Modified Effects of Additives to Petroleum Pitch on the Mesophase Development of the Carbonized Solid Products

Abstract

Comparative studies in carbonization behaviors of petroleum pitch (SS70 pitch) and SS70-pitch–additive mixtures were conducted to develop a better understanding of the modified mechanisms of additives. The carbonization of solvent fractions in SS70 pitch was also investigated to reveal the relationships among solvent fractions and the additives. The characterization of resultant solid products by X-ray diffraction and scanning electron microscope analysis showed that samples obtained from co-carbonization of SS70–aromatic oil (P1) and SS70–aromatics enriched fractions of FCC slurry (P2) mixtures respectively had higher stacking layer numbers of mesogens and flatter morphology than those of specimens produced by carbonization of SS70 pitch and SS70–deasphalt oil (P3) mixtures. Adding additives P1 and P2 into SS70 pitch lowered not only the rates of carbonization but also the aromaticity and size of aromatic molecules in toluene insolubles formed in the early stage of carbonization, both jointly contributing to the formation of well-developed mesophase. The asphaltenes of SS70 pitch were prone to forming the poorly developed mesophase due to its high reactivity and also interfered with the carbonized performance of maltenes. Additives P1 and P2 played the “dominant partner effect” on mesophase development by providing physical fluidity of the reaction system and some chemical stability for asphaltenes via their dilution effect and H-transfer reactions.

Hydroalkylation modification of naphthene-based aromatic-rich fraction and its influences on mesophase development

“…5,6 Therefore, research on the preparation and formation mechanism of petroleum based mesophase pitch are a hotspot and focus in the eld of carbon materials at home and abroad. [7][8][9] As previously reported, the number of alkyl groups in the raw material was one of the most important factors to control the solubility and the anisotropic content of mesophase pitch.…”

Molecular Structure Control in Mesophase Pitch via Co-Carbonization of Coal Tar Pitch and Petroleum Pitch for Production of Carbon Fibers with Both High Mechanical Properties and Thermal Conductivity

“…The larger anisotropic texture size and content of C/P-MP than those of C-MP are attributed to the introduction of short alkyl group (especially methyl groups) and naphthenic structures from PP by the cocarbonization process. The transfer of methyl groups and hydrogen from PP promotes the molecule rearrangement of C/P-MP so that the orientation of C/P-MP becomes more orderly than that of C-MP, , thus enhancing the solubility and fusibility of C/P-MP.…”

“…Some general properties of the three products after thermal polymerization were summarized in that the orientation of C/P-MP becomes more orderly than that of C-MP [6,21], thus enhances the solubility and fusibility of C/P-MP.…”

“…Highly oriented carbon fibers with high thermal conductivity are usually prepared from mesophase pitches. , The high thermal conductivity and ultrahigh tensile modulus of mesophase pitch-based carbon fibers are attributable to the highly oriented aromatic molecules with planar liquid crystal structure in the parent mesophase pitches . The design and modification of the precursors’ chemical composition and molecular structure play an important role in control of the planar molecules’ sizes and the rheological properties (related to alkyl group content of these aromatic molecules) in mesophase pitches. − …”

Effects of In-Process Hydrogenation on Mesophase Development during the Thermal Condensation of Petroleum Aromatic-Rich Fraction

“…As previously reported, the influences of molecular structures of feedstock on optical texture and rheological property of mesophase pitch have been studied widely. − The hydrogenation of raw materials or mesophase precursors was quite an effective method to improve the properties of mesophase pitch. − Menéndez et al have discussed the relationships between structure compositions of petroleum pitches and optical textures of cokes. The structural composition of pitches is proved to be the determining factor for the improvement of the optical textures of products.…”