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二、氢甲酰化反应——改性羰基钴催化剂高压钴催化氢甲酰化反应,真正起作用的活性组份是 HCo(CO)_4。因为它只能在高压下存在,又由于它生成的速度较慢,所以反应需要在高温高压下进行;而且 HCo(CO)_4不能和产物通过精馏简单地分开,循环回合成反应器使用。产物中正、异构醛的比例(以下用 n/i 表示),约在2.5—4.0之间,异构醛经济价值低,生产上希望多得到正构物。这是传统高压法的主要不足之处。在这几方面曾进行许多改进工作,壳牌(Shell)公司开发的膦改性羰基钴催化剂工艺,是其中较成功的。在讨论膦改性钴催化剂前,我们再略加深入地讨论一下反应机理。
Second, hydroformylation - modified cobalt carbonyl catalyst High-pressure cobalt catalytic hydroformylation, the real active ingredient is HCo (CO) _4. Because it can only exist under high pressure, but also because it produces slower, so the reaction needs to be carried out under high temperature and pressure; and HCo (CO) _4 and the product can not simply separated by distillation, recycled back into the reactor. The ratio of normal and isomeric aldehydes in the product (hereinafter expressed as n / i) is about 2.5-4.0. The isomeric aldehydes have low economic value and hopefully more ortho-compounds are produced in production. This is the main disadvantage of the traditional high-pressure method. Many improvements have been made in these areas. Among them, the phosphine-modified cobalt carbonyl catalyst developed by Shell Company is more successful. Before discussing phosphine-modified cobalt catalysts, let’s discuss in more depth the reaction mechanism.