Two-Step Thermal Cracking of an Extra-Heavy Fuel Oil: Experimental Evaluation, Characterization, and Kinetics

Abstract

This work deals with an efficient two-step thermal upgrading process for converting extra-heavy fuel oil to light olefins (ethylene, propylene, and butenes) and fuels (gasoline and diesel fuel). In the first step, mild thermal pretreatment was implemented at different temperatures (360–440 °C) in the liquid phase to obtain a more suitable feedstock for an olefin production unit. Thanks to this cost-effective pretreatment, the upgraded feedstock demonstrated considerable flowability and crackability compared to the initial fuel oil, making the subsequent vapor-phase operation easier to handle at temperatures as high as 800 °C with no severe operational impediments. The quantitative 1H and 13C NMR studies shed light on the enhanced features of the thermally treated feedstock toward lighter and more valuable products. As a result, remarkable olefin production (74.7 or 55.1 wt % light olefins based on the upgraded or the original feedstock) was accomplished in this two-step process. The process could be alternatively stopped at the first stage for maximum liquid fuels (69.3 wt %) with gasoline as the larger constituent. The detailed kinetic investigations of the thermal decomposition of the feedstock using several reliable approaches revealed that the activation energy predictions (42.3–272.9 kJ/mol) by the Kissinger–Akahira–Sunose method almost perfectly matched the trend of a reference Starink model over the whole range of conversion. All model-free methods correlated with a coefficient of determination above 97.9%. Avrami’s theory was further applied to determine the reaction order, and the values were slightly smaller than those from a five-lump kinetic model of the semibatch operation. However, the apparent activation barrier in the reactor was in good correspondence with the range from the microscale nonisothermal decomposition.

Synergistic Coconversion of Refinery Fuel Oil and Methanol over H-ZSM-5 Catalyst for Enhanced Production of Light Olefins

“…Upgrading of the refinery fuel oil over H-ZSM-5 was conducted in a fixed-bed reactor placed in an electrical furnace according to the standard microactivity test units (Figure ), which is also regarded as an accepted representative for the real FCC conditions. More specifications of the experimental procedure ,, appear in the Supporting Information. In order to precisely assess the impact of methanol as a coreactant on fuel oil catalytic cracking, two blank tests with fuel oil and methanol as sole feedstocks were also performed under the same experimental conditions.…”

“…Catalytic cracking of viscous heavy hydrocarbons − is one of the leading technologies in petrorefineries and petrochemical industries to produce light olefins (including ethylene, propylene, and butenes) and middle distillates to meet the growing worldwide demands. − Lower-energy consumption, CO 2 emission, and coke formation, as well as improved selectivity toward the desired products, form the pillars of preference of fixed-bed or fluid catalytic cracking (FCC) approaches over thermal cracking of these heavy feedstocks. − Despite the progress in the FCC and residue FCC (RFCC), it is still challenged by the market demands in the opposite direction of the regular changes in the quality of the feedstock, which entail rapid deactivation of the catalyst because of fouling and poisoning. , Among the most widely applied catalysts in these types of reactions are zeolites, which have astonishing features, such as shape selectivity, high thermal and mechanical stability, tunable acidity, and hydrophilicity. ,− As an example of various types of zeolites, H-ZSM-5 (MFI), probably the most well-known solid acid catalyst, has attracted considerable attention in many reaction systems including the catalytic cracking. , By far, intensive research has been devoted to modify the zeolite characteristics or improve the quality of the applied feedstock prior to the cracking reactions ,− to tackle the abovementioned obstacles.…”

A Look at the Industrial Production of Olefins Based on Naphtha Feed: A Process Study of a Petrochemical Unit

“…The reaction occurs rapidly as the residence time is around some milliseconds and thus the flow rate approaches the speed of sound. When the cracking temperature has been reached, the gas then is quickly quenched in a transfer line heat exchanger or inside a quenching header using quench oil to stop the reaction [10][11][12][13][14][15].…”

Kinetics of different bioreactor systems with Acidithiobacillus ferrooxidans for ferrous iron oxidation

“…Process intensification schemes can always be pursued for higher performance of the established technologies throughout the chemical industry [19][20][21][22][23][24][25][26][27]. Although the bioleaching process is beneficial for climate change mitigation, the slow kinetics of the reactions in this process has to be improved for successful implementation [17], which in turn requires the optimization of the process with respect to the influencing parameters [28].…”