Autothermal Reforming Of Methane Research Articles

Spectroscopic and kinetic insights into the methane reforming over Ce-pyrochlores

High thermal stability and oxygen conductivity of pyrochlores makes them a potential catalyst for the dry reforming of methane (DRM). In this study, noble metal (Pt, Ru) substituted Ce2Zr2O7 and Ce2Ti2O7 pyrochlores have been synthesized by modified Pechini method. The effect of variation of dopant concentration and position was examined to achieve strong metal-support interaction. Ce2Zr1.96Pt0.04O7-δ exhibited the best catalytic activity towards DRM and hence, been studied for partial oxidation (POM) and autothermal reforming of methane (ATR). Syngas ratio (H2/CO) was tuned by varying the O2 concentration in the feed. Insights obtained from both ex-situ and in situ characterization were exploited to discern the reaction mechanism. The surface intermediates were examined by DRIFTS on Ce2Zr1.96Pt0.04O7-δ for DRM, POM and ATR. Besides adsorbed CH4 and CO on Pt, the presence of carbonate and formate species were also identified. Thus, a dual-site mechanism via carbonate and formate formation was proposed for DRM over Ce2Zr1.96Pt0.04O7-δ.

Hydrogen Energy Production from Advanced Reforming Processes and Emerging Approaches

AbstractNo abstract.

Development of Supported Ni Catalysts for Autothermal Reforming of Methane

Development of Supported Ni Catalysts for Autothermal Reforming of Methane

Development of Supported Ni Catalysts for Autothermal Reforming of Methane

Development of Supported Ni Catalysts for Autothermal Reforming of Methane

H2S Poisoning and Regeneration of a Nickel Spinellized Catalyst Prepared from Waste Metallurgical Residues, During Dry Autothermal Methane Reforming

The purpose of this work was to test the resistance to H2S of the nickel upgraded slag oxides (Ni-UGSO), a recent patented catalyst prepared from a negative value metallurgical residue. A previous lab-scale (0.3 g of catalyst) study highlighted that at atmospheric pressure the optimal conditions of autothermal methane reforming, using the Ni-UGSO catalyst are molar CH4/CO2 = 3, CH4/O2 = 2, at 850 °C and GHSV = 4500 ml/h/kg(STP). The present work was performed at these conditions and studied Ni-UGSO deactivation when exposed to 275 ppm of H2S. Two regeneration methods have been assessed: self-regeneration and the regeneration by calcination. At the test conditions, the deactivation of Ni-UGSO took approximatively 2 h with an exponential decrease of CH4 conversion from 92 to 44% (steady state value) and proved reversible. With the regeneration by calcination method, the full activity of the catalyst has been recovered while the self-regeneration led to a partial recovery of the initial activity (77% CH4 conversion). In presence of H2S, Ni-UGSO did not completely deactivate because : (1) its activity is due to a synergistic effect of many elements (not only Ni0) and (2) H2S feeding created a stable equilibrium between Ni0 and NiS, leading to a steady state where Ni-UGSO did not completely lose its activity. In the self-regeneration regime, the lack of H2S along with the reduction environment leads to a conversion of the majority of NiS into Ni0; since a part of NiS remained, this type of regeneration is partial. As opposed to the above, the oxidative calcination regime worked better because, in presence of oxygen, all sulfur is removed as SO2 and SO3, while calcination leads to the reformation of the initial Ni-UGSO structure through Ni spinellization. This new catalyst appears as a potential good competitor of those described in the literature and used in industry, because, while most of them deactivate completely in presence of H2S, Ni-UGSO, in presence of 275 ppm of H2S loose partly its activity. Its high resistance to hydrogen sulphide and its easy regeneration are highlighted in this article.

