A method for refining mesophase pitch by hydrogenation and chain transfer modification

Abstract

The invention discloses a method for modifying and refining intermediate phase pitch through hydrogenation and chain transfer. The method comprises the following specific steps: putting precursor asphalt into a multistage molecular distillation device, separating out a fraction A1 and a residual tower bottom component B1, performing catalytic hydrogenation on the fraction A1, mixing the hydrogenated fraction A1 with the precursor asphalt according to a mass ratio of (1-4): 1, performing pressurized polymerization, and separating out fractions A2 and B2 from pressurized modified asphalt; wherein the initial boiling point of the fraction B2 is 400-500 DEG C, and the final boiling point of the fraction B2 is 540-600 DEG C; carrying out catalytic hydrogenation on a residual tower bottom component C2 and the fraction A2, mixing the product of the catalytic hydrogenation with a precursor, carrying out pressurized polymerization, and directly carrying out thermal polycondensation on the B2 fraction as an intermediate phase asphalt raw material to prepare intermediate phase asphalt. The reactor is a multi-stage distributable tubular reactor, and the interior of the reactor is composed of amulti-stage filter screen, a high-pressure heat flow channel and a lower space of the high-pressure heat flow channel. The intermediate phase pitch with a high hydrogen-carbon ratio and a low softening point can be obtained, is high in structural controllability and low in cost.

Description

technical field [0001] The invention belongs to the technical field of bitumen preparation, and more specifically relates to a method for refining mesophase pitch through hydrogenation and chain transfer modification. Background technique [0002] Mesophase pitch suitable for pitch carbon fiber and carbon foam is a polycyclic aromatic compound with extremely high performance requirements. In order to make the molecules highly oriented, the mesophase pitch needs to have low impurity content, uniform molecular weight distribution, good thermal stability of the molecular structure, and good flatness and flexibility at the same time. Due to the high impurity content and complex composition of natural oil slurry and bitumen, which contain a large amount of long-chain alkanes, olefins, sulfur-containing nitrogen-containing heterocyclic molecules, and a small amount of highly condensed polycyclic aromatic hydrocarbons with ultra-macromolecules, it is necessary to extract the oil sl...

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Problems solved by technology

Patent ZL 201710217039.2 discloses a method of petroleum-based spinnable mesophase pitch, using tetrahydronaphthalene, tetrahydroquinoline, hydrogenated anthracene oil, etc. as a hydrogenation solvent, mixed with high softening point pitch, and pressurized at 400-450°C The hydrogenated pitch is obtained by heat treatment, and the mesophase pitch with a relatively high softening point can be obtained after the hydrogenated pitch is heat treated. This method does not separate the hydrogenated pitch. In order to avoid coking, the degree of hydrogenation needs to be controlled at a low level. The final mesophase Asphalt quality is difficult to improve

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