Activated carbons (ACs) were produced from Ubamegashi by superheated steam carbonization/activation processes. The effects of preparation conditions (i.e., carbonization/activation temperature, carbonization/activation time, and flow rate of superheated steam) on the textural properties of activated carbons were evaluated by N2 adsorption/desorption analysis. The yield of the prepared AC decreases with increase of carbonization/activation temperature, carbonization/activation time, and the flow rate of superheated steam. The optimum condition on the prepared activated carbon was decided the carbonization/activation temperature of 850°C, and carbonization/activation time of 1 h, and the flow rate of superheated steam of 1 g/min. The surface morphological observation of the carbide and activated carbon was performed by scanning electron microscopy (SEM). The adsorption studies on the activated carbon which was prepared under the optimum condition (O-AC) were conducted for adsorption capacities of methylene blue (MB) and methyl orange (MO). The equilibrium adsorption data well fitted by the Langmuir isotherm equation. The maximum adsorbed amount of MB and MO was 322.6 and 384.6 mg/g, respectively. Therefore, it suggests that Ubamegashi based AC by using superheated steam carbonization/activation process would be useful as an industrial adsorbent of dyes.
The water gas shift reaction is an important step in chemical engineering processes. The basic performances of an axial reactor and radial reactor are simulated using computational fluid dynamics (CFD)simulation. Two-dimensional models are constructed for the two types of reactors. Their performances are compared, and the influences of flow rate and steam/CO ratio on their performance are studied. The results show that the pressure and temperature profile of an axial reactor changes linearly along the flow direction, while it is unevenly distributed in a radial reactor. An increase in the flow rate leads to a slight decrease in the conversion rate and an increase in the pressure drop, especially for the axial reactor. The radial reactor can reduce the pressure drop significantly, but at the same time, there is a slight decrease in its conversion rate. This allows for an enlarged commercial reactor design. However, some measures should be taken such as to make the flow perpendicular to the radial direction uniform.