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Process for selectively proudcing C3 olefins in fluid catalytic cracking process

A technology of olefins and catalysts, which is applied in the direction of catalytic cracking, hydrocarbon cracking to hydrocarbons, organic chemical methods, etc., and can solve the problems of cost increase and low selectivity of olefins

Inactive Publication Date: 2002-11-20
EXXONMOBIL CHEM PAT INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, even if a specific catalyst balance can be maintained to maximize overall olefin production, olefin selectivity is generally poor due to undesired side reactions such as extensive cracking, isomerization, aromatization, and hydrogen transfer reactions. Low
Light saturated gases from undesired side reactions can add to the cost of recovering the desired light olefins

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-13

[0023] The following example illustrates the importance of process operating conditions to maintain the purity of chemical grade propylene. The sample is a sample of catalytic naphtha produced by cracking ZCAT-40 (a catalyst containing ZSM-5), which has been heated at 1500°F. (815°C) for 16 hours with steam to simulate industrial equilibrium. A comparison of Examples 1 and 2 demonstrates that increasing the catalyst / oil ratio will increase propylene yield at the expense of propylene purity. The comparison of Examples 3, 4, 5 and 6 shows that lowering the oil partial pressure greatly improves the propylene purity without sacrificing the propylene yield. A comparison of Examples 7, 8, 9 and 10 demonstrates that increasing the temperature improves propylene yield and purity. A comparison of Examples 11 and 12 demonstrates that shortening catalyst residence time increases propylene yield and purity, and Example 13 shows a reactor temperature that can be achieved using a conventio...

Embodiment 14-17

[0029] Cracking of olefins and alkanes contained in naphtha streams (eg, FCC naphtha, coker naphtha) over small or medium pore zeolites such as ZSM-5 can produce significant amounts of ethylene and propylene. The selectivity to ethylene or propylene and the selectivity of propylene to propane varies as a function of catalyst and process operating conditions. It has been found that co-feeding steam and catalytic naphtha to the reactor increases the yield of propylene. The catalyst can be ZSM-5 or other small or medium pore zeolites. Table 2 below shows that propylene yield increases when 5wt% steam is co-fed with FCC naphtha containing 38.8wt% olefins. Although the propylene yield increased, the propylene purity decreased. Therefore, other operating conditions need to be adjusted to maintain the desired propylene selectivity.

[0030] Example

Embodiment 18-21

[0032] The following examples illustrate the effect of varying the oil partial pressure. A full range of catalytic naphthas were cracked over the ZSM-5 catalyst at two different oil partial pressures. Operating conditions included: a temperature of 575°C and a catalyst / oil ratio of 4.5. As shown in Table 3, the examples operated at lower oil partial pressures produced significantly higher ratios of propylene to propane and somewhat higher ratios of propylene to ethylene.

[0033] Example

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Abstract

The invention discloses a method for producing propylene from catalytic cracking or thermal cracking naphtha stream. The naphtha stream is contacted with a catalyst comprising 10-50 wt% crystalline zeolites having an average pore size of less than 0.7 nm under reaction conditions comprising a temperature of 500-650°C and a hydrocarbon partial pressure of 10-40 psia. A separate stream containing aromatics can be fed with the naphtha stream.

Description

[0001] Cross-Referenced Related Applications [0002] This application is a continuation-in-part of US Patent Application Serial No. 09 / 073,085 filed on May 5, 1998. field of invention [0003] The present invention relates to a kind of production C by catalytic cracking or thermal cracking naphtha stream 3 Alkenes method. Background of the invention [0004] The need for low emission fuels has increased the demand for light olefins used in alkylation, oligomerization, MTBE and ETBE synthesis processes. In addition, there is a continuing need for low cost availability of light olefins, especially propylene, as feedstock for polyolefin production, especially polypropylene production. [0005] Fixed-bed processes for the dehydrogenation of light alkanes have recently attracted renewed interest in order to increase olefin yields. However, these types of processes generally require large investment capital and high operating costs. Therefore, it would be advantageous to incr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C4/04C07B61/00C07C4/06C07C11/02C07C11/06C10G11/02C10G11/04C10G11/05C10G11/18C10G35/02C10G35/04C10G35/06C10G35/095C10G51/02C10G51/04C10G57/02
CPCC10G51/023C10G57/02C10G2400/20
Inventor P·K·拉德维格J·E·埃斯普林G·F·斯唐茨W·A·沃奇特B·E·亨利S·C·丰陈诞仁J·F·卡皮希R·G·希尔勒
Owner EXXONMOBIL CHEM PAT INC
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