共查询到20条相似文献,搜索用时 15 毫秒
1.
Nurul Huda Zamzuri Ramli Mat Nor Aishah Saidina Amin Amin Talebian-Kiakalaieh 《International Journal of Hydrogen Energy》2017,42(14):9087-9098
Supported Ni catalysts have been investigated for hydrogen production from steam reforming of glycerol. Ni loaded on Al2O3, La2O3, ZrO2, SiO2 and MgO were prepared by the wet-impregnation method. The catalysts were characterized by nitrogen adsorption–desorption, X-ray diffraction and scanning electron microscopy. The characterization results revealed that large surface area, high dispersion of active phase on support, and small crystalline sizes are attributes of active catalyst in steam reforming of glycerol to hydrogen. Also, higher basicity of catalyst can limit the carbon deposition and enhance the catalyst stability. Consequently, Ni/Al2O3 exhibited the highest H2 selectivity (71.8%) due to small Al2O3 crystallites and large surface area. Response Surface Methodology (RSM) could accurately predict the experimental results with R-square = 0.868 with only 4.5% error. The highest H2 selectivity of 86.0% was achieved at optimum conditions: temperature = 692 °C, feed flow rate = 1 ml/min, and water glycerol molar ratio (WGMR) 9.5:1. Also, the optimization results revealed WGMR imparted the greatest effect on H2 selectivity among the reaction parameters. 相似文献
2.
Xiaodong Wang Na Wang Maoshuai Li Shuirong Li Shengping Wang Xinbin Ma 《International Journal of Hydrogen Energy》2010
Thermodynamic features of hydrogen production by glycerol steam reforming with in situ hydrogen extraction have been studied with the method of Gibbs free energy minimization. The effects of pressure (1–5 atm), temperature (600–1000 K), water to glycerol ratio (WGR, 3–12) and fraction of H2 removal (f, 0–1) on the reforming reactions and carbon formation were investigated. The results suggest separation of hydrogen in situ can substantially enhance hydrogen production from glycerol steam reforming, as 7 mol (stoichiometric value) of hydrogen can be obtained even at 600 K due to the hydrogen extraction. It is demonstrated that atmospheric pressure and a WGR of 9 are suitable for hydrogen production and the optimum temperature for glycerol steam reforming with in situ hydrogen removal is between 825 and 875 K, 100 K lower than that achieved typically without hydrogen separation. Furthermore, the detrimental influence of increasing pressure in terms of hydrogen production becomes marginal above 800 K with a high fraction of H2 removal (i.e., f = 0.99). High temperature and WGR are favorable to inhibit carbon production. 相似文献
3.
《International Journal of Hydrogen Energy》2020,45(5):3509-3515
Steam reforming is the most favored method for the production of hydrogen. Hydrogen is mostly manufactured by using steam reforming of natural gas. Due to the negative environmental impact and energy politics, alternative hydrogen production methods are being explored. Glycerol is one of the bio-based alternative feedstock for hydrogen production. This study is aimed to simulate hydrogen production from glycerol by using Aspen Plus. First of all, the convenient reactor type was determined. RPlug reactor exhibited the highest performance for the hydrogen production. A thermodynamic model was determined according to the formation of byproduct. The reaction temperature, water/glycerol molar feed ratio as reaction parameters and reactor pressure were investigated on the conversion of glycerol and yield of hydrogen. Optimum reaction parameters are determined as 500 °C of reaction temperature, 9:1 of water to glycerol ratio and 1 atm of pressure. Reactor design was also examined. Optimum reactor diameter and reactor length values were determined as 5 m and 50 m, respectively. Hydrogen purification was studied and 99.9% purity of H2was obtained at 25 bar and 40 °C. The obtained results were shown that Aspen Plus has been successfully applied to investigate the effects of reaction parameters and reactor sizing for hydrogen production from glycerol steam reforming. 相似文献
4.
