllably prepared by sol-gel method with adjustable ratio of dual template, and they were further impregnated with aqueous solution of nickel nitrate, followed by calcination in air. The synthesized silica supports and supported nickel samples were characterized using N2-adsorption/desorption, X-ray diffraction (XRD), H2temperature-programmed reduction (H2-TPR), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and thermo-gravimetric analysis (TGA-DTG) techniques. The Ni nanoparticles supported on shell-like silica are highly dispersed and yielded much narrower nickel particle-size than those on other mesoporous silica. The methane reforming with dioxide carbon reaction results showed that Ni nanoparticles supported on shell-like silica carrier exhibited the better catalytic performance and catalytic stability than those of nickel catalyst supported on other silica carrier. The thermo-gravimetric analysis on used nickel catalysts uncovered that catalyst deactivation depends on the type and nature of the coke deposited. The heterogeneous nature of the deposited coke was observed on nickel nanoparticles supported on spherical and peanut-like silica. Much narrower and lower TGA derivative peak was founded on Ni catalyst supported on the shell-like silica. © 2016 Science Press

Methane Coupling Using Hydrogen Plasma and Pt/γ-Al_2O_3 Catalyst

In this paper, methane coupling at ambient temperature, under atmospheric pressure and in the presence of hydrogen was firstly investigated by using pulse corona plasma and Pt/g-Al2O3 catalyst. Experimental results showed that Pt/g-Al2O3 catalyst has catalytic activity for methane coupling to C2H4. Over sixty percent of outcomes of C2 hydrocarbons were detected to be ethylene.

Oxidative reforming of methane for hydrogen and synthesis gas production:Thermodynamic equilibrium analysis

A thermodynamic analysis of methane oxidative reforming was carried out by Gibbs energy minimization （at constant pressure and temperature） and entropy maximization （at constant pressure and enthalpy） methods,to determine the equilibrium compositions and equilibrium temperatures,respectively.Both cases were treated as optimization problems （non-linear programming formulation）.The GAMS 23.1 software and the CONOPT2 solver were used in the resolution of the proposed problems.The hydrogen and syngas production were favored at high temperatures and low pressures,and thus the oxygen to methane molar ratio （O 2 /CH 4） was the dominant factor to control the composition of the product formed.For O 2 /CH 4 molar ratios higher than 0.5,the oxidative reforming of methane presented autothermal behavior in the case of either utilizing O 2 or air as oxidant agent,but oxidation reaction with air possessed the advantage of avoiding peak temperatures in the system,due to change in the heat capacity of the system caused by the addition of nitrogen.The calculated results were compared with previously published experimental and simulated data with a good agreement between them.

Plasma-assisted Ru/Zr-MOF catalyst for hydrogenation of CO2 to methane

As an important type of metal-organic framework(MOF),Zr-MOF shows excellent CO2 adsorption performance.In this work,a Zr-MOF was synthesized by a solvothennal method and adopted to support Ru through simple incipient-wetness impreg nation.Then the Ru/Zr-MOF was applied for CO2 hydrogenation(Vh2:VCO2=4:1)with the assistance of dielectric banner dischai'ge(DBD)plasma.The hydrogenation of Cd2 results showed that methane was produced selectively under the synergistic effect between plasma and the Ru/Zr-MOF catalyst,and the selectivity and yield of methane reached 94.6%and 39.1%,respectively.The XRD and SEM analyses indicate that the basic crystalline phase structure and morphology of the Zr-MOF and Ru/Zr-MOF remained the same after DBD plasma treatment,suggesting that the catalysts are stable in plasma.The guest molecules in the pores of the Zr-MOF are removed and the Ru"ions are reduced to metallic Ru()in the reduction atmosphere according to the BET and XPS results,which are responsible for the high performance of plasma with the Ru/Zr-MOF catalyst.In situ optical emission spectra of pure plasma,plasma with Zr-MOF,and plasma with Ru/Zr-MOF were measured,and the active species of C,H and CH for CO2 hydrogenation were detected.The plasma-assisted Ru/Zr-MOF exhibited high catalytic activity and stability in CO2 hydrogenation to methane,and it has great guiding significance for CO2 hydrogenation by using plasma and MOF materials.

Formation of hydrogen in oxidative coupling of methane over BaCO_3 and MgO catalysts

Hydrogen formed in oxidative coupling of methane （OCM） over BaCO3 and MgO catalysts was measured since the data of H2 selectivity were missing almost in all articles published heretofore. It was found that H2 selectivity achieved about 18%, when C2 hydrocarbon＇s selectivity was maintained at 48%-45% over BaCO3 catalyst at the feed molar ratio of CH4/O2 = 4 in temperature range of 780 °C-820 °C. Under similar conditions, H2 selectivity was about 14%-16% over MgO catalyst, with C2 selectivity maintained at 41%-42%. Possible routes for hydrogen formation in OCM reaction were discussed. Effect of addition of alkali metallic ions was also investigated.

Conversion of Methane to Hydrogen via Pulsed Corona Discharge

Experiments are performed to develop a pulsed corona discharge system for the conversion of methane to hydrogen at atmospheric pressure (≈760 Torr) without using a catalyst. The corona discharge was energized by 10-12 μs wide voltage pulses (≤7 kV) at a repetition rate of about 1.0-1.5 kHz. The residual gases were characterized by mass spectrometry. The conversion of methane is as high as 50.8% producing the 70% yield of hydrogen. The influences of argon on the discharge of methane were studied. This result could be useful for the mass production of hydrogen in both academic and industrial point of view.

