Anis H. Fakeeha

Effects of Selected Promoters on Ni/Y-Al2O3 Catalyst Performance in Methane Dry Reforming

The Ni catalysts supported on γ-Al2O3 were synthesized by an impregnation method. Their catalytic performance in methane dry reforming was investigated. The reforming reactions were carried out in a microreactor using a CO2:CH4 feed ratio of 1:1, a F/W = 2640 ml/(h·g), reaction temperatures between 500-850 (C, and at atmospheric pressure. The influence of Ca, Ce, and Zr promoters on catalyst stability, coke deposition, and the H2/CO ratio were also studied. Effluents were analyzed using an online gas chromatograph equipped with a thermal conductivity detector. The spent and fresh catalysts were characterized by scanning electron microscopy and thermogravimetric analysis. It was found that 3%Ni/γ-Al2O3 promoted with 0.15% Ce and 0.05% Ca gave the best performance and resulted in less coke formation. The highest CH4 and CO2 conversion activities were found to be 94.1% and 98.3% at 850 (C, respectively. Stability tests were carried out for 130 h and this provided a H2 yield of 91%. Moreover, the amount of formed carbon was negligible and did not increase to more than 1.5 wt%.

Separation of BTEX aromatics from n-octane using a (tetrabutylammonium bromide + sulfolane) deep eutectic solvent – experiments and COSMO-RS prediction

Separation of aromatics from aliphatics is a challenging process because of the close range of their boiling points and the formation of several combinations of azeotropes. Until now, no feasible separation process is available for aromatic concentrations below 20 wt%. In this work, we have investigated the possibility of using a selected deep eutectic solvent (DES) for the liquid–liquid extraction of benzene, toluene, ethylbenzene and m-xylene (BTEX) aromatics. The DES used in this work was synthesized by combining tetrabutylammonium salt and sulfolane. Equilibrium data for the ternary system consisting of BTEX aromatics, n-octane and DES were measured at 25 °C and atmospheric pressure. The results showed that the used DESs have comparable distribution ratios and selectivities to those of commercial solvents. In all tested systems, sulfolane was not present in the hydrocarbon layer. It was also found that the selectivity decreases with decreasing polarity of the aromatic compound. The Non-Random Two Liquid (NRTL) model was successfully used to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems. In addition, the performance of COSMO-RS to predict the ternary tie-lines for the studied systems was evaluated and the σ-profiles were used to explain the interaction between the DES and the aromatic compounds.

Role of La2O3 as Promoter and Support in Ni/γ-Al2O3 Catalysts for Dry Reforming of Methane

Abstract The nature of support and type of active metal affect catalytic performance. In this work, the effect of using La2O3 as promoter and support for Ni/γ-Al2O3 catalysts in dry reforming of methane was investigated. The reforming reactions were carried out at atmospheric pressure in the temperature range of 500–700 °C. The activity and stability of the catalyst, carbon formation, and syngas (H2/CO) ratio were determined. Various techniques were applied for characterization of both fresh and used catalysts. Addition of La2O3 to the catalyst matrix improved the dispersion of Ni and adsorption of CO2, thus its activity and stability enhanced.

Stabilities of zeolite-supported Ni catalysts for dry reforming of methane

Ni/γ-Al2O3, Ni/Y-zeolite, and Ni/H-ZSM-5 catalysts were prepared using the incipient wetness impregnation method. Their catalytic performance in dry reforming of methane was studied. The fresh and used catalysts and deposited carbon were characterized using H2 temperature-programmed reduction, temperature-programmed oxidation, N2 adsorption-desorption, X-ray diffraction, and thermogravimetric analysis. The H-ZSM-5-supported Ni catalyst proved to be more stable than the other two catalysts, as it had the lowest carbon deposition.

Modeling and simulation of energy storage in fluidized beds using the two-phase model

Abstract The unsteady state behavior of a fluidized bed of alumina particles is modeled using the two-phase theory of fluidization, and the model validity is verified against experimental data. Using the model, the operation of the fluidized bed as an energy storage device is simulated for the storage and recovery of part of the energy content of a hot air stream. The changes of the thermophysical properties of air are taken into consideration in the model. A preliminary sensitivity analysis on the system shows that an optimum performance of the storage and recovery cycle (with an efficiency of recovery of about 51%) can be realized by the proper choice of bed height, air velocity, and energy recovery duration.

