Chemical Engineering – Gas Processing and Transmission
Mahnaz Pourkhalil
Abstract
A series of copper oxide (CuOx) catalysts supported by oxidized multi-walled carbon nanotubes (OMWNT’s) were prepared by the wet impregnation method for the low temperature (200 °C) selective catalytic reduction of nitrogen oxides (NOx) using NH3 as a reductant agent in the presence of excess ...
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A series of copper oxide (CuOx) catalysts supported by oxidized multi-walled carbon nanotubes (OMWNT’s) were prepared by the wet impregnation method for the low temperature (200 °C) selective catalytic reduction of nitrogen oxides (NOx) using NH3 as a reductant agent in the presence of excess oxygen. These catalysts were characterized by FTIR, XRD, SEM-EDS, and H2-TPR methods. The response surface methodology was employed to model and optimize the effective parameters in the preparation of CuOx/OMWNT’s catalysts in NOx removal by NH3-SCR process. Three experimental parameters, including calcination temperature, calcination time, and CuOx loading were chosen as the independent variables. The central composite design was utilized to establish a quadratic model as a functional relationship between the conversion of NOx as a response factor and independent variables. The ANOVA results showed that the NOx conversion is significantly affected by calcination temperature and CuOx loading. At the optimal values of the studied parameters, the maximum conversion of NOx, 86.3 %, was obtained at a calcination temperature of 318 °C, a calcination time of 3.4 hr., and CuOx loading of 16.73 wt.%; the reaction conditions was as follows: T= 200 °C, P= 1 bar, NO = NH3 = 900 ppm, O2 = 5 vol.%, and GHSV = 30,000 hr.−1. The regression analysis with an R2value of 0.9908 revealed a satisfactory correlation between the experimental data and the values predicted for the conversion of NOx. The XRD and H2-TPR results of the best catalyst showed that the formation of CuO as the dominant phase of CuOx is the key factor in low temperature selective catalytic reduction (SCR) process.
Seyed Ali Hosseini; Sirus Nouri; Sajad Hashemi; Mansor Akbari
Abstract
The removal of sulfur compounds from petroleum is extremely necessary for industrial and environmental reasons. Sulfur in transportation fuels is a major air pollution source. In this work, the efficiency of nanostructured Ni-clinoptilolite adsorbent was investigated in the removal of sulfur from gas ...
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The removal of sulfur compounds from petroleum is extremely necessary for industrial and environmental reasons. Sulfur in transportation fuels is a major air pollution source. In this work, the efficiency of nanostructured Ni-clinoptilolite adsorbent was investigated in the removal of sulfur from gas oil. For this purpose, the design of experiments was performed by selecting effective factors in desulfurization process. Response surface methodology was selected to model the desulfurization process. Ni-containing nanoadsorbents were prepared by a wet-impregnation method. Gas oil model containing 300 ppmW [M. N.1] sulfur was prepared by dissolving a calculated amount of dibenzothiophene (DBT) in n-decane. The concentration of DBT in n-decane was determined by UV-Visible spectrophotometer. The results revealed that sulfur removal extremely depended on the amount of metal and the nature of both metal and support. 5% Ni/support adsorbent resulted in higher sulfur removal efficiency. The optimum ratio of H2O2 to gas oil in the studied conditions was in the range of 5% (v/v) and 240 minutes for the best desulfurization performance during the process.
