Designing a hierarchical nanosheet ZSM-35 zeolite to realize more efficient ethanol synthesis from dimethyl ether and syngas
Designing a hierarchical nanosheet ZSM-35 zeolite to realize more efficient ethanol synthesis from dimethyl ether and syngas
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DOI：
10.1016/j.cattod.2019.02.054
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发表时间：
2020-03-01
期刊：
影响因子：
5.3
通讯作者：
Tsubaki, Noritatsu
中科院分区：
文献类型：
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作者：
Feng, Xiaobo;Zhang, Peipei;Tsubaki, Noritatsu
在这项工作中，提出了一种填充分级纳米片HZSM-35（Hi-NZ35）沸石和CuZnAl催化剂组合的双催化剂床反应器，以实现更高效地从二甲醚（DME）和合成气（CO + H-2）合成乙醇。通过直接水热合成路线制备了纳米片ZSM-35（NZ35）沸石，并通过共沉淀法制备了CuZnAl催化剂。此外，采用水热法将NZ35沸石用不同的NaOH水溶液进一步处理，得到一系列Hi-NZ35(x)沸石（“x”表示NaOH溶液浓度为0.2-0.6 M）。采用X射线衍射(XRD)、N-2吸附-脱附、NH3程序升温脱附(NH3-TPD)、H-2程序升温还原(H-2-TPR)、扫描电子显微镜(SEM)和能谱(EDS)等手段对催化剂的结晶度、孔隙率、酸度、形貌和组成等性能进行表征。研究发现Hi-NZ35(0.4)沸石能更有效地获得分级孔隙结构，中孔体积可达0.131 cm(3) g(-1)。对于单一DME羰基化反应，与传统ZSM-35（CZ35）沸石相比，NZ35沸石表现出优异的催化活性（32.2%）和稳定性。此外，由于其丰富的介孔结构，Hi-NZ35(0.4)沸石的催化活性提高了(42.0%)。结果表明，沸石的分级孔隙率可以有效提高沸石对DME羰基化反应的催化性能。采用优化后的Hi-NZ35(0.4)沸石和CuZnAl催化剂组合合成乙醇时，DME转化率约为47.2%，乙醇产率为840.2 mmol kg(-1) h(-1)。
In this work, a dual-catalyst bed reactor packed with the combination of hierarchical nanosheet HZSM-35 (Hi-NZ35) zeolite and CuZnAl catalyst was proposed to realize more efficient ethanol synthesis from dimethyl ether (DME) and syngas (CO + H-2). The nanosheet ZSM-35 (NZ35) zeolite was prepared via a direct hydrothermal synthesis route and the CuZnAl catalyst was prepared by co-precipitation method. Moreover, a series of Hi-NZ35(x) zeolites were obtained from NZ35 zeolite by further treatment with varied NaOH aqueous solution using hydrothermal process ("x" means the NaOH solution concentration of 0.2-0.6 M). The catalysts properties, such as crystallinity, porosity, acidity, morphology and composition, were characterized by X-ray diffraction (XRD), N-2 adsorption-desorption, NH3 temperature-programmed desorption (NH3-TPD), H-2 temperature-programmed reduction (H-2-TPR), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). It was found that Hi-NZ35(0.4) zeolite was more effective to obtain hierarchical porosity with mesopore volume up to 0.131 cm(3) g(-1). For single DME carbonylation reaction, the NZ35 zeolite exhibited superior catalytic activity (32.2%) and stability compared with conventional ZSM-35 (CZ35) zeolite. Furthermore, improved catalytic activity (42.0%) was observed on Hi-NZ35(0.4) zeolite owing to its abundant mesoporous structure. This result revealed that the hierarchical porosity of zeolite could effectively promote the catalytic performance of zeolite for DME carbonylation reaction. For the ethanol synthesis using the optimized catalysts combination of Hi-NZ35(0.4) zeolite and CuZnAl catalyst, the DME conversion was about 47.2% with higher ethanol productivity of 840.2 mmol kg(-1) h(-1).