共查询到20条相似文献,搜索用时 15 毫秒
1.
D.G. Avraam T.I. Halkides D.K. Liguras O.A. Bereketidou M.A. Goula 《International Journal of Hydrogen Energy》2010
An experimental and theoretical study for the biogas steam reforming reaction over 5%Ru/Al2O3 catalyst have been performed. An apparatus was constructed for the conduction of the experiments, the core of which was a tube reactor, filled with the catalyst in form of pellets. The inlet gas mixture consisted of CH4 and CO2 in various composition ratios as a model biogas and steam. A theoretical model of the process was developed. The experimental reactor was modelled as an isothermal pseudo homogeneous fixed bed reactor. Internal and external transport phenomena were neglected and appropriate effectiveness factors were employed instead. A physical properties model was used for the calculation of the physicochemical properties of the real mixture. Five reactant species, CH4, CO2, H2O, CO and H2, were included in the model, whereas the feed consisted of the first three. Steam reforming and water gas shift were the main reactions. Experimental results and theoretical predictions match closely, stability of the catalyst was assured and an optimal operational window was identified, at GHSV = 10,000–20,000 h−1, T = 700–800 °C, CH4/CO2 = 1.0–1.5 and H2O/CH4 = 3.0–5.0. 相似文献
2.
V. Chiodo S. Maisano G. Zafarana F. Urbani 《International Journal of Hydrogen Energy》2017,42(3):1622-1628
This study reports the influence of biogas poisoning on a Ni based catalyst working under steam reforming conditions (atmospheric pressure, T = 1073 K and H2O/CH4 = 2 mol/mol). A biogas stream composed by CH4 and CO2 with a ratio 55/45 vol.%, added with different chemical species (H2S, hydrocarbons mixture and D5) as contaminants, was used as inlet gas stream.First, effect of poisoning on Ni catalyst were separately evaluated and the boundary concentrations for each contaminants were revealed (0.4 ppm, 200 ppm and 0.5 ppm for H2S, hydrocarbons and D5 respectively) to assure Ni stable performances on time on stream (100 h at 50,000 h?1 of GHSV). Successively, a comparison between Ni catalytic behaviors in presence of two combined poisoning in the biogas (H2S + Hydrocarbons and Hydrocarbons + D5) was carried out.It was found that the effect of combined poisoning, even though it considered in moderate concentration, is harmful for Ni catalyst activity. Methane conversion on time on stream was reduced from 86% to 40% after 50 h, when the couple of poisoning Hydrocarbons + D5 was added to the inlet gas stream, while a lower deactivation pattern (about 73%) was leaded by couple H2S + Hydrocarbons. Both poisoning mixtures promoted coke deposition on Ni catalyst surface (about ≥0.5 mgC/gcat·h) independently by poisoning chemical characteristics probably due to adsorption/deposition of contaminants on catalytic sites. 相似文献
3.
《International Journal of Hydrogen Energy》2022,47(88):37542-37551
A green template-free method is proposed for the synthesis of mesoporous Ni–Cu/Al2O4 catalyst in sub-kilogram scale. In the convenient synthetic method, an intermediate is formed via electrostatic forces and hydrogen bonding interactions between the aluminate ions and the metal ions and/or metal hydroxides under suitable pH conditions. The desired Ni–Cu/Al2O4 composites, with Ni/Cu molar ratios of 10%, 20% and 30% of Cu at Cu/Al molar ratio of 10.0%, respectively, are then obtained from calcination. The nitrogen adsorption-desorption isotherms show that the Ni–Cu/Al2O4 composites have specific surface areas of 136–170 m2g-1. The Ni–Cu/Al2O4 products are used as catalyst materials in the methanol steam reforming (MSR) of hydrogen and are shown to have a high conversion efficiency (>99%), a low methane concentration, good stability, and a high hydrogen yield (H2/methanol molar ratio ≈ 3.0) at low reaction temperatures in the range of 200–300 °C. In addition, the coke formation on the catalyst surface is less than 1.0 wt% even after a reaction time of 30 h. Notably, the Ni–Cu/Al2O4 catalyst can be regenerated by calcination at 800 °C and retains a high methanol conversion efficiency of close to >99% when reused in MSR. 相似文献
4.