The characterization of NiO-CoO/MgO catalyst for autothermal reforming of methane

The characterization of NiO-CoO/MgO catalyst for autothermal reforming of methaneThe drawback of conventional reforming of methane such as partial oxidation and steam reforming was carbon formation. The research was developed a suitable catalyst for combination of partial and steam reforming of methane and called autothermal reforming to reduce the coke formation. The NiO-CoO/MgO catalysts were prepared by an impregnation method and characterized by Temperature Programmed Reduction (TPR), X-ray Diffraction (XRD) and Thermal Gravitymetry Analysis (TGA). The TPR and XRD results reveal that the catalyst characteristic is strongly influenced by the Co/Ni ratio. From TPR and TGA analysis, the sintering phenomena did not occur in the autothermal reforming of methane. The results reveal that Co/Ni ratios have a small effect in the catalytic activity for autothermal reforming. Nevertheless, the catalyst showed an optimum performance in this process when its Co/Ni ratio was 0.75. Keywords: Autothermal ReformingAbstrakMasalah yang terjadi pada proses konvensional reformasi metana seperti oksidasi parsial metana dan reformasi kukus adalah pembentukan karbon. Penelitian yang dilakukan adalah mengembangkan katalis yang sesuai untuk gabungan proses oksidasi parsial dan reformasi kukus atau yang disebut reformasi metana secara autothermal. Katalis NiO-CoO/MgO yang digunakan dibuat dengan metode impregnasi dan dilakukan pengujian dengan TPR, XRD dan TGA untuk mengetahui sifat-sifat dari katalis tersebut. Hasil TPR dan XRD menunjukkan bahwa karakteristik dari katalis sangat dipengaruhi oleh perbandingan CoiN i. Hasil pengamatan TPR dan TGA menunjukan bahwa sintering tidak terjadi di dalam proses reformasi metana secara autothermal. Hasil eksperimen juga menunjukan bahwa perbandingan Co/Ni hanya kecil pengaruhnya pada unjuk kerja katalis. Namun demikian katalis menunjukan unjuk kerja yang optimum pada perbandingan CoiN i = 0.75. Kata Kunci: Reformasi Autothermal

Robust model predictive control of a catalytic autothermal methane reformer for fuel cell applications

Model uncertainty is an inseparable part of a methane reforming process since many of its main parameters describe microscale behavior. A robust control approach for a catalytic fuel reformer is presented to guarantee performance constraints are met even in the presence of model uncertainty. The control strategy is based on a recently developed sampling-based robust model predictive control (RMPC) with a new approach to capturing the uncertainty. Particular features of the control strategy is the use of a metric for coking susceptibility as a constraint on the inlet gas composition, a cost based metric for evaluating decisions on controller commands, and the ability to meet constraints on reactor temperature, outlet gas energy content, and hydrogen to carbon monoxide ratio. Simulation results carried out in MATLAB on random plants show the constraints are met regardless the model uncertainty and measurement noise.

Properties of methane autothermal reforming to generate hydrogen in membrane reactor based on thermodynamic equilibrium model

Methane reforming reaction is one of the most important industrial chemical processes for hydrogen production. Membrane reactor has better performance of methane reforming reaction, can effectively increase methane conversion and hydrogen yield. To utilize this technology more effectively, it is necessary to develop a better understanding of the process of hydrogen generation and the effects of various parameters on the performance of membrane reactor. The characteristics of methane autothermal reforming to generate hydrogen in membrane reactor are studied with the thermodynamic equilibrium model. The results show that increasing permeate side pressure leads to reducing methane conversion and hydrogen permeability. Retentate side pressure has little effect on methane autothermal reforming reaction. The increase of air-methane molar ratio leads to a lower hydrogen production. The hydrogen production increases firstly and then decreases with the elevated steam-methane molar ratio. The H2/CO molar ratio can be regulated by the steam-methane molar ratio. Methane autothermal reforming occurs much more easily when temperature of 973 K, retentate side pressure and permeate side pressure of 0.1 MPa and 0.02 MPa, and the molar ratio of air-methane and steam-methane of 1 and 2 respectively.

