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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >In situ ATR-IR spectroscopic and reaction kinetics studies of water-gas shift and methanol reforming on Pt/Al2O3 catalysts in vapor and liquid phases
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In situ ATR-IR spectroscopic and reaction kinetics studies of water-gas shift and methanol reforming on Pt/Al2O3 catalysts in vapor and liquid phases

机译：Pt / Al2O3催化剂在气相和液相中水煤气变换和甲醇重整的原位ATR-IR光谱和反应动力学研究

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Reaction kinetics measurements of the water-gas shift reaction were carried out at 373 K on Pt/Al2O3 in vapor phase to investigate the effects of CO, H-2, and H2O partial pressures. Results of in situ ATR-IR studies conducted in vapor phase under similar conditions suggest that the Pt surface coverage by adsorbed CO is high (similar to90% of the saturation coverage), leading to a negligible effect of the CO pressures on the rate of reaction. The negative reaction order with respect to the H2 pressure is caused by the increased coverage of adsorbed H atoms, and the fractional positive order with respect to the water pressure is consistent with non-equilibrated H2O dissociation on Pt. Results of in situ ATR-IR studies carried out at 373 K show that the presence of liquid water leads to a slight decrease in the Pt surface coverage by adsorbed CO (similar to80% of the saturation coverage) when the CO partial pressure is the same as in the vapor-phase studies. The rate of the WGS reaction in the presence of liquid water is comparable to the rate under complete vaporization conditions when other factors (such as CO partial pressure) are held constant. Reaction kinetics measurements of methanol reforming were carried out at 423 K over a total pressure range of 1.36-5.84 bar. In situ ATR-IR studies were conducted at 423 K to determine the Pt surface coverage by adsorbed CO in completely vaporized methanol feeds and in aqueous methanol solutions. The decomposition of methanol is found to be slower during the reforming of methanol in liquid phase than in vapor phase, which leads to a lower rate of hydrogen production in liquid phase (0.08 min(-1) at 4.88 bar) than in vapor phase (0.23 min(-1) at 4.46 bar). The lower reaction order with respect to methanol concentration observed for vapor-phase versus liquid-phase methanol reforming (0.2 versus 0.8, respectively) is due to the higher extent of CO poisoning on Pt for reforming in vapor phase than in liquid phase, based on the higher coverage by adsorbed CO observed in completely vaporized methanol feeds (55-60% of the saturation coverage) than in aqueous methanol feed solutions (29-40% of the saturation coverage).
机译：水蒸气变换反应的反应动力学测量是在373 K于气相中对Pt / Al2O3进行的，以研究CO，H-2和H2O分压的影响。在相似条件下在气相中进行的原位ATR-IR研究结果表明，吸附的CO的Pt表面覆盖率很高（接近饱和覆盖率的90％），导致CO压力对反应速率的影响可忽略不计。相对于H2压力的负反应顺序是由于吸附的H原子的覆盖率增加而引起的，相对于水压的分数正顺序与Pt上未平衡的H2O分解相一致。在373 K下进行的原位ATR-IR研究结果表明，当CO分压相同时，液态水的存在会导致吸附的CO的Pt表面覆盖率略有下降（大约是饱和覆盖率的80％）。如气相研究。当其他因素（例如，CO分压）保持恒定时，液态水存在下的WGS反应速率与完全汽化条件下的速率相当。甲醇重整的反应动力学测量在423 K的总压力范围内（1.36-5.84 bar）进行。在423 K下进行了原位ATR-IR研究，以确定完全汽化的甲醇进料和甲醇水溶液中被吸附的CO吸附的Pt表面覆盖率。发现甲醇在液相重整过程中的分解比气相重整慢，这导致液相中的氢气产生速率（在4.88 bar下为0.08 min（-1））比气相中的氢气产生速率低（ 0.23分钟（-1）在4.46巴）。气相和液相甲醇重整相对于甲醇浓度观察到的反应顺序较低（分别为0.2与0.8），这是由于基于气相重整的Pt上CO的CO中毒程度高于液相中的CO中毒程度，基于与甲醇水溶液进料溶液（饱和覆盖度的29-40％）相比，完全蒸发的甲醇进料（饱和覆盖度的55-60％）观察到的被吸附的CO的覆盖率更高。

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