Phosphorus-Modified Zeolite Catalyst Stability in Steam
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Solution Overview
Problem
Existing catalysts for alcohol dehydration and other hydrocarbon processes, such as zeolites, face challenges with catalyst activity, selectivity, and stability when operated in the presence of steam at high temperatures, particularly in processes like alcohol dehydration, olefin cracking, and methanol-to-olefins conversion, where they often require high temperatures and result in unwanted by-products like ethane and heavy hydrocarbons.
Innovation Solution
A method for producing a phosphorus-modified zeolite catalyst involving steps like steaming, ion-exchange, phosphorus introduction via dry impregnation or chemical vapor deposition, mixing with binders, shaping, and calcination, which enhances catalyst stability and activity under high-temperature steam conditions, specifically using zeolites with structures like ZSM-5 and other crystalline silicates with optimized Si/Al ratios and pretreatment to reduce tetrahedral aluminum content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If zeolite catalysts are used for alcohol dehydration at high temperatures, then catalyst activity is improved, but catalyst stability deteriorates due to framework destruction under steam conditions
Solution Approach 1:
Phosphorus serves as an intermediary substance that protects the zeolite framework from steam-induced destruction. The phosphorus modifies the zeolite surface and framework, creating a protective effect that stabilizes the catalyst structure under high-temperature steam conditions while preserving its catalytic activity for alcohol dehydration
Solution Approach 2:
The invention changes the chemical composition parameters of the zeolite by introducing phosphorus through impregnation or ion-exchange methods. This parameter modification (adding phosphorus) fundamentally alters the zeolite's resistance to steam hydrolysis, enabling it to maintain structural integrity at high temperatures where unmodified zeolites would decompose
2Productivity
If high reaction temperatures are used to improve catalyst activity, then conversion efficiency is improved, but unwanted by-products increase
Solution Approach 1:
The phosphorus modification changes the acid site distribution and strength parameters of the zeolite catalyst. This parameter change allows the catalyst to maintain high activity at lower temperatures or selectively promote desired reactions even at higher temperatures, reducing the formation of unwanted by-products like ethane and heavy hydrocarbons
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 phosphorus-modified zeolite catalyst demonstrates improved activity and selectivity in alcohol dehydration, olefin cracking, and methanol-to-olefins conversion, producing lighter olefins with reduced formation of unwanted by-products like ethane and heavy hydrocarbons, while maintaining stability under high-temperature steam conditions.
Implementation Method 1
introducing phosphorus on the zeolite to introduce at least 0.1 wt% of phosphorus, said introduction being made by dry impregnation or chemical vapor deposition
Implementation Method 2
introducing phosphorus on the zeolite to introduce at least 0.1 wt% of phosphorus, said introduction being made by dry impregnation or chemical vapor deposition
Implementation Method 3
steaming said zeolite
Implementation Method 4
optionally calcinating the catalyst
Implementation Method 5
optionally making a ion-exchange
Implementation Method 6
optionally calcinating the catalyst
Data Source
AI summary
The present invention relates, in a first embodiment, to a method to make a phosphorus modified zeolite comprising the following steps in this order, a) providing a zeolite comprising at least one ten members ring in the structure, optionally making an ion-exchange, b) steaming said zeolite, c) introducing phosphorus on the zeolite to introduce at least 0.1 wt% of phosphorus, said introduction being made by dry impregnation or chemical vapor deposition, d) mixing said zeolite of step c) with at least a component selected among one or more binders and shaping additives, e) shaping said mixture, f) introducing a metal, optionally simultaneously with step d), g) optionally washing the catalyst, h) optionally calcinating the catalyst, i) steaming the catalyst, also referred to as the equilibration step. In a second embodiment phosphorus can be introduced by any means and at step i) the steaming severity (X) is at least about 2. In said second embodiment the catalyst is advantageously steamed at a temperature above 625°C, preferably in the range 700 to 800°C. The metal of step f) is advantageously Calcium. The present invention also relates to the use said catalyst in the alcohol dehydration, the olefin cracking to make lighter olefins, the MTO and the alkylation of aromatics by alcohols with olefins and/or alcohols.