Twice-Activated Low Metal Catalyst CO Resistance
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Solution Overview
Problem
Low metal content catalysts used in aromatic hydrocarbon transalkylation and isomerization reactions are susceptible to deactivation due to exposure to carbon monoxide (CO), leading to reduced activity and lifespan, especially when the catalyst precursor contains low concentrations of hydrogenation metal.
Innovation Solution
The catalyst precursor is initially reduced in a hydrogen atmosphere with very low CO concentration (≤1 vppm) and then further activated in a reactor using a second hydrogen atmosphere with higher CO concentration (≥10 vppm), resulting in a twice-activated catalyst with improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the catalyst precursor is reduced in a hydrogen atmosphere with high CO concentration (≥10 vppm) to activate the catalyst, then the activation process can be performed with readily available hydrogen gas, but the catalytic activity and lifespan are drastically reduced due to CO exposure
Solution Approach 1:
The patent applies preliminary action by performing the initial reduction of the catalyst precursor in a low CO concentration atmosphere (≤1 vppm) before exposing the catalyst to high CO concentrations during normal operation. This preliminary reduction step in a protective atmosphere prevents CO-induced deactivation, allowing the catalyst to achieve full activity while maintaining stability during subsequent high CO exposure periods.
2Reliability
If the catalyst precursor is reduced in a hydrogen atmosphere with very low CO concentration (≤1 vppm) to protect against CO deactivation, then the catalytic activity and lifespan are improved, but additional activation steps are required
Solution Approach 1:
The patent merges the initial reduction step performed in a low CO atmosphere with the subsequent activation procedure. By combining these steps into a unified activation protocol that sequences low CO reduction followed by controlled high CO exposure, the method achieves both catalyst protection and full activation without requiring separate, complex equipment or procedures.
3Quantity of substance
If the catalyst contains low concentration of hydrogenation metal (≤0.5 wt %) to reduce costs, then the manufacturing cost is reduced, but the catalyst becomes highly susceptible to CO-induced deactivation
Solution Approach 1:
The patent applies preliminary action by establishing a protective low CO atmosphere during the initial reduction of low metal content catalysts. This preliminary protective measure is especially critical for low metal content catalysts (≤0.5 wt %) as it prevents CO from causing rapid deactivation of the limited active metal sites, thereby extending catalyst lifespan without requiring additional metal loading.
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 enhances the catalytic activity and lifespan of low metal content catalysts by minimizing the detrimental effects of CO exposure, allowing them to maintain activity even in environments with higher CO levels and subsequent oxygen exposure.
Implementation Method 1
activation procedures can include a reducing step for converting metal oxides present in the catalyst precursor to a lower oxidative state (e.g., an elemental state with a zero valency) using a hydrogen-containing atmosphere
Implementation Method 2
the presence of certain gas, such as carbon monoxide (CO), in the hydrogen atmosphere at a high concentration such as 10 vppm or higher, can drastically affect the activity and/or life of the activated catalyst
Data Source
AI summary
Methods are provided for activation of catalysts comprising low amounts of a hydrogenation metal, such as low amounts of a Group 8-10 noble metal. The amount of hydrogenation metal on the catalyst can correspond to 0.5 wt % or less (with respect to the weight of the catalyst), or 0.1 wt % or less, or 0.05 wt % or less. Prior to loading a catalyst into a reactor, the corresponding catalyst precursor can be first activated in a hydrogen-containing atmosphere containing 1.0 vppm of CO or less. The thus first-activated catalyst can be transferred to a reactor with optional exposure to oxygen during the transfer, where it can be further activated using a hydrogen-containing atmosphere containing 3.0 vppm of CO or higher, to yield a twice-activated catalyst with high performance. The catalyst can be advantageously a transalkylation catalyst or an isomerization catalyst useful for converting aromatic hydrocarbons.