Ivana N. Buffoni Martín N. Gatti Gerardo F. Santori Francisco Pompeo Nora N. Nichio 《International Journal of Hydrogen Energy》2017,42(18):12967-12977
This work studies 2 wt% Pt catalysts. The support is a SiO2-C composite whose main features are a high specific surface due to its mesoporosity, a higher thermal stability than the C support, and the absence of surface acid sites which could promote the dehydration reactions that produce coke precursors. The Pt/SiO2-C catalyst has very small metallic particles (dva = 1.37 nm) that favor the CC bond cleavage reactions which allow obtaining total gas conversion at 450 °C. With this catalyst, it is possible to obtain high yields to H2, between 4 and 5, which indicates that the active sites promote the WGS reaction, even with glycerol concentrations of 30 and 50%. Pt/SiO2-C is a very stable catalyst since it loses only 10% of its initial activity after 66 h on stream and is resistant to sintering and coke deposition. 相似文献
5.
N.D. Charisiou G. Siakavelas K.N. Papageridis A. Baklavaridis L. Tzounis K. Polychronopoulou M.A. Goula 《International Journal of Hydrogen Energy》2017,42(18):13039-13060
In the present work, a comparative study of Ni catalysts supported on commercially available alumina and lanthana-alumina carriers was undertaken for the glycerol steam reforming reaction (GSR). The supports and/or catalysts were characterized by PZC, BET, ICP, XRD, NH3-TPD, CO2-TPD, TPR and SEM. Carbon deposited on the catalytic surface was characterized by SEM, TPO and Raman. Concerning the Ni/LaAl sample it can be concluded that the presence of lanthana by: (a) facilitating the active species dispersion, (b) strengthening the interactions between nickel species and support, (c) increasing of the basic sites' population and redistributing the acid ones in terms of strength and density, provides a catalyst with improved performance for the GSR reaction, in terms of activity, H2 production and long term stability. TPO and Raman indicate that the carbon on the Ni/LaAl catalyst was mostly amorphous and was deposited mainly on the support surface. For the Ni/Al catalyst, graphitic carbon was prevalent and likely covered its active sites. 相似文献
6.
The steam reforming of pyrolysis bio-oil is one proposed route to low carbon hydrogen production, which may be enhanced by combination with advanced steam reforming techniques. The advanced reforming of bio-oil is investigated via a thermodynamic analysis based on the minimisation of Gibbs Energy. Conventional steam reforming (C-SR) is assessed alongside sorption-enhanced steam reforming (SE-SR), chemical looping steam reforming (CLSR) and sorption-enhanced chemical looping steam reforming (SE-CLSR). The selected CO2 sorbent is CaO(s) and oxygen transfer material (OTM) is Ni/NiO. PEFB bio-oil is modelled as a surrogate mixture and two common model compounds, acetic acid and furfural, are also considered. A process comparison highlights the advantages of sorption-enhancement and chemical looping, including improved purity and yield, and reductions in carbon deposition and process net energy balance.The operating regime of SE-CLSR is evaluated in order to assess the impact of S/C ratio, NiO/C ratio, CaO/C ratio and temperature. Autothermal operation can be achieved for S/C ratios between 1 and 3. In autothermal operation at 30 bar, S/C ratio of 2 gives a yield of 11.8 wt%, and hydrogen purity of 96.9 mol%. Alternatively, if autothermal operation is not a priority, the yield can be improved by reducing the quantity of OTM. The thermodynamic analysis highlights the role of advanced reforming techniques in enhancing the potential of bio-oil as a source of hydrogen. 相似文献
7.
