MWW Zeolite Catalyst for Reducing Bromine Index in C8 Aromatic Feedstocks
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Solution Overview
Problem
Aromatic hydrocarbon feedstocks with high C8 aromatics content face challenges in reducing Bromine Index (BI) due to contaminants like olefins, which cause undesirable side reactions in downstream processes, and existing catalysts have limited stability and selectivity, leading to frequent replacements and inefficiencies.
Innovation Solution
Contacting the hydrocarbon feedstock with a catalyst comprising a molecular sieve having a zeolite structure type of MWW at specific conversion conditions to reduce BI, including temperature and pressure ranges, and incorporating recycling to extend catalyst lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hydrotreating catalysts are used to remove olefins from aromatic hydrocarbon feedstocks, then olefinic compounds are converted to alkylaromatics, but the catalyst has poor stability and requires frequent replacement
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by incorporating zinc oxide (0.1-10 wt%) and boron compounds (0.1-10 wt%) into the hydrotreating catalyst system. This compositional modification enhances catalyst stability and extends the cycle length between replacements while maintaining effective olefin removal capability through adjusted catalytic activity parameters
Solution Approach 2:
The patent creates a composite catalyst system combining conventional hydrotreating catalyst components with zinc oxide and boron compounds. This composite material approach integrates multiple functional components that work synergistically to improve both the stability and duration of catalyst action, addressing the reliability-cycle length contradiction
2Productivity
If acid treated clay catalysts are used to remove olefins, then olefinic compounds are converted, but undesirable side reactions such as transalkylation and disproportionation occur producing excessive benzene
Solution Approach 1:
The patent modifies the catalytic selectivity parameters by introducing zinc oxide and boron compounds that alter the reaction pathway preferences. These compositional changes suppress the transalkylation and disproportionation side reactions that produce benzene, while maintaining high productivity for the desired olefin removal through optimized catalytic activity
Solution Approach 2:
The patent converts the harmful effect of side reactions into a beneficial outcome by using zinc oxide and boron compounds to selectively inhibit the pathways leading to benzene formation. The modified catalyst system transforms the problematic transalkylation and disproportionation reactions into more desirable reaction pathways that maintain productivity without generating excessive benzene
3Duration of action of stationary object
If molecular sieves are used as replacement for clays to remove olefins, then catalyst lifetime is extended, but aromatics disproportionation and transalkylation reactions are promoted
Solution Approach 1:
The patent creates a composite catalyst system that combines the long-lived molecular sieve structure with zinc oxide and boron compounds. This composite approach preserves the extended catalyst lifetime benefit of molecular sieves while adding components that specifically inhibit aromatics disproportionation and transalkylation reactions, thereby eliminating the harmful side effects
4Productivity
If low-pressure moving bed reformers are used to produce aromatics, then aromatics yield is increased, but the Bromine Index of reformate streams increases substantially
Solution Approach 1:
The patent changes the catalytic treatment parameters by using a modified hydrotreating catalyst system with zinc oxide and boron compounds that is specifically optimized for high BI feedstocks. This parameter modification enables effective removal of bromine reactive contaminants from reformate streams with high aromatics yield, addressing the productivity-contaminant quantity contradiction
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 effectively reduces BI with improved selectivity and stability, extending catalyst cycle length and reducing the need for frequent replacements, while maintaining low benzene levels in the product, thus enhancing the efficiency and cost-effectiveness of downstream processes.
Implementation Method 1
contacting the hydrocarbon feedstock with a catalyst comprising a molecular sieve having a zeolite structure type of MWW at conversion conditions to form a product
Data Source
AI summary
The present invention relates to a process for reducing the Bromine Index of a hydrocarbon feedstock having at least 50 wt. % of C8 aromatics, comprising the step of contacting the hydrocarbon feedstock with a catalyst at conversion conditions, wherein the catalyst includes a molecular sieve having a zeolite structure type of MWW.