Bench-Top Thermal and Steam Catalytic Cracking of Athabasca Residual Fractions: Attainable Upgrading Levels Correlated with Fraction Properties

Abstract

Thermal cracking (TC) of the Athabasca vacuum residue (ATVR) and its deasphalted product [deasphalted oil (DAO)] was studied. A comparison of conversion and product properties between TC and ultradispersed catalytic steam cracking (CSC) upgrading of both feedstocks is also reported, using K–Ni catalysts. Thermal conversions with stable products for the deasphalted fraction (DAO), reached 20% (w/w) higher values than the ATVR. DAOCSC provided 8% (w/w) increased conversion compared to DAOTC, with stable products. Higher thermal conversions for the DAO compared to the vacuum residue were explained in term of the better properties determined for the asphaltenes produced in DAO upgrading, i.e., higher hydrogen content and better solubilization properties due to lower molecular sizes, solubility parameters, and aromaticities. A definitive link between the nature of produced asphaltenes and products stabilities, as measured via P-value, was found. Higher DAO-steam catalytic conversions with stable products were also obtained and rationalized based on the occurrence of water splitting into *H and *OH radicals and hydrogen production from steam reforming/steam cracking reactions occurring during CSC processing. The inhibition of hydrocarbon free radical recombination (coking) by *H capping and hydrogenation facilitated by Ni catalysts are believed key reactions occurring, leading to better DAO product properties. Exploratory evidence gathered with the NiCeMo CSC-catalyst for whole bitumen processing added support to the later findings, i.e, olefin production inhibition was evidenced, indirect evidence of hydrogenation occurrence. A convenient field upgrading process that avoids distillation or separation (deasphalting) carried out at low T, P is, thus, envisaged.

Visbreaking of Vacuum Residue Deasphalted Oil: New Asphaltenes Formation

“…A first-order relationship adequately described conversion of only up to a naphtha yield of 20% visbreaking conversion, with visbreaking conversion expressed in terms of naphtha production and not residue conversion. Moreover, thermal cracking of Athabasca VR DAO has been reported to reach about 48 wt % visbreaking conversion before products showed signs of instability (as measured via the p -value) . In this work, the transition in which a change in product properties occurred was observed beyond 46 wt % conversion, which is similar to the reported conversion in which visbroken products started to show instability, as indicated by their p -value.…”

“…This result suggests that higher achievable conversion levels may be achieved in thermal cracking with the asphaltenes-depleted feedstock. This observation is supported by the work of Ortega et al., where the conversion of Athabasca VR DAO was 20–30 wt % higher than non-deasphalted Athabasca VR. In addition, VR DAO from the Athabasca region was also used in this work, which is the same provenance of the VR DAO used in the work of Ortega et al Conversions of 39.9 and 45 wt % are reported at 416 °C and 30 min and 423 °C and 24 min, respectively, which are similar to conversion values achieved in the present work: 41 wt % with standard uncertainty of 5 wt % at 417 °C and 30 min and 47 wt % with standard uncertainty of 1 wt % at 425 °C and 20 min (Table ).…”

“…Higher conversion can be achieved when visbreaking deasphalted oil is compared to visbreaking oil that was not deasphalted. However, during visbreaking, new asphaltenes are formed, irrespective of whether the feed material is deasphalted or not. ,− The formation of new asphaltenes erodes the conversion advantage gained by solvent deasphalting before visbreaking and is, therefore, a detrimental side reaction.…”

“…The implication of this description is that various different reaction temperature and residence time combinations can be selected that result in the same conversion. This approach has been used to describe conversion and product formation during visbreaking in models of varying complexity, e.g., refs − , some of which consider new asphaltenes formation explicitly.…”

In-Situ Heavy Oil Aquathermolysis in the Presence of Nanodispersed Catalysts Based on Transition Metals

“…The application of formic acid provides redistribution in the group composition of heavy oil, increasing the content of paraffinic-naphthenic and aromatic hydrocarbons. Inhibition of alkene production indicates for hydrogenation reaction [101]. Inorganic and organic salts of formic acids, formamides, which can be injected together with steam, are proposed in patent [102] as an alternative hydrogen donor.…”