Study on the Catalysis of Linear Alkylbenzene Over Modified Mordenite
| Autor: | Che-hsien Lin, 林哲賢 |
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| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 Linear alkylbenzene (LAB) is produced in detergent industry by benzene alkylation with long-chain alkene (e.g., 1-dodecene) in the presence of HF or AlCl3 catalyst. In an attempt to develop an environmental benign process in replacing the existing corrosive liquid catalysts, this study explored the catalytic potential of mesoporous mordenite in LAB synthesis. Mesoporous mordenite samples were prepared from different parent mordenite samples with various post treatments. The effect of post treatment protocol on the catalytic property and also textural property of mordenite was studied by means of X-ray diffraction spectra for zeolite framework structure, BET adsorption isotherm for mesopore and micropore structure, temperature programmed desorption (TPD) of hexane isomers particularly for 12-membered oxygen ring (12MR) micropore. While acid post treatment or steaming treatment on mordenite could partially break framework AlO4 sites, so-called“dealumination”, base post treatment by alkaline metal solution could partially dissolve framework SiO4 sites, so-called“desilication”. It was found that desilication method by base post treatment is more effective than dealumination either by acid post treatment or/and steaming treatment for enlarging mesopore. Mordenite can effectively catalyze LAB synthesis giving 1-dodecene conversion and LAB selectivity up to around 98% at reaction temperature 160°C and pressure of 300 psig. It was found that with parent Zeolon mordenite sample, the catalytic stability is deteriorated after dealumination by acid/steam treatment and is improved after desilication by base post treatment. Furthermore, mordenite sample having large mesopores, such as parent mordenite sample Zeolyst CBV20 and CBV30, base treated mordenite samples, possesses excellent catalytic stability in LAB synthesis using pure 1-dodecene feed. In addition, enlarging mesopore can stabilize catalytic activity of mordenite in octadiene containing 1-dodecene feed. The improvement in catalytic stability is attributed to the increasing diffusivity resulting from the enlarged mesopores. In comparison, among various metal containing mordenite samples, only 0.03 wt% Zn incorporated mordenite showed stabilization effect with sacrificing LAB selectivity. Pt and Pd incorporated mordenite were not applicable due to excessive hydrogenation activity giving low LAB selectivity. The mesoporous mordenite prepared by desilication showed catalytic potential in LAB synthesis. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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