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

Abstract

Naphthene-based aromatic-rich fraction was modified by tetrahydronaphthalene and polyethylene glycol to obtain modified materials which were selected to prepare mesophase pitches by a direct condensation method. The structural composition of modified materials were characterized by simulated distillation (SIMDIS), elemental analysis, Fourier transform infrared spectrometry (FTIR) and 1 H nuclear magnetic resonance ( 1 H NMR) spectroscopy. Influences of the naphthenic structures and alkyl chains in modified materials on the formation and development of mesophase structures were investigated by analyzing variations in optical texture, softening point, carbon residue, molecular and microcrystal structure of mesophase pitch. Results showed that the alkyl structures in modified materials treated by tetrahydronaphthalene and polyethylene glycol were mainly naphthenic structures and alkyl chains, respectively. The existence of alkyl structures in modified materials was beneficial for the formation of mesophase with high quality. Moreover, the naphthenic structures had a better improving effect than alkyl chains. Abundant naphthenic structures or an appropriate amount of alkyl chains in feedstock contributed to the preparation of mesophase pitch with large domain structure, low softening point, high carbon residue and ordered microcrystal structure.

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 molecular stacking heights ( L c ) of C-MP, C/P-MP, and P-MP are 2.89, 3.12, and 3.54 nm, respectively, as shown in Table . It is worth noting that these trends for d 002 and L c in these prepared mesophase pitches are inconsistent with the result reported in refs and , which may be explained by differences in the chemical structure and the rigidity of the mesophase pitch molecules. The semirigid molecular structure especially the aryl–aryl single bond, as described in Figure c, reduces the conjugation of P-MP molecules and lead to a certain degree of molecular plane distortion, reducing molecular flatness, and hence increasing d 002 -spacing.…”

“…It is worth noting that these trends for d002 and Lc in these prepared mesophase pitches are inconsistent with the result reported in Refs. [4,34], which may be explained by differences in the chemical structure and the rigidity of the mesophase pitch molecules. The semi-rigid molecular structure especially the arylaryl single bond, as described in Fig.…”

Spinnable Mesophase Pitch Prepared via Co-carbonization of Fluid Catalytic Cracking Decant Oil and Synthetic Naphthalene Pitch

“…In addition, FDO–NP(0)–MP and FDO–NP(100)–MP possess the lowest and highest H n percentages of 3.30 and 6.04%, respectively, although FDO and NP possess naphthenic structures of 32.7 and 17.6%, respectively, as shown in Table . This suggests that the naphthenic structures of the feedstocks partly remained in their mesophase pitch products after the polymerization, and the naphthenic structures in NP obviously showed higher thermal stability than those in FDO. Additionally, the percent H n value for mesophase pitches prepared via co-carbonization increases with the NP weight ratio in the feedstock, and the experimentally measured H n hydrogen content is higher than the expected linear combination value from FDO–NP(0)–MP and FDO–NP(100)–MP [calculated on the basis of the H n hydrogen content of individual FDO–NP(0)–MP and FDO–NP(100)–MP according to their mass ratios], as shown in Figure b.…”

“…FDO and NP were mixed in mass ratios of 100:0, 90:10, 80:20, 70:30, and 0:100 to form the basic feedstocks, which were labeled as FDO−NP(0), FDO−NP (10), FDO−NP (20), FDO−NP (30), and FDO−NP(100), respectively. These mixtures of FDO and NP (ca.…”

Preparation and characterization of petroleum-based mesophase pitch by thermal condensation with in-process hydrogenation

“…It was proved that the hydrogenation was an effective method to improve the quality of mesophase pitch. 23 The in-process hydrogenation means that a hydrogen donor is used to react with condensation intermediates generated during the formation of mesophase product. This method was generally used in the hydrovisbreaking process of residual oil, aiming to lower the viscosity and improve the rheology of reaction system.…”