Oil Sand Coke Research Articles

Enhancing CO2 Adsorption via Amine-Impregnated Activated Carbon from Oil Sands Coke

In this work, amine-impregnated activated carbon was prepared from oil sands coke, for use in CO2 capture. Delayed oil sands coke was activated using microwave heating and KOH as activation agent. The resulting material was then impregnated with one of diethanolamine, methyl diethanolamine, or tetraethylene pentamine. Analysis of the bulk and surface composition of the impregnated samples using elemental analysis and X-ray photoelectron spectroscopy suggested that the amines were deposited on the surface of the activated carbon. Materials impregnated with diethanolamine performed best for CO2 capture; the highest adsorption capacity achieved was 5.63 mmol CO2/g adsorbent for activated carbon impregnated with 1.15 mmol N/g activated carbon—nearly 75% higher than reported values for zeolite 13X. Adsorption of CO2 on the amine-impregnated activated carbon at 40, 50, 60, and 75 °C showed that the highest adsorption capacity was obtained at 50 °C. Using oil sands delayed coke as a precursor for activated carbo...

Predicting Project Environmental Performance under Market Uncertainties: Case Study of Oil Sands Coke

A method combining life cycle assessment (LCA) and real options analyses is developed to predict project environmental and financial performance over time, under market uncertainties and decision-making flexibility. The method is applied to examine alternative uses for oil sands coke, a carbonaceous byproduct of processing the unconventional petroleum found in northern Alberta, Canada. Under uncertainties in natural gas price and the imposition of a carbon price, our method identifies that selling the coke to China for electricity generation by integrated gasification combined cycle is likely to be financially preferred initially, but eventually hydrogen production in Alberta is likely to be preferred. Compared to the results of a previous study that used life cycle costing to identify the financially preferred alternative, the inclusion of real options analysis adds value as it accounts for flexibility in decision-making (e.g., to delay investment), increasing the project's expected net present value by 25% and decreasing the expected life cycle greenhouse gas emissions by 11%. Different formulations of the carbon pricing policy or changes to the natural gas price forecast alter these findings. The combined LCA/real options method provides researchers and decision-makers with more comprehensive information than can be provided by either technique alone.

Sulfur dioxide as an activating agent for sulfur-impregnated activated carbon produced from dense petroleum coke

To develop novel sorbent materials for capturing vapor mercury from industrial flue gases at high temperatures, high-sulfur oil-sands fluid coke was activated using 50% sulfur dioxide (SO2) at 700°C under various pre-treatment conditions. Pyrolysis in nitrogen prior to activation significantly decreased specific surface area (SSA) of the product, which was attributed to the thermoplastic behavior of coke at high temperatures. Air pre-oxidation suppressed this effect and provided an enhancement over non-pyrolyzed coke, with SSA peaking at 447 m2/g after 5 h activation. Acid washing of air pre-oxidized activated coke in 10% hydrochloric acid increased SSA by removal of inorganic ash which added weight but contributed minimal surface area. Decreasing initial particle size range from 212–300 to 53–106 μm significantly increased SSA, which was attributable to an outer porous layer of constant thickness. Under optimized conditions, an SSA of 531 m2/g was achieved – the highest reported in literature for physically activated fluid coke. Coke activated with SO2 displays a high mesoporous fraction and pore surface coverage by sulfur groups that were thermally stable up to 500°C.

Effects of microwave activation conditions on the properties of activated oil sands coke

Delayed and fluid oil sands cokes were used to prepare activated carbon through a fast activation process that uses microwave heating and KOH as activation agent. Activation parameters such as particle size, humidity of the purge gas, KOH to coke ratio, and microwave heating time were studied for their impact on the quality of the activated cokes obtained. The iodine number, specific surface area, scanning electron microscopic images, elemental analysis and X-ray photoelectron spectroscopy were used to characterize the activated coke obtained. Small particle size, presence of humidity in the purge gas, and high KOH/coke ratio provided higher iodine number and BET surface area. Longer microwave heating time increased the iodine number and surface area of the activated coke, but not monotonically. The differences in the properties of the activated delayed and fluid cokes are related to the structural differences and volatile content of the raw cokes.

