Nano-Dispersed Catalyst in Ebullated-Bed Hydroconversion
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Solution Overview
Problem
Ebullated-bed hydroconversion processes for heavy oils face limitations in conversion efficiency and product quality due to the production of fuel oil and the need for frequent maintenance, as they struggle with the limited hydrogen activation capacity of catalysts and the formation of coke and pitchy deposits.
Innovation Solution
Incorporating a nano-dispersed catalyst based on MoS2 or WS2 into the ebullated-bed reactor system, with concentrations ranging from 1000 to 20,000 ppm, and recycling the non-converted heavy fraction through a separation area to enhance hydrogen activation and cracking activity, allowing for higher conversion and better product quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a supported heterogeneous catalyst is used in an ebullated-bed reactor, then hydrocracking capacity is improved, but hydrogen activation capacity remains limited causing fuel oil production
Solution Approach 1:
The patent combines two different catalyst technologies into a single hybrid system: supported heterogeneous catalyst particles (providing hydrocracking capacity) and nano-dispersed catalyst (providing hydrogen activation capacity). This merging allows the system to simultaneously achieve high hydrocracking activity and sufficient hydrogen activation, thereby converting heavy residues more completely and reducing fuel oil production.
Solution Approach 2:
The invention creates a composite catalytic system where two distinct catalyst materials with complementary functions are used together. The supported heterogeneous catalyst (with cracking activity) and nano-dispersed catalyst (with hydrogen activation activity) form a functional composite that overcomes the limitations of either catalyst type used alone.
2Reliability
If solid hold-up is maintained at low levels in ebullated-bed processes, then catalyst deterioration is reduced, but frequent maintenance interventions are necessary for removing pitchy deposits
Solution Approach 1:
The patent converts the harmful effect of solid deposits (coke and pitchy products) into a beneficial function. By allowing higher solid hold-up levels, the system enables the nano-dispersed catalyst to effectively scavenge free radicals and block the formation of pitchy deposits. The increased catalyst inventory transforms from a potential source of deterioration into a protective mechanism that reduces maintenance frequency.
Solution Approach 2:
The invention changes the operating parameter of solid hold-up from the conventional low level (<0.2%) to a higher level (0.2-2.0%). This parameter change allows the system to tolerate and utilize solid deposits as part of the reaction mechanism, where they serve as additional active sites for hydrogen activation and radical scavenging, thereby reducing the need for frequent maintenance.
3Productivity
If heavy fractions are recycled to improve conversion, then conversion degree increases, but catalyst deterioration accelerates due to pitchy deposits
Solution Approach 1:
The patent converts the previously harmful pitchy deposits into a beneficial component of the reaction system. By allowing higher solid hold-up and using nano-dispersed catalyst for effective radical scavenging, the system transforms pitchy by-products into additional active sites that enhance hydrogen activation. This allows heavy fraction recycling to proceed without accelerating catalyst deterioration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly increases conversion efficiency and product quality by leveraging the synergies between ebullated-bed and slurry technologies, reducing fuel oil production and maintaining low solid hold-up, while allowing for the recycling of heaviest fractions and minimizing catalyst deterioration.
Implementation Method 1
The nano-dispersed catalyst based on MoS2 or WS2, dispersed in the heavy oil sent to the hydroconversion area, in a concentration ranging from 1000 to 20,000 ppm, and the good hydrogenation capacity of the nano-dispersed catalyst
Implementation Method 2
the first component, always present, is a mixture of sulphides, one of which obtained from a metal belonging to group VIB and at least one obtained from a metal belonging to group VIII, the second component consisting of acidic sites
Data Source
Figure 1
AI summary
Process for the hydroconversion of heavy oils, selected from crude oils, heavy crude oils, bitumens from tar sands, distillation residues, distillation heavy cuts, distillation deasphalted residues, vegetable oils, oils from coal and oil shale, oils from the thermodecomposition of waste material, polymers, biomasses, comprising sending the heavy oil to a hydroconversion area, effected in one or more ebullated bed reactors, wherein hydrogen is introduced, in the presence of a suitable heterogeneous, supported, hydroconversion catalyst, in addition to a suitable hydrogenation catalyst, nano-dispersed in said heavy oil, and sending the stream coming from the hydroconversion area to a separation area, in which the separated liquid fraction, containing the nano-dispersed catalyst, is recycled to the ebullated bed reactor (s).