Zeolite Adsorbent with Silica-Rich Clay Binder for Hydrocarbon Purification
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Solution Overview
Problem
Zeolitic adsorbents used for purifying hydrocarbon feeds containing unsaturated molecules suffer from reduced adsorption capacity due to coke formation during successive adsorption-desorption cycles, especially when treating feeds with highly reactive molecules, leading to performance loss over time.
Innovation Solution
The use of a zeolite-based adsorbent with a clay binder having a Si/Al weight ratio of more than 2, which reduces reactivity and coke formation without the need for additional metals or complex shaping steps, maintaining high adsorption capacity and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If zeolitic adsorbents are used to purify hydrocarbon feeds containing unsaturated molecules, then high adsorption capacity for impurities is achieved, but coke formation occurs during successive cycles leading to reduced adsorption capacity
Solution Approach 1:
The patent changes the chemical composition parameters of the adsorbent by incorporating a silica-rich clay binder with SiO2 content of at least 80% by weight and Si/Al molar ratio of at least 5. This compositional modification reduces the overall reactivity of the adsorbent system while maintaining the zeolite's impurity adsorption capacity, thereby preventing coke formation and extending service lifetime
Solution Approach 2:
The patent creates a composite adsorbent material combining zeolite particles with a silica-rich clay binder. This composite structure leverages the high adsorption capacity of zeolite for heteroatom-containing impurities while the silica-rich clay matrix provides chemical inertness that prevents coke formation from unsaturated hydrocarbons, thus resolving the contradiction between initial performance and long-term stability
2Quantity of substance
If zeolitic adsorbents are used to extract impurities, then selective adsorption of heteroatom-containing molecules is achieved, but formation of heavy carbonaceous products clogs pores reducing capacity
Solution Approach 1:
The silica-rich clay binder acts as an intermediary material between the zeolite active sites and the unsaturated hydrocarbon molecules. It provides a chemically inert environment that prevents the oligomerization and cyclization reactions leading to coke formation, while allowing the zeolite to maintain its selective adsorption function for impurities
Solution Approach 2:
By modifying the chemical composition parameters—specifically increasing SiO2 content to at least 80% and Si/Al ratio to at least 5 in the binder—the patent creates a less reactive matrix that suppresses coke-forming reactions while preserving the functional properties needed for impurity removal
3Stress or pressure
If adsorbent particles are made with minimum dimension of 0.5 mm to limit pressure drops, then fluid flow is improved, but mechanical strength requirements become more critical
Solution Approach 1:
The silica-rich clay binder creates a mechanically robust composite structure that can support larger particle dimensions (minimum 0.5 mm) without excessive pressure drops. The composite material provides the mechanical strength needed for large particles while maintaining the low pressure drop characteristics required for efficient fluid flow through the adsorption bed
Data Source
AI summary
The present invention concerns an adsorbent comprising at least one zeolite selected from a zeolite of the 12 MR, 10 MR and 8 MR type and at least one binder comprising a clay with a Si/Al weight ratio of more than 2. It also concerns its preparation process and its use in a process for purifying a hydrocarbon feed comprising unsaturated molecules and at least one impurity comprising at least one heteroatom of the O, S or N type.