Abhimanyu K. Yadav Prakash D. Vaidya 《International Journal of Hydrogen Energy》2017,42(40):25203-25212
Steam reforming of biomass-derived oxygenates is an attractive technique for the renewable production of hydrogen (H2). In this work, steam reforming of n-butanol – a representative of bio-oxygenates – was studied over commercial 5% Ru/Al2O3 catalyst in a fixed-bed reactor. Kinetics of butanol reforming was investigated between temperatures 623 and 773 K at steam/carbon (S/C) ratio equal to 33.3 mol/mol. The W/FA0 ratio (W: mass of catalyst, FA0: molar flow rate of butanol in feed) was varied between 3.3 and 16.7 g h/mol. At T = 773 K, butanol conversion and H2 yield were 93.4% and 0.61 mol/mol. Evaluation of the kinetic data showed that reaction order with respect to butanol was unity. The activation energy for the investigated reaction was 78 kJ/mol. Finally, a Langmuir-Hinshelwood model that assumed the surface reaction between the adsorbed reactants as rate-determining was used to describe the kinetic data. 相似文献
5.
Yuchen Gao Ayub Golmakani Seyed Ali Nabavi Jianguo Jiang Vasilije Manovic 《International Journal of Hydrogen Energy》2021,46(24):12835-12845
Biogas dry reforming is a promising technology for converting biomass into high-value products and reducing greenhouse gas emissions. Recent improvements to biogas reforming have mainly focused on the preparation of functional catalysts; however, little attention has been paid to the effects of catalyst configuration in plug flow reactors. In this study, a Ni/MgO catalyst for biogas reforming was synthesized via the wet impregnation method. Parameters were optimized using an experimental rig and then simulations were performed using an Aspen HYSYS reaction simulator. We simulated loading the same amount of catalyst into 1, 2, 3, or 10 zones inside the reactor and compared performance parameters, including H2 yield, CO yield, CH4 conversion, and CO2 conversion. The results of simulations showed that a 2-zone configuration with a catalyst ratio of 1:4 was optimal, with 88.2% H2 yield, 83.5% CO yield, 96.4% CH4 conversion, and 91.7% CO2 conversion. Catalyst zone number, catalyst distribution, and catalyst zone position all had significant effects on catalytic behavior. The findings of this study provide new insights into the processes of biogas reforming and other heterogeneous catalysis reactions. 相似文献
6.
F. Gallucci A. Basile S. Tosti A. Iulianelli E. Drioli 《International Journal of Hydrogen Energy》2007
In this work a comparison between methanol steam reforming (MSR) reaction and ethanol steam reforming (ESR) reaction to produce hydrogen in membrane reactors (MRs) is discussed from an experimental point of view. 相似文献
7.
《International Journal of Hydrogen Energy》2022,47(84):35709-35722
As a significant by-product of many thermochemical and biological waste conversion processes, acetic acid (AcOH) is often investigated as model feedstock in the production of sustainable hydrogen from non-fossil sources. The kinetics of its steam reforming were extracted from packed bed reactor experiments over an industrially produced 14 wt% Ni/Ca-Al2O3 catalyst at atmospheric pressure. The model consisting of AcOH steam reforming producing CO2 and H2, AcOH decomposition to CO and H2, and water gas shift, achieved the best fit, reflected in the lowest average relative errors (ARE) with experimental results, with ARE values below 5.4% and 6.4% on AcOH and water conversions respectively, and below 4% on H2 mol fraction. This model was validated away from equilibrium using additional experimental points, as well as for a wide range of equilibrium conditions with varying temperature (600–700 °C) and feed molar steam to carbon ratios (3–8) at atmospheric pressure using an independent method. 相似文献
8.
