Stabilized Alumina Catalyst Supports for High-Temperature Partial Oxidation
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Solution Overview
Problem
Catalyst supports used in high-temperature reactions, such as partial oxidation of light hydrocarbons, face challenges with stability and surface area retention due to sintering and phase transformations, particularly with gamma-alumina collapsing at high temperatures, leading to reduced efficiency and catalyst deactivation.
Innovation Solution
A thermally stable aluminum-based support is developed, comprising a transition alumina phase like theta-alumina and a rare earth aluminate with a high aluminum-to-rare earth metal molar ratio, which is stabilized with lanthanum or other rare earth metals, maintaining a high surface area and preventing phase transformation to alpha-alumina at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If gamma-alumina is used as catalyst support to achieve high surface area, then the surface area is improved, but the thermal stability deteriorates at high temperatures leading to phase transformation and sintering
Solution Approach 1:
The patent creates a composite material by combining gamma-alumina with theta-alumina and rare earth metal oxides (such as lanthanum, cerium, or praseodymium oxides). This composite structure allows the catalyst support to maintain the high surface area characteristics of gamma-alumina while incorporating the thermal stability of theta-alumina and rare earth oxides, preventing phase transformation and sintering at high temperatures above 800°C.
Solution Approach 2:
The patent modifies the chemical composition parameters of the alumina support by incorporating specific ratios of rare earth metal oxides (typically 1-20 wt%) and controlling the phase composition to contain gamma-alumina, theta-alumina, and rare earth aluminate phases. This parameter optimization enables the support to resist phase transformation from gamma to alpha alumina while maintaining high surface area, achieving both high surface area and thermal stability simultaneously.
2Productivity
If the catalyst support is heated to high temperatures to achieve complete dehydration and activation, then the catalytic activity is improved, but the surface area decreases substantially due to structural collapse
Solution Approach 1:
The patent performs preliminary stabilization of the alumina structure by incorporating theta-alumina and rare earth metal oxides before the catalyst is subjected to high-temperature operation. This preliminary structural reinforcement prevents the collapse that would normally occur during high-temperature activation, allowing the catalyst to achieve full catalytic activity while retaining high surface area.
Solution Approach 2:
The patent creates local structural differences within the catalyst support by incorporating rare earth metal oxides at specific locations and concentrations. These localized modifications create regions of enhanced thermal stability that prevent overall structural collapse during high-temperature operation, allowing the bulk of the support to maintain its high surface area structure while providing the necessary thermal resistance.
3Stability of the object's composition
If alpha-alumina is used as catalyst support to achieve high thermal stability, then the stability is improved, but the surface area is reduced due to dense crystal lattice
Solution Approach 1:
The patent creates a multi-functional catalyst support that simultaneously provides the high surface area needed for catalytic activity and the thermal stability required for high-temperature operation. By combining gamma-alumina (high surface area), theta-alumina (intermediate stability), and rare earth metal oxides (thermal stability), the support performs multiple functions that would normally require separate materials, achieving both high surface area and thermal stability in a single composite structure.
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 solution provides a catalyst support that maintains high surface area and stability at temperatures above 800°C, enhancing catalyst longevity and productivity in syngas production by preventing sintering and phase transformation, thus improving the efficiency and selectivity of partial oxidation reactions.
Implementation Method 1
maintaining a high surface area and preventing phase transformation to alpha-alumina at elevated temperatures
Implementation Method 2
A thermally stable aluminum-based support is developed, comprising a transition alumina phase like theta-alumina and a rare earth aluminate
Implementation Method 3
maintains high surface area and stability at temperatures above 800°C, enhancing catalyst longevity and productivity in syngas production by preventing sintering and phase transformation
Implementation Method 4
catalysts made therefrom, and their use in partial oxidation... catalytic conversion of light hydrocarbons (e.g., natural gas) to produce synthesis gas... improving the efficiency and selectivity of partial oxidation reactions
Data Source
AI summary
The present invention relates to stabilized supports stable at temperatures above 800° C., and method of preparing such supports, which includes adding a rare earth metal to an aluminum-containing precursor prior to calcining. The present invention can be more specifically seen as a support, process and catalyst wherein the stabilized alumina catalyst support comprises a rare earth aluminate with a molar ratio of aluminum to rare earth metal greater than 5:1 and, optionally, an aluminum oxide. More particularly, the invention relates to the use of catalysts comprising rhodium, ruthenium, iridium, or combinations thereof, loaded onto said stabilized supports for the synthesis gas production via partial oxidation of light hydrocarbons, and further relates to gas-to-liquids conversion processes.