Electrodeposition of NiPd Alloy in Alkaline Ni2+ – Pd2+ – Cl– – NH3 – H2O System

Synthesis of NiPd alloy is investigated in many research centers in the world mainly due to its interesting properties making possible its application as magnetic and catalytic materials. NiPd alloys were investigated also as catalysts in autothermal reforming of methane (1), counter electrode electrocatalyst in liquid-junction solar cells (2), utilization of CO2 and methane in dry reforming process (3), anodes in methanol oxidation (4) and toluene hydrogenation (5). Exchange current density versus the enthalpy of hydrogen adsorption (Log(i0)-dGMe-H) dependence allows on assumption that material composed of Ni and Pd will exhibit high catalytic properties towards hydrogen evolution reaction (HER). Previously we reported studies on electrochemical co-deposition of nickel with palladium from acidic solutions containing aquachloro- complexes of both elements (6) as well as palladium with cobalt (7, 8) and nickel with molybdenum (9). In literature, in spite of its wide application range, few reports exist concerning electrodeposition of NiPd alloys. Existing reports are focused on synthesis of NiPd alloys from suplphate-chloride (5), ethylenediamine (4) and chloride (6) based baths. In present work authors reported studies focused on electrochemical deposition in alkaline ammonia based system for first time. Described studies were started from thermodynamic and UV-Vis analysis enabling qualitative description of analysed system. Electrochemistry of Ni2+ – Pd2+ – Cl– – NH3 – H2O system was analyzed based on results of cyclic voltammetry combined with electrochemical quartz crystal microbalance (EQCM). In further step synthesized alloys were characterized towards their compositions (WD-XRF), morphology (SEM, AFM), structure (XRD) and catalytic properties towards HER.

Modeling of autothermal reforming of methane in a fluidized bed reactor with perovskite membranes

The performance of perovskite membrane-assisted fluidized bed reactors for ultra-high purity hydrogen production through autothermal reforming of methane has been investigated using numerical simulations. Two different three-phase phenomenological models have been developed differing in their description of the mass transfer between the membranes and the emulsion, cloud and bubble phases, where the parameters in the oxygen permeation flux expression were determined from new experimental data. The calculation of the required oxygen-to-carbon ratio is based on overall enthalpy balance. The reactor performance without and with O2 permeable perovskite membranes have been investigated and compared. The two models of perovskite membrane-assisted fluidized bed reactors produce basically the same results, indicating that the external mass transfer from the membranes to the bulk of the fluidized bed is not rate limiting, but clearly show that the fluidized bed membrane reactor can largely outperform ordinary fluidized bed reactors for the autothermal reforming of methane. It has been demonstrated that with perovskite membrane-assisted fluidized bed reactors autothermal operation with a high CH4 conversion and H2 yield can be achieved with a relatively small catalyst inventory.

Comparison of conventional and spherical reactor for the industrial auto-thermal reforming of methane to maximize synthesis gas and minimize CO2

Auto-thermal reforming (ATR), a combination of exothermic partial oxidation and endothermic steam reforming of methane, is an important process to produce syngas for petrochemical industries. In a commercial ATR unit, tubular fixed bed reactors are typically used. Pressure drop across the tube, high manufacturing costs, and low production capacity are some disadvantages of these reactors. The main propose of this study is to offer an optimized radial flow, spherical packed bed reactor as a promising alternative for overcoming the drawbacks of conventional tubular reactors. In the current research, a one dimensional pseudo-homogeneous model based on mass, energy, and momentum balances is applied to simulate the performance of packed-bed reactors for the production of syngas in both tubular and spherical reactors. In the optimization section, the proposed work explores optimal values of various decision variables that simultaneously maximize outlet molar flow rate of H2, CO and minimize molar flow rate of CO2 from novel spherical reactor. The multi-objective model is transformed to a single objective optimization problem by weighted sum method and the single optimum point is found by using genetic algorithm. The optimization results show that the pressure drop in the spherical reactor is negligible in comparison to that of the conventional tubular reactor. Therefore, it is inferred that the spherical reactor can operate with much higher feed flow rate, more catalyst loading, and smaller catalyst particles.

Application of POSS Nanotechnology for Preparation of Efficient Ni Catalysts for Hydrogen Production

