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合成了一系列硅铝比为31—176的ZSM-11沸石,以甲苯-甲醇烷基化、间二甲苯异构化和甲苯歧化三个反应作为探针反应,研究了它们的催化性能。将其与酸性质和晶胞参数相关联发现,低硅铝比适于甲苯歧化,中硅铝比适于间二甲苯异构化,高硅铝比适于甲苯-甲醇烷基化反应。各反应所需的酸强度为甲苯歧化>间二甲苯歧化>间二甲苯异构化>甲苯-甲醇烷基化。Na~+的存在以及用4-甲基喹啉或(CH_3)_3SiCl中毒,可抑制强酸位,明显提高甲苯-甲醇烷基化反应生成对二甲苯的选择性,尤以(CH_3)_3SiCl中毒的低Al/u.c.的NaHZSM-11最佳。
A series of ZSM-11 zeolites with Si / Al ratio of 31-176 were synthesized. Their catalytic properties were investigated using three reactions of toluene-methanol alkylation, m-xylene isomerization and toluene disproportionation. It was found that the low Si / Al ratio is suitable for the disproportionation of toluene, the medium Si / Al ratio is suitable for the isomerization of m-xylene, and the high Si / Al ratio is suitable for the toluene-methanol alkylation reaction. The acid strength required for each reaction was toluene disproportionation> m-xylene disproportionation> m-xylene isomerization> toluene-methanol alkylation. The presence of Na ~ + and the poisoning with 4-methylquinoline or (CH_3) _3SiCl inhibited the strong acid sites and markedly increased the selectivity of toluene-methanol alkylation to p-xylene, especially the toxicity of (CH_3) _3SiCl NaHZSM-11 with low Al / uc is the best.