Coke formation during the process of in-situ combustion is affected by clay minerals, among which montmorillonite shows the most significant effect. A fixed-bed reactor was used to conduct the thermal conversion experiments of heavy oil and model compounds to reveal the mechanism of montmorillonite affecting the coke formation. Under the inert atmosphere, in the presence of montmorillonite, the temperature at which aromatic C–C groups of coke appeared decreased from 500 °C to 450 °C and polymers were formed when toluene was heated, indicating that montmorillonite catalyzed aromatization and polymerization, respectively. The increase in the supporter surface area promoted the formation of coke from pyrolysis by shortening the induction of coking. Under the oxidizing atmosphere, in the presence of montmorillonite, the initial temperature of O₂ consumed by heavy oil decreased from 270 °C to 250 °C, indicating that montmorillonite catalyzed oxygen-adding reaction. The temperature of CO_x released by acetaldehyde and acetic acid decreased, and the release amounts increased, indicating that montmorillonite catalyzed decarbonylation and decarboxylation. Polymers were formed when acetaldehyde, acetic acid, ethanol, and acetone were heated, indicating that montmorillonite catalyzed polycondensation. When the oil mass fraction in the sample was within 18%, further increase in the supporter surface area did not affect the formation of coke from oxidation. The catalysis of montmorillonite was the main mechanism affecting coke formation during the thermal conversion of heavy oil under the inert and oxidizing atmospheres.

原位燃烧过程中的焦炭形成受粘土矿物的影响，其中蒙脱石的影响最为明显。使用固定床反应器进行重油和模型化合物的热转化实验，以揭示蒙脱石影响焦炭形成的机理。在惰性气氛下，在蒙脱石的存在下，焦炭芳族碳原子团出现的温度从500°C降至450°C，并在加热甲苯时形成聚合物，这表明蒙脱石分别催化了芳构化和聚合。 。载体表面积的增加通过缩短焦化的诱导促进了热解过程中焦炭的形成。在氧化气氛下，在蒙脱石的存在下，O的初始温度重油消耗的₂从270°C降至250°C，表明蒙脱石催化了加氧反应。乙醛和乙酸释放的CO _x温度降低，释放量增加，表明蒙脱石催化了脱羰和脱羧。加热乙醛，乙酸，乙醇和丙酮时会形成聚合物，这表明蒙脱石催化了缩聚反应。当样品中的油质量分数在18％以内时，载体表面积的进一步增加不会影响氧化形成焦炭。在惰性和氧化性气氛下，重油热转化过程中，蒙脱石的催化作用是影响焦炭形成的主要机理。