Hydroconversion of Cyclic Pyrolysis Oil for Transportation Fuel
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Solution Overview
Problem
Cyclic pyrolysis oil, which is rich in aromatic structures, is not suited for use as a quality middle distillate transportation fuel due to its boiling point range and molecular structure, and traditional hydrocracking methods result in significant product yield loss.
Innovation Solution
A process involving hydroconversion of cyclic pyrolysis oil at elevated pressure and in the presence of a catalyst, selectively saturating aromatics and adding hydrogen to cyclic structures, allowing for the production of high-yield, quality transportation fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hydrocracking is used to reduce molecular weight and boiling point of cyclic pyrolysis oil, then the fuel boiling point range is improved, but product yield is significantly lost
Solution Approach 1:
The patent applies parameter changes by modifying the hydroconversion conditions, specifically using elevated hydrogen partial pressure (achieved by increasing total process pressure) to shift the reaction selectivity. This changes the dominant reaction pathway from cracking (which reduces yield) to saturation and hydrogen addition (which preserves yield while improving fuel quality).
Solution Approach 2:
The patent employs partial action by applying hydroconversion selectively to the cyclic pyrolysis oil fraction without complete fractionation. By using elevated pressure conditions, the process achieves effective conversion of cyclic structures while minimizing unnecessary cracking of already suitable fractions, thus preserving product yield.
2Device complexity
If cyclic pyrolysis oil is used directly as transportation fuel, then process complexity is reduced, but fuel quality is insufficient due to high cyclic content
Solution Approach 1:
The patent changes the process parameter of hydrogen partial pressure (by increasing total pressure) to transform the hydroconversion reaction selectivity. This enables the process to effectively saturate aromatic rings and add hydrogen to cyclic structures, converting low-quality cyclic pyrolysis oil into high-quality transportation fuel while maintaining process simplicity.
Solution Approach 2:
The patent uses an intermediary approach by applying hydroconversion treatment as a bridging process between the raw cyclic pyrolysis oil and the final fuel product. This intermediary step, controlled by elevated pressure conditions, transforms the molecular structure to meet fuel specifications without requiring complex multi-step processing.
3Loss of substance
If fractionation is performed to direct only high-boiling feedstock to hydrocracking, then product yield is improved, but process complexity increases
Solution Approach 1:
The patent applies partial action in reverse by using elevated pressure hydroconversion to treat the entire cyclic pyrolysis oil stream without strict fractionation. The excessive application of hydroconversion conditions (elevated pressure) ensures that even fractions already in the desired boiling range are converted to high-quality fuel, minimizing yield loss while avoiding the complexity of precise fractionation.
Solution Approach 2:
The patent creates a universal treatment approach where elevated pressure hydroconversion serves multiple functions simultaneously: it saturates aromatics, adds hydrogen to cyclic structures, and adjusts boiling point distribution. This multi-functional process eliminates the need for complex fractionation-based routing while maintaining high product yield.
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 enables the conversion of cyclic pyrolysis oil into a high-yield, quality transportation fuel that meets commercial specifications by effectively reducing the molecular weight and density of the fuel while minimizing yield loss.
Implementation Method 1
in the presence of a hydroconversion catalyst at elevated pressure
Implementation Method 2
The process will be more selective towards saturation of aromatics as well as addition of hydrogen to cyclic structures
Data Source
AI summary
A process and a process plant for production of a hydrocarbon composition useful as a transportation fuel from a hydrocarbonaceous feedstock, including the steps of a. directing a hydrocarbonaceous feedstock to hydrotreatment in one or more steps providing an intermediate product including less than 0.1 wt % oxygen and a specific gravity, for the fraction boiling in the range defined by the commercial transportation fuel specification, above the upper limit of specific gravity under the commercial transportation fuel specification, b. providing a hydrotreated hydrocarbon stream for hydroconversion from the intermediate product, wherein a fraction for hydroconversion has a T50 being below T95 of the commercial transportation fuel specification, c. directing the stream for hydroconversion to contact a hydroconversion catalyst under hydroconversion conditions to provide a hydroconverted hydrocarbon stream, d. fractionating said hydroconverted hydrocarbon stream to provide at least said hydrocarbon composition useful as a transportation fuel.