Modified Zeolite Catalyst for Propylene Selectivity
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Solution Overview
Problem
Current zeolite catalysts used in catalytic cracking of naphtha do not effectively maximize the production of desirable products while minimizing less desirable products, such as benzene, toluene, and xylene, which can deactivate the catalysts.
Innovation Solution
A modified zeolite catalyst is produced by leaching zeolite with a composition of NaOH and Na2CO3, followed by realumination with a realuminating agent, and subsequent modification with metal atoms or ions like Mg, Ba, Sr, Fe, Co, Ni, Cu, Zn, Ga, Ce, Ag, Pd, Bi, Ti, V, Zr, Mo, W, Li, or La, to enhance its catalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional zeolite catalysts are used for catalytic cracking of naphtha, then the cracking process can proceed, but the production of desirable products (propylene) is not maximized and less desirable products (benzene, toluene, xylene) are produced in excessive amounts which deactivate the catalyst
Solution Approach 1:
The patent applies parameter changes by modifying the zeolite catalyst's chemical composition through leaching (removing aluminum) and realumination (adding back controlled amounts of aluminum) processes. This changes the Si/Al ratio and creates specific pore structures that alter the catalytic cracking pathway, maximizing propylene production while minimizing benzene, toluene, and xylene formation. The metal modification further tunes the catalytic properties to achieve selective product distribution.
Solution Approach 2:
The patent creates composite materials by combining modified zeolite structures with specific metal atoms or ions (such as Fe, Co, Ni, Cu, Zn, Ga, Ce, Ag, Pd, Bi, Ti, V, Zr, Mo, W, Li, or La). This composite approach enhances the catalyst's selectivity for propylene production while suppressing the formation of harmful aromatic compounds like benzene, toluene, and xylene that would otherwise deactivate the catalyst.
2Duration of action of stationary object
If conventional zeolite catalysts are used, then the catalytic cracking process can operate, but the catalyst activity decreases over multiple processes due to deactivation by less desirable products
Solution Approach 1:
The leaching and realumination processes fundamentally change the zeolite's structural parameters, creating a more stable framework with optimized Si/Al ratios. This structural modification reduces the catalyst's susceptibility to deactivation by aromatic compounds, allowing it to maintain high activity over multiple naphtha cracking processes. The metal incorporation further stabilizes the catalyst structure against deactivation.
3Productivity
If the zeolite catalyst is modified with multiple treatment steps, then catalytic performance is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The leaching and realumination treatments are performed as preliminary actions during catalyst manufacturing, before the catalyst is deployed for cracking operations. This preliminary modification optimizes the catalyst's pore structure and chemical composition in advance, enabling superior propylene selectivity and catalyst stability during actual use, while the complexity is confined to the manufacturing stage rather than operation.
Solution Approach 2:
The modification process creates local quality variations within the zeolite structure, specifically targeting the pore walls and active sites with controlled aluminum distribution and metal incorporation. This localized modification enhances catalytic performance at critical locations without requiring complete restructuring of the entire catalyst, thereby balancing performance enhancement with manufacturing feasibility.
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 modified zeolite catalyst significantly increases the production of propylene and reduces the production of benzene, toluene, and xylene, maintaining high activity over multiple naphtha cracking processes, thereby improving the efficiency and selectivity of the catalytic cracking process.
Implementation Method 1
contacting the zeolite catalyst with a first composition comprising NaOH and Na2CO3, thereby producing a leached zeolite catalyst
Implementation Method 2
contacting the leached zeolite with a second composition comprising a realuminating agent, thereby producing a realuminated zeolite catalyst
Implementation Method 3
modifying the provided zeolite catalyst, leached zeolite catalyst, or realuminated zeolite with one or more metal atoms or ions comprising Mg, Ba, Sr, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ce, Ag, Pd, Bi, Ti, V, Zr, Mo, W, Li, or La
Implementation Method 4
catalytic cracking of naphtha comprising contacting naphtha with the modified zeolite catalysts
Implementation Method 5
The cracking process takes place when naphtha is contacted with the catalyst at a temperature sufficient to initiate the reaction
Data Source
AI summary
The invention pertains to a zeolite catalyst, methods of making same, and its use in the catalytic cracking of naphtha for the production of lower molecular weight olefins and alkanes, while minimizing production less desirable products. A zeolite is modified by base leaching and by the addition of a metal cation, thereby lowering the Si/Al2 ratio and improving the stability of the formed catalyst.