Effect of Petroleum Feedstock and Reaction Conditions on the Structure of Coal-Petroleum Co-Cokes and Heat-Treated Products

Abstract

Bituminous coal/petroleum co-cokes were produced by coking 4:1 blends of vacuum resid (VR)/coal and decant oil (DO)/coal at temperatures of 465 and 500 °C for reaction times of 12 and 18 h, under autogenous pressure in microautoclave reactors. Co-cokes were calcined at 1420 °C and graphitized at 3000 °C for 24 h. Optical microscopy, surface area measurements, X-ray diffraction, temperature-programmed oxidation, and Raman spectroscopy were used to characterize the products. Product yield distribution analysis suggested an increase in co-coke yield as reaction severity index increases, although the increase yield is small at higher index values. It was found that higher reaction temperature (500 °C) or shorter reaction time (12 h) leads to an increase in the amount of mosaic carbon at the expense of textural components necessary for the formation of anisotropic structure, namely, domains and flow domains in the co-coke texture. Characterization of graphitized co-cokes showed that the quality, as expressed by the degree of graphitization, crystallite dimensions, Raman disorder parameter, and oxidation reactivity temperature of the final product, is dependent on the nature of the precursor co-coke, with products obtained from co-cokes produced at 500 °C showing a higher structural disorder than the corresponding products produced at 465 °C. The products obtained from DO/coal blend also displayed better structural order than products derived from VR/coal.

Comparative Study on Structural Parameters of Graphitized Coal–Petroleum Co-cokes and Pennsylvania Anthracites, with Implications for Their Use

“…The location of the reference sample, opposite end to nuclear-grade samples, is ascribed to the high anisotropic nature of this sample, implying long-range preferential orientation. The addition of coal to petroleum feed, i.e., vacuum resid or decant oil, reduces the concentration of large isochromatic units, such as flow domains, in a co-coke structure. ,,, Large isochromatic units lead to a highly anisotropic graphitic structure upon graphitization of the co-coke. The location of co-cokes in Figure is attributed to the fact that the precursor co-cokes were prepared to be deficient in anisotropic character, by adding coal to petroleum feeds, and that the structure of graphitized co-cokes carries both anisotropic and isotropic characteristics.…”

“…Tables , , and present graphitized co-cokes, graphitized anthracites, and nuclear-grade graphite samples used in this study and their synthesis conditions, respectively. In-depth studies on the synthesis and characterization of these graphitized co-cokes and anthracites have been published separately. , The nuclear-grade graphite samples studied here are among several graphite candidates that have been chosen for use in the Next Generation Nuclear Plant program and represent the isotropic end in this study. It is also important to note that the nuclear-grade graphite samples used were manufactured using a traditional synthesis method, meaning that they were synthesized by graphitizing a mixture of a filler coke and a binder.…”

“…As already mentioned, an indepth study exploring the effect of co-coking feedstock (VR/ coal and DO/coal) and reaction conditions as well as a detailed comparison of semi-anthracite and anthracite in native and demineralized versions have been published separately. 21,22 In our work, we did not mix the co-cokes or anthracites with a binder, to focus on the behavior of these prospective filler materials. The function of a binder phase is to plasticize the filler powder, so that it can be formed into bodies of the required shape or size, which are strong enough to withstand handling in the later stages of manufacture.…”

Citric Acid-Treated Zeolite Y (CY)/Zeolite Beta Composites as Supports for Vacuum Gas Oil Hydrocracking Catalysts: High Yield Production of Highly-Aromatic Heavy Naphtha and Low-BMCI Value Tail Oil

“…The BMCI value was calculated using Equation 4 (Nyathi et al, 2012) to determine the quality of tail oil for steam-cracking feedstock. Poly-aromatic hydrocarbons have the highest BMCI (higher than 200), whereas paraffinic hydrocarbons have the lowest BMCI (<20):…”

“…Heavy naphtha with a high aromatic potential content (APC) (Han et al, 2014) is commonly used as catalytic reforming feedstock to produce aromatics. Tail oil with a low Bureau of Mines Correlation Index (BMCI) value (Nyathi et al, 2012) is used as steam-cracking feedstock to produce ethane.…”