低银含量高选择性银催化剂上乙烯环氧化工艺条件的优化

Process optimization of ethylene epoxidation over low silver content and high selectivity silver catalyst

采用固定床管式反应器,对两种低银含量高选择性银催化剂上的C2H4环氧化反应的工艺条件进行了优化,考察了原料气中C2H4,O2,CO2的含量、抑制剂1,2-二氯乙烷(EDC)的含量以及气态空速对催化剂的活性和选择性的影响,确定了低银含量高选择性银催化剂适合的工艺参数。试验结果表明,与不含造孔剂载体制备的催化剂相比,采用含造孔剂载体制备的催化剂的EDC含量操作下限更低,φ(EDC)为(0.35~0.39)×10-6时,既有利于提高催化剂的选择性又有利于提高活性。采用合适孔结构载体制备的催化剂具有更好的稳定性,在工业装置中为了有更宽和更安全的操作条件,应使用含造孔剂载体制备的低银含量高选择性银催化剂。

The process conditions of ethylene epoxidation over two kinds of low silver content and high selectivity silver catalysts were studied in a fixed bed tube reactor.The effects of ethylene,oxygen and carbon dioxide content in feed gas,1,2-C2H4Cl2(EDC)inhibitor content and GHSV on the selectivity and activity of the catalysts were investigated.The process parameters suitable for the low silver content and high selectivity silver catalysts were confirmed.The test results show that the operation limit of EDC content is relatively lower for the catalyst prepared with pore-forming agent compared with the catalyst prepared without pore-forming agent,thus confirming the optimum range ofφ(EDC)(0.35-0.39)×10-6 to increase both selectivity and activity for the catalyst.The catalyst prepared from carrier with suitable pore structure has better stability.In order to have wider and safer operating conditions in industrial units,the low silver content and high selectivity silver catalyst prepared with pore-forming agent should be used.