POSS (polyhedral oligomeric silsesquioxanes) nanotechnology was applied for preparation of efficient Ni catalysts for hydrogen production through autothermal reforming of methane (ATR of CH4). The novel metal-POSS precursor [Nickel (II) ‒ HeptaisobutylPOSS (C4H9)7Si7O9(OH)O2Ni] of Ni nanoparticles was introduced into Ce0.5Zr0.5O2 support with following calcination and reduction stages of activation. The peculiarity of the genesis of Ni/SiO2/Ce0.5Zr0.5O2nanomaterials and their characteristics versus deposition mode were studied by X-ray fluorescence spectroscopy, thermal analysis, N2adsorption, X-ray diffraction, high-resolution transmission electron microscopy and H2 temperature-programmed reduction. The two kinds of supported Ni-containing particles were observed: highly dispersed Ni forms (1‒2 nm) and large Ni-containing particles (up to 50‒100 nm in size). It was demonstrated that the textural, structural, red-ox and, consequently, catalytic properties of ex-Ni-POSS catalysts depend on the deposition mode. The increase of a portion of difficultly reduced Ni2+species is found upon application of intermediate calcination during Ni-POSS deposition that has detrimental effect on the activity of catalyst in ATR of CH4. The Ni/SiO2/Ce0.5Zr0.5O2 catalyst prepared by one-step Ni-POSS deposition exhibits the highest H2 yield ‒ 80% at T = 800 °C.

Process thermoneutral point in dry autothermal reforming for CO2 utilization

Dry autothermal reforming is a novel CO2 utilization process. Thermoneutral points are considered to be the best operating points in autothermal reforming reactors. A theoretical study was done to determine the process thermoneutral points for complete dry autothermal reforming process considering the basic preheater, reactor and condenser configuration. The results were compared to the product yields at reactor thermoneutral points for the same input feed and temperature conditions. The process thermoneutral points were found be better for operational reasons than reactor thermoneutral points. Dry autothermal reforming of methane was used as model example in this study. This study can be used for different autothermal processes to calculate the optimum conditions at which the process can be operated in heat integrated loop without the need of any external thermal energy.

Ce promoting effect on the activity and coke formation of Ni catalysts supported on mesoporous nanocrystalline γ-Al2O3 in autothermal reforming of methane

In this study methane autothermal reforming (ATR) was investigated over Ni/Al2O3 and Ni/Al2O3–CeO2 catalysts. The catalyst carriers were prepared through a facile one-step method, which produced mesoporous nanocrystalline carriers for Ni catalysts. The samples were characterized by XRD, TPR, BET, TPO and SEM characterization techniques and the catalytic activity and stability were also studied at different conditions (GHSV and feed ratio) in methane ATR. It was found that the nickel catalyst supported on 3 wt.% Ce–Al2O3 exhibited higher activity compared to the catalysts supported on the Al2O3 and promoted Al2O3 with 1 and 6 wt.% Ce. The results also showed that the nickel catalyst supported on 3 wt.% Ce–Al2O3 possessed the highest resistance against carbon deposition in ATR reaction.

Process Intensification in Fuel Cell CHP Systems, the ReforCELL Project

This paper reports the findings of a FP7/FCH JU project (ReforCELL) that developed materials (catalysts and membranes) and an advance autothermal membrane reformer for a micro Combined Heat and Power (CHP) system of 5 kWel based on a polymer electrolyte membrane fuel cell (PEMFC). In this project, an active, stable and selective catalyst was developed for the reactions of interest and its production was scaled up to kg scale (TRL5 (TRL: Technology Readiness Level)). Simultaneously, new membranes for gas separation were developed. In particular, dense supported thin palladium-based membranes were developed for hydrogen separation from reactive mixtures. These membranes were successfully scaled up to TRL4 and used in lab-scale reactors for fluidized bed steam methane reforming (SMR) and autothermal reforming (ATR) and in a prototype reactor for ATR. Suitable sealing techniques able to integrate the different membranes in lab-scale and prototype reactors were also developed. The project also addressed the design and optimization of the subcomponents (BoP) for the integration of the membrane reformer to the fuel cell system.

Low temperature synthesis of metal doped perovskites catalyst for hydrogen production by autothermal reforming of methane

Platinum and rhodium doped CeAlO3 perovskites catalysts have been synthesized by adopting citric acid method at much lower temperature than the high temperature traditional solid state route. Systematic characterization of the precursors at various stages was attempted by XRD, BET, XPS, TEM and SEM-EDS analyses to confirm the structure and properties of the perovskites. These catalysts were evaluated in autothermal reforming of methane for hydrogen production. The results showed that the CH4 conversion was 99% at 650 °C which enhanced after the incorporation of Pt in Rh doped CeAlO3 perovskites. Compared to monometallic Rh catalysts, RhPt bimetallic catalysts exhibit superior catalytic performance in the methane steam reforming due to synergetic effect. The noble metals such as Pt and Rh are stabilized in its ionic form as they are locked in the structure (preventing sintering of metal particles and catalyst deactivation), thus yielding highly stable catalysts under highly reducing conditions.