《International Journal of Hydrogen Energy》2019,44(28):14416-14423
In this study, mesoporous CuFe/silicate catalysts were obtained from a simultaneously mixing the NaOH and metal-ion solution to sodium silicate solution and a hydrothermal treatment under alkaline condition without using any organic template. During hydrothermally reaction, the amorphous metal-silicate would reconstruct and formation of the mesostructured CuFe/silicate. At appropriate pH values, the silicate species can strongly bind with the Cu2+ ions to form the stable CuFe/silicate, and the [Cu2+] in the final filtrated solution is lower than the effluent standard in Taiwan (1.0 ppm). To find the appropriate synthetic parameters, the effects of the pH value, metal to silicate ratio, and the hydrothermal treatment time on the surface areas and mesostructure of the resulted CuFe/silicates were discussed in detail. In practice, the mesoporous CuFe/silicate catalyst with high surface area of 547 m2g-1 demonstrated a high methanol conversion within 1 h up to >99% at 180 °C to be used as high-performance catalysts for steam reformer of methanol. 相似文献
9.
《International Journal of Hydrogen Energy》2022,47(4):2412-2422
The effect of regeneration conditions on the cyclic sorption-enhanced steam reforming of ethanol (SESRE) in a fixed-bed reactor was investigated. Columnar Ni–Ca catalysts were used in the cyclic SESRE experiments. The effects of different parameters, including temperature, purge direction, and purge gas on the regeneration process were discussed. The experimental results reveal that the regeneration temperature strongly affected not only the CO2 desorption rate but also the durability of the CaO sorbent. The stability of the CaO sorbent within the Ni–Ca catalyst was improved owing to the formation of Ca12Al14O33. Moreover, the type of purge gas (N2 or air) for regeneration had negligible effect on the CO2 capture performance of the Ni–Ca catalyst. For regeneration by air purging, coke decomposition over the Ni–Ca catalyst was accompanied by a slight decline in the activity of the Ni catalyst, which was attributed to the cyclic Ni redox. 相似文献
10.
《International Journal of Hydrogen Energy》2022,47(72):30843-30860
Olivine, a natural mineral consisting of different metal oxides (mainly Mg, Si and Fe oxides) was used as a support for nickel catalyst used in steam reforming of ethanol. Catalyst containing different wt% of Ni on olivine were prepared by conventional wet-impregnation method and characterized by BET, XRD, SEM (coupled with EDS) and H2-TPR. The reaction was carried out in a tubular fixed bed reactor. Among all the catalysts, 5% Ni on olivine catalyst gave highest hydrogen yield as well as ethanol conversion through ethanol steam reforming reaction. The catalyst activity was analyzed by varying three important process parameters (temperature, ethanol to water molar ratio and space-time). The reaction was performed in the temperature range of 450 °C to 550 °C with 1:6 to 1:12 M feed ratio of ethanol to water at a space-time range 7.21–15.87 kg cat h/kmol ethanol. A maximum yield of 4.62 mol of hydrogen per mole of ethanol reacted was obtained at 550 °C with ethanol to steam molar ratio of 1:10 and space-time of 7.94 kg cat h/kmol ethanol with the ethanol conversion level of 97%. CHNS analysis of the spent catalyst was performed to find the coke deposited over the catalyst surface during the reaction. The power law and LHHW type kinetic models were developed. The power law model predicts the activation energy as 29.07 kJ/mol, whereas the LHHW type model gives the activation energy as 27.4 kJ/mol. 相似文献
11.
Kantilal Chouhan Shishir Sinha Shashi Kumar Surendra Kumar 《International Journal of Hydrogen Energy》2021,46(53):26809-26824
The paper aims to investigate the steam reforming of biogas in an industrial-scale reformer for hydrogen production. A non-isothermal one dimensional reactor model has been constituted by using mass, momentum and energy balances. The model equations have been solved using MATLAB software. The developed model has been validated with the available modeling studies on industrial steam reforming of methane as well as with the those on lab-scale steam reforming of biogas. It demonstrates excellent agreement with them. Effect of change in biogas compositions on the performance of industrial steam reformer has been investigated in terms of methane conversion, yields of hydrogen and carbon monoxide, product gas compositions, reactor temperature and total pressure. For this, compositions of biogas (CH4/CO2 = 40/60 to 80/20), S/C ratio, reformer feed temperature and heat flux have been varied. Preferable feed conditions to the reformer are total molar feed rate of 21 kmol/h, steam to methane ratio of 4.0, temperature of 973 K and pressure of 25 bar. Under these conditions, industrial reformer fed with biogas, provides methane conversion (93.08–85.65%) and hydrogen yield (1.02–2.28), that are close to thermodynamic equilibrium condition. 相似文献
12.