Adsorption of Acid Extractable Oil Sands Tailings Organics onto Raw and Activated Oil Sands Coke

The accumulation of organic contaminants in process-affected (PA) water represents an environmental liability for oil sands operators. Oil sands coke is a promising adsorbent for removing dissolved organic carbon (DOC), which includes toxic acid-extractable oil sands tailings organics (AEOSTO) found in PA water. The ability of raw and activated delayed and fluid coke to remove DOC and AEOSTO from PA water was assessed. Treatment with 5 g/L of activated delayed and fluid coke removed 91% of DOC and 92% of AEOSTO at levels of 36 mg/L and 60 mg/L, respectively. Heavy metal leaching of vanadium at 5.9 mg/L was observed for a 5 g/L application of activated delayed coke, representing a challenge to the approach. Microtox testing indicated that higher carbon doses of activated cokes were effective in reducing toxic the biological response caused by organic compounds; however, exposure to heavy metals increased the toxic effect with time. The proposed methodology should be coupled with an inorganic treatment technique for complete oil sands tailings water treatment.

Waste Classification of Slag Generated in a Pilot-Scale Entrained-Flow Gasifier

Series of gasification tests have been completed in the pilot-scale entrained-flow slagging gasifier at CanmetENERGY using Canadian coals, oil-sand coke, and blends of these fuels to determine if the produced slags are nonhazardous in nature. Solid wastes generated during these tests were analyzed for their trace metals, crystallinity, and toxic constituent leaching tendency in an attempt to provide more insight into the possibility of disposal or by-product use of gasifier-produced solid waste. The gasification tests were performed at conditions representative of commercial gasifiers using a dry-fuel-feed configuration. The lower-volatility elements were found to partition between the slag and process-water solids (PWS) collected after gasification of the oil-sand coke. The less volatile group 1 elements tended to be enriched in both solid streams, whereas the slightly more volatile group 2 elements tended to exhibit higher enrichment in the PWS. Slag samples were found to be inert with regard to their leaching potential, and so these materials can be considered nonhazardous.

Entrained-Flow Gasification of Oil Sand Coke with Coal: Assessment of Operating Variables and Blending Ratio via Response Surface Methodology

Co-gasification of oil sand fluid coke with sub-bituminous coal was performed in an entrained-flow gasifier. The underlying objective of this work was to assess the combined effects of the operating variables (i.e., temperature and oxygen and steam concentrations) and coal/coke blending ratio in an entrained-flow gasification process, where the focus was to quantify the relationships between the response variables and vital operating factors. With a view to the shortcomings of the classical “one-factor-at-a-time” method in identification of the effect of experimental factors and their interactions, a statistical design of the experiment based on response surface methodology (RSM) was used. The response variables used in this work were H2, CO, H2/CO ratio, gasification efficiency, and carbon conversion. Experiments were conducted over a temperature range of 1000–1400 °C, using steam and oxygen to carbon weight ratios of 0.9–4.3 and 0–0.4, respectively, equivalent to 15–50 vol % steam and 0–3 vol % oxygen in N2 carrier gas. All of the response variables were successfully fitted to either a two-factor interaction or quadratic model. Using RSM, the effects of individual operating factors and their interactions were categorically determined, which were not otherwise possible by the classical design of experiment methodology. Using the resultant response variable correlations, H2 production was optimized as a function of the temperature, steam and oxygen concentration, and different blending ratios. The full potentiality of Canadian oil sand coke for entrained-flow gasification was successfully investigated via RSM. The results of this work, however, are only applicable to entrained-flow gasification systems.

Co-gasification of Biomass with Coal and Oil Sand Coke in a Drop Tube Furnace†

The present paper is aimed at investigating the co-gasification of biomass with coal and oil sand fluid coke. Chars were obtained from individual fuels and blends with different blend ratios of coal, oil sand coke, and biomass in a drop tube furnace at different temperatures. The chars were then gasified in a thermogravimetric analyzer (TGA) under CO2 atmosphere to determine their reactivity. Results showed that the effect of the blending ratio of biomass to other fuels on the reactivity of the co-pyrolyzed chars is more pronounced on chars prepared at low temperatures and the effect becomes less significant as the pyrolysis temperature increases. The increased reactivity at a higher biomass blending ratio is due to the presence of synergetic effects originating from the interaction of the two fuels. Scanning electron microscopy images showed differences in shapes and particle size distribution of char particles from biomass and coal/coke. These also showed the agglomeration of coal and coke chars with bi...

