Sharif Digital Repository

Glycerol might be converted into hydrogen through a catalytic reforming process. In order to design an effective route, the choice of reaction conditions and in particular its medium considered yet a crucial issue still needing further investigations. In this research, a mathematical model of reforming processes in vapor (i.e., steam reforming (SR) and liquid phase (i.e.; aqueous phase reforming (APR)) were developed. This was performed in terms of understudying effects of parameters including the reactor diameter, catalyst morphology (i.e., particle size) and mass flow rate on the glycerol conversion. Then, a superior reaction medium in terms of these variables was determined. For data... 

Xwt% Pt/Al 2 O 3 (X = 1, 3, 5, 8, 10) and 5 wt% Pt-1wt% M/AlO 3 (M = Pd, Rh, Re, Ru, Ir, Cr) catalysts were prepared, characterized and tested for aqueous phase reforming of pure and crude glycerol. Results show drastic dependence of catalytic performance of catalysts on both the active metal loading and the type of applied promoters. 5 wt% was the best Pt loading and Pt[sbnd]Rh/Al₂O₃ shows the best catalytic activity which has the highest hydrogen production rate (mmol/g cat h −1 ) and selectivity (89%) in continuous aqueous phase reforming of 10 wt% pure glycerol solution  

A catalytic membrane reactor was synthesized by coating a 4-5 micron thick Ni/γ-Al2O3 layer on top of a hydrogen selective SiO2/Al2O3 composite membrane using a sol-gel method. Mercury intrusion and BET analysis indicated a uniform size distribution with an average pore size of 285 nm and average surface area of 279 m2 g-1. Single-component permeation tests were carried out for H2, CH4 and CO2 in the temperature range of 650-800 °C and the results showed the same permeance and selectivity values for hydrogen as the composite membrane without a catalytic layer. Performance of the catalytic membrane was evaluated by using as a membrane reactor for the methane steam reforming reaction with a... 

In this study, a series of Ni nano-catalysts supported on Al2O3 and MgO were prepared through the co-precipitation technique. Effects of the Al/Mg ratio on physicochemical characteristics of Ni/Al2O3–MgO catalysts were examined. Moreover, catalytic performance was investigated in order to determine the optimum catalyst for H2 production in aqueous phase reforming (APR) of glycerol. It was revealed that, the APR activity of synthesized catalysts strongly depended on the aforementioned ratio. In addition, it was observed that, the catalytic activity of Ni/MgO and Ni/Al2O3 samples were both lower than that of the corresponding mixed oxide supports. Furthermore, it was shown that, amongst the... 

In this research, a series of NiO-xMgO-SiO2 catalysts with various MgO/SiO2 molar ratios were prepared via precipitation method followed by a hydrothermal treatment in the presence of PVP as surfactant. The synergic effect between MgO and SiO2 leading to the various characteristic and catalytic performance during propane steam reforming was investigated in detail. The results showed that 15 wt% NiO-0.5MgO–SiO2 catalyst possessed the highest catalytic activity (68.9% conversion for C3H8 at 550 °C) with a negligible amount of carbon formation after 20 h of reaction duration. This superior catalytic performance can be attributed to the enhanced basicity strength along with strong metal-support... 

Hydrogen and syngas, as two effective clean fuels, have a considerable stake in the global fuel market. These are dominantly produced from fossil fuels through reforming processes, which lose a large amount of energy and emit numerous amounts of CO2. Bio-renewable glycerol steam reforming is an attractive alternative to traditional reforming for reducing the dependence on hydrocarbon resources and mitigating climate change. This research aims to manage a heat-integrated reactor with three concentric cylinders, containing exothermic-side (methane tri-reforming), endothermic-side (glycerol steam reforming), and permeation-side for co-production of pure hydrogen and syngas. In this process,... 

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... 

In this contribution, NiO-MgO-SiO2 catalysts containing 3 wt. % of CeO2, La2O3, Y2O3, and Zr2O3 were examined for propane dry reforming at 550-750 °C. The samples were synthesized by a co-precipitation route, followed by a hydrothermal treatment, and characterized by BET, XRD and TPX analyses. The results indicated that the addition of promoters enhanced the metal-support interaction and basic characteristics, while the acidic nature of the promoted catalyst was changed in a different way. The highest propane conversion of 39.6% was observed over Ce-promoter sample, while the un-promoted catalyst possessed a value of 36.8% at 700 °C. Nevertheless, La and Y-promoted catalysts possessed a...