Bahador Nabgan Tuan Amran Tuan Abdullah Muhammad Tahir Walid Nabgan Sugeng Triwahyono Aishah Abdul Jalil Yahya Gambo Maryam Ibrahim Kamal Moghadamian 《International Journal of Hydrogen Energy》2017,42(34):21571-21585
The effect of different pellet sizes of nickel (Ni) and lanthanum (La) promoted Al2O3 support on the catalytic performance for selective hydrogen production from polyethylene terephthalate (PET) plastic waste via steam reforming process has been investigated. The catalysts were prepared by impregnation method and were characterized using XRD, BET, TPD-CO2, TPR, SEM, EDX, TEM and TGA. The results showed that NiLa-co-impregnated Al2O3 catalyst has excellent activity for the production of hydrogen. Feed conversion of 88.53% was achieved over 10% Ni/Al2O3 catalyst which increased to 95.83% in the case of 10% Ni-5% La/Al2O3 catalysts with a H2 selectivity of 70.44%. The catalyst performance in term of gas production and feed conversion was further investigated under various operating parameters, e.g., feed flow-rate, and catalyst pellet size. It was found that at 0.4 ml/min feed flow rate, highest feed conversion and H2 selectivity were achieved. The Ni particles, which are the noble-based active species are highly effective, thus offered good hydrogen production in the phenol-PET steam reforming process. Incorporation of La as a promoter in Ni/Al2O3 catalyst has significantly increased the catalyst reusability with prolonged stability. The NiLa/Al2O3 catalyst with larger size showed remarkable activity due to the presence of significant temperature gradients inside the pellet compared to smaller size. Additionally, the catalyst showed only slight decrease in H2 selectivity and feed conversion even after 24 h, although production of carbon nanotubes was evidenced on its surface. 相似文献
13.
A Ni based catalyst supported on a cordierite monolithic substrate was applied to the autothermal reforming (ATR) of biogas to produce hydrogen. When the feed rates of oxygen and steam were constant, the Steam/CH4 (S/CH4) and O2/CH4 ratios changed because of an increase or decrease in the methane concentration of the biogas. The concentration of methane in the biogas fluctuates roughly between 35% and 65% according to factors such as the properties or amount of the waste. Therefore, the effect of S/CH4 and O2/CH4 ratios on catalyst durability was confirmed by using actual biogas, which was produced by anaerobic fermentation of biomass at the biogasification bench-scale plant in Kyoto. Reforming reactions were carried out at ratios of S/CH4 = 0–4, O2/CH4 = 0.5 and at S/CH4 = 2, O2/CH4 = 0.6. The S/CH4 range of 0–2.0 and the O2/CH4 range of 0.5–0.6 had no effect on the catalyst durability and a S/CH4 ratio of more than 3.0 led to decreased catalytic performance. 相似文献
14.
《International Journal of Hydrogen Energy》2023,48(55):21224-21239
The self-regeneration of Ni-based catalysts has been considered as a promising approach to maintain not only a continuous but also economical process. However, the effect of catalyst nature, operating temperature, amount and types of carbon deposits on the effectiveness of the in-situ regeneration is still not well-investigated. Therefore, in this work, the self-regeneration ability of the undoped and Dy-doped Ni/SiO2 catalysts, which were prepared by the same impregnation method, were examined in the dry reforming of methanol. The physicochemical properties of the fresh and spent catalysts were analyzed by various techniques such as X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H2-TPR), oxygen temperature-programmed desorption (O2-TPD), transmission electron microscopy (TEM), N2-BET isothermal adsorption. The nature and chemical reactivity of coke deposits formed during dry reforming at various temperatures (550, 600, and 650 °C) and the regeneration possibility of used catalysts through CO2 gasification at these temperatures were investigated by the in-situ temperature-programmed gasification by CO2 (TPCO2). The Dy additive significantly improves the dispersion of the nickel active sites of Ni/SiO2 catalyst, as demonstrated by the decreased Ni crystal size as well as the increased specific surface area and reduction degree of the catalyst. Furthermore, Dy promotion increases the quantity of oxygen vacancies and the nature of oxygen species, thereby improving the catalyst activity and stability. Specifically, methanol conversion dropped from 93% to 96%–61% and 31% for undoped Ni/SiO2 at 600 °C and 650 °C, respectively and from about 99% to 87% (at 600 °C) and 52% (at 650 °C) for Dy-doped catalyst. 相似文献
15.