Hao Wang Xiaodong WangMaoshuai Li Shuirong LiShengping Wang Xinbin Ma 《International Journal of Hydrogen Energy》2009
In this work, thermodynamics was applied to investigate the glycerol autothermal reforming to generate hydrogen for fuel cell application. Equilibrium calculations employing the Gibbs free energy minimization were performed in a wide range of temperature (700–1000 K), steam to glycerol ratio (1–12) and oxygen to glycerol ratio (0.0–3.0). Results show that the most favorable conditions for hydrogen production are achieved with the temperatures, steam to glycerol ratios and oxygen to glycerol ratios of 900–1000 K, 9–12 and 0.0–0.4, respectively. Further, it is demonstrated that thermoneutral conditions (steam to glycerol ratio 9–12) can be obtained at oxygen to glycerol ratios of around 0.36 (at 900 K) and 0.38–0.39 (at 1000 K). Under these thermoneutral conditions, the maximum number of moles of hydrogen produced are 5.62 (900 K) and 5.43 (1000 K) with a steam to glycerol ratio of 12. Also, it should be noted that methane and carbon formation can be effectively eliminated. 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(78):33239-33258
A comparative study of 10 wt% Co-based catalysts supported on La2O3, AlZnOx and AlLaOx was performed for glycerol steam reforming (GSR). The catalysts physicochemical characterization was done through several techniques. All catalysts were screened in terms of catalytic activity and time-on-stream stability for GSR. The catalytic activity experiments aimed to assess the effect of temperature (400–700 °C) on the glycerol conversion and yield of gaseous products (H2, CO2, CO and CH4). Additionally, catalytic stability experiments were conducted at 625 °C to investigate deactivation of the catalysts, in which a drop in the activity was observed, especially for Co/La2O3. The glycerol conversion into gaseous products as a function of the time-on-stream was more affected for all catalysts in comparison to total glycerol conversion, being this effect assigned to the increase in the formation of liquid products and to the formation of coke. CoAlLaOx was observed to be more carbon-resistant, followed by CoAlZnOx, through the measurement of the quantity of carbonaceous species formed during the GSR experiments. A NiAlLaOx catalyst was also prepared and assessed in terms of catalytic stability for GSR; a stable behavior was observed throughout all experiment in relation to glycerol conversion into gaseous products and H2 yield. 相似文献
9.
10.
《International Journal of Hydrogen Energy》2020,45(60):34888-34917
This review focuses on the recent advances in CO2 adsorbents and H2 permselective membranes that can be integrated to catalytic ethanol and glycerol steam reforming for improving purity and throughput of H2, the key input of mobile and stationary fuel cells and of hydrogenation operations of conventional and bio–refining. Combined with the decentralized availability of ethanol and glycerol, integrated reforming–separation strategies offer the advantage of on–site production of pure H2 with environmental footprints, capital and operating expenses below those of the conventional natural–gas based steam reforming technologies. The review also covers metal organic framework membranes, the materials that offer fluxes significantly superior to those of the existing counterparts, in the context of their hydrothermal stability needed for steam reforming. 相似文献
11.
A thermodynamic analysis of hydrogen production via steam and autothermal reforming of beef tallow has been carried out via the Gibbs free energy minimization method. Equilibrium calculations are performed at atmospheric pressure with a wide range of temperatures (400–1200 °C), steam-to-beef tallow ratios (1–15) and oxygen-to-beef tallow ratios (0.0–2.0). 相似文献
12.
Hydrogen energy has attracted considerable attention because of its efficiency and environmental benefits, and the increasing demand requires finding renewable sources of raw materials to produce it. Glycerol, by-product of biodiesel production and coming from renewable raw materials, could be a bio-renewable substrate to produce hydrogen. The glycerol steam reforming to obtain hydrogen was evaluated using a 5.1 wt% Ni impregnated on Al2O3 catalyst, characterized by nitrogen adsorption, XRD, and FTIR. Deactivation processes were analyzed in successive cycles of reaction at 700 °C, atmospheric pressure, 5 h−1 WHSV, and 3:1 water:glycerol molar ratio, during 12 h. Between reaction cycles, regenerating took place using a He/Air stream. Hydrogen was the main product on the fresh catalyst, following by CO and CH4; during reaction, carbonaceous deposits deactivated catalyst, decreasing H2 and increasing both CO and CH4. Carbonaceous deposits were characterized by TPO, showing a main peak centered at 690 °C; the carbon content reached 11.9%. 相似文献
13.
