충전층반응기를 사용하여 대기압, 160-280 ℃의 온도범위에서, CuO-CeO₂ 촉매상에서의 메탄올 수증기개질반응을 연구하였다. 반응생성물은 주로 수소와 이산화탄소이었고, 소량의 일산화탄소가 생성되었다. 소량으로 생성된 일산화탄소는 수성가스전화 평형값 이하이었다. 이 결과로부터, 이산화탄소와 수소가 반응으로부터 직접 생성되는 것을 확인하였다. 물이 양론비 이상으로 존재할 때 메탄올 전화율은 물의 농도와 무관하였고, 이산화탄소의 농도와도 무관하였다. 반응속도는 반응온도 및 메탄올과 수소분압에 따라 결정되었다. 220 시간 동안 촉매의 활성은 지속적으로 감소하였다. 새 촉매와 220 시간 운전한 촉매 두 가지를 각각 충전층 반응기에 충진하여 다양한 반응조건에서 반응물의 전화율을 측정하였고, 이 자료를 촉매입자의 유효인자를 고려하는 적분형반응기모델식으로 해석하여 각 촉매에 대한 powerlow 및 Langmuir-Hinshelwood 모델의 반응속도식들을 결정하였다. 활성화에너지는 새 촉매의 경우 106 - 108 kJ/mol, 220 시간 사용촉매의 경우 83 kJ/mol이었다. 실험결과를 분석하여, methoxy의 탈수소화반응이 율속단계이며, 수소는 다른 성분들과는 다른 흡착점을 가진다는 반응 메커니즘을 제안하였다.

Methanol steam reforming over a CuO-CeO₂ catalyst was studied using a packed-bed reactor at atmospheric pressure in the temperature range of 160-280 ℃. The reaction products were carbon dioxide and hydrogen with a small amount of carbon monoxide, always less than the amount of the water-gas-shift equilibrium, confirming that the carbon dioxide and hydrogen were directly produced by the reaction. The methanol conversion was not affected by the carbon dioxide concentration and the water concentration in the feed as long as the water concentration was in excess of the stoichiometry. The reaction rate depended on the reaction temperature and partial pressures of methanol and hydrogen. The catalyst showed a slow but steady deactivation during the course of reaction over 220 hours. For the fresh catalyst and the catalyst aged for 220 hours, power-law rate and Langmuir-Hinshelwood rate expressions were determined from an integral analysis of the packed-bed reactor, in which the effectiveness factor of the catalyst particle was also accounted for. Activation energy of the reaction was 106-108 kJ/mol for the fresh catalyst and 83 kJ/mol for the aged catalyst. A reaction mechanism that dehydrogenation of the methoxy species is the rate determining step and hydrogen adsorption occurs on an exclusive kind of sites different from the sites for other adsorbed species was proposed based on the analysis of the experimental data.

Methanol Steam Reforming CuO-CeO₂ Kinetics Power-Law Model Langmuir-Hinshelwood Model Effectiveness Factor

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