在铁铬混合氧化物催化剂流化床中，通过邻甲酚循环将其选择性甲基化为2,6-二甲基苯酚。
Selective phenol methylation to 2,6-dimethylphenol in a fluidized bed of iron-chromium mixed oxide catalyst with o-cresol circulation.
作者信息
Zukowski Witold, Berkowicz Gabriela, Baron Jerzy, Kandefer Stanisław, Jamanek Dariusz, Szarlik Stefan, Wielgosz Zbigniew, Zielecka Maria
机构信息
Cracow University of Technology, Faculty of Chemical Engineering and Technology, ul. Warszawska 24, 31-155 Cracow, Poland.
Industrial Chemistry Research Institute, ul. Rydygiera 8, 01-793 Warsaw, Poland.
出版信息
Chem Cent J. 2014 Sep 16;8(1):51. doi: 10.1186/s13065-014-0051-6. eCollection 2014.
BACKGROUND
2,6-dimethylphenol (2,6-DMP) is a product of phenol methylation, especially important for the plastics industry. The process of phenol methylation in the gas phase is strongly exothermic. In order to ensure good temperature equalization in the catalyst bed, the process was carried out using a catalyst in the form of a fluidized bed - in particular, the commercial iron-chromium catalyst TZC-3/1.
RESULTS
Synthesis of 2,6-dimethylphenol from phenol and methanol in fluidized bed of iron-chromium catalyst was carried out and the fluidization of the catalyst was examined. Stable state of fluidized bed of iron-chromium catalyst was achieved. The measured velocities allowed to determine the minimum flow of reactants, ensuring introduction of the catalyst bed in the reactor into the state of fluidization. Due to a high content of o-cresol in products of 2,6-dimethylphenol synthesis, circulation in the technological node was proposed. A series of syntheses with variable amount of o-cresol in the feedstock allowed to determine the parameters of stationary states.
CONCLUSION
A stable work of technological node with o-cresol circulation is possible in the temperature range of350-380°C, and o-cresolin/phenolin molar ratio of more than 0.48. Synthesis of 2,6-DMP over the iron-chromium catalyst is characterized by more than 90% degree of phenol conversion. Moreover, the O-alkylation did not occur (which was confirmed by GC-MS analysis). By applying o-cresol circulation in the 2,6-DMP process, selectivity of more than 85% degree of 2,6-DMP was achieved. The participation levels of by-products: 2,4-DMP and 2,4,6-TMP were low. In the optimal conditions based on the highest yield of 2,6-DMP achieved in the technological node applying o-cresol circulation, there are 2%mol. of 2,4-DMP and 6%mol. of 2,4,6-TMP in the final mixture, whereas 2,4,6-TMP can be useful as a chain stopper and polymer's molar mass regulator during the polymerization of 2,6-DMP.
背景
2,6 - 二甲基苯酚（2,6 - DMP）是苯酚甲基化的产物，对塑料工业尤为重要。气相苯酚甲基化过程是强烈放热的。为确保催化剂床层温度均匀，该过程采用流化床形式的催化剂进行——特别是商业铁铬催化剂TZC - 3/1。
结果
在铁铬催化剂流化床中由苯酚和甲醇合成了2,6 - 二甲基苯酚，并对催化剂的流化情况进行了研究。实现了铁铬催化剂流化床的稳定状态。通过测量流速确定了反应物的最小流量，确保将反应器中的催化剂床层引入流化状态。由于2,6 - 二甲基苯酚合成产物中邻甲酚含量较高，提出了工艺节点中的循环流程。一系列原料中邻甲酚含量可变的合成实验确定了稳态参数。
结论
在350 - 380°C的温度范围内，且邻甲酚/苯酚摩尔比大于0.48时，带有邻甲酚循环的工艺节点能够稳定运行。铁铬催化剂上2,6 - DMP的合成苯酚转化率超过90%。此外，未发生O - 烷基化反应（气相色谱 - 质谱分析证实）。通过在2,6 - DMP工艺中应用邻甲酚循环，2,6 - DMP的选择性达到了85%以上。副产物2,4 - DMP和2,4,6 - TMP的参与水平较低。在应用邻甲酚循环的工艺节点中，基于2,6 - DMP的最高产率得出的最佳条件下，最终混合物中有2%摩尔的2,4 - DMP和6%摩尔的2,4,6 - TMP，而2,4,6 - TMP在2,6 - DMP聚合过程中可用作链终止剂和聚合物分子量调节剂。
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