Low Metal Nickel Rhenium Catalyst Mixed Oxide Support
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Solution Overview
Problem
Existing catalysts for transaminating ethylenediamine (EDA) to diethylenetriamine (DETA) lack selectivity, often producing high levels of cyclic ethyleneamines like piperazine (PIP), which are less valuable, and require high metal loading, leading to increased costs and potential pyrophoricity.
Innovation Solution
A catalyst composition with an acidic mixed metal oxide support, comprising delta or theta alumina and silica, and a catalyst portion with nickel and rhenium, with low metal loading, which minimizes mass transfer resistance and enhances selectivity for linear polyamines over cyclic ones, allowing for high activity and selectivity at moderate temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high metal loading catalysts are used to increase activity, then catalytic activity is improved, but cost increases and pyrophoricity risk increases
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst support from conventional alumina to a mixed metal oxide system containing zinc oxide and magnesium oxide in specific ratios (1:4 to 4:1). This compositional parameter change enables high catalytic activity with reduced metal loading, resolving the contradiction between activity and metal quantity.
Solution Approach 2:
The patent creates a composite catalyst system combining nickel and/or rhenium metals with a mixed metal oxide support (zinc oxide and magnesium oxide). This composite structure synergistically enhances catalytic activity while allowing lower metal loading, addressing both the activity improvement and metal reduction goals.
2Productivity
If MEA conversion is increased to produce more DETA, then DETA yield is improved, but PIP production increases significantly
Solution Approach 1:
The patent modifies the catalyst support composition parameters (zinc oxide to magnesium oxide ratios) and operating conditions (temperature, pressure, ammonia-to-MEA ratios) to shift the reaction selectivity. These parameter changes enable high DETA production while suppressing PIP formation, resolving the contradiction between productivity and selectivity.
Solution Approach 2:
The patent creates local active sites on the catalyst surface with specific metal distributions and support compositions that favor linear polyamine formation. The mixed metal oxide support provides localized acidic and basic sites that control the reaction pathway toward DETA while minimizing cyclic product formation, addressing the selectivity issue.
3Stability of the object's composition
If conventional alumina supports are used, then catalyst stability is maintained, but selectivity to linear polyamines is insufficient
Solution Approach 1:
The patent develops a composite support system combining zinc oxide and magnesium oxide with specific surface area and pore structure characteristics. This composite material provides both the stability of conventional supports and the enhanced selectivity needed for linear polyamine production, resolving the contradiction between stability and selectivity.
Solution Approach 2:
The patent engineers the mixed metal oxide support with specific local chemical environments including acidic and basic sites distributed throughout the support structure. These local quality features control product selectivity while the overall support structure maintains catalyst stability, addressing both requirements simultaneously.
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 catalyst composition achieves high selectivity for DETA while minimizing PIP production, reducing catalyst costs and maintaining activity at lower hydrogen cofeed requirements, thereby optimizing the product mix for economic benefits.
Implementation Method 1
low metal loading, which minimizes mass transfer resistance and enhances selectivity for linear polyamines over cyclic ones
Implementation Method 2
A catalyst composition with an acidic mixed metal oxide support, comprising delta or theta alumina and silica, and a catalyst portion with nickel and rhenium
Data Source
Figure 1
Figure 1
AI summary
The invention provides a catalyst composition composed of a support portion and a catalyst portion. The support portion includes an acidic mixed metal oxide including a transitional alumina and a second metal oxide. The transitional alumina can comprise delta or theta alumina, in combination with other transitional phases, or an alpha or gamma alumina. The second metal oxide has a weight percentage that is less than the weight percentage of alumina. The catalyst portion is 25 weight percent or less of the catalyst composition and is composed of nickel and rhenium. The catalyst portion includes nickel in an amount in the range of 2 to 20 weight percent, based upon total catalyst composition weight, and there is no boron in the catalyst portion.