Haisheng Chen Tianfu Zhang Bilin Dou Valerie Dupont Paul Williams Mojtaba Ghadiri Yulong Ding 《International Journal of Hydrogen Energy》2009,34(17):7208
A non-stoichiometric thermodynamic analysis is performed on the adsorption-enhanced steam reforming of glycerol for hydrogen production based on the principle of minimising the Gibbs free energy. The effects of temperature (600–1000 K), pressure (1–4 bar), water to glycerol feed ratio (3:1–12:1), percentage of CO2 adsorption (0–99%) and molar ratio of carrier gas to feed reactants (1:1–5:1) on the reforming reactions and carbon formation are examined. The results show that the use of a CO2 adsorbent enhances glycerol conversion to hydrogen and the maximum number of moles of hydrogen produced per mole of glycerol can be increased from 6 to 7 due to the CO2 adsorption. The analyses suggest that the most favourable temperature for steam–glycerol reforming is between 800 and 850 K in the presence of a CO2 adsorbent, which is about 100 K lower than that for reforming without CO2 adsorption. Although high pressures are favourable for CO2 adsorption, a lower operating pressure gives a higher overall hydrogen conversion. The most favourable water to glycerol feed ratio is found to be 9.0 above which the benefit becomes marginal. Carbon formation could occur at low water to glycerol feed ratios, and the use of a CO2 adsorbent can suppress the formation reaction and substantially reduce the lower limit of the water to glycerol feed ratio for carbon formation. 相似文献
14.
Thermodynamic analyses of cracking, partial oxidation (POX), steam reforming (SR) and oxidative steam reforming (OSR) of butane and propane (for comparison) were performed using the Gibbs free energy minimization method under the reaction conditions of T = 250–1000 °C, steam-to-carbon ratio (S/C) of 0.5–5 and O2/HC (hydrocarbon) ratio of 0–2.4. The simulations for the cracking and POX processes showed that olefins and acetylene can be easily generated through the cracking reactions and can be removed by adding an appropriate amount of oxygen. For SR and OSR of propane and butane, predicted carbon formation only occurred at low S/C ratios (<2) with the maximum level of carbon formation at 550–650 °C. For the thermal-neutral conditions, the TN temperatures decrease with the increase of the S/C ratio (except for O/C = 0.6) and the decrease of the O/C ratio. The simulated results for SR or OSR of propane and butane are very close under the investigated conditions. 相似文献
15.
In this paper the energetic optimization of a proton exchange membrane fuel cell integrated with a steam reforming system using ethanol as fuel is analysed. In order to obtain high hydrogen production, a thermodynamic analysis of the steam reforming process has been carried out and the optimal operating conditions has been defined. Moreover, the overall efficiency of the PEMFC-SR system has been investigated as a function of the fuel utilization factor and the effects of the anodic off-gas recirculation have been evaluated. 相似文献
16.
Hydrogen production from steam reforming of glycerol in a fluidized bed reactor has been simulated using a CFD method by an additional transport equation with a kinetic term. The Eulerian–Eulerian two-fluid approach was adopted to simulate hydrodynamics of fluidization, and chemical reactions were modelled by laminar finite-rate model. The bed expansion and pressure drop were predicted for different inlet gas velocities. The results showed that the flow system exhibited a more heterogeneous structure, and the core-annulus structure of gas–solid flow led to back-mixing and internal circulation behaviour, and thus gave a poor velocity distribution. This suggests the bed should be agitated to maintain satisfactory fluidizing conditions. Glycerol conversion and H2 production were decreased with increasing inlet gas velocity. The increase in the value of steam to carbon molar ratio increases the conversion of glycerol and H2 selectivity. H2 concentrations in the bed were uneven and increased downstream and high concentrations of H2 production were also found on walls. The model demonstrated a relationship between hydrodynamics and hydrogen production, implying that the residence time and steam to carbon molar ratio are important parameters. The CFD simulation will provide helpful data to design and operate a bench scale catalytic fluidized bed reactor. 相似文献
17.
