Investigation of High-Temperature and High-Pressure Gas Adsorption in Zeolite H-ZSM-5 via the Langatate Crystal Microbalance: CO2, H2O, Methanol, and Dimethyl Ether
Investigation of High-Temperature and High-Pressure Gas Adsorption in Zeolite H-ZSM-5 via the Langatate Crystal Microbalance: CO2, H2O, Methanol, and Dimethyl Ether
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DOI：
10.1021/acs.jpcc.5b06591
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发表时间：
2015-10-15
影响因子：
3.7
通讯作者：
Dittmeyer, Roland
中科院分区：
文献类型：
--
作者：
Ding, Wenjin;Klumpp, Michael;Dittmeyer, Roland
采用高温高频振荡微天平（langate crystal microbalance， LCM）研究了H-ZSM-5沸石在50-150℃、0-18 bar压力范围内对CO2、H2O、甲醇和二甲醚（DME）气体的吸附。需要确定的吸附数据来验证详细的模拟模型，该模型旨在帮助优化合成气一步合成二甲醚的双功能核壳催化剂的制备。传统的石英晶体微天平（QCM）被限制在低于80摄氏度的温度下，与之相比，LCM可以在更高的温度下使用，即在或接近一步二甲醚合成的反应温度（200-300摄氏度），因为在熔点（1470摄氏度）之前没有晶体相变。采用蒸汽辅助结晶（SAC）法制备了沸石H-ZSM-5晶体。通过x射线衍射（XRD）、波长色散x射线能谱（WDX）和扫描电镜（SEM）等手段证实了H-ZSM-5 （Si/Al摩尔比为100）在langate晶体上的负载。吸附实验表明，H-ZSM-5对CO2、甲醇和二甲醚的吸附可以用单点Langmuir模型拟合，而H-ZSM-5对H2O的吸附则需要双点Langmuir模型。测定的吸附参数，即吸附容量、吸附焓和吸附熵与文献数据比较良好。
The adsorption of gases CO2, H2O, methanol, and dimethyl ether (DME) in zeolite H-ZSM-5 in the temperature range of 50-150 degrees C and pressure range of 0-18 bar has been investigated using a high-temperature, high-frequency oscillating microbalance (langatate crystal microbalance, LCM). The determined adsorption data are needed to validate a detailed simulation model, which is meant to assist in the optimization of the preparation of bifunctional core shell catalysts for one-stage DME synthesis from syngas. Compared to the conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 degrees C, LCM can be used at higher temperatures, i.e., at or close to the reaction temperature of one-stage DME synthesis (200-300 degrees C), owing to the absence of crystalline-phase transitions up to its melting point (1470 degrees C). Zeolite H-ZSM-5 crystallites have been synthesized on the langatate crystal by steam-assisted crystallization (SAC). The loaded H-ZSM-5 (Si/Al molar ratio 100) on the langatate crystal has been confirmed and characterized with X-ray diffraction (XRD), wavelength-dispersive X-ray spectroscopy (WDX), and scanning electron microscopy (SEM). The adsorption experiments showed that the adsorption of CO2, methanol, and DME in H-ZSM-5 is fitted well by the single site Langmuir model, while the dual-site Langmuir model is needed for the adsorption of H2O in H-ZSM-5. The determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data.