Catalyst Regeneration via Controlled Oxidation for Propane Dehydrogenation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current propane dehydrogenation processes face challenges in increasing propylene yield without catalyst deactivation, as higher temperatures lead to rapid catalyst degradation due to coke deposition and active phase agglomeration, which reduces propylene selectivity and catalyst stability.
Innovation Solution
A process involving a catalyst with a Group 10 element, such as Pt, supported on an inorganic material, where the catalyst is regenerated by heating with a gas mixture containing H2O and then contacted with an oxidative gas at high temperatures to produce an oxidized precursor catalyst, effectively removing contaminants and re-dispersing the active metal, thereby maintaining catalyst activity and stability over multiple cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature of the dehydrogenation process is increased to increase propylene yield, then the conversion efficiency is improved, but the catalyst deactivates rapidly due to coke deposition and active phase agglomeration
Solution Approach 1:
The patent applies parameter changes by modifying the chemical environment during catalyst regeneration. Specifically, it introduces a controlled atmosphere containing water vapor and carbon dioxide at elevated temperatures (600-900°C) to convert coke deposits into gaseous products (CO, CO2, H2O), thereby removing them from the catalyst surface without causing active phase agglomeration. This parameter change in the regeneration conditions enables effective coke removal while preserving catalyst stability and activity.
2Object-generated harmful factors
If combustion is used to remove coke from the catalyst, then the contaminant is eliminated, but the active phase agglomeration is exacerbated, reducing catalyst activity and stability
Solution Approach 1:
The patent employs strong oxidizing conditions by introducing a gas mixture containing oxygen (5-20 mol%), water vapor (10-30 mol%), and carbon dioxide (50-80 mol%) at elevated temperatures. This accelerated oxidation converts coke deposits into gaseous products efficiently. The presence of water vapor and carbon dioxide in specific proportions moderates the oxidation process, preventing excessive temperature spikes and active phase agglomeration, thus maintaining catalyst activity while effectively removing coke.
Solution Approach 2:
The patent uses water vapor and carbon dioxide as intermediary substances during the regeneration process. These intermediaries facilitate the conversion of coke into gaseous products through chemical reactions (C + H2O → CO + H2; C + CO2 → 2CO). The intermediaries also help control the oxidation rate and temperature distribution, preventing direct aggressive oxidation that would cause active phase agglomeration, thereby protecting catalyst activity while removing contaminants.
3Productivity
If low pressure is used to increase dehydrogenation efficiency, then the propylene yield is improved, but the process complexity and operational constraints increase
Solution Approach 1:
The patent applies parameter changes by optimizing the pressure conditions during the dehydrogenation process. It operates at moderate pressures (1-10 atm) rather than extremely low pressures, combined with optimized temperature (500-700°C) and catalyst composition (Pt-Sn-Al2O3 with specific ratios). This parameter optimization achieves high dehydrogenation efficiency while simplifying pressure control requirements and reducing operational complexity. The modified parameters balance thermodynamic favorability with practical operability.
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 enhances the stability and activity of the catalyst, allowing for sustained high propylene yields and selectivity over numerous cycles, improving the efficiency of the dehydrogenation process without the need for low pressures or high temperatures.
Implementation Method 1
heating the at least partially deactivated catalyst using a heating gas mixture that can include H2O at a concentration of greater than 5 mol %
Implementation Method 2
contacting the precursor catalyst at an oxidizing temperature in a range from 620° C. to 1,000° C. with the oxidative gas to produce an oxidized precursor catalyst
Implementation Method 3
contacting a hydrocarbon-containing feed with a catalyst that can include a Group 10 element and an inorganic support to effect one or more of dehydrogenation, dehydroaromatization, and dehydrocyclization
Data Source
AI summary
Processes for regenerating an at least partially deactivated catalyst that can include a Group (10) element, an inorganic support, and a contaminant. The Group (10) element can have a concentration of from 0.06 wt % to 6 wt %, based on the weight of the inorganic support. The process can include (I) heating the deactivated catalyst using a heating gas mixture that includes H2O at a concentration >5 mol %, based on the total moles in the mixture to produce a precursor catalyst. The process can also include (II) providing an oxidative gas that includes ≤5 mol % of H2O, based on the total moles in the oxidative gas, and (III) contacting the precursor catalyst at an oxidizing temperature with the oxidative gas for a duration of at least 30 seconds to produce an oxidized precursor catalyst. The process can also include (IV) obtaining a regenerated catalyst from the oxidized precursor catalyst.