Propylene Oligomerization in Distillation Column Reactor
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Solution Overview
Problem
Existing propylene oligomerization processes using tubular reactors face severe reaction conditions, short catalyst life, and poor selectivity, with previous catalysts like supported phosphoric acid and zeolites requiring high temperatures and pressures, and zeolites losing activity and needing costly regeneration.
Innovation Solution
The process involves using MCM-22 zeolite catalyst in a distillation column reactor at lower temperatures (below 300°F) and pressures (below 500 psig) for propylene oligomerization, allowing concurrent reaction and distillation, which improves catalyst life and selectivity, producing higher molecular weight olefins like C6 and C9 with a distillation structure that supports both reaction and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tubular reactors with supported phosphoric acid or zeolite catalysts are used for propylene oligomerization, then conversion of propylene can be achieved, but severe reaction conditions (high temperature 330-482°F and high pressure 1000-1215 psig) are required
Solution Approach 1:
The patent combines reaction and distillation functions into a single distillation column reactor. The MCM-22 zeolite catalyst is packed within the distillation column, allowing propylene oligomerization to occur concurrently with product separation. This integration enables operation at lower temperatures and pressures because the continuous removal of oligomer products shifts the equilibrium toward conversion without requiring severe conditions.
Solution Approach 2:
The patent changes the operating parameters from the conventional high temperature (330-482°F) and high pressure (1000-1215 psig) to lower temperature (below 300°F, preferably below 200°F) and lower pressure (below 500 psig, preferably 200-450 psig). This parameter change is made possible by the distillation column reactor configuration that continuously removes products, maintaining favorable equilibrium conditions for oligomerization at milder parameters.
2Productivity
If supported phosphoric acid catalyst is used, then propylene oligomerization can proceed, but catalyst life is short (less than 1000 tons of product per ton of catalyst)
Solution Approach 1:
The distillation column continuously separates and removes oligomer products from the reaction zone. This prevents product accumulation and catalyst fouling, extending catalyst life. The continuous distillation process effectively 'recovers' the catalyst activity by maintaining a clean reaction environment, allowing the MCM-22 zeolite to operate for much longer periods without deactivation.
3Duration of action of stationary object
If zeolite catalysts are used, then catalyst life is extended (1500 to 3000 tons of product per ton of catalyst), but activity is lost and regeneration is required at considerable expense
Solution Approach 1:
The distillation column operates continuously to remove oligomer products from the reaction zone. This continuous product removal prevents catalyst deactivation by maintaining favorable reaction conditions and preventing heavy product accumulation. The useful action of the catalyst is sustained over longer periods without requiring shutdowns for regeneration, improving both catalyst life and reliability.
4Productivity
If conventional catalysts are used, then propylene conversion can occur, but selectivity toward desired C6 and C9 oligomers is poor
Solution Approach 1:
The MCM-22 zeolite catalyst provides specific local active sites within the distillation column that favor the formation of C6 and C9 oligomers. The catalyst's molecular structure creates localized reaction environments that promote selective oligomerization to desired products. Combined with the distillation separation that removes products as they form, this achieves high selectivity for the target oligomer range.
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 achieves 70-75% conversion of propylene to desirable oligomers, with improved catalyst life and selectivity, particularly producing branched products suited for oxy chemistry, while reducing operational costs by avoiding the need for regeneration and minimizing fouling.
Implementation Method 1
contacting propylene with MCM-22 zeolite catalyst in a reaction distillation zone under conditions of temperature and pressure to concurrently react the propylene to produce oligomers thereof
Implementation Method 2
separate the oligomer products from unreacted propylene by fractional distillation
Implementation Method 3
separate the oligomer products from unreacted propylene by fractional distillation
Data Source
AI summary
A process for the oligomerization of propylene is disclosed wherein MCM-22 zeolite prepared as a distillation structure is used in a reaction distillation zone under conditions of temperature and pressure to concurrently react the propylene to produce oligomers thereof and separate the oligomer products from unreacted propylene by fractional distillation in a distillation column reactor. Compared to the prior art tubular or plug flow reactors, lower temperatures and pressures are used to produce higher conversions and selectivities to preferred isomeric forms.