Method for preparing propylene through catalytic conversion of olefin raw material

Abstract

The invention relates to a method for preparing propylene through a catalytic conversion of an olefin raw material. The method comprises the steps of: introducing a raw material rich in C4<=> - C8<=> olefins into a fluidized bed reactor of a catalytic conversion device so as to contact and react with a catalytic cracking catalyst, separating a reaction product and a spent catalyst, subjecting the separated spent catalyst to steam stripping and coke burning regeneration for recycling use, and fractionating the separated product so as to obtain light olefins, gasoline, diesel oil, heavy oil and other low molecular saturated hydrocarbons. The catalytic conversion device consists of a riser reactor, a fluidized bed reactor, a settler, a stripper and a regenerator, wherein, the stripper is located under the fluidized bed reactor and is communicated with the bottom of the fluidized bed reactor, the outlet of the riser reactor is communicated with the bottom of the fluidized bed reactor, the outlet of which is communicated with the inlet of gas-solid separation equipment within the settler, and the catalyst outlet of the settler is communicated with the bottom of the fluidized bed reactor. The light olefins obtained by the method of the invention have high selectivity.

Description

technical field [0001] The invention relates to catalytic conversion of hydrocarbons, more specifically, to a method for selectively producing small molecule olefins, especially propylene, through catalytic cracking reaction of C4-C8 olefins in the presence of a catalyst containing mesoporous small molecule olefins with good selectivity. Background technique [0002] At present, low-carbon olefins (ethylene + propylene) mainly come from steam cracking units, and the rest mainly come from by-products of refineries (mainly catalytic cracking units). In addition, cracking reactions can occur through the contact of hydrocarbons, especially olefins, with zeolite-containing catalysts. Take light olefins. For example, CN1414068A discloses a method for producing ethylene and propylene by contacting low-value-added olefins with a ZSM-5 zeolite catalyst selected from a silicon-aluminum ratio of 20 to 70. The zeolite contained in the catalyst is modified by metal elements selected fro...

AI Technical Summary

Problems solved by technology

[0006] In the riser reactor of catalytic cracking in the prior art, the concentration of the catalyst decreases with the increase of the gas volume. Generally speaking, the mass concentration of the catalyst in the second half of the riser decreases significantly, and the reaction temperature also decreases significantly at the same time. Therefore, it is difficult to fully crack the feedstock rich in C4-C8 olefins to produce small molecule olefins such as propylene

In addition, C4-C8 olefins are more difficult to convert than heavy oil raw materials, so a higher reaction temperature is required, and the corresponding oil contact temperature is also high, resulting in a higher dry gas yield

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