Scheme for Hydrotreatment of Fluid Catalytic Cracking Decant Oil with Reduced Hydrogen Consumption and High Needle Coke Yield upon Carbonization

Abstract

Two decant oils with different sulfur contents and their vacuum distillation fractions were hydrotreated in a fixed-bed flow reactor to produce a feed with sufficiently low sulfur content for needle coke production. Products from hydrotreatment were subsequently carbonized in a tubing bomb reactor to characterize the carbonaceous mesophase development seen in the resulting semicoke. Although the purpose of the hydrotreatment is to reduce sulfur content, hydrogenation of aromatic compounds also takes place during the treatment, thus increasing the hydrogen consumption. Modest hydrogenation of decant oil from the hydrotreatment improved the mesophase development but resulted in a significant decrease of the semicoke yield upon carbonization of the treated product. As a remedy to conserve hydrogen during hydrotreatment and achieve higher coke yields in the subsequent carbonization, only the middle fraction from vacuum distillation of the decant oil was hydrotreated and blended back with the vacuum bottoms to simulate the coker feed. This scheme was successful to attain the desirable sulfur reduction in the feedstock without the penalty of a reduced coke yield upon carbonization or useless hydrogen consumption.

Molybdenum Carbide and Sulfide Nanoparticles as Selective Hydrotreating Catalysts for FCC Slurry Oil to Remove Olefins and Sulfur

“…The hydrogen type classification was referenced from previous literature [7,50]. A slight decrease of the aromatic hydrogen content (H car ) was found in this study, suggesting the mild hydrogenation of aromatics [51]. Consequently, the content of naphthenic hydrogen (H cβ and H cα ) has been raised.…”

Carbon Nanostructure Curvature Induced from the Rapid Release of Sulfur upon Laser Heating

“…As such, sulfur imparts a relatively unobservable impact on the nanostructure, but rather acts to cause micro-cracks upon rapid evolution in the form of H 2 S and CS 2 upon subsequent graphitization heat treatment. The micro-cracks result in an observed volume increase, and therefore, the process has been termed puffing [28][29][30]. Puffing has been evaluated on the micro-and macro-length scales.…”

“…The structural defects imparted on the carbon from oxygen removal set the stage for the trajectory of lamellae growth upon additional heat treatment, whereas in the case of sulfur, the lamellae are significantly annealed with trajectory set after heat treatment at 1000 • C. As such, sulfur imparts a relatively unobservable impact on the nanostructure, but rather, acts to cause micro-cracks upon release upon subsequent graphitization heat treatment, in the forms of H 2 S and CS 2 . The micro-cracks result in an observed volume increase, and therefore, the process has been termed puffing [28][29][30]. This is primarily a problem for the needle coke industry as needle coke is often used as the primary filler in the production of graphite electrodes and micro-cracks, acting to reduce the electrodes' desired properties [28][29][30].…”

“…The micro-cracks result in an observed volume increase, and therefore, the process has been termed puffing [28][29][30]. This is primarily a problem for the needle coke industry as needle coke is often used as the primary filler in the production of graphite electrodes and micro-cracks, acting to reduce the electrodes' desired properties [28][29][30]. The added thermal stability of sulfur in carbon versus oxygen is understood by the enthalpy of formation of the leaving species.…”

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

“…As a result, such mesophase pitches usually exhibit a high softening point and low solubility. To avoid these problems, several additional steps, such as hydrotreatment, , extensive removal of volatile components, , and extraction of non-fusible components, , have been used to prepare high-quality mesophase pitch. However, this inevitably decreases the yield and raises the process complexity and cost of the mesophase pitch.…”