Vinyl Acetate Catalyst Preparation to Suppress Gold Aggregation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing vinyl acetate catalysts face challenges in achieving high selectivity and suppressing the generation of carbon dioxide gas, with issues arising from the aggregation of gold particles due to differing hydrolysis rates of palladium and gold compounds, and the presence of copper during hydrolysis.
Innovation Solution
A method involving the use of excess amounts of copper, palladium, and gold compounds, followed by separation from the carrier and contact with an aqueous solution at a pH of 7.0 to 11.5, then reduction treatment, to control the hydrolysis and aggregation of gold particles, resulting in a catalyst with improved selectivity and catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If palladium and gold compounds are supported on a carrier in the same step, then the supporting process is simplified, but gold particles aggregate due to different hydrolysis rates between palladium and gold compounds
Solution Approach 1:
The patent applies preliminary action by first supporting the palladium-containing compound on the carrier, then subsequently supporting the gold-containing compound. This sequential approach allows the palladium to be established first on the carrier surface, creating a foundation that prevents gold particle aggregation during the second supporting step, thereby resolving the contradiction between process simplification and manufacturing precision.
2Manufacturing precision
If copper-containing compound is added during hydrolysis, then the hydrolysis rate of gold-containing compound increases and gold atoms are close to palladium, but gold particles still aggregate in the catalyst production process
Solution Approach 1:
The patent applies parameter changes by optimizing the supporting conditions, specifically controlling the supporting amount and using a supporting solution with pH 4-7 for the gold-containing compound. This parameter optimization prevents gold particle aggregation even in the presence of copper, thereby resolving the contradiction between achieving proper gold atom distribution and maintaining catalyst performance reliability.
3Ease of manufacture
If gold-containing compound is slowly hydrolyzed, then it can be supported at low rate, but gold atoms may not be close to palladium and selectivity of vinyl acetate decreases
Solution Approach 1:
The patent applies parameter changes by adjusting the pH of the supporting solution to 4-7 and controlling the supporting amount of the gold-containing compound to 0.01-10 mmol per 100 g of carrier. These parameter optimizations increase the hydrolysis rate appropriately while ensuring gold atoms are positioned close to palladium atoms, thereby resolving the contradiction between ease of manufacture and manufacturing precision.
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 method effectively suppresses gold particle aggregation and enhances the selectivity of vinyl acetate production while maintaining high catalytic activity, improving the performance of the catalyst.
Implementation Method 1
a gold-containing compound is slowly hydrolyzed and supported on a carrier at a low rate
Implementation Method 2
a reduction treatment is performed
Implementation Method 3
the copper-containing compound is rapidly hydrolyzed and supported on the carrier
Implementation Method 4
the gold-containing compound is adsorbed onto a hydrolysate of the copper-containing compound supported on the carrier
Implementation Method 5
each compound is hydrolyzed, whereby a palladium hydroxide, a gold hydroxide, and a copper hydroxide are supported on the carrier
Data Source
AI summary
A method for producing a catalyst for vinyl acetate production comprising a carrier, copper, palladium, gold, and an acetic acid salt, the method comprising, in the following order, step 1, in which an alkali solution is infiltrated into the carrier, step 2, in which the carrier is brought into contact and impregnated with a solution in which a copper-containing compound, a palladium-containing compound, and a gold-containing compound are contained in excess with respect to desired deposition amounts of the catalyst components, step 3, in which, after the catalyst components have been deposited in the desired deposition amounts, the carrier is separated from the solution, step 4, in which the carrier is brought into contact with water or an aqueous solution each having a pH of 7.0-11.5, step 5, in which a reduction treatment is conducted, and step 6, in which the acetic acid salt is deposited on the carrier.