Ru Catalyst on Ce-Lanthanide Composite Oxide Carrier
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Solution Overview
Problem
Current ammonia synthesis catalysts, particularly those with ruthenium supported on ceria-based composite oxides, do not exhibit sufficient ammonia synthesis activity under milder conditions, necessitating the development of a catalyst with enhanced activity for efficient ammonia production.
Innovation Solution
A composite oxide carrier is created by solid-solutionizing additive metal elements like titanium, zirconium, or silicon into a cerium-based composite oxide with a lanthanide, and ruthenium is supported on this carrier, optimizing the molar fractions and composition to improve reducibility and electron donation for enhanced ammonia synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ruthenium is supported on ceria-based composite oxide carriers (such as La0.5Ce0.5O1.75 or CeO2—PrO2), then ammonia synthesis activity is improved compared to simple ceria, but the activity is still not sufficiently high
Solution Approach 1:
The patent employs a composite oxide carrier composed of cerium oxide and lanthanum oxide in a specific molar ratio (0.3≤x<0.5 where Ce_xLa_(1-x)O_(2-δ)), creating a synergistic material that combines the advantages of both oxides. This composite structure provides enhanced catalytic support properties compared to simple ceria or other rare earth oxide carriers, contributing to higher ammonia synthesis activity.
Solution Approach 2:
The patent systematically optimizes the molar fraction parameter x of cerium in the composite oxide carrier, establishing a specific range (0.3≤x<0.5) that maximizes ammonia synthesis activity. This parameter optimization approach allows fine-tuning of the carrier's electronic structure, oxygen mobility, and interaction with ruthenium particles to achieve peak catalytic performance.
2Productivity
If the Haber-Bosch method using iron catalyst is used, then industrial ammonia production is achieved, but synthesis requires harsh conditions (high temperature and pressure)
Solution Approach 1:
The patent utilizes ruthenium, a Group 8 metal, as the active catalytic component supported on the optimized ceria-lanthanum oxide carrier. Ruthenium inherently exhibits higher catalytic activity for ammonia synthesis than iron, enabling the reaction to proceed at lower temperatures and pressures while maintaining industrial production capability. The specific carrier composition further enhances this effect by improving ruthenium dispersion and electronic properties.
Solution Approach 2:
The combination of ruthenium metal particles with the ceria-lanthanum oxide composite carrier creates a bimetallic-like catalytic system where the support actively participates in the catalysis. The composite structure provides oxygen storage capacity, enhances electron transfer to ruthenium, and stabilizes active sites, all of which contribute to reduced operating conditions compared to traditional iron-based Haber-Bosch catalysts.
3Productivity
If ruthenium is supported on simple ceria (CeO2), then ammonia synthesis can be performed, but the activity is lower than when supported on composite oxides
Solution Approach 1:
The patent creates a composite oxide carrier combining cerium oxide and lanthanum oxide in a controlled molar ratio (Ce_xLa_(1-x)O_(2-δ) where 0.3≤x<0.5). This composite provides synergistic effects: cerium contributes oxygen storage capacity and redox properties, while lanthanum enhances structural stability and basicity. The resulting carrier offers superior ruthenium dispersion, electronic interaction, and catalytic performance compared to simple ceria, justifying the increased compositional complexity.
Solution Approach 2:
The patent establishes a specific molar fraction range for cerium (0.3≤x<0.5) in the composite oxide carrier to optimize the balance between oxygen mobility, structural stability, and electronic properties. This parameter control ensures that the carrier provides maximum benefit to ruthenium catalysis without excessive complexity, achieving optimal ammonia synthesis activity through precise compositional tuning.
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 resulting ammonia synthesis catalyst demonstrates improved ammonia synthesis activity, enabling efficient ammonia production under milder conditions with higher energy efficiency, suitable for hydrogen energy applications.
Implementation Method 1
a composite oxide carrier in which a predetermined amount of the additive metal element is solid-solutionized in a composite oxide containing Ce and a lanthanide other than Ce
Implementation Method 2
an ammonia synthesis catalyst in which ruthenium (Ru) is supported on the composite oxide carrier
Implementation Method 3
a method of synthesizing ammonia using the same... bringing a gas containing hydrogen and nitrogen into contact with the ammonia synthesis catalyst to synthesize ammonia
Data Source
AI summary
An ammonia synthesis catalyst, includes a composite oxide carrier in which at least one additive metal element selected from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), and tin (Sn) is solid-solutionized in a composite oxide containing cerium (Ce) and a lanthanide other than Ce and having a composition represented by the following formula:CexA1-x-yByOd (in the formula, A represents a lanthanide other than Ce, B represents the additive metal element, x represents a molar fraction of Ce, y represents a molar fraction of the additive metal element, 1−x−y represents a molar fraction of a lanthanide other than Ce, x and y satisfy 0.1≤x≤0.9, 0.01≤y≤0.3, and 0.11≤x+y≤0.91, d represents a molar ratio of oxygen atoms, and 1.5≤d≤2 is satisfied);and ruthenium (Ru) supported on the composite oxide carrier.