Abstract
In the present work, we have made attempts to prepare petroleum pitches from paraffinic-rich clarified oil (CLO) by giving thermal treatment at 370 °C in the presence of Cu and Cr catalysts. The feed CLO is predominantly paraffinic in nature, so it takes fairly large thermal soaking time (21 h) to convert into pitch having mesophase content below countable limits. To increase the mesophase content in the pitch or to make mesophase pitch, 3 wt % transition metal catalysts (Cu and Cr) were added to CLO. Addition of transition metal catalysts not only enhances mesophase formation but also helps to reduce thermal treatment time by promoting polymerization and condensation reactions at a faster rate. The mesophase formation pattern reveals that Cu and Cr catalysts increase the mesophase content from below countable limit to 12 and 9 vol %, respectively. This indicates that Cu and Cr showed better catalytic activity for mesophase formation growth. The effect of transition metal catalysts on physico-chemical properties (softening point, coking value, toluene insolubles and quinoline insolubles) as well as the optical texture and physical properties of mesophase pitches were investigated by optical microscope, FT-IR, SEM, NMR, TG/DTG and XRD.
Highlights
Mesophase pitches are prepared either by thermal [6, 13] or catalytic polymerization [18, 20, 22, 23] processes from low-value petroleum and coal by-products, i.e., decant oils
I.e., clarified oil (CLO)-Cr-3 and CLO-Cu-3, prepared from CLO using Cr and Cu catalysts, respectively, exhibit increased value of physico-chemical properties, i.e., softening point (SP), pitch yield (PY), coking value (CV), mesophase content (MC), toluene insolubles (TI) and quinoline insolubles (QI) as compared to CLO-0-0 pitch whose properties are reported in our previous paper [9]
Thermal soaking time is reduced because catalyst particles promote the polymerization and condensation reactions among the polycyclic aromatic molecules which lead to the gradual rise of SP, PY, CV, MC, TI and QI of the resultant mesophase products
Summary
Mesophase pitches are prepared either by thermal [6, 13] or catalytic polymerization [18, 20, 22, 23] processes from low-value petroleum and coal by-products, i.e., decant oils. In our previous paper [9], we have used cobalt and nickel salts in petroleum residues (paraffinic clarified oil and aromatic heavy extract) to enhance the mesophase contents, pitch yields and other physico-chemical properties. In our previous reported paper [9], paraffinic clarified oil (CLO) took a very large thermal soaking time (21 h) to convert into petroleum pitch at 370 °C having mesophase content below countable limit.
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