Термический и каталитический крекинг смесей асфальтены / мальтены

The composition of the products of thermal and catalytic cracking of mixtures of deasphaltened crude oil (DAO) or maltenes with 0, 8, 12, 16 % of asphaltenes was studied. Cracking was carried out in a batch reactor at a temperature of 450 °C for 2 hours. Microsized NiCrWC powder as an additive for catalytic cracking was used. Data on the composition of products of cracking were obtained. It was found out that in the course of thermal and catalytic cracking of DAO mixtures with different content of asphaltenes the yield in gaseous and solid by-products increased with increase in their content. At the same time, the yield of distillate fractions ibp‑360 °C also increased, while the content of secondary resins and asphaltenes decreased. The structure of the initial asphaltenes undergone significant changes in the course of thermal and catalytic cracking. Hence, they decreased in size, became more aromatic and had a much lower number of alkyl substituents. It was noted that the addition of NiCrWC in the cracking of DAO mixtures with different asphaltene content did not significantly affect the destruction of asphaltenes and did not contribute to an increase in the yield of the ibp – 360 °C fractionВ работе изучен состав продуктов термического и каталитического крекинга смесей деасфальтенизированной нефти (DAO) с 0, 8, 12, 16 % асфальтенов. Крекинг проводился в реакторах (автоклавах) при температуре 450 °C в течение 2 часов. При каталитическом крекинге в качестве добавки использовался NiCrWC в виде порошка микронного размера. Получены данные по составу продуктов крекинга. Установлено, что в процессе термического и каталитического крекинга смесей DAO с различным содержанием асфальтенов по мере увеличения их содержания увеличивается выход побочных – газообразных и твердых продуктов; при этом также увеличивается выход дистиллятных фракций НК‑360 °C, снижается содержание вторичных смол и асфальтенов. Структура исходных асфальтенов претерпевает значительные изменения в процессе термо- и каткрекинга – они уменьшаются в размерах, становятся более ароматичными с гораздо меньшим количеством алкильных заместителей. Отмечено, что добавка NiCrWC при крекинге смесей DAO с различным содержанием асфальтенов не оказывает значимого влияния на деструкцию асфальтенов и не способствует увеличению выхода фракции НК‑360 о

Uncatalyzed Hydrogen Transfer during 100–250 °C Conversion of Asphaltenes

The reactivity and reactions of asphaltenes were explored over the temperature range 100–250 °C following reports of reactivity and meaningful free radical content in asphaltenes. This study employed industrial pentane precipitated asphaltenes from Athabasca oilsands bitumen. The presence of free radicals in the asphaltenes feed was confirmed. On heating the asphaltenes to 150 °C, the aromatic hydrogen content increased relative to the feed by a factor 1.12. It was also found that on heating the asphaltenes to 150 °C the <i>n</i>-heptane insoluble fraction increased from 67% to 75%. Almost no gas phase products were produced. The observed changes were ascribed to hydrogen transfer reactions and addition products formed by combination reactions. Direct evidence of hydrogen transfer reactions taking place in the asphaltenes was obtained through the use of the model systems, α-methylstyrene and cumene, as well as anthracene and 9,10-dihydroanthracene. The extent of hydrogen transfer was of the order 1.8 mg H/g asphaltenes in 1 h at 250 °C. Asphaltenes also caused dimerization of model compounds, providing indirect evidence that free radical combination reactions took place in the asphaltenes. Interpretation relying on thermodynamic arguments combined with experimental results indicated that at 250 °C the reactive species in asphaltenes were incapable of abstracting hydrogen by hydrogen transfer that had bond strengths (based on homolytic bond dissociation energy) exceeding around 353 kJ mol^–1. Using similar arguments, it was deduced that the ratio of reactive species in asphaltenes capable of abstracting hydrogen with bond strengths in the range around 315–353 kJ mol^–1, compared to transferable hydrogen in asphaltenes with a bond strength less than 315 kJ mol^–1 was about 2:1

Исследование состава и структуры смолисто-асфальтеновых продуктов термолиза нефтяных масел различного состава

На данный момент тема по превращению масляных компонентов весьма ограничена и не позволяет оценить влияние состава масел на строение генерируемых ими САВ, что является важнейшей фундаментальной задачей для оптимизации технологий переработки тяжелых нефтей. В данной работе изучено влияние состава масел нефтей различного состава на образование смолисто-асфальтеновых веществ. Показано, что наличие гетероатомных компонентов способствую большому образованию смол в термическом превращении, структура которых имеет большое содержание ароматических соединений.At the moment, the topic of the conversion of oil components is very limited and does not allow us to assess the influence of the composition of oils on the structure of the SAW generated by them, which is the most important fundamental task for optimizing heavy oil refining technologies. In this paper, we studied the effect of the composition of oil oils of various compositions on the formation of tarry asphaltene substances. It is shown that the presence of heteroatomic components contributes to the large formation of resins in the thermal transformation, the structure of which has a high content of aromatic compounds