Efficient and Eco-friendly Process for the Synthesis of Bi(indolyl)methanes Catalyzed by Sodium Hydrogensulfate Monohydrate in Ionic Liquid n-Butylpyridinium Tetrafluoroborate

Efficient electrophilic substitution reaction of indoles with various aromatic aldehydes were carried out with a catalytic amount of sodium hydrogensulfate monohydrate （NaHSO4·H20） in ionic liquid n-butylpyridinium tetrafluoroborate （[Bpy]BF4） to afford the corresponding bi（indolyl）methanes in excellent yields. The notable advantages of this protocol in terms of low cost of catalyst and ionic liquid, mild conditions, simple operation, short reaction time, high yields and recycling of the ionic liquid.

Hydrogen and methane gases are frequently detected in the stomach

AIM： To investigate the incidence of bacterial overgrowth in the stomach by using a new endoscopic method in which intragastric hydrogen and methane gases are collected and analyzed. METHODS： Studies were performed in 490 consecutive patients undergoing esophagogastroscopy, At endoscopy, we intubated the stomach without inflation by air, and 20 mL of intragastric gas was collected through the biopsy channel using a 30 mL syringe, Intragastric hydrogen and methane concentrations were immediately measured by gaschromatography, H pylori infection was also determined by serology. RESULTS： Most of intragastric hydrogen and methane levels were less than 15 ppm （parts per million）. The median hydrogen and methane values （interquartile range） were 3 （1-8） ppm and 2 （1-5） ppm, respectively. The high hydrogen and methane levels for indication of fermentation were decided if the patient had the values more than 90 percentile range in each sample. When a patient had a high level of hydrogen or methane in one or more samples, the patient was considered to have fermentation. The overall incidence of intragastric fermentation was 15.4% （73/473）, Intragastric methane levels were higher in the postoperative group than in other groups. None of the mean hydrogen or methane values was related to Hpylori infection. CONCLUSION： Hydrogen and methane gases are more frequently detected in the stomach than expected, regardless of the presence of abdominal symptoms. Previous gastric surgery influences on the growth of methaneproducing bacteria in the fasting stomach.

Effects of ceramsite on methane and hydrogen sulphide productions from macroalgae biomass

The easy acidification and high hydrogen sulfide （H2S） production during anaerobic digestion of macroalgae limited its application in biomethane production. In order to investigate the effects of ceramsite on methane and HzS productions during anaerobic digestion of macroalgae, batch experiments ofMacrocystis pyrifera were carried out. Four groups named C0, C1, C2 and C3 added with 0, 1.5, 3.0 and 4.5 g/g substrate of ceramsite, respectively, were studied and compared. The highest cumulative methane yield of 286.3 mL/g substrate is obtained in C2, which is 40.11% higher than that of CO. The cumulative HzS yields of C1, C2 and C3 are 32.67%, 44.66% and 53.21% lower than that of CO, respectively. Results indicate that ceramsite addition permits higher methane yields, shorter lag-phase time and lower HzS yields during anaerobic digestion of Macrocystispyrifera.

Effects of Promoters on the Ignition Process over NiO/Al_2O_3 Catalyst for Autothermal Reforming of Methane to Hydrogen

The catalysts Ni/Al2O3, Ni/ZrO2-CeO2-Al2O3 and Ni/CuO-ZrO2-CeO2-Al2O3 were prepared by the co-precipitation method at a pH of 9 using Na2CO3 as the precipitant. The Ni loading(mass fraction) of the catalysts was 10%. The ignition process on the catalysts for the autothermal reforming of methane to hydrogen was investigated and the surface properties of the catalysts were characterized by XPS. The results showed that the Ni/Al2O3 catalyst could not ignite the process of autothermal reforming of methane to hydrogen. However, the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst could ignite the process of autothermal reforming of methane to hydrogen at lower reaction temperature(650 ℃) with the conversion of methane reaching 76%. The result of XPS analysis indicated that the promoters could change the binding energy(BE) of Ni2p3/2 obviously. The species of Cu in the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst comprised Cu2 O and Cu2+. The formation of ZrO2-CeO2 solid solution and a large amount of Cu2 O might be the reason leading to good oxygen storage capacity and mobility of lattice oxygen of the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst, which could ignite the process of autothermal reforming of methane to hydrogen at lower reaction temperature.

Methane Steam Reforming on Supported Nickel, Effect of Nickel Content for Product Hydrogen

The steam reforming of methane over NiO/ZnO mixed oxides with different nickel contents was studied. Solids to x% Ni/ZnO (x = 4 and 10%) were deposited on ZnO by impregnation from nickel nitrate solution;after vaporization the solid is calcined at 500°C for 6 h. The catalysts were characterized by X-ray diffraction (XRD) and BET method, scanning electron microscopy (SEM) and temperature programmed reduction (TPR). The XRD patterns revealed the NiO phase for all calcined catalysts. The chemical analysis confirmed the theoretical values of nickel. The catalysts were pre-treated under hydrogen at 500°C in situ, overnight before testing for the steam reforming of methane reaction (CH4/H2O/Ar = 10/10/80) in the temperature range (475°C - 650°C) under atmospheric pressure. The activities of both catalysts were investigated in a fixed-bed reactor for the Methane Steam Reforming (MSR) reaction. Globally, it was shown that the catalyst 10% nickel content has an important effect on the catalytic performances of solids i.e. the better results of hydrogen production were obtained with 10% wt. Ni/ZnO (28 ′ 10-3 mol/g catalyst).