Kuo-Hsin Lin Wen-Hsiung Lin Chia-Hsing Hsiao Hsin-Fu Chang Alex C.-C. Chang 《International Journal of Hydrogen Energy》2012
The aim of this study is to produce hydrogen through the glycerol steam reforming process. The reaction is carried out in a traditional reactor and an electrolessly plated Pd/Ag alloy membrane reactor, with varying reaction temperature, weight hourly specific velocity (WHSV) and water glycerol molar ratio (WGMR). The non-catalytic test was also employed for comparative purposes. The results show that the reaction is highly depending on temperature, and the maximum glycerol conversion achieved to 96.24% at 800 °C with a hydrogen yield of 5.82 mol-H2/mol-C3H8O3. It also found that the Pd/Ag membrane can effectively separate hydrogen from the reaction side and subsequently enhance the reaction rate in the membrane reactor. TGA measurements were employed to quantify the amounts of deposited carbon and the results also confirmed that the CeO2 modified catalyst can improve the carbon resistance as well as activity and stability. 相似文献
18.
Increasing biodiesel production has resulted in a glut of glycerin that has led to a precipitous drop in market prices. In this study, the use of glycerin as a biorenewable substrate for hydrogen production, using a steam reforming process, has been evaluated. Production of hydrogen from glycerin is environmentally friendly because it adds value to this byproduct generated from biodiesel plants. The study focuses on nickel-based catalysts with MgO, CeO2, and TiO2 supports. Catalysts were characterized with thermogravimetric analysis and X-ray diffraction techniques. Maximum hydrogen yield was obtained at 650 °C with MgO supported catalysts, which corresponds to 4 mol of H2 out of 7 mol of stoichiometric maximum. 相似文献
19.
Thermodynamics was applied to investigate propane dry reforming (DR) and steam reforming (SR). Equilibrium calculations employing the Gibbs free energy minimization were performed upon a wide range of pressure (1–5 atm), temperature (700–1100 K), carbon dioxide to propane ratio (CPR, 1–12) and water to propane ratio (WPR, 1–18). From a thermodynamic perspective, it is demonstrated that DR is promising for production of synthesis gas with low hydrogen content, as opposite to SR which favours generation of synthesis gas with high hydrogen content. Complete conversion of propane was obtained for the range of pressure, temperature, CPR and WPR considered in this study. Atmospheric pressure is shown to be preferable for both DR and SR. Approximately 10 mol of synthesis gas can be produced per mole of propane at a temperature greater than 1000 K from DR when CPR is higher than 6. The optimum conditions for synthesis gas production from DR are found to be 975 K (CPR = 3) for a H2/CO ratio of 1 and 1100 K (CPR = 1) for a H2/CO ratio of 2. The greatest CO2 conversion (95%) can be obtained also at 1100 K and CPR = 1. Preferential conditions for hydrogen production from SR are achieved with the temperatures between 925 and 975 K and WPRs of 12–18. The maximum number of moles of hydrogen produced is 9.1 (925 K and WPR = 18). Under conditions that favour hydrogen production, methane and carbon formation can be eliminated to negligible level. 相似文献
20.
《International Journal of Hydrogen Energy》2020,45(43):22448-22458
NiZrAl layered double hydroxides (LDH) precursors were synthesized by co-precipitation and homogeneous precipitation processes. The introduction of hydrothermal treatment into crystallization showed its significant influences on structure of LDH as well as mixed-metal oxides after thermal decomposition. The characterization results showed that the catalysts prepared by hydrothermal synthesis involved bigger pore diameter of ca. 13.5 nm and wider pore size distribution of 2–60 nm, and hydrothermal treatment was helpful to enhance the reduction of NiO species weakly interacted with support and to enhance the interaction among the metal oxides. Although the Ni dispersion, the surface area as well as the ability of anti-sintering were evidently improved, the ability of coke resistance decreased by 2 times for samples prepared by co-precipitation and by nearly 10 times for the ones prepared by homogeneous precipitation due to the enlarged pores. The maximum value of conversion to gaseous products (96.5%) and minimum deposited coke (36 mgc/gcat.) were achieved on NiZrAl-u sample. 相似文献