Spherical Zeolite Catalysts for Propylene Selectivity
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Solution Overview
Problem
Existing propylene production processes using ZSM-5 zeolites are costly due to high energy consumption and result in significant catalyst attrition, with low selectivity towards propylene, leading to substantial production of undesirable by-products like isobutene.
Innovation Solution
A process utilizing spherical zeolite-based catalysts with specific porosity and alumina support, prepared using a porogen and surfactant emulsion, operates in a moving bed reactor to enhance propylene selectivity and reduce energy consumption by minimizing recycled C4/C5 olefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ZSM-5 zeolite catalysts are used in fluidized bed technology for propylene production, then propylene can be produced, but investment cost is high and catalyst attrition is significant
Solution Approach 1:
The patent employs ZSM-5 zeolite catalysts with specific porosity characteristics (microporous structure with controlled Si/Al ratio) to enhance propylene production while maintaining catalyst stability. The porous structure facilitates selective propylene formation and reduces catalyst degradation through optimized mass transfer and reduced mechanical stress.
Solution Approach 2:
The invention uses composite catalyst systems combining ZSM-5 zeolite with specific promoters and support materials to create a more robust catalyst formulation. This composite approach improves catalyst resistance to attrition while maintaining high propylene production activity and selectivity.
2Productivity
If ZSM-5 zeolites with high Si/Al ratio are used to limit hydrogen transfer reactions, then selectivity towards propylene improves, but production of by-products like isobutene remains significant
Solution Approach 1:
The patent optimizes the Si/Al ratio parameter of ZSM-5 zeolite within a specific range (180-1000) to control hydrogen transfer reactions. By precisely adjusting this compositional parameter, the catalyst achieves maximum propylene selectivity while minimizing unwanted by-products such as isobutene, dienes, and aromatics through controlled reaction pathways.
Solution Approach 2:
The invention creates local active sites within the zeolite structure with specific acid strength and distribution characteristics. The heterogeneous acid site distribution within the catalyst particles enables selective propylene formation at certain sites while suppressing by-product forming reactions at other sites, achieving high selectivity.
3Productivity
If recycled C4/C5 olefins are used to maintain identical propylene production, then productivity is maintained, but energy consumption increases significantly
Solution Approach 1:
The patent changes the operational parameters including reducing the recycling ratio of C4/C5 olefins by optimizing catalyst activity and reaction conditions. This parameter adjustment allows maintaining propylene production rates while minimizing the energy-intensive recycling loop, thereby reducing overall energy consumption of the process.
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 higher propylene selectivity and yield with reduced energy consumption and lower catalyst attrition, improving economic viability by minimizing by-product formation and recycling rates.
Implementation Method 1
uses at least one catalyst in the form of spherical beads prepared in the presence of a porogen so as to create macroporous domains within the porosity of each of said beads
Implementation Method 2
presents a porous distribution such that the macroporous volume measured by mercury porosimetry is between 0.10 and 0.20 ml/g and the mesoporous volume measured by mercury porosimetry is between 0.25 and 0.35 ml/g
Data Source
Figure 1
AI summary
A process is described for the direct conversion of a hydrocarbon feed comprising at least olefins having 4 carbon atoms and at least olefins having 5 carbon atoms for the production of propylene, said process comprising passing said feed through at least one reaction unit provided with at least one catalyst in the form of spherical beads of diameter between 1 and 3 mm, each of said spherical beads comprising at least one zeolite and at least one alumina-based support and having a porosity distribution such that the macroporous volume measured by mercury porosimetry is between 0.10 and 0.20 ml/g and the mesoporous volume measured by mercury porosimetry is between 0.25 and 0.35 ml/g.