• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.813-818
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• 2008

Various additives were added in small amounts on Ni/YSZ anode of SOFC (solid oxide fuel cell) in order to improve reactivity and to inhibit deactivation due to coke deposition during methane reforming using a low mole ratio steam ($H_2O/CH_4=1.5$) at $800^{\circ}C$. Ni/YSZ catalysts added with various perovskites did not show any improvement but exhibited a gradual decrease in the methane conversion. K-doped Ni/YSZ showed a steady increase and maintenance of the conversion up to 42 hours, after which there was an abrupt deactivation of catalyst owing to potassium loss by volatilization. Addition of 5% of $K_2Ti_2O_5$ on Ni/YSZ showed a stable maintenance of the conversion without K loss, and was able to prevent coke formation during a long time operation. Deactivation of catalyst during the reaction was mainly caused by the accumulation of graphidic carbon on the catalyst surface.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.176-185
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• 2018

As global warming accelerates, greenhouse gas reduction becomes more important. Carbon dioxide dry reforming is a promising green-house gas reduction technology that can obtain CO and $H_2$ which are high value-added materials by utilizing $CO_2$ and $CH_4$ which are greenhouse gases. However, there is a significant coking problem during operation of the dry reforming reactor. Because the carbon dioxide dry reforming is a strong endothermic reaction, the temperature of the reactor drops near the reactor inlet and causes coke formation. To solve this problem, it is important to ensure that the reaction takes place in a temperature range where coke production is minimized. In this study, we proposed a design method that can maintain reaction temperature in the region where the coke is rarely generated by using the new catalyst configuration method. The design method also optimizes the reactor by solving the optimization problem which minimizes the reactor length for a given reaction conversion by using the fuel flow rate, catalyst density, and output temperature by section as optimization variables.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.3
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• pp.56-61
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• 2021

In this study, Al₂O₃ and H-ZSM-5 were coated on the inner wall of the stainless steel tube for the stable use of liquid hydrocarbon fuel and an endothermic catalyst used as coolant for hypersonic flying vehicles. Coke production is inevitable by the endothermic decomposition reaction of the liquid hydrocarbon fuel, and Fe, Ni metals induce the production of the filamentous coke by using a stainless steel tube reactor as a cooling channel. By coating the stainless steel with H-ZSM-5, Fe and Ni metals are prevented from being directly exposed to the liquid hydrocarbon fuel, and the formation of the filamentous coke is inhibited. In addition, Al₂O₃ is coated between the stainless steel and H-ZSM-5 to enhance adhesion bond strength.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.481-486
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• 2021

In a hypersonic vehicle to solve the heat problem generated during flight, a cooling technology is being developed which uses the endothermic effect that appears during the decomposition reaction of the mounted fuel. In this study, the decomposition reaction of n-dodecane fuel was performed using HZSM-5 as a catalyst, and the catalyst was coated on metal foam to maximize the endothermic effect of the catalytic decomposition reaction and suppress coke formation. The reactor was a stainless steel flow reactor with a outer diameter of 1.27 cm, and the reaction temperature was 550 ℃, the reaction pressure was 4 MPa, and the flow rate was 12 ml per minute. As a result of the catalytic decomposition reaction using a catalyst coated with HZSM-5 on the metal foam, the heat sink was 2887 kJ/kg as a maximum, the gas phase conversion rate was 34%, and the amount of coke produced on the metal foam decreased by about 56% as the catalyst was coated compared to the uncoated catalyst.