Post-Treated Silver Catalysts for Epoxidation
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Solution Overview
Problem
Current epoxidation catalysts for olefins, despite improvements with alkali metals like potassium, require further enhancement in activity and efficacy, particularly through post-treatment with additional metal salts to optimize the epoxidation process.
Innovation Solution
A method involving the post-treatment of silver catalysts with two metal salts, including potassium nitrate and other nitrates, followed by chemical reduction and calcination, to deposit metals like rhenium and molybdenum on a solid component, enhancing the catalyst's activity for epoxidation reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If alkali metals like potassium are introduced to silver catalysts, then catalytic efficiency is improved, but further enhancement requires post-treatment with additional metal salts which increases process complexity
Solution Approach 1:
The patent applies preliminary action by incorporating promoter metals (rhenium, molybdenum) into the catalyst structure before the main epoxidation reaction. This pre-treatment with metal salts prepares the catalyst surface in advance to enhance its activity and selectivity, allowing the catalyst to achieve higher productivity without requiring complex post-reaction modifications or additional processing steps during operation.
Solution Approach 2:
The patent creates a composite catalyst material by combining silver with promoter metals (rhenium, molybdenum) and alkali metals (potassium). This composite structure integrates multiple functional components: silver provides the base catalytic activity, promoters enhance selectivity and stability, and alkali metals improve overall efficiency. The composite material approach achieves high productivity while managing complexity through a unified catalyst formulation rather than separate treatment steps.
2Productivity
If post-treatment with metal salts is applied to enhance catalyst activity, then epoxidation efficiency increases, but the number of processing steps increases
Solution Approach 1:
The patent merges multiple functions into a single integrated catalyst formulation. Instead of applying separate treatments for promoters, alkali metals, and support modification in distinct sequential steps, the invention combines these components into one composite catalyst material where silver, rhenium, molybdenum, and potassium work synergistically. This merging reduces the number of processing steps while maintaining enhanced epoxidation efficiency.
Solution Approach 2:
The patent optimizes catalyst performance by carefully controlling the composition parameters - specifically the ratios of silver to promoter metals to alkali metals, and the loading amounts of each component. By adjusting these parameters within optimal ranges, the catalyst achieves high epoxidation efficiency with a simplified preparation process, avoiding the need for multiple iterative treatment steps.
3Manufacturing precision
If multiple metal salts are deposited on the catalyst, then selectivity and yield of epoxides improve, but catalyst composition complexity increases
Solution Approach 1:
The patent applies local quality by positioning specific promoter metals (rhenium, molybdenum) and alkali metals (potassium) in optimized locations and concentrations within the catalyst structure. Rather than uniformly distributing all metal components, the formulation creates localized active sites with specific compositions that enhance selectivity for epoxide formation. This localized optimization achieves high manufacturing precision in terms of product selectivity while managing overall composition complexity through targeted placement.
Solution Approach 2:
The patent achieves improved selectivity and yield by precisely controlling the compositional parameters - the specific weight percentages of rhenium (0.05-5%), molybdenum (0.05-5%), and potassium (0.05-4%), along with their ratios to silver. By optimizing these parameters within defined ranges, the catalyst delivers high epoxide selectivity and yield while maintaining a manageable composition complexity that can be consistently reproduced in manufacturing.
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 approach significantly improves the catalytic efficiency for epoxidation reactions, increasing the yield and selectivity of epoxides from olefins and aralkenes, with optimized reaction conditions and catalyst composition.
Implementation Method 1
The epoxidation of olefins with silver catalysts is an industrially useful process for preparing such compounds as ethylene oxide and propylene oxide. The introduction of alkali metals including potassium has been shown to improve the efficacy of these silver catalysts.
Implementation Method 2
Step B) further comprises reacting the solid component under conditions sufficient to cause a chemical reduction of the deposited silver to elemental silver.
Implementation Method 3
The catalyst is calcinated at a temperature from 250 °C to 500 °C.
Data Source
AI summary
The present disclosure generally relates to a silver-based epoxidation catalyst. In certain embodiments, a method is provided for modulating the reactivity of the silver-based epoxidation catalyst, comprising the catalyst being post-treated with at least two different salt solutions. In some embodiments, the treatment results in the deposition of one or more metals onto the surface of the catalyst. In further embodiments, method is also provided of using the silver catalyst to generate an epoxide from an olefin.