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Moradi G.R.,Catalyst Research Center | Yaripour F.,Iran National Petrochemical Company | Vale-Sheyda P.,Catalyst Research Center
Fuel Processing Technology | Year: 2010

The conversion of methanol to dimethyl ether was carried out over various commercial mordenite and ion-exchanged catalysts to evaluate the catalytic performance of mordenite catalysts with different pore structures and acidities. These catalysts were compared for their catalytic properties in a fixed-bed reactor at 1 atm, 573 K and LHSV of 2.84 h- 1. The catalysts were characterized by BET, ICP, NH3-TPD, XRD, TGA and FT-IR techniques. The ion-exchanged mordenite showed higher activity, selectivity and good stability in dehydration of methanol due to the addition of medium acid sites. Also, the effect of water on catalyst deactivation was investigated over two selected catalysts in order to develop a suitable catalyst for synthesis of dimethyl ether. It was found that the H-mordenite catalyst supplied by Süd-chemie Co., (MCDH-1) was more active and less deactivated than another one in a feed containing 20 wt.% water. © 2009 Elsevier B.V. All rights reserved.

Asadieraghi M.,University of Malaya | Asadieraghi M.,Iran National Petrochemical Company | Wan Daud W.M.A.,University of Malaya
Energy Conversion and Management | Year: 2014

To eliminate the negative impacts of inorganic constituents during biomass thermochemical processes, leaching method by different diluted acid solutions was chosen. The different palm oil biomass samples (palm kernel shell (PKS), empty fruit bunches (EFB) and palm mesocarp fiber (PMF)) were pretreated by various diluted acid solutions (H2SO4, HClO4, HF, HNO3, HCl). Acids with the highest degrees of demineralization were selected to investigate the dematerialization impacts on the biomass thermal characteristics and physiochemical structure. Thermogravimetric analysis coupled with mass spectroscopy (TGA-MS) and Fourier transform infrared spectroscopy (TGA-FTIR) were employed to examine the biomass thermal degradation. TGA and DTG (Derivative thermogravimetry) indicated that the maximum degradation temperatures increased after acid pretreatment due to the minerals catalytic effects. The main permanent evolved gases comprising H 2, CO2, CO were detected online during analysis. The major permanent gases produced at the temperature range of 250-750 °C were attributed to the condensable vapors cracking and probably some secondary reactions. The physiochemical structure change of the acid-treated biomass samples was examined by using Brunauer Emmett Teller (BET) method, Scanning Electron Microscope (SEM) and FTIR. The pyrolysis kinetics of the different palm oil biomasses were investigated using first order reaction model. © 2014 Elsevier Ltd. All rights reserved.

Hosseinpour V.,Sharif University of Technology | Kazemeini M.,Sharif University of Technology | Mohammadrezaee A.,Iran National Petrochemical Company
Applied Catalysis A: General | Year: 2011

In this study, central composite design (CCD) at five levels (-1.63, -1, 0, +1, +1.63) combined with response surface methodology (RSM) have been applied to optimise methanol carbonylation using a ruthenium-promoted iridium catalyst in a homogenous phase. The effect of seven process variables, including temperature, pressure, iridium, ruthenium, methyl iodide, methyl acetate and water concentrations, as well as their binary interactions, were modelled. The determined R 2 values greater than 0.9 for the rate and methane formation data confirmed that the quadratic equation properly fitted the obtained experimental data. The optimum conditions for maximum rate and minimum methane formation were obtained via the RSM to be: temperature of 191 °C, pressure of 32.48 barg, iridium concentration of 939.40 ppm, ruthenium concentration of 2099.22 ppm, methyl iodide concentration of 14.46 wt.%, methyl acetate concentration of 17.55 wt.% and water content of 7.60 wt.%. The results predicted by the developed correlation at the optimum determined conditions, 28.63 mol/l h for the reaction rate and 1.97 mol% CH 4, were reasonably compared with the experimental data obtained for the reaction rate and methane formation of 27.10 mol/l h and 3.06 mol% CH 4, respectively. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved.

Ghasemi H.,Iran National Petrochemical Company
Engineering Failure Analysis | Year: 2011

Being inexpensive and readily available, carbon steel is considered as the material of choice for majority of applications in the petroleum refining industry. However, carbon steel is unsuitable for applications involving certain corrosive species such as sulfur compounds. In this work the causes of heater tubes rupture in BPC have been investigated. Our results indicate that the major cause for premature failure is high temperature sulfidation along with erosion due to turbulence. This study shows that the corrosion rate of the tubes does not follow McConomy law and it is much higher than the one predicted by McConomy curves. As a result, carbon steel is not a suitable material for such heater tubes, where the gas condensate contains high amount of sulfur compounds especially mercaptans. © 2010 Elsevier Ltd.

Yaripour F.,Amirkabir University of Technology | Shariatinia Z.,Amirkabir University of Technology | Sahebdelfar S.,Iran National Petrochemical Company | Irandoukht A.,Research Institute of Petroleum Industry RIPI
Microporous and Mesoporous Materials | Year: 2015

The effect of boron incorporation into H-ZSM-5 nanocatalyst on the stability, product distribution and hydrocarbons selectivity in methanol to olefins (MTO) reaction was investigated. The reference and boron-modified ZSM-5 nanocatalysts were prepared by hydrothermal method. The fresh and used nanocatalysts were characterized using TG-DTA, XRD, FE-SEM, BET, FT-IR, TPH, TPO and NH3-TPD techniques. The performance test runs of the two H-ZSM-5 and [B]-H-ZSM-5 samples were conducted in a fixed-bed reactor at T = 480 °C, P = 1 atm, methanol WHSV = 0.9 h-1 with methanol to water weight ratio of unity in the feed. The results revealed that propylene selectivity does not change significantly with the isomorphous substitution of B in H-ZSM-5 zeolite. However, the lifetime of the modified zeolite (1300 h) showed a significant increase compared to that of the reference sample (340 h). The considerable enhancement of the lifetime and catalytic stability could be attributed to reduction of strong/mild acid sites ratio as well as small crystal size of the [B]-H-ZSM-5 nanocatalyst. The characterization of the deactivated nanocatalysts showed that incorporation of boron decreased both rates of coke formation and coke-susceptibility of the ZSM-5 nanocatalyst. © 2014 Elsevier Inc. All rights reserved.

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