Modeling of a circulating fluidized bed for ammoxidation of propane to acrylonitrile

Abstract The catalytic ammoxidation of propane over V–Sb–Al catalyst in a circulating fluidized bed (CFB) is investigated. A mathematical model for the system based on combining the kinetics of reaction and the hydrodynamics of the bed is used to simulate the reactor performance. Sensitivity analysis of the effect of operating conditions shows that the acrylonitrile yield increases as reaction temperature increases or as propane feed mole fraction decreases. The acrylonitrile yield decreases as solid circulation rate, and gas superficial velocity increase.

A mathematical model achieving the twin objectives of simplicity and accuracy for the simulation of immobilized packed bed fermentors

A mathematical model for the alcoholic fermentation process using immobilized whole cells in continuous tubular fermentors is developed. One set of experimental results is used to adjust some of the kinetic parameters, then the model is used without any adjustable parameters to simulate other experimental results. The model is much more accurate than previous models although it is mathematically simpler. The present model, therefore, achieves, to a reasonable extent, the twin objectives of simplicity and accuracy.

Ni/Y- Zeolite Catalysts for Carbon Dioxide Reforming of Methane

Carbon deposits play a crucial role in the performance of catalysts, in terms of controlling both reaction selectivity and activity, this is most often manifest through catalyst deactivation. Understanding the structure and electronic properties of the carbon deposits formed on the surface of a catalyst is therefore an importance key. In this study the catalytic performance of Ni based on Y-Zeolite (CBV300) prepared by incipient wetness impregnation. The prepared catalyst was tested in a micro tubular reactor using temperature ranges of 500, 600 and 700 °C at atmospheric pressure, using a total flow rate of 36 ml/min consisting of 2 ml/min of N2, 17 ml/min of CO2 and 17 ml/min of CH4. The calcination was carried out in the range of 500–900 °C. The catalyst is activated inside the reactor using hydrogen gas.The conversion of CH4 observed over 5wt%Ni/ Y-Zeolite at 700 °C were 59.6%. The supported Ni catalysts were characterized by BET and TG/DTA techniques.

Investigation of Suitable Pretreatment for Dry Reforming of Methane Over Ni/Al2O3

Carbon dioxide reforming of methane to synthesis gas over an alumina-supported 1% Ni-based catalyst was investigated at atmospheric pressure. The effects of activation and calcination temperatures and the addition of calcium promoted on dry reforming catalysts supported on low surface area alumina Ni/α-Al2O3 (SA-5239) were studied experimentally. In this study, the prepared catalyst was tested in a micro tubular reactor at temperature ranges of 500, 600, 700 and 800°C, atmospheric pressure, using a total flow rate of 33 ml/min. of feed gas 3 ml/min of N2, 15 ml/min of CO2 and 15 ml/min of CH4. The calcination was carried out in the range of 500-900°C. The catalysts were activated inside the reactor at 500-800°C using hydrogen gas. It was observed that calcination enhances catalyst activity which increases as calcination and reaction temperatures were increased. It was found essential activating reforming catalysts with H2.The highest process activity was obtained at 800°C reaction temperature by using catalyst calcined and activated at 900°C and 700°C respectively. The addition of Ca promoter decreases the coke formation on catalyst, however, It initially reduces the activity. The catalyst characterization conducted supported the observed experimental result

Study of Methane Decomposition on Fe/MgO-Based Catalyst Modified by Ni, Co, and Mn Additives

Catalytic decomposition of methane (CDM) generates clean hydrogen and carbon nanomaterials. In this study, methane decomposition to hydrogen and carbon was investigated over Ni-, Co-, or Mn-doped Fe/MgO catalysts. The doping effect of different metals, varying from 3 to 10 wt%, was investigated. The catalytic performance of the obtained materials (noted 15%Fe+x%metal/MgO) revealed that the doping effect of Ni, Co, and Mn significantly improved the activity of Fe/MgO. Among the Ni-doped catalyst series, the 15%Fe+3%Ni/MgO catalyst performed better than the rest of the Ni catalysts. The 6%Co-containing catalyst remained the best in terms of activity in the Co-doped catalyst series and the 15%Fe+6%Mn/MgO solid showed better methane conversion for the Mn-doped series. Overall, 3%Ni-containing catalyst displayed the best catalytic performance among all Ni-, Co-, and Mn-doped catalysts. XRD, N2 sorption, and H2 temperature-programmed reduction (TPR), Laser–Raman spectroscopy, thermogravimetric analysis (TGA) under air, and temperature-programmed oxidation (TPO) were used for catalyst characterization. The results revealed that all the doped catalysts exhibited better metallic active site distribution than 15%Fe/MgO and proved that metal doping played a crucial role in catalytic performance.