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Technical collaboration is the key
Upgrading heavy-oil and bitumen-derived feeds
Growing global demand for oil, reduced conventional oil supply, increased competition and tighter environmental controls are driving some oil producers to modify their production sites to process synthetic crude oils, including extra-heavy and bitumen-derived crudes.
Processing such feedstocks presents many challenges: their nature and the associated technical and operational issues can greatly complicate hydroprocessing.
In Canada, a major source of synthetic crude, refined products originate from extra heavy crudes (i.e., Cold Lake) and oil sands (i.e., Athabasca bitumen).
But there is global potential for this type of production.
Energy consulting firm IHS CERA predicts that oil sands production will grow from 1.7 million barrels a day in 2012 to 3.2 million barrels a day in 2020.
It also says that markets outside North America, particularly in Asia, hold potential for refining this additional production from oil sands; China, for example, is expected to nearly double its current refining capacity of 10 million barrels a day by 2030.
Many facilities have increased their use of heavy-oil and bitumen-derived feeds in order to maximise asset utilisation and facility margins.
This often requires increased processing and technology capabilities in several refining process units, particularly the hydroprocessing assets.
The magnitude of the impact depends on the feed being processed, the flexibility of the
facility and the ability to offset the increased processing requirements.
Criterion Catalysts & Technologies (Criterion) has collaborated with refinery operators to develop customised catalyst systems and operating practices to improve days on-stream, generate higher yields and facilitate the processing of more challenging feeds.
Hydroprocessing of bitumen-derived crude oils can be challenging, as Kevin Carlson, Business Development Manager, Criterion, explains.
“Difficulties arise owing to the high concentrations of sulphur, nitrogen, aromatics, asphaltene and arsenic, and of metals such as nickel and vanadium that are detrimental to catalyst performance.
Asphaltenes can foul process equipment and lead to unexpected pressure drops, and arsenic will rapidly deactivate catalysts even at very low concentrations.
“Through technical collaborations with upgrader and refinery operators, we have learned how refineries can develop bitumen-derived feedstock processing capabilities with minimal adaptation and investment,” he continues.
“The following examples illustrate some of the challenges associated with processing these crudes and the solutions that we have developed to mitigate them.”
Improved guard catalyst for arsenic removal
Some petroleum resources, including Athabasca bitumen, contain high levels of arsenic,
which is a catalyst poison that leads to significant loss in hydrodesulphurisation (HDS) and hydrodenitrogenation (HDN) activity and a shift of the reactor axial temperature profile owing to reduced hydrogenation activity in the arsenic-poisoned top layers.
Consequently, protecting catalysts from arsenic poisoning became a priority, as Max Ovchinnikov, Senior Scientist, Shell Global Solutions, explains,
“The development of high-performance hydrotreating catalysts enabled the processing of difficult crudes and prompted refiners and catalyst suppliers to look for dedicated arsenic abatement solutions to protect the main catalyst beds and catalysts in post-treatment reactors from arsenic poisoning.
Criterion addressed this challenge by launching several dedicated arsenic guard catalysts with high HDS and HDN activities.”
Through technical collaborations with upgrader and refinery operators we have learned how refineries can develop bitumen-derived feedstock processing capabilities with minimal daptation and investment.
Ovchinnikov points to a joint research and development programme between Criterion and a North American refiner to develop a new guard catalyst for managing arsenic in naphtha–kerosene feed blends derived from oil sands.
“This technical collaboration resulted in MaxTrap[As]syn catalyst,” he says.
“This exhibits a 70% improvement in volumetric arsenic uptake capacity compared with the previous generation while providing over 50% better utilisation of nickel for arsenic capture and better and more stable HDS and HDN activity, as evidenced by pilot plant testing using 100% coker naphtha feedstock.
The first commercial deployment of MaxTrap[As]syn catalyst occurred in early 2013.”
Low-cost hydrogen makes high-value products
The costs of natural gas fuel and hydrogen production have dropped significantly over the past decade.
Using low-cost hydrogen for heavy crude processing can increase liquid volume yields and boost the production of highervalue products.
Advances in catalyst technology employed during the global clean fuels initiatives have led to many hydroprocessing units having underutilised capabilities.
This offers the opportunity for drop-in solutions during a catalyst change-out.
Working in close technical collaboration with plant operators, Criterion can provide additional reactor volume to enable further hydrogen utilisation upgrades and extend days-onstream.
Examples of the benefits include:
- aromatic saturation to enable density upgrades, smoke point improvements, feed difficulty capability, and fluidised catalytic cracking (FCC) yield gains;
- selective ring opening to further improve density and volume swell while improving diesel cetane. Selective ring opening maximises cetane improvement per unit of hydrogen consumption.
- conversion through mild hydrocracking (distillate, vacuum gas oil and residue) to minimise lower-value fuel yields, increase heavy oil processing capacity and improve product quality and margins; and
- shape-selective paraffin cracking and isomerisation to improve distillate cold flow properties.
The available technologies enable the hydrogen utilisation/volume expansion achieved to be tailored to specific refiners’ capabilities and objectives.
Increased capability with bitumen-derived feeds
FCC feed pretreatment (FCC PT) units often process bitumen-derived feeds.
Catalysts that operate in this service must have optimised sulphur, nitrogen and aromatic saturation performance to drive the FCC unit’s economic performance and be able to operate stably in an environment with significant levels of contaminants such as nickel, vanadium, silicon, sodium, arsenic and asphaltenes.
CENTERA® catalyst DN-3651 combines the proven stability and contaminant-tolerance features of ASCENT DN‑3551, an established NiMo FCC PT catalyst, with unique CENTERA active site architecture.
This combination offers step-out performance in HDS, HDN and aromatics saturation along with high catalyst stability in FCC PT applications.
A significant aspect of the CENTERA DN-3651 development programme is that the catalyst was developed specifically for FCC PT applications utilising high-throughput experimentation while targeting improvements in challenging synthetic feeds.
This sort of work helps to expedite the testing process, as Carlson explains.
“The high-throughput reactor system makes use of multiple tubular flow reactors with automated process control and sampling.
This significantly accelerates catalyst development compared with conventional testing techniques.
Leads generated with the high-throughput equipment were confirmed by conventional-scale pilot plant testing.”
Applying technology improvements such as CENTERA DN-3651 requires a holistic joint approach to ensure that the operator gains full benefits from the technology with respect to site-specific constraints and objectives.
In this example, Criterion utilised a collaborative approach with the customer to improve catalyst performance and facilitate processing of a more difficult oil-sands-derived feedstock.
After extensive collaborative testing, the customer decided to use the CENTERA DN‑3651 catalyst as part of its next catalyst change-out along with an optimised demetallisation catalyst package.
“Many refiners have chosen to upgrade their capabilities in processing difficult to-treat feeds.
Making the right decisions about this kind of move requires good understanding and modelling of the facility, and strong knowledge of the sources and processing requirements of the available crudes.
With the continuing development and increased availability of such feeds, this knowledge needs to be continuously updated to minimise operational surprises.
Ongoing research and development and technical collaboration will be invaluable in this process,” Carlson concludes.
CENTERA is a Criterion Catalysts & Technologies trademark.
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