Para-selectivity of modified HZSM-5 zeolites by nitridation for ethylation of ethylbenzene with ethanol
Para-selectivity of modified HZSM-5 zeolites by nitridation for ethylation of ethylbenzene with ethanol
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DOI：
10.1016/j.molcata.2005.12.032
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发表时间：
2006-04
影响因子：
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通讯作者：
Xinxin Guan;Li Na;Guangjun Wu;Jixin Chen;Fuxiang Zhang;N. Guan
中科院分区：
文献类型：
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作者：
Xinxin Guan;Li Na;Guangjun Wu;Jixin Chen;Fuxiang Zhang;N. Guan
采用流动纯氨对工业HZSM-5沸石进行高温氮化改性。XRD、BET和SEM分析表明，改性后的HZSM-5分子筛保持了前驱体的高结晶度和高比表面积。NH_3-TPD和吡啶-IR分析表明，改性后的HZSM-5分子筛表面强酸位明显减少，氮化反应主要发生在B酸位上。改性后的HZSM-5分子筛用于乙醇的二乙基化反应时，对二乙苯的选择性和稳定性都比原HZSM-5分子筛有显著提高。强酸中心的减少可以抑制对二乙苯的异构化反应，提高对位选择性。研究了改性沸石中氮含量对二乙苯转化率和选择性的影响。
The modification of HZSM-5 zeolite was carried out by nitridation of commercial HZSM-5 zeolites with flowing pure ammonia at high temperature. The modified HZSM-5 zeolites maintained high crystallinity and high specific surface areas of precursors testified by XRD, BET and SEM analysis. Compared with parent HZSM-5, the surface strong acid sites of modified HZSM-5 zeolites decreased severely as characterized by means of NH3-TPD analysis and pyridine-IR spectroscopy shows that nitridation mainly occurred in Brønsted acid sites. The modified HZSM-5 zeolites exhibited much higher selectivity to para-diethylbenzene (DEB) and significantly enhanced stability than parent HZSM-5 when applied in the reaction of ethylbenzene ethylation with ethanol. The reduction of strong acid sites can suppress the isomerization of para-diethylbenzene and improve the para-selectivity. The effects of nitrogen contents in modified zeolites on the conversion and selectivity to p-DEB were also studied.