Abstract
Mesocellular foam carbon (MCF-C) is one the captivating materials for using in gas phase dehydrogenation of ethanol. Extraordinary, enlarge pore size, high surface area, high acidity, and spherical shape with interconnected pore for high diffusion. In contrary, the occurrence of the coke is a majority causes for inhibiting the active sites on catalyst surface. Thus, this study aims to investigate the occurrence of the coke to optimize the higher catalytic activity, and also to avoid the coke formation. The MCF-C was synthesized and investigated using various techniques. MCF-C was spent in gas-phase dehydrogenation of ethanol under mild conditions. The deactivation of catalyst was investigated toward different conditions. Effects of reaction condition including different reaction temperatures of 300, 350, and 400 °C on the deactivation behaviors were determined. The results indicated that the operating temperature at 400 °C significantly retained the lowest change of ethanol conversion, which favored in the higher temperature. After running reaction, the physical properties as pore size, surface area, and pore volume of spent catalysts were decreased owing to the coke formation, which possibly blocked the pore that directly affected to the difficult diffusion of reactant and caused to be lower in catalytic activity. Furthermore, a slight decrease in either acidity or basicity was observed owing to consumption of reactant at surface of catalyst or chemical change on surface caused by coke formation. Therefore, it can remarkably choose the suitable operating temperature to avoid deactivation of catalyst, and then optimize the ethanol conversion or yield of acetaldehyde.
Highlights
The renewable energy has high impact to the world in the last decade, especially in many countries, in order to use the renewable clean fuel with eco-friendly environment such as bioethanol
It is recognized that the mesocellular foam carbon (MCF-C) is one of the robust carbon catalysts, which can be employed in ethanol dehydrogenation in order to produce acetaldehyde
The spent catalysts under specified condition were collected after each run and characterized by nitrogen-physisorption, X-ray diffraction (XRD), scanning electronic microscopy (SEM), thermogravimetric analysis (TGA), ammonia temperature-programmed desorption ( NH3-TPD), carbon dioxide temperature-programmed desorption (CO2-TPD) and Fourier transform infrared spectroscopy (FT-IR) in order to observe the changes of catalysts after being used
Summary
The renewable energy has high impact to the world in the last decade, especially in many countries, in order to use the renewable clean fuel with eco-friendly environment such as bioethanol. According to Montero et al.[17], they investigated the deactivation of Ni/La2O3-α-Al2O3 catalyst in ethanol steam reforming (ESR) with different operating condition as either temperature between 500 and 650 °C or space time up to 0.35 gcatalysth/gEtOH. They reported that catalyst deactivation was merely motived by coke deposition, remarkably via encapsulating coke inside of the catalyst. The selection of catalysts in each specific reaction is captivating to exhibit either high activity or resistance to deactivation caused by coke formation. The etching of silica was used as sodium hydroxide (NaOH, SigmaAldrich)
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