Abstract Molybdenum naphthenate was used as a catalyst to study the effects of the catalyst dosage on the product distribution, and the properties of suspended coke (Cokesus) and depositional coke (Cokedep) during slurry-bed hydrocracking of an atmospheric residue from Merey. The colloidal stability of product system, microscopic appearance of catalysts in coke, and the types and relative contents of Mo on coke surface were also investigated to elucidate the reason for those effects. The results showed that adding the Mo catalyst restrained the coke formation effectively, particularly the Cokedep. With the increase in catalyst dosage, the H2 consumption, gas, light oil, Cokesus, and Cokedep yields all initially decreased and then increased, while the conversion rate of raw materials initially increased and then decreased. In all cases, the highest yields were obtained at the same catalyst dosage. This indicated that increasing the catalyst dosage did not always improve the catalytic effect. The change trends of the colloidal stability of product system and the relative Mo4+ content on coke surface were consistent with the change trend of hydrogenation effects as the catalyst dosage increased. Increasing the catalyst dosage could result in the formation of more Mo4+ species with higher hydrogenation activity than other Mo valence states, which improved the system colloidal stability. However, when catalyst dosage exceeded a certain threshold, further increase decreased the relative Mo4+ content and reduced the system colloidal stability. This accounts for the influence of the catalyst dosage on the catalytic effects toward the heavy oil slurry-bed hydrocracking reaction.

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催化剂用量对重油浆态床加氢裂化结焦影响的初步研究

摘要 以环烷酸钼为催化剂，研究了Merey常压渣油浆态床加氢裂化过程中催化剂用量对产物分布的影响，以及悬浮焦（Cokesus）和沉积焦（Cokedep）的性质。还研究了产物体系的胶体稳定性、焦炭中催化剂的微观外观以及焦炭表面钼的类型和相对含量，以阐明这些影响的原因。结果表明，加入Mo催化剂能有效抑制结焦，尤其是Cokedep。随着催化剂用量的增加，H2消耗量、气、轻油、焦炭和焦炭的收率均先降低后升高，而原料转化率先升高后降低。在所有情况下，在相同的催化剂用量下获得了最高的产率。这表明增加催化剂用量并不总能提高催化效果。随着催化剂用量的增加，产物体系胶体稳定性和焦炭表面Mo4+相对含量的变化趋势与加氢效果的变化趋势一致。增加催化剂用量会导致形成更多的具有比其他 Mo 价态更高的加氢活性的 Mo4+ 物种，从而提高了体系的胶体稳定性。然而，当催化剂用量超过一定阈值时，进一步增加会降低Mo4+的相对含量，降低体系胶体稳定性。这说明了催化剂用量对重油淤浆床加氢裂化反应催化效果的影响。