| 张嘉良,薛冰,许杰,刘平,李永昕.络合浸渍MgO改性MCM-22择形催化合成对二甲苯[J].分子催化,2011,(6):514-519 |
| 络合浸渍MgO改性MCM-22择形催化合成对二甲苯 |
| Shape-selective Catalytic Synthesis of P-xylene over MgO Modified MCM-22 Prepared by Complexation Impregnation |
| 投稿时间：2011-10-24 修订日期：2011-11-29 |
| DOI： |
| 中文关键词: 络合浸渍 择形催化 MCM-22 对二甲苯 |
| 英文关键词:complexation impregnation shape-selectivity MCM-22 p-xylene |
| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| 摘要点击次数: 2021 |
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| 中文摘要: |
| 以硝酸镁为前驱体，苹果酸为络合剂，通过络合浸渍法制备了不同负载量的MgO/MCM-22催化剂。在气相连续流动固定床反应器上进行甲苯与碳酸二甲酯(DMC)烷基化合成对二甲苯的研究，并采用XRD、NH3-TPD、吡啶吸附IR、N2吸脱附等手段对催化剂进行表征。实验结果表明：以9 %负载量的MgO/MCM-22分子筛为催化剂，在380 癈反应物料配比n(甲苯):n(DMC)=4:1、重时空速1 h-1 的条件下，甲苯转化率为29.0 %，对二甲苯选择性为48.2 %。表征结果显示：采用络合浸渍的方法制备MgO改性MCM-22分子筛催化剂不仅可以有效覆盖分子筛外表面酸性位，而且不会影响其孔内的酸性位，从而可以在维持较高对二甲苯选择性的同时实现甲苯转化率的提高。 |
| 英文摘要: |
| MgO modified MCM-22 was prepared by complexation impregnation method in the present of malic acid as the complexing agent. Selective synthesis of p-xylene by alkylation of toluene with dimethyl carbonate（DMC）was carried out in a continuous flow fixed-bed rector over MgO-modified MCM-22 zeolite. Physico-chemical properties of the catalysts were characterized by means of XRD, NH3-TPD, pyridine-IR and BET. It was found that under the optimal conditions, i.e. reaction temperature of 380 癈, n (toluene): n (DMC) of 4 and WHSV of 1 h-1, the conversion of toluene and the selectivity to p-xylene were 29.0 % and 48.2 %, respectively. The results of characterization show that the complex compounds derived from the malic acid-coordinative Mg2 loaded only on the external surface of MCM-22 and did not enter the pores. As a result, the cover of the external acidic sites and the protection of the inner acidic sites of zeolite can be achieved simultaneously. Consequently, catalysts prepared by complexation impregnation method exhibits high para-selectivity along with high activity in alkylation of toluene with DMC. |
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