CO2-to-Jet Fuel Catalytic Process at Moderate Pressure
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Solution Overview
Problem
Existing processes for converting CO2 into jet fuel and propylene are inefficient, thermodynamically constrained, and require high pressures, often producing light olefins and aromatics, which are difficult to purify and costly to separate, limiting the production of sustainable aviation fuel (SAF) and chemical-grade propylene on an industrial scale.
Innovation Solution
A dual-function catalyst comprising a Cu and Cr-free MeOH synthesis catalyst with Zn and Zr oxides, combined with a 10-ring zeolite, is used to convert CO2 to methanol and olefins at moderate pressures, followed by oligomerization and hydrogenation to produce jet fuel and propylene, while maintaining low methanol partial pressure to enhance selectivity to desired olefins and reduce aromatics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure (70 bar) is applied for CO2 hydrogenation to methanol, then methanol synthesis is thermodynamically favorable, but the process requires high pressure operation and subsequent pressure reduction for olefin production
Solution Approach 1:
The patent combines methanol synthesis and olefin production into a single integrated reactor system with a dual-function catalyst. This merging eliminates the need for separate high-pressure methanol synthesis and low-pressure olefin production steps, allowing the process to operate at moderate pressure (20-60 bar) while achieving both methanol conversion and olefin formation in one step.
Solution Approach 2:
The patent changes the operating pressure parameter from conventional high pressure (70 bar) to moderate pressure (20-60 bar) by using a bifunctional catalyst system. This parameter change is enabled by the catalyst's ability to perform both methanol synthesis and olefin production functions simultaneously, resolving the thermodynamic constraint that previously required high pressure.
2Stress or pressure
If conventional catalysts are used for CO2 to olefins conversion, then the process can operate at moderate pressure, but mainly light (C2-C4) olefins are produced which are not suitable for jet fuel
Solution Approach 1:
The patent uses a composite bifunctional catalyst comprising a methanol synthesis catalyst (e.g., Cu/ZnO/Al2O3) combined with an olefin production catalyst (e.g., ZSM-5 zeolite). This composite material enables the system to produce C3-C8 olefins with high selectivity suitable for jet fuel, rather than just light olefins, while operating at moderate pressure.
Solution Approach 2:
The bifunctional catalyst provides different catalytic functions in different regions or active sites within the same catalyst structure. The methanol synthesis component converts CO2 to methanol, while the olefin production component (zeolite) converts methanol to specific olefin ranges (C3-C8), achieving local optimization of product distribution for jet fuel applications.
3Productivity
If existing processes produce light olefins and aromatics, then the conversion efficiency is achieved, but purification and separation become difficult and costly
Solution Approach 1:
The patent changes the product distribution by using a bifunctional catalyst that selectively produces C3-C8 olefins (propylene, butenes, pentenes, hexenes) which are the desired jet fuel precursors. This parameter change in product selectivity simplifies the downstream purification system compared to conventional processes that produce a broad mix of light olefins and aromatics requiring complex separation.
4Productivity
If copper-containing catalysts are used for methanol synthesis, then high activity is achieved, but copper loss and catalyst deactivation occur reducing longevity
Solution Approach 1:
The patent extracts or removes copper from the catalyst formulation, using alternative catalyst systems (e.g., ZnO-based or In2O3-based methanol synthesis catalysts) that do not contain copper. This eliminates the problem of copper loss and sintering that leads to catalyst deactivation, thereby extending catalyst longevity while maintaining acceptable activity through the bifunctional design.
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
The process achieves high selectivity to C3-C8 olefins, low aromatics content, and efficient production of jet fuel and propylene, suitable for SAF and chemical-grade propylene, with improved catalyst longevity and energy efficiency, overcoming thermodynamic constraints and separation challenges.
Implementation Method 1
A dual-function catalyst comprising a Cu and Cr-free MeOH synthesis catalyst with Zn and Zr oxides, combined with a 10-ring zeolite, is used to convert CO2 to methanol and olefins at moderate pressures
Implementation Method 2
The hydrogenation of CO2 to produce methanol suffers from unfavorable thermodynamics and requires a high pressure
Implementation Method 3
followed by oligomerization and hydrogenation to produce jet fuel and propylene
Data Source
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AI summary
A process for producing a hydrocarbon stream comprising hydrocarbons boiling in the jet fuel range, said process comprising: a) passing a synthesis gas (syngas) stream comprising a carbon oxide and hydrogen over a fixed bed comprising a dual-function catalyst active in the conversion of syngas to the oxygenate(s) methanol (MeOH) and/or dimethyl ether (DME), and the conversion of said oxygenate(s) to an olefin product stream; wherein the dual-function catalyst comprises: a MeOH synthesis catalyst, in which the MeOH synthesis catalyst is a Cu and Cr-free catalyst comprising an oxide of Zn in combination with an oxide of any of: Zr, Al, Si, Ti, Ce, La, Ga, In, Mo, Mn, Mg, Y, or combinations thereof; and an oxygenate conversion catalyst comprising a zeolite with a framework having a 10-ring pore structure, in which the 10-ring pore structure comprises a unidimensional (1-D) pore structure selected from any of: *MRE (ZSM-48), MTT (ZSM-23), TON (ZSM-22), or combinations thereof; b) passing at least a portion of the olefin product stream through an oligomerization step over an oligomerization catalyst, and optionally subsequently conducting a separation step, for thereby producing an oligomerized stream; c) passing at least a portion of the oligomerized stream through a hydrogenation step over a hydrogenation catalyst, and optionally subsequently conducting a separation step, for thereby producing said hydrocarbon stream comprising hydrocarbons boiling in the jet fuel range, optionally also comprising hydrocarbons boiling in the diesel fuel range. The invention provides also a plant for conducting the process.