Precious Metal Catalyst Activation Process
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Solution Overview
Problem
Catalysts with low precious metal content in aromatic hydrocarbon conversion processes are sensitive to carbon monoxide in hydrogen, leading to precious metal sintering and decreased activity, requiring high-purity hydrogen for activation, which is costly and not always available.
Innovation Solution
A process involving initial activation with a low CO concentration hydrogen gas followed by exposure to higher CO concentration hydrogen gas at elevated temperatures to achieve high catalyst activity without the need for large volumes of high-purity hydrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-purity hydrogen is used for catalyst activation, then precious metal sintering is inhibited and catalyst activity is maintained, but cost increases significantly
Solution Approach 1:
The patent applies preliminary action by conducting the first activation step at lower temperature (150-300°C) with high-purity hydrogen before the second activation step. This preliminary low-temperature treatment prepares the catalyst surface and reduces metal oxidation state, making the subsequent high-temperature activation more effective while using less high-purity hydrogen overall
Solution Approach 2:
The patent changes parameters by implementing a two-stage activation process where temperature and hydrogen purity are varied between stages. Stage 1 uses lower temperature (150-300°C) and high purity hydrogen, while Stage 2 uses higher temperature (300-500°C) and lower purity hydrogen. This parameter variation allows effective activation while reducing the volume of expensive high-purity hydrogen required
2Quantity of substance
If low-purity hydrogen with elevated CO concentration is used for activation, then cost is reduced, but precious metal sintering occurs and catalyst activity decreases
Solution Approach 1:
The first activation step at lower temperature (150-300°C) with high-purity hydrogen serves as a preliminary protective treatment that establishes a favorable surface condition before exposure to CO-containing hydrogen. This preliminary action prevents the metal from being highly susceptible to sintering during the second stage
Solution Approach 2:
The patent changes the temperature parameter between stages, using lower temperature (150-300°C) in Stage 1 and higher temperature (300-500°C) in Stage 2. This temperature progression allows the catalyst to undergo beneficial structural changes in Stage 1 that protect against sintering during the higher-temperature Stage 2 with CO-containing hydrogen
3Loss of time
If single-stage high-temperature activation is used, then activation time is reduced, but precious metal sintering occurs with CO present
Solution Approach 1:
The patent segments the activation process into two distinct stages with different temperature and hydrogen purity conditions. Stage 1 (150-300°C, high purity hydrogen) and Stage 2 (300-500°C, lower purity hydrogen) are separated by temperature and composition boundaries, allowing each stage to perform its specific function without causing sintering
Solution Approach 2:
The patent implements parameter changes by varying both temperature and hydrogen purity between stages. The temperature increases from 150-300°C in Stage 1 to 300-500°C in Stage 2, while hydrogen purity decreases from high to lower. These coordinated parameter changes enable effective activation while preventing sintering
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
This method effectively inhibits precious metal sintering, reduces the requirement for high-purity hydrogen, and maintains catalyst activity, offering a cost-saving solution for aromatic hydrocarbon conversion processes.
Implementation Method 1
Catalysts comprising a precious metal are routinely activated before normal use thereof by using hydrogen to reduce the precious metal in oxidized state (e.g., PtO2) to elemental state (e.g., Pt)
Implementation Method 2
a small amount of CO can bind irreversibly to Pt during the conversion process, most likely resulting in a weakened interaction with metal support, which then leads to metal migration, agglomeration, and sintering
Data Source
AI summary
Processes for activating precious metal-containing catalysts. The processes can decrease the amount of high purity hydrogen required for starting up a catalytic conversion process such as transalkylation of heavy aromatics, without detrimental impact to the metal activity. The processes can include a low temperature treatment step with a high purity first gas, such as hydrogen generated by electrolysis and/or reformer hydrogen diluted with high purity inert gas, and a high temperature treatment step with a low purity second gas such as the reformer hydrogen. Also, the processes can include mixing a hydrogen gas of high or low purity with a high purity inert gas to form a gas mixture with a proportion of hydrogen no less than 2% and a reduced carbon monoxide concentration relative to the low purity hydrogen, and contacting the catalyst with the gas mixture.