Transition metal catalysts widely used in refineries are provided as oxides and require pre-reduction to become activated. The auto-reduction of a NiO/Al2O3 catalyst with acetic acid (HAc) followed by HAc steam reforming was investigated in a packed bed reactor. Effects of temperature and molar steam to carbon ratio (S/C) on reduction kinetics and catalyst performance were analysed. Results showed that a steady steam reforming regime along with complete NiO reduction could be obtained after a coexistence stage of reduction and reforming. A 2D nucleation and nuclei growth model fitted the NiO auto-reduction. The maximum reduction rate constant was attained at S/C = 2. Steam reforming activity of the auto-reduced catalyst was just below that of the H2-reduced catalyst, probably attributed to denser carbon filament formation and larger loss of active Ni. Despite this, a H2 yield of 76.4% of the equilibrium value and HAc conversion of 88.97% were achieved at 750 °C and S/C = 3. 相似文献
16.
Lorena Espinoza Fabián Guerrero Nicolás Ripoll Mario Toledo Lorna Guerrero Andrea Carvajal Andrea Barahona 《International Journal of Hydrogen Energy》2018,43(33):15693-15702
Biogas conversion to syngas (mainly H2 and CO) is considered an upgrade method that yields a fuel with a higher energy density. Studies on syngas production were conducted on an inert porous media reactor under a filtration combustion mode of biogas with steam addition, as a non-catalytic method for biogas valorization. The reactor was operated under a constant filtration velocity of 34.4 cm/s, equivalence ratio of 2.0, and biogas concentration of 60 vol% Natural Gas/40 vol% CO2, while the steam to carbon ratio (S/C) was varied between 0.0 and 2.0. Total volumetric flow remained constant at 7 L/min. Combustion wave temperature and propagation rate, product gas composition, reactants conversion as well as H2 and CO selectivity were measured as a function of S/C ratio. Chromatographic parameters, method validation and measurement uncertainty were developed and optimized. It was observed that S/C ratio of 2.0 gave optimal results under studied conditions for biogas conversion, leading to maximum concentrations of 10.34 vol% H2, 9.98 vol% CO and highest thermal efficiency of 64.2% associated with a modified EROI of 46.3%, which considered energy consumption for steam supply. Conclusions indicated that the increment of the steam co-fed with the reactants favored the non-catalytic conversion of biogas and thus resulted in an effective fuel upgrading. 相似文献
17.
Clémence Fauteux-LefebvreNicolas Abatzoglou Nadi BraidyInes Esma Achouri 《Journal of power sources》2011,196(18):7673-7680
Liquid hydrocarbons (LC) are considered as fuel cells feed and, more particularly, as solid oxide fuel cell feed. Cost-effective LC-reforming catalysts are critically needed for the successful commercialization of such technologies. An alternative to noble metal catalysts, proposed by the authors in a previous publication, has been proven efficient for diesel steam reforming (SR). Nickel, less expensive and more readily available than noble metals, was used in a form that prevents deactivation. The catalyst formulation is a Ni-alumina spinel (NiAl2O4) supported on alumina (Al2O3) and yttria-stabilized zirconia (YSZ).SR of commercial diesel was undertaken for more than 15 h at high gas hourly space velocities and steam-to-carbon ratios lower than 2. Constant diesel conversion and high hydrogen concentrations were obtained. Ni catalyst characterization revealed no detectable amounts of carbon on the spinel catalyst surface Ni. The effect of catalyst composition (Ni concentration and YSZ presence) was studied to understand and optimize the developed catalyst. Two phenomena were found to be influenced by relative catalyst composition: water-gas-shift vs reforming reaction extent, and concentration of light hydrocarbons in products. 相似文献
18.
