Zeolite Catalyst Olefin Oligomerization Branching Control
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Solution Overview
Problem
Current olefin oligomerization processes face challenges in producing olefin oligomers with a limited extent of branching, which affects their properties and suitability for specific applications, such as surfactants and lubricants, due to variations in catalyst selectivity and reaction conditions.
Innovation Solution
The use of zeolite catalysts with specific frameworks like MTT, TON, MWW, MRE, MTW, and MFI, modified by steaming, organic acids, transition metals, or NiO impregnation, under controlled oligomerization conditions to produce olefin oligomers with a targeted size range and low branching index, specifically C10-C13 olefins with an average branching index of 2.2 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solid phosphoric acid catalysts are used for olefin oligomerization, then the reaction can proceed effectively, but pressure drop over the catalyst bed increases gradually due to coking and swelling, limiting run length
Solution Approach 1:
The patent changes the physical-chemical parameters of the catalyst by using molecular sieve catalysts with specific pore sizes and acid site densities instead of solid phosphoric acid catalysts. This parameter change allows the reaction to proceed while preventing coking and swelling, thereby eliminating pressure drop increase and enabling longer run lengths.
2Manufacturing precision
If zeolite catalysts are used to produce olefin oligomers with limited branching, then product selectivity improves, but catalyst activity and stability vary requiring optimization
Solution Approach 1:
The patent applies local quality by creating heterogeneous acid sites within the zeolite catalyst with different strengths and distributions. This is achieved through controlled synthesis conditions and post-treatment methods, which create specific local environments that promote oligomerization while limiting branching, and simultaneously enhance catalyst stability through optimized pore structures and acid site configurations.
3Manufacturing precision
If bulky amine treatment is applied to ZSM-22 and ZSM-23 zeolite catalysts to enhance product selectivity, then selectivity improves initially, but amines desorb during operation leading to decreased selectivity and poorer product purity
Solution Approach 1:
The patent extracts the problematic amine modification step from the catalyst preparation process. Instead of using bulky amine treatment that temporarily enhances selectivity but then desorbs during operation, the invention uses inherently stable zeolite catalysts with optimized pore structures and acid site distributions that provide consistent selectivity throughout the catalyst's operational life without requiring removable modifiers.
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 enhances the selectivity and tunability of olefin oligomers, optimizing their properties for targeted applications by maintaining a low branching index even after functionalization, thereby improving their biodegradability and performance.
Implementation Method 1
The condensation reaction or process is referred to herein as 'oligomerization,' and the condensation products (oligomerization products) are low molecular weight olefin oligomers formed through condensation of up to about 12 olefin molecules with each other
Implementation Method 2
U.S. Pat. No. 7,425,662 and International Patent Application Publication WO 2003/082780, for example, describe the use of ZSM-22 and ZSM-23 zeolite catalysts that have been treated with a bulky amine to enhance product selectivity during olefin oligomerization. Since the amine is essentially chemisorbed to acidic sites of the zeolite catalyst
Data Source
AI summary
A feed mixture comprising at least one C3 olefin and/or at least one C4 olefin may be contacted with a zeolite catalyst under oligomerization reaction conditions to form a product mixture comprising a plurality of olefin oligomers. The zeolite catalyst, optionally with one or more further modifications, may be selected for operability at high WHSV values that may produce at least C12 olefins in the product mixture having an average branching index of about 2.2 or less, such as about 1.3 to about 2.0. Under suitable conditions, C10-C13 olefins may comprise at least about 25% of the product mixture, based on total olefin oligomers. Percentage conversion of the at least one C3 olefin and/or at least one C4 olefin may impact the average branching index of C12 olefin oligomers and selectivity for C10-C13 olefin oligomers. An amount of C4 olefin in the feed mixture may produce a targeted selectivity for C12 olefins.