Experimental investigation of methane auto-thermal reforming in hydrogen-permeable membrane reactor for pure hydrogen production

An experimental investigation was investigated in order to assess the performance of the methane auto-thermal reforming (MATR) for hydrogen production over a nickel catalyst on an alumina support in both a traditional reactor (TR) and a membrane reactor (MR). The results show that the property of the reformer is dependent on the reformer temperature, the feed flow rate, the purge gas flow rate and the mole ratio of air-methane and steam-methane. The performance of the membrane reactor is better than the traditional reactor. The optimum conditions for high methane conversion and high hydrogen yield are air-methane and steam-methane mole ratio of 1 and 2, respectively. Under these conditions, a methane conversion of 96.13%, a hydrogen yield of 70.43% and hydrogen permeation rate of 81.61% can be achieved. Experimental results in terms of methane conversion, hydrogen yield and hydrogen permeation rate were compared with the traditional reactor and literature data.

Hydrogen production by autothermal reforming of methane over lanthanum chromites modified with Ru and Sr

The partial substitution of La by Sr in lanthanum chromites (La1−ySryCr0.85Ru0.15O3, y = 0.01, 0.02, 0.05) produced changes in the size, insertion degree of Ru and oxygen vacancies of the perovskite structure. The surface and structural modifications of the La1−ySryCr0.85Ru0.15O3 perovskites brought about by substitution of La by Sr directly affected the catalytic behaviour of the perovskites in the autothermal reforming of methane (ATR). It was found that all La1−ySryCr0.85Ru0.15O3 perovskites showed excellent ATR activity that it increased with the Sr substitution degree in the perovskite. The most active Sr-substituted chromite also showed high stability and thiotolerance in the long ATR durability test in the presence of 50 ppm of sulphur. Characterization of used samples revealed not only good structural stability of the Sr-substituted perovskites under the ATR conditions but also absence of carbon deposition on the surface of used catalyst in the ATR reaction.

Process Intensification via Membrane Reactors, the DEMCAMER Project

This paper reports the findings of a FP7 project (DEMCAMER) that developed materials (catalysts and membranes) and new processes for four industrially relevant reaction processes. In this project, active, stable, and selective catalysts were developed for the reaction systems of interest and their production scaled up to kg scale (TRL5 (TRL: Technology Readiness Level)). Simultaneously, new membranes for gas separation were developed; in particular, dense supported thin palladium-based membranes for hydrogen separation from reactive mixtures. These membranes were successfully scaled up to TRL4 and used in various lab-scale reactors for water gas shift (WGS), using both packed bed and fluidized bed reactors, and Fischer-Tropsch (FTS) using packed bed reactors and in prototype reactors for WGS and FTS. Mixed ionic-electronic conducting membranes in capillary form were also developed for high temperature oxygen separation from air. These membranes can be used for both Autothermal Reforming (ATR) and Oxidative Coupling of Methane (OCM) reaction systems to increase the efficiency and the yield of the processes. The production of these membranes was scaled up to TRL3–4. The project also developed adequate sealing techniques to be able to integrate the different membranes in lab-scale and prototype reactors.

Preparation and characterization of mesoporous nanocrystalline La-, Ce-, Zr-, Sr-containing Ni[sbnd]Al2O3 methane autothermal reforming catalysts

The promotion effect of La, Ce, Sr and Zr on the catalytic and structural properties of nanocrystalline mesoporous γ-Al2O3 supported Ni catalysts was investigated in autothermal reforming of methane. Mesoporous nanocrystalline γ-Al2O3 powder and promoted ones with high specific surface area (>220 m2/g) were prepared by solid state reaction method and employed as the support for nickel catalysts. The prepared catalysts were subjected to autothermal reforming reaction and characterized by XRD, BET, DR-UV-Vis, TPR, TPO and SEM techniques before and/or after the reaction. The effect of experimental conditions, such as temperature was investigated on the catalysts. Ce promoted catalyst, containing small amounts of CeO2 as a separate phase, was found the most effective catalyst between both promoted and unpromoted ones.