The experiments of reforming the methane of coke-oven gas with steam were performed. The effects of the thermodynamic factors, such as the H2O/CH4 ratio, the conversion temperature (T) of methane and the reaction time (t), on the methane conversion rate have been investigated. The experimental results show that the H2O/CH4 ratio within the range of 1.1–1.3 and the temperature 1223–1273 K are the reasonable thermodynamic conditions for methane conversion. A methane conversion of more than 95% can be achieved when the H2O/CH4 ratio is 1.2, the conversion temperature is above 1223 K and the conversion time is up to 15 s respectively. In additional, kinetic data of different reaction conditions were measured, and a dynamic model of methane conversion was proposed and verified. All results demonstrated that the results of the dynamic models agree well with the experiments, of which the deviation is less than 1.5%. 相似文献
19.
Bahador Nabgan Muhammad Tahir Tuan Amran Tuan Abdullah Walid Nabgan Yahya Gambo Ramli Mat Ibrahim Saeh 《International Journal of Hydrogen Energy》2017,42(16):10708-10721
Ni/Pd-co-promoted Al2O3–La2O3 catalysts for selective hydrogen production from polyethylene terephthalate (PET) plastic waste via steam reforming process has been investigated. The catalysts were prepared by impregnation method and were characterized using XRD, BET, TPD-CO2, TPR-H2, SEM, TGA and DTA. The results showed that Ni-Pd-co-impregnated Al2O3–La2O3 catalyst has excellent activity for the production of hydrogen with a prolong stability. The feed conversion of 87% was achieved over 10% Ni/Al2O3 catalyst which increased to 93.87% in the case of 10% Ni-1% Pd/Al2O3–La2O3 catalysts with an H2 fraction of 0.60. The catalyst performance in term of H2 selectivity and feed conversion was further investigated under various operating parameters, e.g., temperatures, feed flow rates, feed ratios and PET concentrations. It was found that the temperature has positive effects on H2 selectivity and conversion, yet feed flow rate has the adverse effects. In addition, PET concentrations showed improved in H2 selectivity in comparison to when only phenol as a solvent was involved. The Ni particles, which are the noble-based active species are more effective, thus offered good hydrogen production in the PET steam reforming process. Incorporation of La2O3 as support and Pd as a promoter to the Ni/Al2O3 catalyst significantly increased catalyst stability. The Ni–Pd/Al2O3–Al2O3 catalyst showed remarkable activity even after 36 h along with the production of carbon nanotubes, while H2 selectivity and feed conversion was only slightly decreased. 相似文献
20.
Fahad Maqbool Syed Z. Abbas Sergio Ramirez-Solis Valerie Dupont Tariq Mahmud 《International Journal of Hydrogen Energy》2021,46(7):5112-5130
Kinetic data relevant to steam methane reforming (SMR) are often applied to catalysts and conditions for which they have not been derived. In this work, kinetic rates for the two SMR and water gas shift reactions were derived for 12 commonly used reforming catalysts based on conversion data obtained from the literature. Subsequently, these rates were tested in dynamic operation, steady-state, and equilibrium using a 1-D reactor model developed in-house with gPROMS model builder. Modelling outputs were further validated independently at equilibrium using the software chemical equilibrium with applications (CEA), and the literature. The effect of variables such as temperature, pressure, steam to carbon ratio (S/C), and gas mass flux (Gs) on the performance of the SMR process was then studied in terms of fuel and steam conversion (%), H2 purity (%), H2 yield (wt. % of CH4) and selectivity of the carbon-based products. A comparative study was then performed for the 12 catalysts. Some catalysts showed better activity owing to their fast kinetics when they are tested in mild industrial conditions, while others performed better in more severe industrial conditions, substantiating that the choice of a catalyst ought to depend on the operating conditions. 相似文献