Characterization of pore coking in catalyst for thermal down-hole upgrading of heavy oil

Abstract

a b s t r a c tHeavy oil and bitumen are a potential alternative energy source to conventional light crude. However, recovery of these resources can have substantial environmental impact. Downhole upgrading offers the prospect of both improving recovery, and decreasing environmental impact. However, use of catalysts to enhance downhole upgrading is limited by the need for one that can survive the extreme coking conditions arising from the cracking of heavy oil. In this work the potential of hydrogen donors to improve upgrading and enhance catalyst lifetime was considered. In order to extract detailed information on the catalyst structural evolution during reaction a novel parallel adsorption and thermoporometry characterization method was used. This technique allows detailed information to be obtained on the spatial juxtaposition of different pores, and their relative connectivity, as well as on size distributions. For catalyst operated at the conditions studied, it has been found that coking arises in smaller pores branching off the larger pores providing access to the catalyst interior. It has been found that while coking following use of different types of hydrogen donor leads to similar primary patterns of evolution in the pore-scale descriptors of the remaining accessible void-space, differences do arise in the overall accessible volume. Hence, it seems the hydrogen donor affects the location rather than general nature of the pore structure changes. However, at a secondary level of scrutiny, some differences in porescale evolution are also identified for different hydrogen donors. These differences identified helped the understanding of variations in the performance of different hydrogen donor and catalyst combinations.

Effect of cyclohexane as hydrogen-donor in ultradispersed catalytic upgrading of heavy oil

“…Notably, upgrading with CH:oil ratio of 0.04 g·g −1 under nitrogen atmosphere had a similar effect to adding hydrogen. The results presented in Tables 5 and 6 show that the trend in the amount of coke and API gravity after upgrading is consistent with the report of Dim et al [18]. The slight increase in API gravity with increasing CH:oil ratio whilst suppressing coke formation suggests that significant carbon-rejection in the upgrading reaction is required for a remarkable API gravity rise.…”

“…Hydrogen helps to stabilise generated free radicals that are formed during cracking reactions, to narrow the molecular weight distribution of the product. It has been reported that the dehydrogenation of cycloalkanes such as cyclohexane, methylecyclohexane, and decalin can provide an effective hydrogen supply to cap generated coke precursors during catalytic upgrading [16,18,20]. Dehydrogenation of cyclohexane (CH) could liberate hydrogen for hydrocracking and hydrogenation reactions, if the partial pressure of hydrogen is high enough.…”

“…In the light of this, a hydrogen-donor solvent such as cyclohexane, tetralin, and decalin, for example can be injected to supplement the produced hydrogen from hydrocarbons and steam. The use of hydrogen-donor solvents such tetralin, decalin, and cyclohexane for coal/oil shale liquefaction and thermal/catalytic upgrading of heavy oil vacuum residues have been extensively recognised in the literature [14][15][16][17][18].…”

Recent Approaches, Catalysts and Formulations for Enhanced Recovery of Heavy Crude Oils

“…The ISC method uses vertical producer wells except in the toe-to-heal air injection (THAI) variant which consists of a combination of direct or staggered vertical injection (into which air is injected at 600 to 700 °C) and horizontal producer wells [63]. Today, due to huge cost limitation and requirement of special operation conditions, only a few ISC operate.…”

Deep Conversion of Venezuela Heavy Oil via Integrated Cracking and Coke Gasification–Combustion Process

“…Coke deposits could block the pore structures and active sites for oil conversion, and consequently, the catalyst could regain its utmost cracking activity via complete carbon removal. 43 Table 3 presents the pore properties of different FCC catalysts analyzed by N 2 -absorption. As anticipated because the original FCC catalyst had the most developed pore structures, the surface area of A-FCC catalyst substantially decreased during the hydrothermal treating process, also with slightly lower pore volume and larger pore diameter, which might be caused by the agglomeration of some tiny pores in the hot steam atmosphere.…”