Process for selectively producing propylene in fluid catalytic cracking process

A propylene and catalyst technology, applied in the field of C3 olefin production of polypropylene, can solve the problems of increased cost and low olefin selectivity, etc.

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 low 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] Use the following examples to illustrate the importance of process operating conditions for maintaining the purity of chemical grade propylene. The sample is a catalytic naphtha sample produced by cracking ZCAT-40 (a catalyst containing ZSM-5). This catalyst has been heated at 1500 ° Steam treatment at F (815°C) for 16 hours 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 a...

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 further adjusted to maintain the desired propylene selectivity.

[0030] Reality

Embodiment 18-20

[0032] Light catalytic naphtha (boiling point less than about 140 ℃). Steam and light catalytic naphtha are added together in a ratio of 1:1. The catalyst starts with no coke on it and when coke builds up on the catalyst the yield is a function of the time the catalyst is in the stream The selection of propylene in the distillate has been improved.

[0033] Example

[0034] The light olefins produced by the preferred process can be used as feedstock in processes such as oligomerization, polymerization, copolymerization, trimerization, and related processes (hereinafter "polymerization") to form macromolecules. These light olefins can be polymerized alone or in combination with other substances according to polymerization methods known in the art. In some cases, light olefins may require their separation, concentration, purification, upgrading, or other processing prior to polymerization. Propylene and ethylene are the preferred polymerization feedstocks. Polyprop...

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Abstract

The invention discloses a method for selectively producing olefins from catalytic cracking or thermal cracking naphtha streams and producing polypropylene from the olefins. The naphtha stream is contacted with a catalyst containing 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. The catalyst may be pre-coked with a carbonaceous feedstock. Additionally, carbonaceous feedstock for coking the catalyst may be added with the naphtha feedstock.

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 C which is selectively produced by catalytic cracking or thermal cracking naphtha stream 3 Process for the production of polypropylene from olefins. 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 the production of polyolefins, especially polypropylene. [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 ope...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C4/04C07B61/00C07C4/06C07C11/02C07C11/06C08F10/06C10G11/02C10G11/04C10G11/05C10G11/18C10G35/02C10G35/04C10G35/06C10G35/095C10G51/02C10G51/04C10G57/02
CPCC10G51/023C10G11/18C10G51/026C10G57/02C10G2400/20
Inventor P·K·拉德维格J·E·阿斯皮林G·F·斯顿兹W·A·沃奇特B·E·亨利
Owner EXXONMOBIL CHEM PAT INC
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