Modification of temperature dependence of pitch viscosity for carbon article manufacture

Inactive Publication Date: 2019-12-19
EXXON RES & ENG CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008]In an aspect, a method for forming a modified pitch is provided. The method includes performing solvent extraction on a pitch comprising a T0 value to form an extract comprising a first fraction of the pitch and a raffinate comprising a second fraction of the pitch. At least a portion o

Problems solved by technology

In order to overcome this difficulty, conventional production of carbon fiber from pitch requires the process to be operated within a narrow temperature window, which can be challenging to maintain under commercial production conditions.
Additionally, dif

Method used

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  • Modification of temperature dependence of pitch viscosity for carbon article manufacture
  • Modification of temperature dependence of pitch viscosity for carbon article manufacture
  • Modification of temperature dependence of pitch viscosity for carbon article manufacture

Examples

Experimental program
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example 1

ng Characteristic Temperature and Characteristic Viscosity

[0059]Characteristic temperature values corresponding to T0 values and characteristic viscosities corresponding to ηinf values were determined for three representative vacuum resid fractions. The dots in FIG. 2 correspond to measured values for viscosity at various temperatures. It is noted that the vertical axis in FIG. 2 corresponds to the log of the viscosity. The lines in FIG. 2 correspond to fits of the measured values to Equation (2), the Arrhenius-style equation for the viscosity-temperature relationship as described above. As explained in association with Equation (2), D was set to 7.5 for purposes of fitting the curve to the data. As shown in FIG. 2, the form of Equation (2) provides a relatively good fit for the shape of the data for each of the vacuum resid fractions. Table 1 shows the resulting T0 and ηinf values determined based on the curve fitting.

TABLE 1Characteristic Temperature and Viscosity ParametersSample...

example 3

of Extract and Raffinate to Form Modified Mesophase Pitch

[0063]The following example is a prophetic example. In this example it is assumed that the initial feed has T0=300 K and ηinf=8×10−5 Pa*s. The initial feed is then separated into two streams with different T0 and ηinf. Stream 1 has T0=230 K and ηinf=8×10−5 Pa*s and stream 2 having T0=315 K and ηinf=8×10−5 Pa*s. Stream 1 corresponds to 18 vol % of the initial feed, while Stream 2 corresponds to 82 vol % of the initial feed. The streams were combined in the volumetric fractions ϕ1=0.30 and ϕ2=0.70, producing a modified product with T0=289.5 K and ηinf=8×10−5 Pa*s.

[0064]FIG. 4 show a comparison of the temperature dependence of the viscosity for the initial feed and the modified product. In FIG. 4, the viscosity is plotted on a log scale. As shown in FIG. 4, the modified product has a reduced temperature dependence for all temperatures, including those temperature near 550 K to 595 K that correspond to a desirable temperature rang...

embodiment 1

[0067]A method for forming a modified pitch, comprising: performing solvent extraction on a pitch comprising a T0 value to form an extract comprising a first fraction of the pitch and a raffinate comprising a second fraction of the pitch; and blending at least a portion of the first fraction with at least a portion of the second fraction to form a modified pitch having a modified T0 value less than the T0 value of the pitch.

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Abstract

Methods are provided for reducing or minimizing the temperature dependence of a pitch feed or fraction for use in carbon fiber production, such as a mesophase pitch feed or fraction or an isotropic pitch feed or fraction. A pitch sample can be characterized to determine a characteristic temperature and a characteristic viscosity for the sample. One or more solvent extraction processes can also be performed on the pitch and/or the extract and raffinate fractions formed by the solvent extraction(s). The resulting raffinate and extract fractions are then used to form a modified pitch fraction with a T0 value that is lower than the T0 value of the original pitch. The modified pitch fraction can optionally also have a different ηinf value relative to the original pitch.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Application Ser. No. 62 / 685,571 filed Jun. 15, 2018, which is herein incorporated by reference in its entirety.FIELD[0002]Systems and methods are provided for modifying the temperature dependence of pitch feedstocks, such as mesophase pitch feedstock and / or isotropic pitch feedstocks, for use in production of carbon fiber.BACKGROUND[0003]Isotropic pitch and mesophase pitch are carbon-containing feedstocks that can be formed from residues generated during processing of coal or petroleum feedstocks or by other methods, such as acid catalyzed condensation of small aromatic species. As an example, one of the fractionation products from a catalytic cracking process or slurry hydrocracking process can be a bottoms or “pitch” fraction. Such a pitch fraction can correspond to isotropic pitch. For some grades of carbon fiber, isotropic pitch can be used as an initial feedstock. For other grades,...

Claims

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Application Information

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IPC IPC(8): C10C3/08
CPCC10C3/08C10C3/005D01F9/145
Inventor SMITH, STUART E.SIROTA, ERIC B.BROWN, STEPHEN H.
Owner EXXON RES & ENG CO
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