Sharif Digital Repository

In this contribution, NiO-MgO-SiO2 catalyst was prepared and calcined at different temperatures of 500, 600, 700 and 800 °C. The resulting samples were characterized by BET-BJH, XRD, TPX, CO-chemisorption, EDS and SEM analyses. These were employed toward syngas production via propane dry reforming. The increment in the calcination temperature from 500 to 800 °C decreased the basicity of the catalysts. In addition, the active surface area and Ni dispersion were gradually declined by increasing the calcination temperature from 600 to 700 °C due to active metal sintering during the activation process. The calcined sample at 600 °C displayed the highest propane and CO2 conversions of 93% and 78%... 

Background: A new design for a methanol plant is proposed in which CO 2 addition, as one of the important parameters, is used to optimize the synthesis gas composition. An attempt has been made to assess the environmental features as well as the process operability of the proposed plant, in which the required CO 2 is provided from reformer flue gas. As a starting point, simulation of a conventional reference methanol case (RMC) and also the proposed green integrated methanol case (GIMC) are performed to obtain operational and kinetic parameters. In order to compare properly GIMC and RMC, the objective function is defined so that SynGas production, and thereby methanol production, in the GIMC... 

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... 

Catalytic partial oxidation of methane in short residence time rhodium coated monolithic reactors offers an attractive route for syngas production. The plug flow and boundary layer flow approximations are considered as computationally efficient substitutes for the full Navier-Stokes model of the reactor while including detailed heterogeneous and homogeneous chemistry. The one dimensional plug flow model has trivial computational demands but only a limited range of application. The boundary layer model provides an excellent, computationally manageable substitute for the full Navier-Stokes model over a wide range of operating conditions. Using the 38-step elementary surface reaction mechanism... 

In this study, 15 wt. % NiO-MgO-SiO2 catalysts modified by La2O3 promoter were prepared through a co-precipitation route and employed for syngas production via propane steam reforming. Various techniques including X-Ray diffraction, BET, TPR, CO2-TPD, CO-chemisorption, TPO, and Scanning electron microscopy were utilized to characterize the final samples. The results indicated that the incorporation of La2O3 enhanced the metal-support interaction providing less reducible Ni species. In comparison with the La-free catalyst, the promoted ones possessed higher metal dispersion and smaller Ni particles. Nonetheless, excessive amounts of La covering the active sites negatively decreased the Ni...