Delaminated SSZ-70 Zeolite Catalyst for Hydroprocessing
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Solution Overview
Problem
Hydroprocessing of hydrocarbons using conventional zeolites often results in overcracking due to the diffusion of products out of micrometer-scale zeolitic channels, leading to reduced reaction efficiency and product quality, and reducing acidic strength to prevent this also decreases catalyst activity.
Innovation Solution
The use of delaminated SSZ-70 zeolite as a catalyst, which maintains zeolitic acidity strength and spatial constraint, allowing for controlled placement of acidic sites and improved isomerization selectivity by eliminating mass transfer limitations and reducing severe coking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional micrometer-scale zeolites are used as catalysts, then catalyst activity is maintained, but overcracking occurs due to mass transfer limitations and product diffusion issues
Solution Approach 1:
The zeolite structure is segmented into ultrathin layers with thickness of 1-2 unit cells, transforming the conventional micrometer-scale zeolite into nanoscale delaminated zeolite. This segmentation eliminates mass transfer limitations and prevents overcracking while maintaining catalyst activity, as products can exit the zeolite channels immediately without undergoing further cracking reactions
Solution Approach 2:
The physical parameter of zeolite thickness is changed from micrometer scale to nanoscale (1-2 unit cells), fundamentally altering the mass transfer characteristics. This parameter change resolves the contradiction by maintaining sufficient catalyst activity through preserved acidic sites while eliminating overcracking through drastically reduced diffusion paths
2Object-generated harmful factors
If acidic strength is reduced to prevent overcracking, then overcracking is suppressed, but catalyst activity decreases
Solution Approach 1:
Instead of modifying chemical properties (acidic strength), the physical structure is segmented into ultrathin layers. This allows maintaining the original acidic strength and catalyst activity while preventing overcracking through the shortened diffusion path, avoiding the need to compromise catalyst activity
Solution Approach 2:
The harmful effect of overcracking is extracted and eliminated by removing the mass transfer limitation inherent in thick zeolite structures. The delaminated structure extracts the problematic diffusion path while retaining the beneficial acidic catalytic sites
3Stability of the object's composition
If regular SSZ-70 zeolite is used, then catalyst structure is maintained, but mass transfer limitations reduce isomerization selectivity
Solution Approach 1:
The SSZ-70 zeolite is segmented into delaminated ultrathin layers, preserving the crystalline framework structure while eliminating mass transfer limitations. This segmentation enables precise control over reaction pathways, significantly improving isomerization selectivity without compromising framework stability
Solution Approach 2:
The zeolite structure transitions from a three-dimensional bulk structure to a two-dimensional ultrathin layer structure. This dimensional change reduces the diffusion path from micrometer to nanometer scale, eliminating mass transfer limitations while maintaining the spatial constraint and structural integrity of the zeolite framework
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
Delaminated SSZ-70 catalysts achieve superior isomerization selectivity and product control, enhancing diesel cold flow properties and reducing overcracking, with significant improvements in C7+ product yield and isomerization selectivity compared to regular SSZ-70 catalysts.
Implementation Method 1
Zeolites are widely used as acidic catalysts for refining applications attributed to their unique and uniform pore structure
Implementation Method 2
hydroprocessing products often experience varying degrees of continuous (over)cracking when they diffuse out of micrometer-scale zeolitic channels
Data Source
AI summary
Provided is an improved hydroprocessing process allowing one to realize superior isoselectivity. The process comprises contacting a feed comprised of normal hydrocarbons under hydroprocessing conditions with a catalyst comprising delaminated SSZ-70. The delaminated SSZ-70 has been found to provide unexpected improvements in the catalysis of hydroprocessing hydrocarbons. Delaminated SSZ-70 offers a zeolite layer with a single unit cell of thickness in one dimension, allowing an elimination of mass transfer in comparison with non-delaminated SSZ-70.