A two-stage preparation process for propylene

Abstract

The invention discloses two-section preparation process of propylene. Methanol and refinery carbon teterolefin are used as raw materials, water is used as a diluent, and a two-section fixed bed reactor is adopted for preparation. Catalyst in the first section of the fixed bed reactor contains 50%-85% ZSM-5 molecular sieve, and catalyst in the second section of the fixed bed reactor is magnesium element modified ZSM-5 molecular sieve catalyst. By means of the two-section preparation process of the propylene, water amount in the diluent is reduced, operation temperature is reduced, propylene selectivity and P / E ratio are effectively improved, conversion rate of the raw material methanol can reach as high as 100%, conversion rate of the refinery carbon teterolefin can reach above 85%, and one-way selectivity of propylene can reach as high as 50%.

Description

technical field [0001] The invention relates to a two-stage preparation process of propylene, in particular to a process for preparing propylene by coupling methanol with refinery C4-olefins. Background technique [0002] In the current prior art, there are mainly two processes for preparing propylene from methanol: MTO technology and MTP technology. Compared with MTO technology, MTP technology uses a fixed-bed reactor, which is easy to scale up, has low risk, and has great confidence in industrialization. At the same time, the by-product market is gasoline, liquefied petroleum gas and fuel gas with a large capacity, which has high economic benefits . However, the preparation of low-carbon olefins by methanol is a strong exothermic reaction, and a large amount of heat of reaction is generated in the process of generating low-carbon olefins. The heat of reaction is difficult to remove, and a large amount of water is required as a diluent, resulting in high operating costs; ...

AI Technical Summary

Problems solved by technology

However, the preparation of low-carbon olefins by methanol is a strong exothermic reaction. A large amount of heat of reaction is generated in the process of generating low-carbon olefins, and the heat of reaction is difficult to remove. A large amount of water is required as a diluent, resulting in high operating costs; Existence will lead to catalyst carbon deposition and deactivation too fast, which is not conducive to the stability of the catalyst