Entrained‐flow gasifier fuel blending studies at pilot scale

AbstractFor the foreseeable future, coal and petroleum‐based materials, such as petroleum Coke, residuals, and high‐sulphur fuel oil, are being adopted as the feedstocks of choice for gasification projects. Of particular interest from a Canadian perspective is Coke generated from the thermal cracking of the oil sands in Western Canada. Oil sand Coke contains high sulphur (5–6%), and also typically has a low volatile content, and lower reactivity than most coals. Experimental runs have recently been conducted on the pilot‐scale entrained‐flow gasifier at CETC‐Ottawa, blending oil sand Coke with sub‐bituminous and lignite coals, to try and enhance the gasification potential of these materials. Blending Genesee sub‐bituminous coal with the delayed oil sands Coke was found to alleviate problems encountered with slag plugging the reactor when running with Genesee coal alone. Blends of Genesee sub‐bituminous and Boundary Dam lignite coals with Coke achieved higher carbon conversions and cold gas efficiencies than runs completed with the Coke by itself. While using CO2 as the conveying gas into the gasifier was not found to significantly affect the conversion obtained, steam addition was found to have a marked effect on CO and H2 concentrations in the syngas.

Speciation of vanadium in oilsand coke and bacterial culture by high performance liquid chromatography inductively coupled plasma mass spectrometry

A simple and sensitive method for the speciation of vanadium(III), (IV), and (V) was developed by using high performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC–ICPMS). The EDTA-complexed vanadium species were separated on a strong anion exchange column with an eluent containing 2 mM EDTA, 3% acetonitrile, and 80 mM ammonium bicarbonate at pH 6. Each analysis was complete in 5 min. The detection limits were 0.6, 0.7 and 1.0 μg L −1 for V(III), V(IV), and V(V), respectively. The method was applied to coke pore water samples from an oilsand processing/upgrading site in Fort McMurray, Alberta, Canada and to Shewanella putrefaciens CN32 bacterial cultures incubated with V(V). In the coke pore water samples, V(IV) and V(V) were found to be the major species. For the first time, V(III) was detected in the bacterial cultures incubated with V(V).

97/01706 Effect of reaction conditions on molten-caustic leaching of oil-sand coke residues

97/01706 Effect of reaction conditions on molten-caustic leaching of oil-sand coke residues

Effect of reaction conditions on molten-caustic leaching of oil-sand coke residues

The effect of reaction conditions on the desulfurization of oil-sand coke residues was studied. The variables investigated were temperature, reaction time, heat-transfer resistance and mode of caustic soda addition. The results show that oil-sand coke de sulfurization increases with temperature, reaction time and heat-transfer rate. In an oxidative environment, coke combustion during molten-caustic leaching (MCL) commences at temperatures above 500 °C. The mode of caustic addition has no effect on coke desulfurization.

Structural Features of Activated Carbon Produced From Oil Sands Coke

AbstractThe physical and structural properties of oil sands coke were investigated in an attempt to produce activated carbon from this material via steam activation. Although the activation process resulted in over 60 wt. % burnoff from the starting raw coke, the particle size distribution of the activated coke was similar or slightly larger than that of the raw coke. The changes in bulk density with activation showed a linear decrease with activation, thus indicating that the mass losses occurred mainly in the interior of the coke particles. Absolute density measurements showed an increasing trend with activation between a mass burnoff of 35 wt.% and 50 wt.%., which is consistent with a modification in the amorphous structure within the coke matrix. Scanning electron microscopic examination of the structural features of the activated coke revealed hollow spherical particles composed of concentric layers of carbonaceous matter with void volumes between the layers. The formation of the concentric layers promotes the activation process, thus enhancing internal surface area development.

Upgrading of oil sand coke residues

The application of molten caustic leaching, MCL, for the desulphurization and ash removal from delayed and fluid oil sand coke residues has been studied at a temperature of 400°C. The variables studied were sodium hydroxide to coke weight ratio (1.0–2.0), reaction time (0–2 h) and coke washing conditions. The results obtained indicate that both coke samples were amenable to molten caustic leaching. The optimum reaction time for desulphurization and ash removal for both cokes at 400°C was determined to be 30 min. It is shown that the desulphurization conditions that will concurrently give high carbon recoveries correspond to a desulphurization index of 80% for both coke residues.

Experimental evaluation of molten caustic leaching of an oil sand coke residue

AbstractAn evaluation of molten caustic leaching, MCL, for the desulfurization and demineralization of Syncrude fluid coke has been carried out. The results obtained indicate that with the incorporation of an acid washing step, a treated coke product having sulfur and ash contents of less than 1 % may be obtained. Scanning electron microscopy confirm that vanadium is released during molten caustic leaching. At caustic to coke mass ratio in the range 1.8 ‐ 2.0, the dedlurization reaction was determined to be independent of particle size, thus suggesting chemical reaction control.

Reactivity of caustic treated oil sand coke residues

Thermogravimetry (TG) and Fourier transform infra-red (FTIR) spectroscopy have been used to study the pyrolysis behavior and oxidative reactivity of molten caustic treated and untreated oil sand coke residues. In comparison with the Suncor delayed coke, the Syncrude fluid coke gave higher levels of CO/CO 2 during pyrolysis while CH 4 was only observed with the latter. However, the CO/CO 2 evolution during pyrolysis of the caustic treated coke residues was determined to be similar and higher than the values obtained with the untreated fluid coke. This is attributed to the displacement of sulphur in the coke matrix by oxygen during molten caustic leaching. The oxidation reactivity of the coke residues was found to increase with caustic treatment. This increase is attributed to the increased surface area of the cokes.

Gasification of oil sand coke

Cokes derived from two Alberta oil sands operations were gasified at feed rates of about 20 kg h −1 in steam and oxygen using a 0.30 m diameter atmospheric pressure gasifier operated as either a fluidized or a spouted bed. Effects of oxygen/coke ratio and temperature on gas composition, heating value and carbon conversion are presented. In situ sulphur capture using dolomite was demonstrated and the effect of gasification catalyst shown. Gas composition is compared with predictions of an equilibrium model.

Surface structure and oxidation reactivity of oil sand coke particles

Fractions of particles of varying mean diameter were isolated from coke obtained from the fluid coking of Athabasca bitumen. Correlations were established between the rate of oxygen sorption and the apparent surface area as measured by carbon dioxide adsorption. The rate of oxygen sorption, r 0, could be related to particle radius, R, by the equation: r 0 ∝ R D − 3 over a range of particle size where D is the fractal dimension of the coke. The existence of such correlations may be related to the iterative processes which form the particles.

Catalytic effect of lignite ash on steam gasification of oil sand coke

Steam gasification of Suncor and Syncrude cokes was carried out in the presence of ash obtained after burning Onakawana lignite. Catalytic effects of the ash were evident at 930°C whereas at 830°C little effect was observed. These observations were attributed to the combined actions of Ca- and Fe-containing species in the ash, in which the former neutralized the sulphur in the cokes to prevent poisoning of Fe oxides.

Leaching of vanadium and other metals from Athabasca Oil Sands coke and coke ash

Flexicoker coke derived from Athabasca Oil Sands bitumen contains a number of heavy metals, including vanadium, nickel, iron and titanium, which are susceptible to extraction by hydrometallurgical procedures. The leaching behaviour has been studied as a function of pH, temperature and the presence of salts and redox agents. Greater than 50% extraction of the vanadium, iron and nickel can be achieved by acid leaches, but only about 20% of the titanium can be extracted. Weakly acidic leaches extract about 30% of the nickel content but no significant amounts of the other metals. If cokes derived from Athabasca Oil Sands bitumen by the flexicoking process or the conventional delayed-coker coking process are combusted at temperatures below 500 °C, the vanadium and nickel values in the residual ash are readily susceptible to acid leaching.